West, Ian M. 2020. Barton and Highcliffe - Coast Erosion and Sea Defences: Geology of the Wessex Coast of southern England. Internet site: http://www.southampton.ac.uk/~imw/barteros.htm. Version: 15th July 2020.
Barton and Highcliffe - Coast Erosion, Geology of the Wessex Coast by Dr Ian West

See also the closely-related webpage: this runs in parallel: Barton and Highcliffe - General Geology - Eocene and Pleistocene strata

Ian West,
Romsey, Hampshire

Faculty of Natural and Environmental Science,
University of Southampton
Website hosted by iSolutions, Southampton University

Aerial photographs courtesy of the The Channel Coastal Observatory
Website archived at the British Library

Click here for the full LIST OF WEBPAGES

Home and Contents - Geology of the Wessex Coast |Field Guides Introduction |Hordle Cliff |Barton and Highcliffe - General |History of Coast Erosion at Barton-on-Sea, Highcliffe and Christchurch Bay |Highcliffe, Barton and Hordle - Bibliography |Hengistbury Head |New Forest Geology |Lepe Beach |Hurst Spit |Solent Estuaries - Introduction

Rapid erosion of the Barton Sand or Becton Sand Formation taking place in the cliff at the mouth of Becton Bunny, east of Barton-on-Sea, Hampshire, as seen on the 10th July 2020, Ian West

An unstable and temporary erosional feature in the Barton Sand or Becton Sand Formation in the cliff at the mouth of Becton Bunny, east of Barton-on-Sea, Hampshire, as seen on the 10th July 2020, Ian West

An view southeast of part of Barton-on-Sea, Hampshire, and towards Hurst Spit, with notes on the coastal erosion situation as in late 2019, Ian West

A broad view from the west of the slow landslide area between the old Sea Road Access and Hoskin's Gap, Barton-on-Sea, Hampshire, as seen on the 21 January 2016

An introduction: if you walk a very short distance westward from the cliff-top, car park at Barton-on-Sea, you get an idea of the state of the cliffs, whether stable and unchanging or with some limited coastal retreat at that particular place, on that particular date (note that the photograph above is an old one from 2016). The cliff situation may be different from year to year (all photographs here are dated).

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[Introduction - Including Terminal Groyne Syndrome (near Becton Bunny)]

A general, but compressed, view of the cliffs looking eastward from the central, Barton Court area of Barton-on-Sea, Hampshire, 2018, Ian West

Terminal Groyne Syndrome at the coastal cliffs, Becton Bunny, Christchurch Bay, English Channel, southeast of Barton-on-Sea, Hampshire, England, 2017

Approaching Becton Bunny, looking southeast, and seeing the continuing erosion of the cliffs in this area, just southeast of the end of the Barton sea defences, Hampshire, England, 10th September, 2019

Seen from down near the shore, the Terminal Groyne Syndrome at the coastal cliffs, Becton Bunny, Christchurch Bay, English Channel, southeast of Barton-on-Sea, Hampshire, England, 2018

Warning of hazards from the increased erosion, of Terminal Groyne Syndrome type at the coastal cliffs, near Becton Bunny, Christchurch Bay, English Channel, southeast of Barton-on-Sea, Hampshire, England, 2018

Down at the beach, on the footpath over the rock armour, looking at the cliff recess or the Terminal Groyne Syndrome near Becton Bunny, east of Barton-on-Sea, 2018


Introduction: This is a progressively enlarging record of recent erosion, landsliding and mudsliding at the classic, coastal locality of Barton-on-Sea. On the stretch of the Barton and Highcliffe coast, over centuries, part of a castle, a coastguard station, a cafe and part of a court building have either gone over the cliffs, or been demolished before they fell. Particular places in Christchurch Bay, such as some of the Mudeford area and the well-known Hurst Castle have survived for a very long time. There are special reasons for survival of an old coastline at the ends of bay, with more erosion in the middle.

Barton-on-Sea, in particular, is a well-known place to study coast erosion and sea-defence work, some successful, some partly successful, and some failed. More erosion at the present (2016-2017) is occurring further east, down drift, in the Barton Golf Course and Hordle Cliff area, as a result of the Barton Sea Defences (the so-called "Terminal Groyne Syndrome") which commonly occurs at the end of sea defences holding back natural shingle. Hurst Spit contains material, including fossils, from the Barton Cliffs, which fed it, but it is not now supplied because of human interference at Barton. Thus the ancient spit tends to break, in part, periodically. It has in the pase been necessary in a sense to choose either major sea defences at Barton or a continuation of the natural processes of erosion and thus a natural feeder supply to the spit. The major sea defences were chosen.

Another factor that could affect Barton and elsewhere on the south coast is the return of a great, exceptional storm. The disastrous 1 in about 250 year storm was last here in 1824. Earlier there was a tsunami in 1755 due to the Lisbon Earthquake but we do not know whether it was serious at Barton-on-Sea or minor (it affected ships at Portsmouth, a more protected locality). Of course we do not know what happened before. Now there is the factor of sea-level is rising in relation to global warming, although this is slow.

On other matters, note that the the offshore sea area directly to the south of the Barton cliffs, 98/7b and 98/12 (part) is licenced to the Australian, oil company NWE Mirrabooka. It probably contain thermally mature, Jurassic oil shales (source of Wytch Farm oil). The present low oil price may reduce chances of offshore exploration very near to Barton-on-Sea in the near future.

[This was written in the past. Note in October 2018. The oil price is now high again, and "fracking" has restarted in the north of England.]



(Note: You can download this educational site to SurfOffline, WebCopier or similar software to keep a safe permanent offline copy, but note that at present there is periodic updating of the live version.)


See also associated webpages:
Barton-on-Sea and Highcliffe - Geological Field Guide

History of Coast Erosion and Sea Defences at Barton-on-Sea and Highcliffe

Highcliffe, Barton and Hordle - Bibliography .

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CONTENTS [in preparation - restructuring in progress!]




4. - [blank - ready]


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[Additional Safety Warning: Avoid risk at Barton. Do not go onto mudslides, like those shown below, or any soft muddy ground on the Barton-on-Sea cliffs. Unless you are expert on these cliffs there is serious risk of being firmly stuck in wet, soft mud. There are special risks of cliff fall at the Terminal Groyne Syndrome area, at eastern end of the Barton sea defences, near Bection Bunny; see relevant photograph, above.]

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Old, 2009, aerial photographs showing the location of the Sea Road Access to Hoskin's Gap, 2013 Landslide complex, west of Barton Court, Barton-on-Sea, Hampshire

The mudslide situation near central Barton-on-Sea as in 2017, aerial photograph of GE, with recent slide locations emphasised

A map showing the coastal retreat at Barton-on-Sea, Hampshire, from 1870 to 1970, modified after Hooke and Riley, 1991


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The following sections will be re-organised in more systematic form. Work is in progress.




---- General Views in the Barton Court and Hoskin's Gap Area

A view looking west of the unstable, but only slowly moving landslide between the old Sea Road Access and Hoskin's Gap, Barton-on-Sea, Hampshire, 21 January 2016

A broad view from the west of the very slow landslide area between the old Sea Road Access and Hoskin's Gap, Barton-on-Sea, Hampshire, 21 January 2016

The car park at Hoskin's Gap, Barton-on-Sea, Hampshire, showing previous cliff fall, but relative stability on 21st January 2016, and with the parking area limit moved back

A view from the mid-cliff area showing the relics of major mudslide activity on the cliffs between Sea Road Access and Hoskin's Gap, Barton-on-Sea, as seen on 21st January 2016

Debris from old sea defence works together with slumped clay and gravel being eroded at the foot of the cliffs between Sea Road Access and Hoskin's Gap, Barton-on-Sea, as seen on 2nd February 2016


---- Notice Board at Barton, explaining the Managed Realignment Policy etc.


An old notice board at Barton-on-Sea, recording the current policy of Managed Realignment


An old notice board at Barton-on-Sea, explaining the borehole investigation programme that was planned for the autumn and winter of 2012, and has now taken place

This Managed Realignment scheme seems moderate and unlikely to cause many objections. It involves some drainage schemes and allows retreat of the cliff. It is not extreme.


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---- New Mudslide-Movement Phase at the Old Sea Road Access - 2016 (still active)

Fencing at the greensward area above the old Sea Road Access landslide, and some suggestions of future, minor enlargement, 2nd February 2016

The graben in the landslide at the old Sea Road Access continues to open a little even after after some drainage piping has been emplaced, 21st January 2016

The landslide at the old Sea Road Access, Barton-on-Sea, 2nd March 2016, showing slow, continuing movement

The Back Graben
As is obvious from the photographs shown here, the main slip plane is curved descending from the back cliffs to near sea-level. There is both near-vertical movement (at the back cliff) but in the central and seaward parts the movement is southward and near-horizontal. Of course this situation results in tension at the back, landward side. In this region a graben is an expected feature. Examples are seen in the Lyme-Regis - Axmouth Landslide, the Ventnor Landslide. The little graben seen at the old Sea Road Access site is a small-scale example, but it will deepen to some extent. Such a graben can collect water and facilitate the lubrication of the main low-angle slip plane.

The Landslides and Sea Defences in this Region of Coast
Incidently, this Sea Road Access Landslide will expand to some extent at the landward end and some more of the greensward will fall away. It seems unlikely to have any effect on the Cliff House Hotel nor Marine Drive. In years to come, however, there will be many more landslides like this and they will eventually become not just an interesting curiousity, but eventually a nuisance to residents. As on the Isle of Wight, they gradually cut off access to the coast, although in intermediate stages, ladders can be used (c.f. Whale Chine, Isle of Wight). Civil Engineering work at Barton-on-Sea has had some success in the eastern part. In the western part old coastal defence works have failed between the Cliff House Hotel area and up to the Barton Court area. They have been repaired or covered over for the present at Barton Court and the repairs have lasted for some years. Long-term survival would require good luck.

Further collapse of the back cliff of Pleistocene gravel and Brickearth at the old Sea Road Access, 9th February 2016


There has been movement here for some years. Details of early movement, with old photographs from here, are shown further down in this web page. The mudslide has after years accelerated up to medium speed, and it is quite fast in the lower part and dropping debris in the sea. At the top it is still slow, but accelerating a little. It is probable, but not certain, that landward it has reached about its back limit. No major movement has been observed at the gravel cliff top of the west side and this western top area, in the vicinity of the Cliff House Hotel, does not seem active, at least at present. The gravel top of the eastern side has cut back, but might be near-static now (I am not sure). In general over the last few years the collapse has deepened greatly where it has cut the old Sea Road access, but has not retreated landward very much. By early 2016 the landslide had become more sharply defined and adopted the classic shape and profile of a Barton mudslide. Its importance is not, at least at the moment, any threat to buildings, but it has destroyed a Barton-on-Sea coastal access location. The original Barton-on-Sea coastguard station was here, but it was destroyed by landslide, and a new one built much further inland. In addition the soft mudslide at the base may generally prevent walking along the beach from Highcliffe to Barton-on-Sea, but after some washing away be the sea and some drying out, it might become passable again. This type of process has all happened before and is normal for Barton-on-Sea. It does not usually affect buildings unless they are unfortunately close to the cliff edge. By far the majority of buildings are, fortunately, far back, on the landward side of Marine Drive. Obviously, it is impossible to make any real predictions because coastal processes are very irregular, and there is no knowledge of long timescale events. Just what did the November 1824 "Great Gale" do? Sir Charles Lyell recorded that the Hurst Spit was driven back about 40 yards (approx. 40 metres) during this great event. Until recent rebuilding there were numerous fossil shells from the Barton Cliffs present on Hurst Spit (I have a small collection). Major erosion of the Barton Clay at Barton would have supplied these numerous shells and the "Great Gale" would have greatly increased supply. Of course the return of the "Great Gale" is expected, sooner or later. This approximately one in 250 year event is not normally taken into account with regard to coastal planning and sea defences, for obvious reasons, including the huge cost involved in making defences strong enough.

A sketch diagram of mudslide locations and hypothetical depths at central Barton-on-Sea cliffs, as at 1st February 2016


See: History of Coast Erosion and Sea Defences at Barton-on-Sea and Highcliffe An example map from this is shown below. Note how the sea road has been cut through at Sea Road Access. Marine Drive and the houses on the cliff are very new features.

Redrawn map of part of the Barton-on-Sea coast, based on a map from about 1850


A view of the new, well-defined mudslide at the Old Sea Road Access, with plastic drainage piping, like that once used at the adjacent Cliff House Landslide, Barton-on-Sea, Hampshire, 21st January 2016

Looking down the Sea Road Access Landslide, into sunlight, at Barton-on-Sea, Hampshire, 28th January 2016

The sea attacks the soft muddy base of the Old Sea Road Mudslide at Barton-on-Sea, Hampshire, with remains of the drainage system in the sea, 28th January 2016

The back Pleistocene Gravel and Brickearth scarp, NE side, at the upper part of the Old Sea Road Access mudslide, Barton-on-Sea, Hampshire, 21st January 2016

Details of tension cracks and other features of the upper part of the Old Sea Road Access mudslide, Barton-on-Sea, Hampshire, 21st January 2016

It is surprising that plastic pipes have been inserted into the Pleistocene gravel at a high level and above permeable Barton Sand, not at the level at which water would be expected to  accumulate, location - the Sea Road Access Landslide, Barton-on-Sea, Hampshire, 28th January 2016

Another view of the new, well-defined mudslide at the Old Sea Road Access, with plastic drainage piping, seen a week later than a previous photograph, note minor cliff fall, Barton-on-Sea, Hampshire, 28th January 2016

A mudslide at the old Sea Road Access has restarted, with tension gashes, after a pause, 21st January 2016


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[4 - Intro - West of Hoskins Gap, Subsection]


A broad view from the west of increased landslide activity between the old Sea Road Access and Hoskin's Gap, Barton-on-Sea, Hampshire, March 2013

Back-spalling at the landslide near Hoskin's Gap,Barton-on-Sea, Hampshire, on the 11th April 2013

A new phase of retreat of the cliff top at the greensward, west of Hoskins Gap, Barton-on-Sea, Hampshire, 4th March 2013

A view from mid-cliff area of the long backscarp of the Sea Road Access to Hoskin's Gap landslide, Barton-on-Sea, Hampshire, 4th October 2013

The March 2013 cliff collapse west of Hoskin's Gap, Barton-on-Sea, Hampshire, seen from the mid-cliff level

The western limit of the 2013 Landslide between the old Sea Road Access and Hoskin's Gap, Barton-on-Sea, Hampshire, 4th March, 2013

The western limit at the cliff top of the Sea Road Access to Hoskin's Gap, 2013 Landslide, Barton-on-Sea, Hampshire

Small-scale downfaulting on fissures in the gravel road, mid-cliff level, near Hoskin's Gap, Barton-on-Sea, Hampshire, 4th March, 2013

The eastern lateral margin, low in the cliff near Hoskin's Gap, the 2013 Sea Road Access to Hoskin's Gap Landslide, Barton-on-Sea, Hampshire, photographed 4th March 2013

A former landslide area, to the west of Hoskin's Gap at Barton-on-Sea, seen in dry, non-active conditions, 3rd September 2018


[4 - Intro - Barton Court Cliffs, Subsection]

. A general view of the cliff-top, with Pleistocene gravel in the central part of the Barton cliffs, Barton Court area, as seen in 2018

The old, Pleistocene, gravel, cliff-top in the central part of the Barton cliffs, Barton Court area, as seen in more detail, 2018

Two pigeons perch on an ornamental cliff-edge lookout near the western end of the Barton Court area, as seen in 2018

A notice about investigations into instability at Barton-on-Sea, Hampshire, 2013

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Erosion in the central Barton-on-Sea cliff area, shown by comparison of part of a 1936 map and part of a 2008 aerial photograph


Looking eastward along the collapsing cliffs of Barton-on-Sea, Hampshire in 1961, a time when they were still very good for fossil collecting, photo modified by imw after an original by Alan Morton


The dramatic collapse of the Stage 2 Coastal Protection Works at Barton Court, Barton-on-Sea, Hampshire, in 1975


[Beach Huts, east of Barton Court]

Beach huts immediately to the east of the Barton Court area and east of the 1975 collapse area, and with some old, steel sea-defences buried under dumped gravel, Barton-on-Sea, Hampshire, 2018

A row of beach huts east of the Barton Court area on an apparently stable, modified cliff area that has been successfully drained since about 1975 and is seen here in September 2018


[Beach Huts - historic]

Beach huts start to slide down the cliff in the 1975 Barton Court Landslide, Barton-on-Sea, Hampshire


[Barton Court Area]

An old oblique aerial photograph of the Barton Court area, Barton-on-Sea, Hampshire, after the 1975 Barton Court Landslide and some remedial work

Aerial photograph of the central coastal section of Barton-on-Sea, Hampshire, showing landslide locations, photo courtesy of the Channel Coastal Observatory

A large scale map of the Barton Court area at Barton-on-Sea, Hampshire, in 1936, for comparison with modern aerial photographs

Aerial photograph of the Marine Drive West part of Barton-on-Sea, Hampshire, coast, 2004, courtesy of the Channel Coastal Observatory

The greensward at the cliff top, Marine Drive, Barton-on-Sea, Hampshire, in 2004

A laid-back attitude to coast erosion at Barton-on-Sea, Hampshire, England, 2007


[Hosking's Gap Westward]

Start of cliff-top landslide at Barton-on-Sea, Hampshire, as seen on the 18th May 2008

A cliff-top landslide at Hoskin's Gap West, Barton-on-Sea, Hampshire, as seen on 29th May 2008

The Hoskin's Gap West Landslide at Barton-on-Sea, Hampshire, on the 6th June 2008

The Hoskin's West Landslide at Barton-on-Sea, Hampshire, on the 21st June 2008

The Hoskin's West Landslide at Barton-on-Sea, Hampshire, on the 16th July 2008

The Hoskin's West Landslide at Barton-on-Sea, Hampshire, on the 26th January 2009

The Hoskin's West Landslide at Barton-on-Sea, Hampshire, with a paraglider, 6th March 2009

Progressive failure of cliffs and sea defences west of the shops at Barton-on-Sea, Hampshire, from 2004 to 2007

Sheet iron from old sea defences turning and sliding seaward at the Hoskin's Gap West Landslide, between Hoskin's Gap and the Sea Road access, Barton-on-Sea, Hampshire, as seen in April 2007

Remedial work on an active landslide, Hoskin's West Landslide, Barton-on-Sea, Hampshire, 5th February 2009

Storm wave, Christchurch Bay

Erosion of Barton Sand, near Becton Bunny, east of Barton, January 2002

Storm waves eroding Barton Clay at Naish Farm near Highcliffe, with surfers undeterred by the wave conditions

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Related Field Guides and Bibliography

Barton and Highcliffe - General (introduction to the geology of Barton and Highcliffe)
Barton, Highcliffe and Christchurch Bay - History of Coast Erosion
Barton and Highcliffe - Geological Bibliography (extensive, with many abstracts and additional notes)
Hordle Cliff (continuation eastward. Headon Hill Formation etc.)
Hurst Spit (barrier beach at the southeastern end of Christchurch Bay)
Hengistbury Head (Eocene and Pleistocene exposures; ironstone)
Bournemouth Cliffs (Eocene and Pleistocene exposures; leaf beds etc.)

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Barton-on-Sea, Hampshire

See Barton-on-Sea location on zoomable Bing aerial photographs and maps. See also Google Earth.

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Safety and Risk Assessment

For information on safety at the cliffs of Barton and Highcliffe please go to the safety section in the introductory webpage to the Barton and Highcliffe coast. In addition beware of any danger associated with sea-defence works such as loose, moving rock, projecting metal work, machinery etc. and do not climb on unsafe structures. Individual geological visitors and field leaders should make their own risk assessments and no liability is accepted.

Type of Webpage:

This webpage on coast erosion at Barton and Highcliffe is intended primarily for geological and geomorphological education and general introductory information. It is not a specialist engineering geology assessment of the cliffs, suitable for professional or legal use. Risk to properties on the cliff top is not discussed in detail here. Of course, it is well-known that losses of buildings have taken place in the area, from the days of the original Highcliffe Castle and before that. The history and the problem of future losses has made the coast of Barton-on-Sea and Highcliffe a notable place for environmental and geographic studies. An overview of the problem from a planning and coastal management perspective is given in Few, Brown and Tompkins (2004). For specific local information see particularly the key publications of New Forest District Council on coastal management and plans. Every effort is made to give correct factual data and references but no technical advice or criticism is intended to be given here and no liability is accepted. If attention is drawn by email to any errors then they will be corrected.

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Coast Erosion at Barton and Highcliffe - Section 1: Introduction

"... Christchurch Bay in southern England, where communities face long term threats of increased coastal erosion and flooding" ( Few, Brown and Tompkins (2004).)

General setting and environment  of the Barton and Highcliffe Coast, southern Wessex

Location sketch map of the Barton and Highcliffe Coast, Hampshire

Locations at Barton-on-Sea, Hampshire - Hoskin's Gap, 2007

Locations in the  Barton-on-Sea area, Hampshire, - the Chewton Bunny, Highcliffe Car Park

Barton, Highcliffe and Hordle cliff section

General process of cliff retreat at Barton-on-Sea, Hampshire, simplified diagram

Warning of landslide at Barton-on-Sea

The cliffs of Barton and Highcliffe are most famous, geologically for their remarkable fossil content and provide a classic section of Eocene strata. They are of shelly sea-floor sediments returning progressively to the sea. The fossils can be found because the sea attacks the cliffs and regains its former territory at a maximum rate of about 1 metre per annum. Eventually the whole New Forest, inland of Barton, with its shell beds, coral beds and shark and turtle remains will return to the water, but it will take thousands of years and we will not see this. Barton and Highcliffe are at the cutting-edge; here the geological processes are relatively fast in relation to the limited area and can be studied in progress.

Thus, like the London Clay cliffs of the Isle of Sheppey, the coast of Barton and Highcliffe is very well-known as a site of rapid coast-erosion and a location where there have been major civil engineering activities to try to stop or retard this action. The circumstances are particularly interesting because there is a relatively soft Eocene clay (the Barton Clay) with a water-bearing Eocene sand (the Barton Sand or Becton Sand) above in parts of the cliffs. In addition most this stretch of coast has cliffs capped by porous and permeable Pleistocene gravel. Water directly from precipitation and runoff drains into this. Thus the cliffs have a structure that is particularly appropriate for landslides. In addition this coast of soft Tertiary sediments is on part of the English Channel coast subject to quite major waves with a long fetch.

Pressures for coastal defence schemes probably result from the fact that Barton and Highcliffe are popular residential areas and there has been much development of housing on the coast here. It is a nice, healthy, middle-class place to live, a part of Britain notable for a very mild climate, a good environment, low crime-rate and the longevity of the inhabitants (Highcliffe is within the area of Christchurch which, compared with some places in Britain, would seem to be able to provide about a decade of extra life!). It is between the beautiful New Forest and the sea, yet with easy access to Bournemouth and Southampton and little more than an hour from London by train. Not surprisingly, there are many retired people here who enjoy the sea-views and who are often to be seen walking their dogs on the cliff tops and undercliff. No doubt the pleasant environment will have have increased the value of housing here. Fortunately, most of the houses are set back from the cliff and there is a greensward separating them from the edge. The cliff-top road at Barton, the Marine Drive, is separated from the cliffs by a greensward, an stretch of grass that has not generally been built on. This green is of great value in allowing some potentially sacrificial land between most of the houses and the cliff edge. On the north, the landward, side of the Marine Drive, there are large house and some flats. The sea-view is undoubtedly an important asset here. Fortunately, the Marine Drive is well-separated from the cliff and seems to be sufficiently far landward not to be under any threat at the present time from coast erosion problems. It will probably take many decades for the sea to destroy the greensward, but the rate is very difficult to estimate. Further inland there is an extensive estate of bungalows and other fairly modern buildings. These are generally out-of-reach of coastal problems with regard to the near-future.

The central cliff-top area of Barton-on-Sea Greensward west of Barton Court area

The eastern end of the greensward at Marine Drive East, Barton-on-Sea, Hampshire, as at 2 May 2007

Cliff top at the car-park near the golf course, Barton-on-Sea

Unfortunately, though, in addition to the newer buildings that are generally little affected by coastal erosion, there are a small number of older houses in the Barton Court area, that are now situated quite close to the cliff. The Local Authority persective on these has been given in print. Wright (1998) has stated "Buildings in the Barton Court area will probably be lost in the next 10-20 years; a number of them are already within 20m of the cliff edge, some as close as 3m" . An area at risk from erosion has been identified in the District Local Plan and is defined by the line to which the cliff could recede in the next 60 years. Apparently there has been some recent revision to this plan.

The present website deals with cliff processes and not with individual houses at risk. Thus, anyone concerned about the safety and future of houses should consult the New Forest District Local Plan and the paper of Wright (1998) (part of Bray and Hooke (1998) )and other contributions in Hooke (1998) . See also the New Forest Coastal Management Plan (1997) and the Christchurch Bay Shoreline Management Plan. These can be consulted at the New Forest District Council Offices at Appletree Court, Lyndhurst, Hampshire. The New Forest District Council Website should be seen and this contains maps which can be downloaded.

Of the houses in the Barton Court area the newspaper cutting indicate that at least one property has been demolished. The protection of the more vulnerable houses here has been a major consideration with regard to the construction of sea-defences. However, because of the geological importance of the cliffs here the building of sea-defences has not been done without opposition, and there has been much debate. The newspaper cutting suggest that it was sometimes a little heated. Some of it is referred to in this webpage or in the Barton and Highcliffe Geological Bibliography , associated, but that is not claimed to be comprehensive. A search of backnumbers of local newspapers would reveal more.

The erosion, the landslides and the coastal defence schemes of this region have proved to be of much interest to students. Various student projects have been undertaken here, and individual students and parties often visit to see these aspects, in addition to the general geology and the fossil content. This website is intended primarily for the students of geology, engineering geology, civil engineering, geography and environmental science. It does not enter into great detail but it is introductory and intended to provide some general information on a variety of aspects of Christchurch Bay coast erosion and sea defences. It should also "set the scene" for more advanced studies. Researchers and advanced students, however, should consult the extensive literature and, ideally, receive advice from the engineering geology and local authority specialists.

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Ground Investigation and Monitoring in 2000 - Follow-up

In the year 2000, Fort et al. 2000 presented the results of ground investigation and monitoring at Barton-on-Sea. Their conclusions seem very sound and they predicted the present situation in the area from just east of Hoskins Gap to Cliff House Hotel. To summarise they stated that although coastal erosion has been largely arrested by the construction of coastal defences, the pore water pressures in the clay are recovering (i.e. increasing) "which unless remedial action is taken, will result in the progressive reduction of the factors of safety of deep-seated failure mechanisms possibly resulting in further failures in the future". Actually since 2000 through to 2013 (the present) failures have developed on a large scale in exactly this area, as shown in the photographs here. The area is under investigation, once again, though.

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The Shoreline Management Plans should be used with caution. Predictions for 100 years ahead seem rather strange and it rarely happens in other spheres of activity. Some aspects are probably broadly right because they are based on very obvious erosion. It makes people aware of coastal erosion and may increase civil engineering work and related employment. However, many aspects are bound to be wrong, particularly in terms of scale. The map scheme is very uniformitarianist and optimistic. It is based on an assumption of remarkable continuity of coastal processes. However the time length is far too great for it to be really meaningful. A disastrous 1 in 200 year event has, of course, a 50 percent chance of happening within a hundred years. Yet, by a hundred years ahead financial, political and scientific invention factors may change the erosional prospects enormously. There are bound to be unexpected coastal processes.

[Example: Hengistbury Head was eroding fast on the south side in the 1950s. So a calculation could be made as to how long the headland would last, and it was not long, at least in geological terms. However, it was not known then that large quantities of sand would be regularly dumped on Bournemouth beaches as the process of beach replenishment. Now longshore drift is to the east, although only from the beaches east of Bournemouth Pier. This replenishment sand is regularly transported by the longshore drift to Hengistbury Head. Thus the Head has not eroded back. It remains much the same as in the 1950s (when, as a boy, I lived near the Head). If a Shoreline Management Plan had been made in the 1950s it would been marked as gone by now.]

Having said that the Shoreline Management Plans are still useful because they are based on present data and therefore they show to some extent what is happening at present. I use them occasionally, for some purposes, but not really to find out anything about 100 years ahead. So they are a certainly a useful additional piece of information for informed geologists, civil engineers etc. They could help a member of the public trying to find out about erosion hotspots. However,they must be recognised for what they are: only crude predictions determined on present and past events, and with total ignorance of the future. Of course, this is obvious; but some members of the public may not understand.

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More Information

As noted above, the present website deals with cliff features and processes and is only introductory. Specialists or researchers needing more detailed information or anyone concerned about the safety and future of property should consult some or all of the following maps and publications of the New Forest District Council. These can be consulted at the New Forest District Council Offices at Appletree Court, Lyndhurst, Hampshire (southwest of Boltons Bench and the Beaulieu Road). The New Forest District Council Website should be seen and this contains maps which can be downloaded. Some plans can also be purchased from the New Forest District Council but they are not necessarily cheap.

New Forest District Local Plan

New Forest Coastal Management Plan (1997)

Christchurch Bay Shoreline Management Plan.

See also the paper of Wright (1998) (part of Bray and Hooke (1998) )and other contributions in Hooke (1998) .

Useful information on pore pressure conditions and on the relationship of landsliding to rainfall will be found in the paper of Fort et al. (2000): e.g. [p. 570] "Accelerating ground movements in October/November generally appear to commence when the average monthly rainfall for the average current and preceding months (antecedent 2 month average) is in excess of about 80mm/month... [continues].

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Poole and Christchurch Bays, Shoreline Management Plan - SMP - Key Publications

See these important documents on the plans for the coastal management or shoreline management of the area. Summarised contents of a version are given below and look for the section of interest. However, this SMP is not the final version, and there will be an update. If you do not find it directly from the links here, search by Google etc for the latest version, using the keywords - "Poole Christchurch SMP".

Poole and Christchurch Bays Coastal Management Group. 2010. (SMP - Shoreline Management Plan)
Poole and Christchurch Bays Coastal Management Plan (or SMP - Shoreline Management Plan). Draft SMP2. Draft version of the SMP, later to be replaced by final version (see this when it is available. SMP2 is due to be published in April 2010.). Available online as PDFs at Poole and Christchurch Bays Coastal Management Plan.

Contents: Draft SMP2
Section 1, Introduction
Section 2, Environmental Assessment
Section 3, Basis for Development of the Plan
Section 4, Appraisal of Options and Rationale for Preferred Plan:
Section 4.1, Introduction.
Section 4.2, Policy Development Zone 1 Central and Eastern Sections of Christchurch Bay (Hurst Spit to Friars Cliff).
Section 4.3, Policy Development Zone 2 Christchurch Harbour and Central Poole Bay (Friars Cliff to Flag Head Chine).
Section 4.4, Policy Development Zone 3 Poole Harbour and Associated Coastline (Flag Head Chine to Handfast Point, including Poole Harbour).
Section 4.5, Policy Development Zone 4 Swanage (Handfast Point to Durlston Head).
Section 5, Summary of Preferred Plan and Implications
Section 6, Policy Summary, including Policy Summary Map.
Appendices (all documents open in a new window)
Appendix A, SMP Development.
Appendix B, Stakeholder Engagement.
Appendix C, Baseline Process Understanding, including Coastal Process Report and Flood and Erosion Mapping. Accessible from a separate page including No Active Intervention (NAI) and With Present Management (WPM) assessments, and summaries of the data used in assessments.
Appendix D, Natural and Built Environment Baseline (Thematic Review).
Appendix E, Issues and Objective Evaluation.
Appendix F, Strategic Environmental Assessment.
Appendix G, Scenario Testing.
Appendix H, Economic Appraisal.
Appendix I, Estuary Assessment.
Appendix J, Habitat Regulation Assessment - Appropriate Assessment.
Appendix K, The Metadatabase, GIS and Bibliographic Database is provided to the operating authorities on CD. It will be included in the final SMP.
Appendix L, Water Framework Directive (WFD)
Appendix M, Review of Coastal Processes and Associated Risks at Hengistbury Head.

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The Highcliffe and Barton Coast from West to East

In terms of coastal geomorphological features and sea defences, the stretch of Christchurch Bay with outcrops of the Barton Clay and Barton Sands (Becton Sand) can be divided into five main parts. These have quite different features. The following will now be considered in turn from west to east:

View eastward from Friars Cliff, Highcliffe towards the Holm Oak covered cliffs of Lower Barton Clay and on to the landslipping cliffs of Middle Barton Clay at Naish Farm and beyond to Barton-on-Sea

Friars Cliff, Mudeford to Highcliffe Castle (broad sandy beach mostly without major sea defences. The best beach.).

Highcliffe Castle to Chewton Bunny
(sea defences and largely vegetated cliffs, attractive with Holm Oak near the castle. With buildings above that are very close to the cliffs).

Naish Farm Area
(no sea defences, retreating and collapsing cliff, good exposure of fossiliferous Barton Clay - conservation area and best for geology. A narrow sandy beach).

Central Barton with Sea-Defended Cliffs
This is from the Cliff House area (Marine Drive West) eastward to where the shops and Barton Court are located on the cliff top. It is a sensitive area of previous high erosion rate which was initially reduced by extensive coastal protection work in the 1960s. The sea defences have failed in places but the collapse have been covered over in front of the shops and seems stable at present. There has been failure near Cliff House and there is current failure to the west of the shops. These are barren gravelly cliffs with very little vegetation, rock armour at the base, and not much beach at high tide.

Cliffs below Marine Drive East
Here, east of Barton Court and along to the edge of the Golf Course, there is a steep back cliff of Barton Sand and Pleistocene gravel. The undercliff is still protected by sea defences and the drainage system is still operational. This was once a very collapsed area because the notorious Chama Bed (H) is low in the cliffs.

Becton Bunny Cliffs
Here, further east of the Marine Drive East cliffs and near the Golf Course there is increased erosion. This has resulted from "Terminal Groyne Syndrome" at the eastern (downdrift) end of the Barton sea defences. There are excellent exposures of the Barton Sand (Becton Sand). There is a sand and gravel beach.

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Friars Cliff, Mudeford to Highcliffe Castle.

View westward from Highcliffe West of Highcliffe Castle there is a well-developed beach of sand with some subangular flint pebbles. The photograph has been taken at the rock groyne seaward of Highcliffe Castle, looking eastward at dusk. This is the western most of the large groynes at the present time (December, 2001). With adequate sand this western part of Christchurch Bay has been relatively stable for some years and there is little need for sea defences here. The stability is shown by the fact that the undercliffs have a dense, mainly wooded, vegetation cover that was planted long ago and they have developed an aesthetically attractive, natural appearance. This stretch of coast has not always been so relatively free from erosion. The vertical cliff of Highcliffe Sands, presumably the original "high cliff", is the consequence of undercutting by the sea, although it reaches the cliffs now. This western stretch of coast is protected to some extent from erosion by southwesterly storm waves (the prevailing wind is southwesterly) by the projecting headland of Hengistbury Head. The origin of the large sandy beach is more complicated. At certain times in the past Mudeford Spit has extended from Hengistbury northward to the Run (the entrance to Christchurch Harbour) and then northeast and parallel with the coast in the direction of Highcliffe. The details of this will, in due course, be discussed separately, but in the meantime, please consult the papers of Burton (1931) and Tyhurst (1994). These consider the possible consequences of the removal of ironstone from Hengistbury Head in the 19th Century in allowing sand from Poole Bay (Bournemouth coast etc) to travel eastward round the headland and extend the spit. After breaches of the spit much of this sand has finished up on the shore at Avon Beach and Friars Cliff.


Footnote: Smugglers and the Riding Officer on this Beach
The beach shown in the photograph above was not always just a peaceful place for dog-walkers. Not being far across the Channel from France and being relatively sheltered and sandy it was once a favourite place for smuggling. In 1784 the Battle at Mudeford took place near the western end of the beach. This was between the Navy and smugglers and in spite of the skirmish, about 300 people were involved in getting the contraband away in fifty wagons. During the "battle" a naval sailing-master was killed, and as a later consequence a leading smuggler was hung and his body suspended in an iron cage on Haven Point.

Because of the continuation of so much smuggling activity in the bay, Mr Richard Newman, one of the Assistant Riding Officers of Customs set a trap in 1799 for the smugglers (Morley, 1994). He took several customs officers with him and ordered them to dig themselves slit trenches, or "graves" as the men dubbed them, into the beach, spread from Chewton Bunny to Mudeford. Each man was armed with a cutlass, pistol and musket. Newman camouflaged each of his long-suffering colleagues with a layer of sand and a mask and head-dress of seaweed. For many nights the Preventative Officers hid entombed on the beach. At last a lugger came over from France and into the bay at night and landed a cargo of brandy-kegs. The crew stacked them up on this beach unaware of the presence of the hidden officers and rowed back to their lugger and set sail. The objective of the Riding Officer was to let these sailers go but to catch the local, land-based smugglers, the landers, red-handed. In due course the landers arrived and started to deal with the kegs. Mr Newman rose out of his trench and blew a whistle. The landers fled and escaped, so only the goods were seized. He sent the consignment to the Poole Customs House on wagons with two grooms from the Inn. As they crossed the Great Heath that is now Bournemouth, they drank the brandy and fell asleep with slack reins. After a while the horses, as they instinctively do given an opportunity, turned back for the home stables. They returned to Christchurch with the brandy safe and the waggoners sound asleep. So the Riding Officers ambush did not go quite to plan, and a great chance was missed on this sandy beach in 1799. (For more information both on this and the smugglers' Battle of Mudeford see Morley, 1994)

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Highcliffe Castle to Chewton Bunny

Rock groyne sea-defences at Highcliffe, Hampshire, 2003

Rock groyne at Highcliffe

Rock groynes at Highcliffe and protection by Hengistbury Head

Rock groynes at Highcliffe

Within rock armour from the basal Purbeck of the Isle of Portland - a hollow mould of a narrow, tree trunk in a thrombolite mound, sea front adjacent to Chewton Bunny, Highcliffe, Hampshire, 24th February 2017

As the photographs above show, this stretch is protected by groynes constructed of blocks of Portland Stone with the renourishment of brown subangular flint gravel on the landward side. The cliffs are much controlled with drainage schemes and footpaths laid out. Above the cliffs at the western end of this stretch is Highcliffe Castle. It is an old stately home, destroyed in a fire but now basically repaired; it is not threatened by coast erosion because it has a small area of pleasant forested grounds between the house and the cliff. There is a small car park, cafe and access to the beach here. Much of the wider estate of the castle to the east has been used for modern housing, including large bungalows and some small blocks of flats. Most of this housing is well back from the cliff and not directly threatened by coast erosion. There are some buildings fairly close to the cliff edge. The combination of the presence of the sea-defences and less tendency for erosion than further east means that they seem relatively safe at present. The cliffs have not been subject to erosion here for a long time and are well vegetated with pine and other trees.

The rock groynes, a revetment and a large cover of renourishment gravel prevents marine erosion of the toe of the cliff in this stretch. It allows an accumulation of slipped debris to cover the base of the undercliffs thus reducing both the overall slope angle and the degree of exposure (Barton, 1998). The original revetment was constructed in 1967-1969 to stop toe erosion of the undercliff (Barton, 1973) . This toe erosion had followed depletion of the beach from 1960 onwards. According to Barton by 1972, although marine erosion had ceased, there has still been some degradational activity on the undercliff, resulting from the previous toe erosion. In general while the western part of this stretch is very vegetated, the eastern part still shows some signs of its original state of benches (terraces) and scarps like the collapsing cliffs at Naish Farm, on the eastern side of Chewton Bunny. The scarps are mostly degraded and vegetated but some small cliffs of weathered Barton Clay are visible.

Just west of the stream valley of Chewton there is a very large car park, and this is a good access point to the cliffs. This is the eastern end of the series of rock groynes or strongpoints (see photograph above) . There are rather barren grassy areas next to the big car park, although perhaps the lack of trees facilitates broad views of the sea. The originally attractive, wooded mouth of the glen, quite notable in the 1950s, is now a particularly bare area of grass slopes, with piles of rock, and the former beauty spot has not been restored with trees.

Although geologists would probably prefer to see the Lower Barton Clay in its natural state of erosion, in general, the sea defences in this stretch give the impression of functioning well. The authorities have taken some trouble to establish vegetation on the cliffs, especially further west. They have used the rock groynes to hold sand in small embayments between them. Their work has probably been assisted by natural sand accumulation in the western part of Christchurch Bay (probably largely derived from the destruction of the once extended Mudeford Spit), and the protection from southwesterly storm waves provided by Hengistbury Head (as shown in a photograph above). Not only do coast erosion problems at the present seem rather less here than at Barton, but another factor is that there is no junction between permeable Barton Sand and the impermeable Barton Clay in this stretch of cliffs. The permeable Plateau Gravel does lie above Barton Clay, but the gravel is thinner than the Barton Sand deposits. There are key publications on this area by Tyhurst .

Notice some advantages of rock groynes. They effectively retard coast erosion, although they may not necessarily stop it. Unlike some forms of sea-defences, they do not hinder public access to the sand beaches between them. They are more resistant than timber structures. They can have a relatively natural appearance, especially as they weather and mellow, and molluscs etc become attached to them. A disadvantage is that like most sea-defences they can stop supply of beach material by longshore-drift to other parts of the coast, in this case eastward.

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- Introduction

Erosion at the Naish Farm locality, Highcliffe, Hampshire, with some minor recent collapse of the top, Pleistocene gravel cliff, February 2017


The eroded cliff top at Naish Farm, with a view eastward to Chewton Bunny and Highcliff, with a rock armoured beach

Aerial view of Chewton Bunny outflow, Highcliffe, 2005, with engineered slopes on the left and with increased erosion on the right resulting from cut off of natural sediment supply

The artificial outflow of the Chewton Bunny Stream, Highcliffe, between strongpoint groynes of rock armour

Affects of Terminal Groyne Syndrome east of Chewton Bunny (Naish Farm),Highcliffe, Christchurch Bay, 1st January 2010

A sign of coastal retreat - loss of beach material at Naish Farm, Highcliffe, Hampshire, revealing an erosional platform of Lower Barton, A2 grey-green clay, with fallen septarian nodules lying loose above

Aerial view of slumping cliffs of Barton Clay at Naish Farm, to the east of Highcliffe, 2005

The landsliding cliffs at Naish Farm and beyond, between Highcliffe, Dorset, and Barton-on-Sea, Hampshire

Sea erosion of the foot of cliff of Barton Clay at Naish Farm, Highcliffe,  30 September 2006

The effects of wave-swash during storm erosion at the Naish Farm section of colluvium from the Barton Clay, near Highcliffe, Dorset, 9 Dec 2007

Naish Farm section beyond last strongpoint eastward at Highcliffe, Hampshire, 2003 Collapsing cliffs south of Naish Farm, Highcliffe, Hampshire

The Naish Farm section of cliffs from Chewton Bunny at Highcliffe eastward to Barton Cliff House forms the conserved stretch where erosion still continues and where there is a high degree of exposure and fossils can be collected. The cliffs here are retreating in a manner similar to that of the natural recession of the coast. A consequence of this is a low-angle, pleasant sand and gravel beach of natural appearance which is used by walkers, swimmers and surfers. It is, therefore, a useful amenity. Geologists and conservationists, in particular, consider this remaining section too important to conceal with sea-defences. At the top of the cliff there is a holiday camp rather than permanent housing, but unfortunately, as the pictures show. this much suffer some problems from the coastal retreat. Much of the remainder of the Barton and Highcliffe coast once looked natural, with eroding cliffs, like this Naish Farm area. For understanding degradation processes here consult the papers of Dr Max Barton.

The original coastline was relatively straight (examine old maps), in balance, and supplying shingle destined for Hurst Castle Spit (which contains Barton Clay fossils from here - Clavilithes). This present Naish Farm section of the coast is not natural in the sense that it represents an embayment between sea-defences. Loss of natural supply of beach material by longshore drift (from west to east) probably enhances the local erosion rate, but later when the embayment is deeper it might erode at a slower rate than would open unprotected coast. It will take some more years to find out whether this will happen. For more on the erosion rate, here, see the separate Naish Farm erosion section.

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Naish Farm [Naish Estate] Section continued

- Coastal Recession of the Barton Clay

Various papers by Dr Max Barton and his co-authors have provided important information on the erosion and degradation of the Barton Clay. There has been a particular invesigation into the cliff degradation of the Barton Clay cliffs at the Naish Farm area of Highcliffe where erosion of this clay is most obvious.

First the rate at which the coast has retreated must be considered. Barton and Coles (1984) stated that the rate of recession here in the nineteen fifties was only 0.4m per annum. Although this is still quite a high rate for the south coast of England, it was not extreme because there was already an excess quantity of beach material here. Barton and Coles (1984) said that this had been discussed by Wise (1963), although the present writer has not seen this report. Certainly Burton (1931) discussed changes in the position of the Run at Mudeford and the periodic breaching of Mudeford Spit, and this resulted in a supply of sand to the western parts of the Highcliffe coast. Later when the excess of material was lost by longshore drift (eastward), the coastal recession which accelerated to 1.3m per annum.

There was a further change to a significantly rapid rate of to 1.9m per annum at Naish Farm during the nineteen seventies, probably because the Highcliffe groynes were constructed just before this decade (in 1968-1970). Beach material here, shingle and sand moves in general in an easterly direction by longshore drift. The groynes trapped much of the material from passing from west to east, as, of course, they are designed to do. This, however, led to some "starvation" of the beach at Naish Farm and some "terminal scour" as a consequence (see the Joint Local Inquiry Report of the Secretary of State, Department of the Environment, 1975). The originally fairly uniform coast now has a notable "step" in it and a new shallow bay has been created. This now, though has a sandy beach with some shingle, quite pleasant for tourists, and with "natural" fossiliferous cliffs that are educational and informative.

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Naish Farm Section continued

- Collapse of Barton Clay Cliffs to Form Benches

Process of cliff-collapse at Naish Farm, after Dr Max Barton

The cliffs at Naish Farm, and in the past, all along the Barton coast section, are conspicuously terraced. These terraces or benches and their mode of formation was investigated by Barton and Coles, (1984) in their studies on the degradation of the cliffs just here (and see also other papers by M. Barton). Prior to their study the increase erosion in this area, as discussed above, steepened of the overall cliff angle from an average of 14 degrees in 1947 to a maximum recorded average of 19 degrees in 1976. The cliffs were, thus, particularly prone to landsliding and were found to collapse predominantly on a series of major shear planes (Barton, Hillier and Watson, 2006), more or less horizontal, but curved up at the back (at the landward side). The shear planes are located at certain lettered and numbered, geological horizons within the Barton Clay. These are shown in the cliff section illustration. They result in obvious benches or terraces in the cliff. These benches consist of collapsed clay debris and have top surfaces several metres or more above the specific shear planes. The benches have been named by Barton and Coles, (1984) as in the following sections:

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Naish Farm Section continued

- - - The Top Scarp

Top Scarp of Plateau Gravel, between Barton and Highcliffe Top scarp of Plateau Gravel with some collapse at Naish Farm

Naish Farm, collapse at top of the cliff Details of cliff collapse at Naish Farm, top of the cliff

The Top Scarp, shown here, is a cliff of a few metres high in brown-stained, subangular flint gravel, with some Brickearth or loam above. Both the gravel and the brickearth are of Pleistocene age. This is the Tenth River Gravel Deposit of the Geological Survey. Palaeolithic artefacts have been found in the gravels of this stretch of cliff. Slices of the gravel and loam cliff top subside on curving shear surfaces in the Barton Clay beneath.

The top-left photograph was taken in 2001 about midway between Barton and Highcliffe, and just west of the western end of the Barton section of sea-defences. There is a greensward on the top of the cliff here. Notice the block with brickearth which is out of position on the right, still with its soil and grass capping. A semicircular area has collapsed on the left. Incidently, you can see sand lenses in the periglacial, braided-river gravels.

The top-right photographs and the bottom photographs, all taken in 2003, shows collapse of the gravel at the Top Scarp at Naish Farm, just east of Chewton Bunny. Here coast erosion is a constant problem. Clearly some of the falls are quite recent.

Naish Farm seen at the cliff top with Chewton Bunny and Highcliffe beyond

The eastern fence of the Naish Farm holiday estate, Highcliffe, with Chewton Bunny and the Highcliffe car park in the middle distance, 28th October 2019, Ian West


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- - - F2 Bench

This bench is near the top, in front of the top scarp. It is a narrow bench based in a shear plane at the base of bed F2, and with Plateau Gravel forming much of the back-scarp cliff. You can see it in the photograph above and in the central photograph below. The bench contains collapsed gravel debris and is broken up by a number of fissures parallel to the cliff. The flint gravel is progressively disrupted and becomes mixed with clay and turves of soil and grass, and slides gradually down the cliff.

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Naish Farm Section continued

- - - D Bench

Barton Cliffs, towards Highcliffe

Barton cliffs, west of Barton

Pond on D bench, west of Barton

As shown in the left and central photographs above, the middle bench, forms the extensive central part of the cliffs. There is the F scarp at the landward (northern) side of it with exposure of the upper part of the Middle Barton Clay. Shearing curves down from the scarp and continues nearly horizontally near the base of bed D, and beneath the terrace shown. See Barton, Hillier and Watson (2006 ) for information on the initial origin of the D shear surface by a lateral rebound response to coastal recession.

This middle bench is complex in pattern with much colluvium (debris) and also ponds developed as a result of rotational movement (notice the bullrushes in the pond in the central photograph, although they are have largely died off in this winter scene). These ponds, shown in the photographs, are mostly present near the F scarp. Small alluvial fans extend into the ponds and miniature deltas develop, as shown in the right-hand photograph (looking southward with reflection from the sun; note the little distributaries on the delta; note also how the reeds have grown on the shallower southern slope, away from the clay scarp). Not shown in these pictures are amphitheatre-like features which develop in places as a result of specific landslides.

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D Scarp and D Shear Surface

The D Scarp

Shear surface in D Scarp

Horizontal landslide movement at the D shear surface, seen in the D scarp, between Naish Farm and Sea Road Access, Barton-on-Sea, Hampshire, 2006

Collovium sliding seaward above the D Shear Surface, east of Naish Farm, between Highcliffe and Barton-on-Sea, Hampshire, 24th November 2007

The C to D slip plane or basal D slip plane, seen in the cliff near the old gun emplacement, between Highcliffe and Barton-on-Sea, Hampshire, 24th February 2017, showing active movement on the right or westward, but only dribbling clay on the left

Details of the D slip plane, Barton-on-Sea, Hampshire, on the 24th February 2017

The D Scarp contains the D Shear Surface, shown in the photographs here. The name has been given by Barton and Coles (1984) because of this shear plane. Do not confuse this reference to D with the strata present in this scarp. It is mostly in Bed C, the Voluta suspensa Bed, the shear surface being almost at the base of Bed D. Lower down and in front of it is the A3 Bench of colluvium. Debris is falling onto this from the shear surface, which is very slowly moving forward. If you stand on the beach in this area, you may sometimes see small pieces of clay falling from the shear plane. However, this only happens when sliding is very active. This fresh, damp debris is browner in colour than the older material. It is dominantly weathered sandy clay from the Barton Formation, but with some yellowish-brown, flint gravel intermixed. This gravel has come from the Pleistocene, Plateau Gravel high in the cliff and has fallen into the other colluvium on a higher bench. Apart from this there is some plant material, and pieces of septarian nodules.

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- - - A3 Bench

This is the low bench extending upto about 3m above the beach, and obvious from the shore at Naish Farm. The shearing is at the base of A3. Further east, near the old gun emplacement, this disappears eastward under the beach, and the lowest sea cliff is then formed by bed C, beneath the D Bench.

Thus, the presence of the three shear surfaces at various elevations within the cliff produce a benched type of cliff profile, comparable with that seen in the Gault and Lias Clay controlled cliffs of Fairy Dell, near Charmouth, Dorset and can be seen in the London Clay of the Isle of Sheppey. Barton and Coles (1984) pointed out that excavating the toes of such landslides has reactivated slides of this type in the USA.

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- - - Degradation Processes

Degradation of Barton Clay cliffs

The degradation processes, according to Barton and Coles (1984), include scarp slumping, spalling (including toppling and soil falls), bench sliding (involving movement of colluvium over a preferred bedding plane), debris sliding (including movement of screes over clay scarps), mud sliding (i.e. traditional lobate 'mudflows'), mud runs (true flows), stream (or gully) erosion and man-related processes. The diagram alongside, after Barton and Coles, shows the main processes. Regular surveying and monitoring using a variety of techniques and having to surmount difficult field conditions, has begun to elucidate the characteristics, rates and inter-relationships of these processes. A flow chart representing the systematic transfer of soil from the in situ state via various colluvial modes (including the three bench levels) en route to the sea and an accompanying colluvial soil budget for the year July 1981 to July 1982 has been drawn up. It is shown that bench sliding is by far the most significant process in terms of volume of colluvium moved through the undercliff, accounting for 93 percent of the total volume of colluvium contained in the area. Mud and debris sliding, although important processes, are of relatively minor importance.

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- Exposure Ratio

Barton (1998) has put forward the theory of Exposure Ratio. This, ER = (sum of exposed strata height/total cliff height) x 100. In other words it is just the relative height of exposed strata.

The table below, from Barton (1998), gives approximate values of exposure ratio in the Naish Farm area, east of Highcliffe. Accumulations of colluvium now cover the basal scarp at locations 1 and 2 because of the construction of a strong point at Chewton Bunny. Prior to this the exposure ratio at both of these locations would have been larger.

Easting Range
Recession Rate (m. /annum)
Exposure Ratio (%)
(maximum value)
1 2182-2183 0.74 34
2 2186-2190 1.14 39
3 2215-2225 1.14 54
4 2230-2235 1.71 55
5 2245-2250 0.94 47
6 2260-2270 0.60 23
1.045 42

An important point made by Barton (1998) is that the type of cliff degradation that takes place results in much of the cliff being covered by colluvium (see diagram above). This means that only certain limited stratigraphical horizons are well-seen at any one time. Before the sea-defences were constructed various parts of the Barton succession were seen at different places along the coast. For instance, the Earthy Bed (E) is actually present at Naish Farm but is now rarely seen in good condition. The main exposures of this were further east and I used to collect from it in the area now covered by the Barton-on-Sea sea-defences. The old geological literature on the coast shows that various parts of the dipping succession have been seen at various places and at various different times. The cliffs have never been static and neither have the positions of the exposures. Dr Barton explains that certain specific stratigraphical levels, of around 0.5 to 1.0m above the preferred plane shear surfaces, have never received the stratigraphical and palaeontological study such has been devoted to the rest of the sequence. From a stratigraphical point of view, the colluvium never makes up the deficiency since the solid strata are completely remoulded within the interior of the benches by the intense shearing suffered by the softened material as it accomodates to the markedly non-circular slip surfaces.

Dr Barton states that the prediction of the likely exposure ratio of benched-form clay cliffs following partial toe protection will need to encompass a series of factors which he lists. The main objective is to avoid both the high rates of recession associated with rapid toe erosion and the eventual slope coverage associated with zero toe erosion. The aim therefore is for the state of moderate toe erosion (perhaps aiming at a value of about 0.3 to 0.6 metres per annum, although this would be subject to negotiation).

Such moderate toe erosion might be achieved at Naish Farm by an offshore breakwater or by partial beach replenishment. With the Chewton Bunny Stongpoint already reducing the exposure ratio at the western end of Naish Farm it is unlikely to please geologists and conservationists; with the cliff still retreating it may not please local objectors. It is, however, one possible way to resolve the problem of these cliffs and the original ideas in the Barton (1998) paper should be studied. If this scheme had originally been applied to the whole Christchurch Bay coastline and the blanketing sea-defences never constructed, it might have been acceptable to all. If and when the sea-defences ever collapse an offshore bar right round Christchurch Bay might be a solution but is likely to be unacceptable or impracticable or both (see section on the "Oceanus" scheme mentioned below).

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Between Naish Farm and the Barton Sea Defences

(see also the note on the D shear surface given above in the Naish Farm section)

Eroding stretch of Barton Clay between Chewton Bunny, Highcliff and the Barton Sea Defences, Hampshire, 24th February 2017


A gun emplacement from World War II is a useful marker at the eastern end of the Naish Farm section, and between Highcliffe and Barton-on-Sea

World War II gun emplacement, east of the Naish Farm cliffs, Highcliffe, indicating loss of beach material between 2004 and 2007

A relatively minor cliff fall at a small mudslide west of Barton-on-Sea, 28th October 2019


During 2007 there seems to have been some loss of beach material. This is know to have happened at Highcliffe early in the year the authorities carried out remedial work in the western Highcliffe area. Here further east there seems to have been some loss of beach material in 2007, although the exact date of the event is not known. The old gun emplacement of World War II, once on the cliffs, but now buried in the beach, acts as a marker. Scour has taken place around this and a coarser basal lag deposit of the beach has been exposed. A similar case of exposure of beach lag deposits has happened this year at Chilling Cliff in Southampton Water.

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The Cliff House Hotel Landslide of 2001

Aerial view of the lower lobe of the mudslide near Cliff House, Barton-on-Sea, Hampshire, in 2001

Rotational landslide and mudslide in the Cliff House area, Barton-on-Sea, in 2001 Old sheet-piling rotated by landslide and mudslide in the Cliff House area, Barton-on-Sea, 2001

There was collapse of an area of sea defences at the western end of these, near Cliff House, (west of Barton Court) and also on a smaller scale between the Cliff House and Barton Court areas. The main feature, as shown in the photographs above, was a rotational landslide which had developed in the Barton Clay, probably facilitated by water from the Becton Sand or Barton Sand (upper part of the cliff). The rotation produced an upbulge in the lower cliff. This had broken and lifted a drainage system. In addition sheet piling in the area had been moved by the landslide and rotated from the vertical to various angles. This sheet piling is probably some of that emplaced in the 1960s or 1970s as part of an original scheme, which with the piping, was meant to control water within the cliff. When rexamined in November 2003, it was seen that a quantity of medium-sized, fossiliferous, Portland Stone blocks had been placed over the toe of the landslide, as some sort of remedial action.

Please go to the:
Barton Erosion History webpage for more information.

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Sea Road Access Landslide - 2009-2013 (and continuing?)

The Sea Road Access Landslide is situated at the former southern continuation of Sea Road. It near the site of the old coastguard station that was destroyed by erosion. It is referred to as an "Access" because it was used by the council workers for the access of machinery and trucks to the cliff stabilisation works. Like Hoskin's Gap, another former access point, it no longer provides access for vehicles, and recently not for walkers either. Only at Fisherman's Walk (east of Barton Court) is vehicle access to the cliffs possible now. At present much of the sea defence works at Barton can be repaired to some extent (especially east of Barton Court), but access is progressively being lost as the 1960s and subsequent coastal stabilisation works and cliff roads disappear into landslides. Natural processes are taking place and the cliffs are gradually returning to their pre-1960s state.

The middle part of the Sea Road Landslide, Barton-on-Sea, Hampshire, at the 1st January 2010

More rapid movement at the Sea Road Access landslide,Barton-on-Sea, Hampshire, 1st January 2009

Enlarging fissure and backscarp fault at the Sea Road Access, Barton-on-Sea, Hampshire, as a new landslide develops, 22nd November 2009

Major collapse of the Sea Road Access in March 2013, Barton-on-Sea, Hampshire

Further enlargment of a fissure and backscarp fault at the Sea Road Access, Barton-on-Sea, Hampshire, as a new landslide develops, 17th December 2009

Small graben forms as the Sea Road Access Landslide develops at Barton-on-Sea, Hampshire, 17th December 2009

The southern boundary fault of the small graben at Sea Road Access, Barton-on-Sea, Hampshire, 28th January 2011

Collapse of the roadway at the small graben at Sea Road Access, Barton-on-Sea, Hampshire, 4th March 2013

A new landslide in the middle cliff south of the Sea Road Access, Barton-on-Sea, Hampshire, 22nd November 2009

Collapse of part of the middle cliff at the Sea Road Access, Barton-on-Sea, Hampshire, 17th December 2009

The western margin of the Sea Road Access Landslide in the upper cliff on the 17th December 2009, Barton-on-Sea, Hampshire

The Sea Road Access Landslide is part of a composite set of mudslides between Hoskin's Gap and Sea Road Access. The landslide in 2013 and earlier has now cut off the original road down the cliffs here. The middle cliff has substantially collapsed and and the landslide became major and wide by March 2013. The rock armour at the base does not seem to have been moved forward or up, as in the Cliff House Landslide.

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Central Barton Section from Cliff House Hotel to Barton Court (with sea defences)

The houses of the Barton Court area, Barton-on-Sea, Hampshire, seen from the east in the area of the Fishermans Walk path

An old photograph of the cliffs at Barton-on-Sea, Hampshire, in the 1950s or early 1960s before sea defences were constructed


The collapsing cliffs of Barton-on-Sea, Hampshire, looking westward from Barton, towards Highcliffe and on to Hengisbury Head

[Note: The Barton Clay cliffs in the 1950s were more natural and unaffected by sea defences. They were, of course, eroding and collapsing down to the sea for a large part of the bay. Part of the coast in the Barton - Highcliffe area is still like this. However, in the 1950s the beach of Christchurch Bay was continuous and beach material from Barton could still travel all the way to Hurst Spit. Although the spit was overwashed on occasions, it could naturally repair itself by the supply of material from the Barton Cliffs. In the past, if you hunted amongst the pebbles at the end of Hurst Spit, you could find the occasional, worn, Barton fossil (Clavilithes etc.), but most of the spit is of dumped gravel now. Hurst Spit has no functioning natural resupply system at present. The spit is disconnected from the supply areas at Barton-on-Sea by the Barton sea defences, by a sea-wall at Milford and by rock armour at the landward end of the spit. The coast of the whole bay is, or would be, naturally retreating. Therefore, it is not surprising that buildings at Barton and Milford have coastal protection measures in front of them. These defences prevent continuous longshore drift. N.B. - this website is merely descriptive and does not put forward any view for or against particular sea defences. Students, though, may wish to discuss the pros and cons.]


- Introduction

- see also the History Section the part on a new collapse of the cliff between Cliff House and Barton Court area. --

The cliffs at Barton-on-Sea in the central part of Christchurch Bay are a place of scientific interest, civil engineering work, controversy, study, pleasure and concern. The discussion here is from a geological viewpoint. Obviously, most of the soft coast here, as elsewhere in southern England, is relatively temporary in geological terms. The sea will, of course, continue its transgression northwards across the soft clays and towards the New Forest. It could, perhaps be stopped, but only at enormous expense.

The sea has flooded the valley of the English Channel during the Flandrian Transgression of the last 10,000 years and the process has not finished. Indeed global warming might give a new boost, but this is not obvious yet. Christchurch Bay is a young feature resulting partly from sea-flooding and more particularly from erosion of the soft Eocene strata. There are numerous septarian nodules (concretions) on the seafloor that have come from former Barton Clay cliffs, long-since washed away. However, it must be stressed that the natural coastal retreat is not very fast in human terms and it may take a 1000 years or much more to go back a kilometre. With this background we will consider the critical central part of the Barton Cliffs.

The centre of the cliff section at Barton-on-Sea, Hampshire, showing the site of the 1975 landslide and destruction of sea defences

Cliff-top with sea defences below, west of Barton Court

Cliff-top between the Sea Road Access and the Cliff House Hotel, with small spalling landslides in the top gravel cliff, above the large Cliff House Hotel Landslide, western end of the Barton sea-defences, 2003

Possible processes of cliff top retreat at Barton-on-Sea, Hampshire

The piece of coast considered here includes the central part of the Barton cliffs. There are various buildings here some of which are shown on old maps some way inland. There are quite large car parks on either side of these cliff-top buildings. A cafe on the western side has been demolished because it was being undercut by cliff erosion, but most of the original buildings still remain and relatively little has happened for about a quarter of century.

This is an important area for study, because the existence of the buildings here was the main reason for the construction of the Barton sea defences in the 1960s. They were not successful and failed in 1975, resulting in further work and the limited demolition on the cliff top. It is important to have some idea of future prospects here, although there is no certain information, especially regarding the rate of coast erosion. The diagram above shows some possibilities regarding long term future processes in the area. There are many unknowns and the rates of erosion are not easily predicted. Erosion does not take place a steady rate. There are phases when the cliffs are dormant, and other phases when excess rain and groudwater or great storms have drastic effects.

If you should have any have particular interest in this area it is recommended that you examine the data and coast erosion maps etc of the New Forest District Council . They provide much valuable information and alos indicate the area of ground at risk from coast erosion in the relatively near future.

This interesting central stretch is taken as extending from Barton Cliff House east to the end of the Barton Clay outcrop. This is some way east of Naish Farm Holiday Village to beneath Barton Golf Course. It is below part of Marine Drive West and beneath all of Marine Drive East. It is now backed by predominantly residential suburban development, with a small cluster of shops and other facilities. There are approximately 150 beach huts along the under-cliff at present (Wright, 1998).

Cliffs at Barton-on-Sea in 2001, with only one landslide visible

The stretch of Barton cliffs on either side of Barton Court and the cliff-top houses is now protected to a large extent by sea-defences, shown above. Its former natural condition is shown by by old photograph from the 1950s (right-hand photograph). It was similar to the Naish Farm stretch with Barton Clay terraces, but with Barton Sands in the upper cliff as a source of landslide problems. The whole stretch of coast was relatively straight though with fairly even erosion throughout and there were no large embayments at Naish Farm or Becton Bunny at that time. However, coastal retreat at Barton was attaining about 1 metre per annum and was a cause of concern to some residents.

sea defences east of Barton in 2002

Broken limestone, sea defences, Barton in 2002

groyne east of Barton in 2002

sea defences at Barton, viewed westward

The cliffs here have been seen by geologists in the past as an impressive natural coast with excellent exposures of the Barton Clay, and a great attraction. However, in the 1930s the land above gradually became a suburban area of housing. The natural retreat of the cliffs caused a threat to some older houses near Barton Court. This has concerned local authorities and this part of the coast turned into a site of civil engineering works. The cliff was receding at almost a metre per annum and the cliff collapsing into terraces. Comparison can be made to the Naish Farm area, discussed separately. As a result a revetment for toe protection was built, drainage works took place and the slopes were covered with gravel and regraded. This is discussed further below. They are holding at present (2006), at least near the central buildings.

These main Barton sea defences have been described in the past by Muir Wood (1967;1971) and there is a more up-to-date report by Wright, D. (1998) which although brief is very informative and should be consulted. The following notes are partly based on these publications.


Central Barton Section with Buildings on the Cliff Top

The site of the now-demolished cafe at the western end of the Barton Court area, showing some old foundations, 3rd September 2018


1974-75 Winter - Failure of Part of the Stage 2 Works
(repeated here)

In that winter, there was a deep seated failures in the undercliffs in front of the buildings. This penetrated beneath the sheet-piling causing rotation, bowing and splitting of the barrier. Although later this was mostly covered over by dumping gravel, the rotated barrier is visible from time in new landslides. At the time mudslides surged over the sea-cliff and revetment and onto the beach. The cliff top receded 5-10m over a 150m front in 1975 (Clark et al., 1976 ; Wright, D., 1998). Failures in the clay seem to have been deeper than expected.

Landslide in the Barton Court area displacing sheet-iron of sea-defences

Problems with the Barton cliff top in 1975

Displaced sheet-iron is shown above. With this illustration is a reproduction from Anonymous (undated, Coastal Erosion at Barton-on-Sea) showing some newspaper cuttings from that year. Another newspaper article follows, below, but it is not necessarily correct in every detail (the restaurant extension referred to reopened three weeks later). In particular, though, it is too optimistic in suggesting that there was no deep-seated problem, just a cliff-top fall. Here is the article, in entirety, but without paragraphs:

Sightseers Warned of Crumbling Cliffs
(Echo Staff Reporter. Southern Evening Echo, Newspaper, 23rd April, 1975)

"An appeal to the public to keep away from the crumbling cliffs at Barton-on-Sea where a house stands perilously only two feet from the edge and others are threatened, came yesterday from New Forest District Council. Hundreds of people have visited Barton since the cliffs began falling last Thursday and yesterday the council's chief executive, Mr Peter Bassett warned that the cliffs are dangerous and that they could accept no responsibility. Sightseers, he said, were adding to their problems. The council's Amenities Committee called for a report on the possible demolition of Mr. Jack Murrell's 40,000 pound home, Manor Lodge, perched above a 70 ft. drop. Principal engineer, Mr Frank Harris, said people living on the cliff top had been warned a few months ago of increasing danger to their properties. He said that dangerous structure notices had been served on Manor Lodge and the new dining room extension of the Ventana Hotel next door. Barton Court which was divided into five flats, was not imminently threatened. Mr. Harris said that the cliff fall was unfortunate but not unexpected. In 1960 Sir William Halcrow and Partners, the council's consulting engineers, had said that in the long term the buildings could not be saved. Mr H. E. Stopher, Lymington's former borough engineer, had stated that in spite of holding the undercliff stationary the cliff would gradually move until it reached its natural angle of repose. The engineer said that last week's fall was confined to the top. There was no suspicion of movement in the undercliff. He said that there was nothing that they could do about the cliffs. They were pushing soil against the cliff to decrease the amount of vertical face. Mr. Harris said that it was impossible to stop people going to the cliffs over the weekend. Large notices warning of the danger were to be erected. The chief executive denied that vibrations from machinery engaged on undercliff stabilisation had anything to do with the fall."

Thus retreat of the cliff top at Barton during the early part of 1975 caused problems with certain houses in vulnerable positions. The fundamental problem in this particular year was a new landslide in the undercliff, affecting the cliff-top. An important point was made by the Lymington former borough engineer stating that the cliff top will gradual move back in any case over a period of time. The existence of sea-defences might have given an impression that coastal retreat had completely ceased. The defences do not completely stop changes taking place, but can successfully retard cliff retreat for a number of years.

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Beach Remnants

flotsam on the gravel beach east of Barton in 2002

Gravel beach material east of Barton in 2002

At Barton-on-Sea there is not much width beach now, unless the tide is unusually low. Originally, it was fairly narrow but you could once walk along it. There is still some beach gravel adjacent to the groynes, and this increases in width towards the eastern end of the Barton sea defences. This is the result of longshore drift affected by the prevailing southwesterly winds. Other beach debris is also accumulated on the west sides of groynes.

As shown better in another photograph, the beach material is subangular flint gravel, typical of that in the Pleistocene gravel terraces of this area, although lacking coarse very coarse gravel or boulders. Almost all the material is flint. It is quite well-sorted, but has not been very rounded, like the pebbles on the Chesil Beach. The gravel has most likely come from artificial renourishment by Pleistocene flint gravel from some local gravel pit. Gravel derived from the cliff is not likely to be very different. Erosion of the cliff gravel in this particular area is now almost stopped by the sea defences. In the past this was part of the important supply area of gravel to Hurst Castle Spit (which also has reworked Barton Clay fossils). The flints in the Pleistocene source gravels, wherever they may have been, at first had many conchoidal fractures, but these were partly rounded off during abrasion in the seasonally, fast-flowing, periglacial river. See a worn, relict conchoidal fracture in a flint pebble in the bottom left corner of the right-hand photograph. The white pebbles are leached from the upper part of a podzol soil profile. This type of acid soil which is common here contain humic acid (from organic matter) which dissolves iron, a common constituent of the gravel, and transports it downward in solution.

There are in both photographs damaged pink shells of the modern Slipper Limpet Crepidula fornicata. It is a mesogastropod, of American origin, that has spread along the south coast of Britain. It is very abundant in the Bournemouth region. The species lives in piles or chains, one animal resting upon another. The lowest and largest specimens are female and the top smaller ones are male. Those in the middle change from male to female. The characteristic slipper-shaped shells of this seem more common than those of other molluscs on this stretch of coast. The seaweed is some type of wrack with gas bladders, perhaps Fucus or Ascophyllum. The cuttle-bones of the common cuttle-fish Sepia officinalis are frequently washed-up after storms. They are sometimes collected for budgerigars to peck (and as a boy I used to carve and paint the soft calcium carbonate of these to make ornaments).

Before the sea-defences were here this coast more resembled that at Naish Farm. There was sand and some gravel. In the 1950s the beach had several small, springs of blue-grey quicksand or soft mud coming from the Chama Bed. Slurries of loam washed down onto the beach. The Chama squamosa and Turritella sulcifera and Turritella imbricateria were abundant. There were many pieces of the brick-red, Stone Band, of siderite and shells. This is at the top of the Barton Clay Formation. Small, rather flattened slabs contained numerous Turritella and other molluscan remain. Some of this can still be found west of the Barton sea-defences. Plastic was not common in the 1950s and not generally washed up onto the beach. There was always timber on the shore here.

The upper cliffs and slopes are interesting. They are mostly very barren embankments. Presumably the combination of previous instability, the recent civil engineering works, the salt spray shown in the photographs, the high exposure to wind and the waterlogged clay (with acid springs) seem to have retarded growth of vegetation to some extent, although it is quite well-developed west of the Sea Road Access.

Comparison of the Barton cliffs with the vegetated ones of eastern Highcliffe is not entirely justified. There is greater exposure to wave action, wind-action and salt spray on the Barton cliffs. Hengistbury Head, as a barrier, and recent sand accumulations do not afford some protection here. Above the works and a gravel track, the highest part of the cliff, the top scarp of Plateau Gravel with some Becton Sand (Barton Sand) beneath is still in relatively natural condition.

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- Degradation to the Ultimate Angle of Stability

Generally the retreat of the cliff toe and cliff top in the Barton area have been more or less parallel (Barton, 1973, fig. 3). Stopping the erosion at the toe would not, however, prevent the cliffs from degrading with the cliff top still retreating. Water supplied through the Becton Sand (Barton Sands) and Plateau Gravel facilitate cliff collapse. If marine erosion ceases and nothing further is done the cliffs will slowly degrade to a stable slope with an ultimate angle of stability. This angle is likely to be low. It is attained in an exponential relation involving considerable movement over the first decade with final stability being reached only after several thousand years (Barton, 1998). Collapse of much of the greensward above and accumulation of colluvium on the former cliff area would eventually produce this gentle seaward slope. Sea defence works at Barton, in addition to protection of the toe, also involve drainage schemes and sheet piling on the undercliff, to try to stabilise the cliffs. A relatively stable situation has been achieved at Highcliffe where there is little bedrock exposed and the former cliff is mostly covered by colluvium (Barton, 1998).

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Rock-Armour - Carboniferous Limestone Blocks

To see the source quarry of the rock armour go to:

Mendip Hills webpage.


Crinoid ossicles in Carboniferous Limestone rock armour at Barton-on-Sea, probably Clifton Down Limestone from Merehead or Torr Works Quarry, eastern Mendips

The tabulate coral Syringopora in Carboniferous Limestone rock armour at Barton-on-Sea, Hampshire

Lithostrotion in Clifton Down Limestone, Carboniferous rock armour from Torr Quarry, at Barton-on-Sea, Hampshire

Carboniferous Limestone, Clifton Down Limestone,  dipping south and striking east-west, Torr Works Quarry or Merehead Quarry, Mendip Hills, Somerset, 2010

For rock armour at Barton there has been much use of large blocks of Carboniferous Limestone from the Foster Yeoman Torr Works Quarry at Merehead, East Cranmore, Shepton Mallet, Somerset Lewis, Donovan and Sawford (2003). It is transported by both rail and road into the region, although these blocks were apparently brought by road.

More specifically, the limestone is Clifton Down Limestone Formation of the Holkerian of the Dinantian (Lower Carboniferous or Mississipian). Lewis, Donovan and Sawford (2003) reported a rich fauna of echinoderms, corals, bryozoans, trilobites, brachiopods and gastropods. The echinoderms include plates of the tests of the echinoids Palaechinus sp., Archaeocidaris sp. and an indeterminate echinoid. Numerous crinoid ossicles are present and calyces have been found of the crinoids platycrinitid sp., Actinocrinus sp. aff. A. rotundatus Wright, monobathrid sp. indet., camerate sp. indet. and Taxocrinus sp.

This Palaeozoic limestone was deposited as carbonate sands and mud about 350 million years ago. It was probably almost white on the tropical sea-floor but contained much organic matter which on burial produced the dark colour. Originally it would have been fairly porous, resembling Jurassic limestones. It has, however, been deeper buried than the Mesozoic strata. The Hercynian Orogeny about 300 million years ago was probably the major cause, though, of its almost complete loss of porosity, so that now it is denser and more brittle than most Jurassic limestones.

Similar rock armour has been used at Lepe Beach, Hampshire and see this webpage for further information.

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Carboniferous Limestone - Fissure Fills

Within some of the Carboniferous Limestone blocks at Barton, Highcliffe, Lepe Beach and other places there may be fracture systems containing red, yellow or grey sediment. These are the Mendip fissures of the type that have been described in a well-known paper by Wall and Jenkyns (2004) [Gavin R.T. Wall and Hugh C. Jenkyns]. The reference and abstract of this paper is given below:

Wall, R.T. and Jenkyns, H.C. 2004. The age, origin and tectonic significance of Mesozoic sediment-filled fissures in the Mendip Hills (SW England): implications for extension models and Jurassic sea-level curves. Geological Magazine, vol. 141, part 4, pp. 471-504. (The full paper is available online).

Abstract: In the eastern Mendip Hills, on the northern margin of the Wessex Basin, SW England, the Carboniferous Limestone is cut by numerous fissures that are filled with Mesozoic sediments (sedimentary dykes, neptunian dykes). The fissures contain a record of Triassic-Lower Jurassic sediments that are only sparingly preserved in their normal stratigraphical position between the Carboniferous Limestone and the unconformably overlying Upper Inferior Oolite of Bajocian age. Detailed analysis of cross-cutting relationships, facies analysis, biostratigraphy, lithostratigraphy and strontium - isotope ages of relevant Mesozoic sediments has allowed the construction of an Upper Triassic-Lower Jurassic fissure - fill stratigraphy for the eastern Mendip area. Most fissures were clearly formed by rapid influx of unlithified sediment from the land surface or sea floor. Some smaller cavities, or larger cavities with restricted access to the unconformity, were apparently filled by sediment that trickled down into the fissure system. The vast majority of the Mendip fissures are interpreted as having formed as a response of the Carboniferous Limestone, north of major basin - bounding faults, to pulses of tectonic extension during Ladinian-Norian/Rhaetian, late Hettangian-early Sinemurian, late Sinemurian-early Pliensbachian, mid-Pliensbachian, late Pliensbachian and Bajocian times. Triassic - earliest Jurassic fissures have a broad spread of strike from E-W to NW-SE to N-S, accommodating extension in a roughly NE-SW direction. Younger Jurassic fissures show well-defined E-W and N-S trends with the former becoming dominant through time. Total extension of about 4.7 percent N-S and approximately 0.6 percent E-W was produced by the formation of Triassic-Jurassic fissures within the Carboniferous Limestone. Such patterns of extension are thought likely to be characteristic of the subsurface geology in much of southern England and Wales. Major implications of this study are that: (1) the presence of seismically unresolvable sediment-filled fissures in supposedly rigid fault blocks can lead to a significant underestimate of regional extension based on the restoration of motion on normal faults on seismic-reflection profiles, and (2) the isolation of pulses of tectonic activity with a temporal resolution of 105-106 years may provide a means of identifying a tectonic signal in relative sea-level curves derived from the Jurassic sedimentary record.


A fissure fill with calcite and yellow sediment in a Carboniferous Limestone block at Barton-on-Sea, Hampshire

Red siltstone filling an extensional fissure system in Carboniferous Limestone rock armour at Lepe Beach, Hampshire (neptunean dyke)

Red fissure fill, showing progressive expansion, within Carboniferous Limestone, rock armour at the Barton last groyne, just to the west of Becton Bunny, near Barton-on-Sea, as seen on 3rd September, 2018

Interesting fissure fills ("neptunian dykes") with red and yellow sediment occur in the blocks of Carboniferous Limestone at Barton-on-Sea. See the paper of Wall and Jenkyns (2004) for a discussion of the origin of sediment-filled fissures in the Carboniferous Limestone of the Mendip Hills. Another example from similar Carboniferous rock armour at Lepe Beach is also shown for comparison.

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Rock-Armour - Replaced Evaporites in Dolomite or Dolomitic Limestone
(casts of halite - rock-salt etc. Within blocks of Carboniferous Limestone from the eastern Mendip Hills or Mendips).

Calcite pseudomorphs after halite and calcite-replaced anhydrite or gypsum nodules in Carboniferous Limestone, rock armour, Barton-on-Sea, Hampshire

If the rock armour of Carboniferous Limestone, from the eastern Mendip Hills, at the Barton shore just east of Hoskin's Gap is examined at low tide, some interesting evaporites will be found. Particularly conspicuous in an unfossiliferous dolomite are good calcite pseudomorphs after halite. Some of these are feathery or skeletal. They have all formed in the carbonate sediment when it dried out with a content of very hypersaline (near 350 ppt) brine. Associated with the halite is much nodular calcium sulphate replaced by calcite. This may have originated as gypsum, but in proximity to so much halite it is almost certain that it was changed diagenetically to anhydrite at an early stage.

Calcitised nodular anhydrite or gypsum in a Carboniferous dolomite or dolomitised limestone of sabkha facies, and used in sea defences, Barton-on-Sea, Hampshire

Recent nodules of anhydrite, one with chicken wire structure, Dukhan Sabkha, Qatar

A calcite-replaced anhdydrite or gypsum nodule in rock armour of Carboniferous Limestone at Milford-on-Sea, west of Barton-on-Sea, Hampshire, an example showing that sulphate-replacement was early and took place before the end of compaction

General overview of a calcite-replaced anhdydrite or gypsum nodules in Carboniferous Limestone rock armour at Milford-on-Sea, west of Barton-on-Sea, Hampshire

[Note: the syn-Carboniferous calcitisation date: The example shown above, although from Milford-on-Sea, rather than Barton-on-Sea, shows that the calcitisation of the sulphate was quite early and prior to major overburden compaction. If, indeed, the calcitisation had not been pre-compaction, the nodule would, of course, been severely distorted by compaction.]

Go to the Qatar Sabkhas webpage to see more on modern analogues.


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Cliffs Below Marine Drive East

Aerial view, 2004, of the coast south of Marine Drive East, Barton-on-Sea, Hampshire, courtesy of the Channel Coastal Observatory

Cliffs beneath Marine Drive East, Barton-on-Sea, Hampshire, as seen on 2 May 2007

Now we look again at the coast below Marine Drive East, eleven years later! The amount of shingle has increased.

Coast with shingle accumulation beneath Marine Drive East, Barton-on-Sea, Hampshire, as seen on 3rd September 2018

An old photograph of the cliffs at Barton-on-Sea, Hampshire, in the 1950s or early 1960s before sea defences were constructed

An old photograph of the collapsed undercliff in front of Marine Drive East, Barton-on-Sea, Hampshire, before the 1967 sea defences and drainage scheme

The cliffs under Marine Drive East have always been steeper than those to the east. This is because there is a substantial thickness of Barton Sand overlain by Pleistocene gravel and Brickearth. These beds stand easily in near-vertical cliffs.

The problems are with the lower part of the cliff. The quicksand-like Chama Bed (H) is notorious for slumping when it is wet. It usually contains much water because it is at the base of the Barton Sands or Becton Sands. In the past many people have been stuck in the Chama Bed quicksands. This stratum also forms quicksands at springs in the New Forest and I have been temporarily stuck on horseback in such a sandy bog.

The 1967 sea defence works have so far been successful in this stretch and have not, as yet, failed. Successful drainage of the Chama Bed is a key factor. The bed is under the lower grassed slope. If the drainage system fails as a result of a minor landslide or through blocking of the pipes then there will collapse problems here of some extent. The original (pre 1967) state of the cliffs here was one of almost total collapse as shown in the old photographs above.

Although the cliffs below Marine Drive East are showing no significant sign of damage at present, it should be noted that they are not necessarily immune to the effects of a one in 250 year hurricane. When such a rare event next occurs it could erode the lower slopes and break up the drainage system. This stretch of coast is less threatened, though, than some other places. However, when such disastrous damage does hit the English Channel coast it is unlikely to receive much immediate repair because of serious problems elsewhere. Thus it must be remembered that very major storms could (and may) return this artificial piece of coastline to its natural slumped and eroding condition. In the meantime it is well-protected by sea defences, drainage and shingle nourishment. It is more secure than the central Barton stretch and comparable in some ways to the defended and drained Highcliffe stretch between Chewton Bunny and Highcliffe Castle.

In overview, with much shingle nourishment of the beach and longshore drift of shingle from west to east towards the groynes here, this is probably the best protected part of the Barton-on-Sea coast.

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- - - Introduction

A high overview of the Becton Bunny, Terminal Groyne recess, and its beach, looking eastward towards Barton-on-Sea, 2018

Aerial view, 2004,  courtesy of the Channel Coastal Observatory, of the eastern Barton to Becton Bunny cliffs with Terminal Groyne Syndrome, Hampshire

Terminal groyne syndrome at the  eastern end of the Barton sea-defences


Terminal Groyne Syndrome east of Barton-on-Sea

[compare and contrast photographs from 2013 and 2017]

Terminal scour at the downdrift side of rock-armour, sea defences, cliffs at Barton Golf Course, east of Barton-on-Sea, Hampshire, southern England, GE image


Terminal Groyne Syndrome effect, a new collapse of the Barton Sand in the cliff just east of the eastern end of the Barton sea defences near Becton Bunny, between Barton-on-Sea and Hordle Cliff, Hampshire, southern England, 22nd February 2018

A small sand fall taking place in the Becton Bunny embayment that has formed at the eastern end of the Barton-on-Sea coastal defences, as seen on the 10th July 2020

Details of active cliff erosion and cliff collapse just to the west of Becton Bunny, Barton-on-Sea, Hampshire, southern England, 2nd October 2019

Erosion taking place at the coast just east of Becton Bunny, Hampshire, southern England, 2nd October 2019


A view from the cliff edge of the terminal groyne syndrome at the eastern end of the Barton-on-Sea sea defences, with Becton Bunny and Hordle Cliff beyond, Hampshire, 4th March 2013

Terminal Groyne Syndrome at the coastal cliffs, Becton Bunny, Christchurch Bay, English Channel, southeast of Barton-on-Sea, Hampshire, England, 16th December 2017, Ian West

Cliff falls and terminal groyne erosion, just west of Becton Bunny, and seen from the last rock armour on the beach, 3rd September 2018

Looking down at the eroding cliff edge, near Becton Bunny, at the Terminal Groyne Syndrome area, southeast of Barton-on-Sea, Hampshire, 16th December 2017, Ian West

More details, looking down at the eroding cliff edge, near Becton Bunny, at the Terminal Groyne Syndrome area, southeast of Barton-on-Sea, Hampshire, 16th December 2017, Ian West


Erosional overhang of Pleistocene gravel and soil at the promontory adjacent to the terminal groyne eastward, near Becton Bunny, Barton, 16th December 2017, foreshortened view


Above the embayment at the terminal groyne of the Barton-on-Sea, coastal defences, there is a hazardous area of overhanging cliff edges, that is best avoided by keeping back from the cliff. From time the time the cliff path here has been moved landwards and is now, in part, actually on property that is part of Barton Golf Course. A notice there explains this. Obviously, the landward movement of the cliff top will continue. Next time a rare, full hurricane, like that of 1703 hits the area, substantial cliff retreat may suddenly occur. Even a lesser hurricane like that of 1824 will cause major coastal damage here and elsewhere. (in the meantime the coast retreats quite significantly under the effects of less violent, storms like those of 2014). Christchurch Bay is a rather new coast, characterised by "soft rock" cliffs of weak sandstone and clays.

The Chama Bed of the Barton Sand Formation was exposed in December 2017, at the foot of the eroding re-entrant at the eastern end of the sea defences of Barton-on-Sea, Hampshire, a view from the beach

A white fluid, probably a ferrous sulphate solution, from oxidation of pyrite, emerging from the Chama Bed in the vicinity of the last groyne between Barton-on-Sea, Becton Bunny, Hampshire, 16th December 2017


Becton Bunny is an example of the chines which are developed in relatively soft strata on the coast of Bournemouth and the Isle of Wight. They are small steep-sided ravines incised into broader valleys. This incision is the result of rapid retreat of the coast so that the stream has become rejuvenated and cut down to adjust to the new cliff location. Becton Bunny is very oblique to the coast and in the early 19 century the Bunny and Taddiford Gap were very close. The name "Becton" is, incidently, probably a corruption of "Beacon" which is used in some old publications. Unfortunately, the short, steep, ravine-like chine is probably doomed to disappear in a while by the very rapid coast erosion, leaving just the broader upper valley, which extends across the golf course.

The Becton Bunny area is a section of retreating and rapidly eroding coast without sea-defences at the eastern end of the Barton protected section. It is seaward of the Barton Golf Course. Here the Barton Sand (Becton Sand) is exposed and coastal recession is rapid due to relative starvation of beach material. This is known as "terminal groyne syndrome" or "terminal scour". In the original natural conditions the coast here was relatively straight and there was no embayment. The long-shore drift direction here is from west to east, as a result of prevailing southwesterly winds. Subangular flint shingle on the beaches travelled eastward to Hurst Spit . The Barton sea-defences have severely restricted supply and movement of shingle to this locality. However, some gravel from beach renourishment schemes may enter this area and, furthermore, the collapse of the cliffs just here provides some supply of gravel. Retreat may not necessarily proceed at a high rate indefinately because strongpoints exist both east and west of this stretch and they might form small headlands with a fairly stable bay in between.

To the east of the first embayment, which includes the mouth of small oblique valley of Becton Bunny is a promontory that formerly was occupied by a prominant old sewer pipe, a conspicuous iron construction. This was removed, probably for reasons of safety, in 2002. Rock armour has been placed at the site of the old pipe and this forms a strongpoint, retarding shingle movement eastward. Beyond there is yet another embayment at the beginning of the Hordle Cliff stretch of coast. Go to the Hordle Cliff Webpage for more information on this.

Erosion west of Becton Bunny, Sept 2002

Erosion west of Becton Bunny, Oct 2003

Examine these two photographs taken just over a year apart (September 2002 and October 2003). A steep or overhanging section of Pleistocene flint gravel is at the top. This is above sands and clays which mostly belong to the Becton Sands (Barton Sands) of the Barton Group (i.e. above the Chama Member and Barton Clay). The sands and clays are being rapidly eroded by the sea with some collapse and slumping. The cliff is unstable, oversteepened and retreating and it is important to keep away from the edge, which is often overhanging. There has been a bite-like retreat of the cliff-top in the year and erosion is moving rapidly in the direction of the Becton Bunny valley. The seats and path here clearly will not last for more than a few years.

In 1975 an application to extend sea-defences to this area by Lymington Council was rejected (Secretary of State, 1975). More details are given below. Beyond to the east is Hordle Cliff, discussed separately. In the past this Becton Bunny area has been part of the supply area for Hordle Cliff, Milford and Hurst Castle Spit. If shingle can pass the sewer pipe promontory to the east of these cliffs then it may still be helping to a limited extent to supply (and assist the protection of) the coast further east.


Fissures in the grassy cliff top near Becton Bunny, Barton-on-Sea, Hampshire, as seen on the 16th December 2017

A seat with the timbers removed, close to the eroding cliff edge, just west of Becton Bunny, near Barton-on-Sea, as seen on the 2nd October 2019


Collapse of gabions at the Becton Bunny chine, east of Barton-on-Sea, Hampshire, the result of coast erosion, as seen on the 16th December 2017, Ian West

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- - - From the Beach

Embayment at eastern end of Barton sea-defences, from the beach

From the beach the proximity of the last strongpoint of the Barton sea-defences, left in the photograph, and the actively-eroding embayment is obvious. This embayment differs appreciably from that at the eastern end of the Highcliffe sea defences. The cliff is very much steeper and contains beds of sand, parts of the Becton Sand or Barton Sand. The terraces and shear planes that are major features of Naish Farm are not present. Although there are some beds of clay, this type of failure does not seem to have occurred within them.

The Becton Bunny valley is seen oblique to the coast. This was once a rather larger chine. The steeper, seaward part within a broad valley has been formed by rejunenation caused by coast erosion moving the cliff-line and thus base-level landward. The stream has at some time cut a new thalweg adjusted to a new sea-coast position. The chines of Bournemouth and the Isle of Wight are of this origin. Becton Bunny is unusual in that coast erosion is now so fast here that soon the ravine-like chine part of the valley will be lost to the sea (compare with say - Alum Chine, Bournemouth). Note that the Long Mead End or Taddiford valley at Hordle Cliff has no such steep ravine because water-flow is northward to the Danes Stream and not to the sea.

The outflowing water of Becton Bunny normally passes through the beach shingle. When water-flow is high a small pond is developed at the back of the beach. There is an outflowing spring to the sea on the lower part of the beach where the water comes out of the beach shingle. The features are variable, though, according to recent rainfall; at the time of the photograph there was dry weather and very limited flow.

Erosion of Becton Sand (Barton Sand), east of Barton, January 2002

Becton Sand with Becton Bunny Bed, west of Becton Bunny, Barton

Left-hand image: photograph of the Becton Bunny stretch of coast shows that there was rapid erosion in January 2002. The evidence is the unusually clean and steep cliff face, revealing the subdivisions of the Becton Sand (Barton Sands). Of course, this would have been a peak time of year for erosion.

Right-hand image: This was taken in October 2002. During the summer degradation may have been dominant over retreat of the base of the cliffs and material has fallen and slumped. The autumn photograph probably show the results of this. An interesting factor is that there now seems to be more gravel present, protecting the cliffs. Is this from renourishment or natural processes such as the effects of constructive waves?

Debris apron of material fallen from the Becton Sand

Trickles of iron-stained mud, west of Becton Bunny

These photographs of the 6 November 2003 show the steep cliffs with sand and clay debris at the Becton Bunny embayment. In the left-hand picture both clay and sand can be seen to have fallen from the Becton Sand cliffs. There has been some renewed erosion by the sea at the foot of the cliff after the falls. This has reactivated a sand apron which shows signs of failure in the form of cracks at various angles. It seems to be sliding over the clay. The right-hand image probably shows the effects of recent heavy rain after a long dry summer. Much limonite (or goethite) occurs in the lower part of the Pleistocene flint gravel. These gravels are generally brown because of iron oxide content. In particular, though, iron-pans commonly form at the base of the gravel due to downward transport of the dispersed iron oxide during development of a podzol soil profile. Water passing though the permeable gravels may emerge just above the base. Such water may be ferruginous and mixing with mud can produce these brown trickles down the cliff. With this brown mud there are some fallen blocks of iron-pan (containing pebbles). This is probably the explanation of the features seen, although it should be noted that an alternative source of iron is provided by chalybeate springs which emerge from the Becton Sands because of the oxidation of pyrite. Examples can be seen in the Becton Bunny Bed in the cliffs at the sewer pipe promontory. Thus, the higher part of the cliff needs examination to determine for certain as to whether these brown trickles are from the Pleistocene gravel or from pyritous parts of the Becton Sand.

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Becton Bunny Cliffs - Application for Coast Protection Works, 1975.

There was a Public Inquiry into a proposal to construct Sea Defences at the cliffs near Becton Bunny. Here is a summary of the Inspector's report.

Secretary of State, Department of the Environment. 1975. Town and Country Planning Act 1971. Application by the former Lymington Council. This is from a copy of a letter regarding a Joint Local Inquiry into an application by the former Lymington Borough Council to carry out coast protection works involving the construction of stone and concrete tripod revetments at Barton Cliff below the golf course and east of Becton Bunny. It gives the statement of the Inspector and is authorised by the Secretary of State. The Inspector said: "1. Bearing in mind the above findings of fact I am of the opinion that the construction of the proposed sea defence work would defeat the purpose of notifying the Barton Cliffs as a Site of Special Scientific Interest whose international importance as demonstrated by the support given to the case by the Nature Conservancy Council by geologists and others from all parts of the world. Also I am not satisfied that the works proposed would be more than a short term palliative and it seems probable that further remedial measures would be needed in the future.. 2 (unreadable few lines of the copy)...obscures the lower sections. The marked contrast between protected and unprotected cliffs (particularly in the most important sections) is such as to convince me that the proposed development would seriously diminish if not eliminate, the value and purpose of the SSSI. It would clearly be contrary to the provisions of the development plan and hence is unacceptable... 3. The history of coastal protection in Christchurch Bay seems to have been one of piecemeal construction of groynes and revetments, followed by small additions to protect the previous works. This has resulted in starvation of beach sediment on the down-current (eastern) end of any works and consequent severe cliff erosion. The likelihood is that the works covered by the application would merely displace the area of intense erosion to a point further eastwards and reduce the supply of protective beach material. 4. In view of the great importance of the SSSI to geology and the absence of valuable building land or property in the threatened area (only one green on the golf course might be affected and it is already very close to the cliff edge), I consider that planning permission should not be granted to the present proposals and that coastal protection in this area should be studied in a general survey by a body specialising in that subject. It is highly desirable that small lengths of sea defences should not be built until the outcome of such an investigation is known, but it this proves impossible, only protective measures which do not conflict with the geological requirements of the SSSI should be undertaken. From the evidence adduced, it seems to me that the proposed scheme is of doubtful merit, and other methods should be considered. 5. The Assessor, Dr. E.C. Freshney, agrees with my conclusions... The Inspector recommended that planning permission should not be granted." ... This continues with further comments of the Secretary of State and which are generally in agreement with the Inspectors conclusions. Planning permission is refused.

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Storms and Sea-erosion


Major and damaging storms occur, then, at fairly distant intervals of time, with relatively little happening between. They are particularly damaging to the Barton and Highcliffe area if they are from the southwest, where there is the greatest fetch. The coast is fairly well protected from the southeast by the Isle of Wight, and the fetch from the south is not so great as from the southwest. Of course, iff the storms coincide with high spring tides then the likelyhood of rapid coastal retreat is greater.

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Recession Rates - Barton, Highcliffe, Hordle and Elsewhere

The following table provides some additional data on coastal recession at Barton and elsewhere. It is mostly from the classic work of Dr Max Barton. Most of the Barton (1973) data is only estimated approximately from fig. 3 in that paper. The original diagram should be consulted for precise information on Christchurch Bay coastal recession. It provides plots of recession for toe and top of the cliff at six localities: Highcliffe Castle, Beacon Lodge, Highcliffe Car Park, Lob's Hole, Barton Cliff (west) and Barton Court. The information is based on Ordnance Survey 1:2,500 maps from 1869 to 1959 with aerial photographs for 1947, 1957 and 1966.

The Barton recession seems to be close to a metre per annum at maximum. It is interesting to note, however, that coastal recession more extreme than at Barton, and probably the greatest in the region, occurs at Hurst Castle Spit (Nicholls and Webber, 1987). Here it has attained 3.5m per annum from 1968 to 1982. The construction of sea-defences at Milford-on-Sea from 1936 to 1968 have limited the sediment supply and are a major factor in this rapid retreat.

Recession Rate (m. /annum)
1982-1993 Naish, 2182-2183 0.74 Barton, 1998
1982-1993 Naish, 2186-2190 1.14 Barton, 1998
1982-1993 Naish, 2215-2225 1.14 Barton, 1998
1982-1993 Naish, 2230-2235 1.71 Barton, 1998
1982-1993 Naish, 2245-2250 0.94 Barton, 1993
1982-1993 Naish, 2260-2270 0.60 Barton, 1993
1869-1966 Beacon Lodge, Highcliffe 0.23 (cliff toe) Barton, 1973, fig. 3
1869-1966 Lobs Hole (Naish) 0.52 (cliff toe) Barton, 1973, fig. 3
1869-1966 Barton Court 0.86 (cliff toe) Barton, 1973, fig. 3
1869-1966 Barton Cliff, West 0.96m (cliff top) Barton, 1973, in text
1960s Barton cliffs - general 0.6-0.9m Wright, 1998
1867-1968 Hurst Castle Spit 1.5m Nicholls and Webber (1987)
1968-1982 Hurst Castle Spit 3.5m Nicholls and Webber (1987)
. . . .

West of Chewton Bunny the beach was seriously depleted from 1960 onwards according to Barton (1973) , referring to Wise (1963). Erosion of the undercliff toe commenced until stopped by the construction of the revetment in 1967-1969.

East of Chewton Bunny, that is to say, on the main stretch of cliffs fronting Barton-on-Sea, there had been only limited and localised build up of beach material by the 1970s (Barton, 1973). The result was major erosion here, with the cliff top recession reaching its maximum of 93.6 m in 97 years at Barton Cliff, West (i.e. west of Barton Court). Here with a recession rate of 0.96m, almost a metre a year, a serious problem existed. There was little beach material, wet collapsing, clay cliffs and a piece of coast unprotected by Hengistbury Head from southwesterly storm waves.

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Degradation to the Ultimate Angle of Stability

Generally the retreat of the cliff toe and cliff top in the Barton area have been more or less parallel (Barton, 1973, fig. 3). Stopping the erosion at the toe would not, however, prevent the cliffs from degrading with the cliff top still retreating. Water supplied through the Becton Sand (Barton Sands) and Plateau Gravel facilitate cliff collapse. If marine erosion ceases and nothing further is done the cliffs will slowly degrade to a stable slope with an ultimate angle of stability. This angle is likely to be low. It is attained in an exponential relation involving considerable movement over the first decade with final stability being reached only after several thousand years (Barton, 1998). Collapse of much of the greensward above and accumulation of colluvium on the former cliff area would eventually produce this gentle seaward slope. Sea defence works at Barton, in addition to protection of the toe, also involve drainage schemes and sheet piling on the undercliff, to try to stabilise the cliffs. A relatively stable situation has been achieved at Highcliffe where there is little bedrock exposed and the former cliff is mostly covered by colluvium (Barton, 1998).

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Sea Defences - Downdrift Problems

In the direction of longshore drift away from sea defences there is often a shortage of beach material. This can result in erosion in another area. As Bray and Hooke (1998) pointed out "major cliff segments at Highcliffe, Barton and Milford have been stabilised and protected with consequent loss of sediment supply. Associated shoreline structures and large rock groynes have intercepted beach drift and caused fragmentation of the natural littoral transport pathway. These practices have caused a downdrift sediment deficit that has depleted Hurst Spit, which nevertheless continues to lose material offshore. The spit has become increasingly susceptable to overtopping and recent surveys have shown a major acceleration of recession compared with historical rates. Only continuous short term remedial works culminating in a major replenishment scheme in Autumn 1996 have prevented its destruction. The replenishment is unusual in that it is intended to dredge the fill material from the Shingles Bank. Such actions are not normally permitted so close inshore, or in such shallow water due to fears of adverse shoreline impacts. In this case the fill can be expected to return to its point of origin, so the scheme would constitute a recycling of material within a limited part of a single process system and wider impacts should be minimal. It is an example of geomorphological compatible solution based on systems understanding. The alternative of permitting natural cliff inputs to resume updrift is not presently feasible due to the high concentration of cliff top properties that would be put at risk."

Hurst Castle Spit will be discussed separately in a forthcoming webpage. An interesting sideline to this is that the end of the Spit contains numerous worn specimens of the large gastropod Clavilithes macrospira from the Barton Clay. Dr R. Nicholls and myself have collected large numbers of these, and illustrations and details will given in a webpage later. These Barton fossils at the end of the Spit clearly show that much of the material of the Spit has come from the Barton cliffs, where the Plateau Gravel has supplied the subangular flint pebbles. This material has not been able to pass sea defences for many years now and presumably is relict material from when the coast was in a natural condition.

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Conservation versus Protection

For various reasons, different people are likely to have different and quite strong views on dealing with this coastline. Some people will want to control and alter the cliffs drastically by civil engineering methods; some will want to use conservation methods with minimal civil engineering; some people will want to conserve cliffs in natural state but to limit future housing development so that it does not approach the cliffs (note the value of the greensward at Barton in saving most of the housing from immediate crisis).

Dr M.E. Barton (1998) has discussed this matter, and discussed the possibility of controlling the cliffs but with a reduced erosion rate. He wrote that there is a growing conflict between geological conservation bodies seeking to retain the natural state of the actively eroding cliffs and local authorities (encouraged by their residents) wishing to prevent marine erosion and cliff-top recession. Many soft rock cliffs provide excellent geological exposures, affording opportunities for research and education, and sometimes unique exposures of internationally important stratotypes. English Nature (formerly the Nature Conservancy Council) have vigorously campaigned for such cliffs to be left in an actively eroding state so that geological exposures may be renewed and freshened up (McKirdy, A.D. 1987). Barton argued that the processes and pattern of natural cliff degradation are also important for geomorphological research and education and provide a further argument for conservation of the eroding cliff line.

The argument against conservation is that the inevitable landward recession destroys buildings and land. Public pressure is exerted on local authorities to protect cliffs from sea erosion in order to stop cliff-top recession. It is rare for it to be completely stopped but this seems to have happened for about a century at the more sheltered cliffs of Bournemouth, and perhaps, in certain circumstances it is possible in other areas of soft strata. The amount of public pressure probably depends on how built-up is the area, and the land north of the cliffs at Barton, and parts of Highcliffe is now quite suburban. Obviously, it also depends on how close the housing is to the cliffs and on the usual rate of coastal recession (fairly rapid here - details will be given below). It is naturally very reasonable and understandable to urge for the construction of sea-defences if a person were to possess a house close to a retreating cliff of soft strata. Fortunately, most of the houses at Barton and Highcliffe are well-separated from the cliff by a stretch of grassland or forest, and are under no immediate threat, but there are a few which are close.

Even if sea-erosion is halted the cliffs may degrade by landsliding, with the cliff top still retreating. Slope stabilisation works then need to be installed on the cliffs. This and the toe protection works will lead to loss of geological exposures and inhibit the geomorphological processes (Barton, 1998). Such works will be in direct conflict with the process of conservation but will be popular with residents who give first priority to protection.

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What is the Future of Christchurch Bay?

Will the sea-defences be maintained and replaced as and when necessary to hold either the existing line or one a short distance landward of it? Pressures from residents might require this. Of course, unlike natural processes, this depends on government policy, local management policy and the availability of finance to undertake this. It seems unlikely that in the short term the sea defences will be abandonned to their fate but there is no guarantee that money will always be available for maintenance or costly major repair.

What would happen in the unlikely case of a long term decline of sea defences? How would the coast return to a relatively natural cliff environment? Would the coast recession still be slowed in the formerly protected areas by the sea-defence relics or it would it 'catch up' so that the long-term average is unchanged? In other words, would the coast straighten (in relative terms to the pre-defence pattern) or would it retain projections and bays?

What might be the effects, if any, of the recent increase in the rate of sea-level rise, now doubled to about 4mm per annum (Cundy, 1994; Cundy and Croudace, 1995) ? Would sea-level a few centimetres higher have much effect? Think about a possible increase in the frequency of winds from the southeast rather than the (normal) southwest, perhaps as some effect of climate change. There is no special reason to think that this might happen, but it warrants brief consideration. If such a change did occur it would have a drastic effect on Christchurch Bay because the coastline here is relatively stable only in relation to dominant southwest winds. The point is mentioned because Calshot Spit and perhaps the Chesil Beach have been broken by southeast winds according to 16th Century reports. The possibility of the effects of great hurricanes like that which at the beginning of the 18th century changed the mouth of the Beaulieu Estuary, should not be forgotton.

Think about the Barton, Highcliffe and Hordle Cliff area, not just in insolation, but consider the effects of changes and possible changes in the upstream, beach supply area (Mudeford, Hengistbury). Supposing, for instance, there was major erosion at Hengistbury Head which protects some of the Highcliffe coast from the southwesterly winds. Would erosion increase at Highcliffe or, instead, would that area once again benefit from a large influx of beach material from Hengistbury and Bournemouth? Think too about the consequences and possible further consequences of sea defences on the downdrift area (Milford, Hurst Spit). Note that the dominant areas of erosion have been changed by artificial action and this could happen again.

No prediction is made here, only background information is provided, and the reader is left to weigh up this matter from the limited information given here and the much more extensive, published literature . See particularly the work of Barton and the book by Hooke (1998) , entitled "Coastal Defence and Earth Science Conservation", and the various papers within it. The book provides valuable technical information and a variety of views and procedures which are not all discussed here. If you are interested in the topic, try to formulate your own views on the controversial matter of the future of coast erosion and sea-defences in Christchurch Bay.

Footnote: Long term effect of the limestone blocks.

As mentioned in the main text, sea defences at Barton may be regularly maintained and repaired when necessary for many decades. Even if, however, as is quite likely in the long term, the sea advances landward, then new defences may be built landward, still effectively retarding further advance of the sea. Major repair has already taken place at Barton after the 1970s landslide collapse, and it seems unlikely that they would be left to decline completely. It is possible, however, that a very great hurricane and/or landslide was to seriously damage them and for whatever reason no repair or landward replacement took place. Most important then would be the imported Portland and Basal Purbeck stone blocks because these would survive for quite a long time after much of the renourishment gravel has gone. They would form a rocky-shore type of coast, resembling some parts of the Isle of Portland or Purbeck and would still retard erosion to some extent even at that stage (see the effect of natural Portland Stone blocks at Houns-Tout, Chapman's Pool, Dorset). Eventually though, the boulders will sink (like the gun emplacement - see below) and leave just as a linear rocky shadow under the water, like the remains of the old Southbourne promenade or the old sea-wall at Jordan Cliff, Weymouth. Such a scenario is unlikely but there is no doubt that, whatever happens, the limestone blocks are probably of much long-term value in reducing cliff retreat below that of the undefended average.

Note also, as a matter of interest, that stone blocks have been removed from the region as well as added. Hengistbury Head formerly ended to the east in a mass of smooth brown, ironstone blocks, forming a reef-like feature. These Beerpan Rocks consisted of siderite nodules from the Hengistbury Beds (possibly equivalent to the Lower Barton Clay). Although some remain at the present eastern beach, a large proportion were removed for iron ore in the 19th century. Changes in the form of Mudeford Spit and the Run have been blamed on this form of quarrying (Burton, 1931) . The removal of the rocks may, indeed, have let sand round the headland from Poole Bay. In addition, though, a small amount of wave protection to Christchurch Bay has been lost by this action, in addition to natural protection to Hengistbury Head. There is now a large groyne at the southeastern end of Hengistbury Head which prevents much erosion and also holds back Poole Bay sand and shingle from reaching Christchurch Bay.

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Christchurch Bay - Offshore

Palaeovalleys of Velegrakis et al. 1999 in Poole and Christchurch Bays

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Reclamation to Avoid Coast Erosion.

Linaker's Suggested "Oceanus" Scheme.

Linaker's scheme for reclaiming Christchurch Bay, Hampshire and Dorset, southern England

The "Hostile Natives" of Barton give the "Bronx Cheer"!

(Edward E. Linaker article, 1981 - extract.)

"The writer was asked to address a meeting on the project at the local community centre. Expecting to be hailed as a possible deliverer - for the "rotten" or Barton Clay cliffs are subject are subject to ceaseless erosion, with the cliffs dangerous and parts of the beach sometimes inaccessible through landslides, and houses near the cliff edge endangered, the instigator of the project "Oceanus" went to the meeting only to be met with a very cool reception. The locals wanted nothing to do with the scheme, only a few with houses near the receding cliff edge offering any support. The suggestion of a new town construction had clearly been a cardinal error and the "Ocean Tramp", a shy man and no orator, gave the locals best, informed the Dredging contractors and other potential supporter of the public meeting, pointing out that they would get the "Bronx Cheer" if they tried to push the development against the wishes of the hostile natives."

Large scale protection of the whole bay has been considered, in a suggested plan of 1966, put forward again by the originator, Edward E. Linaker, in 1981 ). The above extracts are from his 1981 publication comes the above extract. His proposal was to reclaim the whole bay and construct huge marinas, car parks and fish farms offshore. Roads would be built on the breakwaters, with an approach roads coming in through Hengistbury Head and Hurst Castle Spit.

Linader seems to have wanted to develop two great sea-walls and peninsulas, swinging out from each end of the bay. These would provide huge car parks and adjacent marinas.

Obviously, in some respects, ahead of his time, Linaker (1981) seems to have been the first to propose a type of offshore wind farm, off the Dorset - Hampshire coast, although he planned to use it for pumping freshwater rather than producing electricity. He said:

"wind power at average velocity along the ten mile breakwater could if harnessed provide more than sufficient power for this purpose ...."

Linaker also pointed out in 1981, that with increased local oil exploration, his scheme would be of value in reducing accidental oil pollution.

"Perhaps with the latest threat of oil rigs off this stretch of coast, the citizens of the coastal towns might, if tactfully approached, consider a breakwater out to sea and development along the lines suggested an acceptable alternative to possibly oil polluted beaches."

"Protection of the existing beach from oil slicks either from wildcat oil rig gushers or from tanker wrecks."

While this might solve the coast erosion problem once and for all, its environmentally damaging implications were clearly obvious at the date it was proposed. At the public meeting on the scheme there was, as recorded, a cool reception from the local people.

Considered at the [then - when written] present, later date of 2013 the view of the area is slightly different. Now it is known that there are possible potential oil fields much nearer the coast (Beacon and Hurst Spit Prospects). However, they could be reached, if necessary, by ERD (Extended Reach Drilling) from the present coast and do not need expensive artificial peninsulas. It is also of interest that the main depocentre of organic-rich, Jurassic source rocks is offshore from Barton-on-Sea. It starts about 10 kilometres to the south, so it is a long way south of Barton, and not too far from the Isle of Wight. Linaker's hypothetical reclamation scheme would not extend far enough, to the south to reach the main depocentre, should it, in any case, ever be necessary to approach it. So the major reclamation scheme seems extremely improbable, even if considered in conjunction with oil exploration, windfarms, tidal energy schemes, fishfarms, marinas or anything else.

Linaker (1981) thought that foreign financial capital might be available for "Oceanus", the great construction project. He considered that low interest rates (present now but not in 1981) were needed. Perhaps it has some similarities to the Dubai reclamation scheme.

One cannot predict the future, but the "Oceanus" scheme is probably an impossibility both in terms of cost and in terms of public acceptance. I am not aware that there are any serious proposals for it now. Was it just an extreme and impractical pipe-dream? This might be a suitable discussion point for students.

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Comparison of the Barton Sea-Defended Coast with other Coasts

It is interesting to compare the defended Barton section this with the cliffs between Highcliffe and Friars Cliff. Here vegetation including (planted) trees is well-developed, even where there are no significant sea-defences. The reason is partly because that stretch is not subject to the same severe wave action. The prevailing wind and wave direction is from the southwest and Hengistbury Head to some extent protects the area, west of Highcliffe, but not Barton. Changes in position of the Run at Mudeford (Burton, 1931), and subsequent supply of sand to the beach have probably reduced coast erosion in this area. Although once significantly eroded, the area near Highcliffe Castle has been fairly stable for about 70 years. This stability has allowed vegetation to flourish. The Barton sea defences have been in place for about 30 years but as noted above various factors, including continuing remedial work, seem to prevent this becoming a vegetated cliff of fairly natural appearance.

Compare the Barton section with the cliffs at Bournemouth. At the foot of the Bournmouth cliffs is a very strong, Pubeck limestone-faced promenade and road. The cliffs have, unfortunately lost most of their yellow sandy appearance but they are quite well-vegetated with bushes. Sea defence at Bournemouth is much easier than at Barton. This is partly because the coast is protected from the southwesterly storms by the projecting Isle of Purbeck. Another factor is that the sandy Eocene cliffs were once sufficiently eroded to supply much beach sand and most of this has remained for a long time. When it started to diminish in the last few decades, the beach has been renourished by pumping in sand from the sea-floor, using barges. The Bournemouth cliffs are not generally of slumping clay and sand horizons allow water to seep away to the chines and beaches without problems. The sea-defences at Bournemouth are about 85 years old and some of the longest surviving in the region. They did not start to suffer serious problems by loss of beach material until about 65 years into their life, but, as noted, that was dealt with.

We will now compare the Barton cliff area with Southbourne, east of Bournemouth. This is more comparable to Barton because, here, the effect of the protection from the Isle of Purbeck is less. A little further east, at Hengistbury Head, erosion has been a very serious problem. Southbourne has at the present a promenade, like that at Bournemouth, and it is holding against sea attack, but is only about 40 years old or less, it is very strongly built on the Bournemouth pattern, and the locality does not have the problem of extensive clay cliffs like those at Barton.

A previous sea-wall and promenade was built at Southbourne from 24th September 1883 to 1st August 1885. The following notes are based on Young (1989) who provides interesting detail regarding the early coastal development here. The cost of this early wall and promenade was then was 15,000 pounds [sterling] and it was at the time the only such development in Poole Bay, preceding the Bournemouth undercliff drive. The Southbourne promenade consisted of a curved roadway forty feet wide, with a pedestrian pathway sixteen feet wide on the seaward side, the whole entending for about a third of a mile. The sea wall rose to about 8 feet above beach level, with foundations from six to nine feet below it. The lowest portion was nearly seven feet thick throughout, and the superstructure varied in thickness from seven feet at the bottom to four feet at the top. There was a central approach road with an easy gradient for carriages. Six large houses were erected on the drive, as a terrace. In 1887 a pier was built extending about 800 feet into the sea.

This construction seemed very substantial, but it was hit by a storm of great severity only a few years later. After Christmas 1900, the closing days of December brought gales, and a storm of exceptional ferocity swept over the country on 18th December. At Southbourne the sea wall was breached and the pier damaged severely; further storms early in January extended this damage. The promenade was not beyond repair but the Land Company responsible could not afford the cost and collapsed financially. The pier was dismantled, the houses on the remains of the promenade demolished. The sea destroyed what was left of the sea wall and promenade and cut the cliffs further back. Photographs in Young (1989) suggest that the cliff was about 35m back from the line of rocks marking the sea wall of the promenade. Considering the original width of the promenade the cliff retreat was probably about 18m in 30 years or about 0.6m per annum. The modern promenade at Southbourne has, for the present, apparently stopped the retreat. It is likely that in the long term the promenade will be maintained, repaired and the beach renourished at intervals so as to hold the present position, but, of course, the sea could to some extent resume its natural work. The history of destruction of the old Southbourne sea defences illustrates the significance of occasional severe storms (once in a hundred or once in two hundred year storms?) and of the necessity of having substantial finances for repair work. Incidently, the remains of the old promenade could still be seen as offshore rocks in relatively recent times, and more precise data on coastal recession might be obtainable by anyone interested in surveying the details of the coast here.


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EXERCISE - Assessment of Unknown Cliffs

Exercise on aerial photograph of cliffs of an unknown locality

An exercise is set above. This is a student exercise suitable for someone who has studied the Barton cliffs. This aerial photograph shows an area selected for having some similarity to the coast at Barton-on-Sea. The questions above can be answered to some extent without knowing where this is and without having been there.

Further exercises are possible regarding measures for coastal defence and drainage. If necessary the place can be found, but most of the exercise above can be completed in ignorance of the exact locality.

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More coast erosion? Continue eastward along the cliffs to the Hordle Cliff Section?


Go west to Hengistbury Head Hengistbury Head?

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I am particularly grateful to the staff and students who have accompanied me on the Barton and Highcliffe coast sections and entered into discussion about the strata and coast. I thank Professor Max Barton, Professor Robert Nicholls, Professor Ken Collins, Sarah Snowdon and Sue Collins, amongst others. The Barton specialist Paul Clasby has been very helpful and Caroline Clasby has joined me on field work on this coast. My grandson, Daniel Bentley, has enthusiastically assisted. Southampton University Computing Services have generously provided webspace for running this site, and this is much appreciated. I thank Vince for accompanying me on field work at Becton Bunny in 2017. I am particularly grateful to the Director and staff of the The Channel Coastal Observatory for permission to use their excellent, vertical, aerial photographs. I am obliged to Steve of the local paragliding club for providing me with some fine oblique photographs taken from the air. I thank Mr and Mrs Page of Barton-on-Sea for kindly providing me with photographs of the early stages of development of the upper cliff, landslide of Hoskins Gap West in May 2008. I thank Alan Morton, the palaeontologist with a remarkable webpage on Eocene fossils, for 1960s photographs of Barton-on-Sea, collapsing cliffs. I appreciate the help of others, unnamed here who have assisted me from time to time over more than half a century.

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Bibliography and References

Please go to Highcliffe, Barton and Hordle Cliff - Bibliography and References .

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See also associated webpages:
Barton-on-Sea and Highcliffe - Geological Field Guide

History of Coast Erosion and Sea Defences at Barton-on-Sea and Highcliffe

Highcliffe, Barton and Hordle - Bibliography .

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|Home and Contents - Geology of the Wessex Coast |Barton - General |History of Coast Erosion at Barton-on-Sea, Highcliffe and Christchurch Bay |Highcliffe, Barton and Hordle - Bibliography |Hordle Cliff |Hurst Spit

Copyright © 2020 Ian West, Tonya West and Joanna Bentley. All rights reserved. This is a purely academic website and images and text may not be copied for publication or for use on other webpages or for any commercial activity. A reasonable number of images and some text may be used for non-commercial academic purposes, including field trip handouts, lectures, student projects, dissertations etc, providing source is acknowledged.

Disclaimer: Geological fieldwork involves some level of risk, which can be reduced by knowledge, experience and appropriate safety precautions. Persons undertaking field work should assess the risk, as far as possible, in accordance with weather, conditions on the day and the type of persons involved. In providing field guides on the Internet no person is advised here to undertake geological field work in any way that might involve them in unreasonable risk from cliffs, ledges, rocks, sea or other causes. Not all places need be visited and the descriptions and photographs here can be used as an alternative to visiting. Individuals and leaders should take appropriate safety precautions, and in bad conditions be prepared to cancell part or all of the field trip if necessary. Permission should be sought for entry into private land and no damage should take place. Attention should be paid to weather warnings, local warnings and danger signs. No liability for death, injury, damage to, or loss of property in connection with a field trip is accepted by providing these websites of geological information. Discussion of geological and geomorphological features, coast erosion, coastal retreat, storm surges etc are given here for academic and educational purposes only. They are not intended for assessment of risk to property or to life. No liability is accepted if this website is used beyond its academic purposes in attempting to determine measures of risk to life or property.

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Dr Ian West, author of these webpages

Webpage - written and produced by:

Ian West, M.Sc. Ph.D. F.G.S.

at his private address, Romsey, Hampshire, kindly supported by Southampton University, and web-hosted by courtesy of iSolutions of Southampton University. The website is an unfunded, private activity, and does not necessarily represent the views of Southampton University. Any field activities shown are not necessarily those of any specific organisation and mostly represent private field work.