West, Ian M. 2019. Studland - Tertiary Cliffs and the Agglestone; Geology of the Wessex Coast of southern England. Internet site: www.southampton.ac.uk/~imw/Studland-Tertiary.htm. Version: updated, 13th April 2019.
Studland - Tertiary Cliffs Field Guide

By Dr. Ian West,
Romsey, Hampshire

and Visiting Scientist at:
Faculty of Natural and Environmental Sciences,
Southampton University,
Webpage hosted by courtesy of iSolutions, Southampton University
Aerial photographs by courtesy of The Channel Coastal Observatory ,
Website archived at the British Library

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Other Webpages on Studland and Adjacent Area:

|Studland - South Haven Peninsula (the main page on Studland) |Studland Peninsula - Poole Harbour Side |Brownsea Island Geology |Studland - Tertiary Cliffs (this webpage) |Harry Rocks, Ballard Point |Swanage Bay |Studland and Harry Rocks; Bibliography |Swanage Bay |Sandbanks Peninsula |Petroleum Geology of the South of England (re Wytch Farm Oilfield)

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

On Studland Beach, Dorset, looking NNW towards Redend Point with coloured sands of the Broadstone Sand Member of the Poole Formation, in 2014

On Studland Beach, Dorset, an introductory general view looking southeast towards the Chalk cliffs and Old Harry Rocks, late afternoon on the 1st April 2019

Studland Beach, Dorset, southern part, looking south towards the complex junction of the  top Cretaceous Chalk with the Eocene, London Clay and Poole Formation, for details see BGS Swanage geological map></A>
The junction of the Eocene strata with the underlying Cretaceous Chalk at the southern end of Studland Bay is not simple. The complications are not visible in the photograph above because some of the cliff is covered with vegetation and some is exposed. The latest British Geological Survey map, Swanage, 1:50,000, Solid and Drift Geology, Sheets 342 (east) and 343, published in th year 2000, shows a faulted junction of Eocene strata with the Chalk. For this locality the outcrop details are shown substantially different from those shown on older Swanage map. You might need to enlarge the appropriate section to gain a full understanding of the (interpreted) structure. (incidently, note that the .

Coloured sandstone in the Broadstone Sand Member, Poole Formation at Redend Point, Studland, Dorset, with the old, tilted concrete pillbox, 5th June 2014


Coloured sandstone in the Broadstone Sand Member, Poole Formation, Eocene, at Redend Point, Studland, Dorset, 5th June 2014


Redend Point of the Broadstone Sand Member, Poole Formation, Eocene, Studland, January, 2003

The Agglestone, Studland, Dorset, from the south, 2004

Iron-staining in the Broadstone Sand Member, Poole Formation, close-up, Redend Point, Jan 2003

Click on images for large, high resolution versions!
(do not use browser zoom on the low resolution versions)

1.1 INTRODUCTION - Location and Access

Isle of Purbeck Location Map

Studland is a small attractive village situated on the east coast of the Isle of Purbeck, north of Swanage and the Chalk downs, the Purbeck Hills. A major Chalk promontory with Harry Rocks extends eastwards, just to the south of the village and as continuation of the Purbeck Hills. Close to the village are cliff exposures of Eocene strata, including the Reading Formation, the London Clay and the "Bagshot Beds" (or now Poole Formation of the Bracklesham Group). The latter include coloured sands at Redcliff Point, resembling those at Alum Bay, Isle of Wight, although on a smaller scale. To the north is the scenically attractive, South Haven Peninsula of sand dunes, lakes and heathland, much of which has built up in an area of shallow sea since the 17th Century.

Most of the Studland area of geological interest belongs to the National Trust. The National Trust car park at Middle Beach provides access to the north side of Redend Point. There are toilets and a cafe there. Note that except at low tide it is not possible to walk (at least without wading) around Redend Point. The main part of the section is a short walk to the south but the National Trust car-park (map ref: SZ 038825) adjacent to the Bankes Arms pub, Manor Road, Studland is most convenient and the beach is just down the small valley or chine from here. There are toilets (rest-rooms) close to this car park.

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1.2 INTRODUCTION: Geological Maps

It is important to note that for an area such as Studland there have nomenclatural changes from the old series of BGS geological maps to new Bournemouth and the new Swanage maps. Re regard to the Chalk note that the Portsdown Chalk Formation is in the zone of Belemnitella mucronata. The older literature uses the zonal name, as the Formation name is relalively new. This should not cause much problem at Studland, and in webpages dealing largely with the Chalk, a conversion table is provided.

The Palaeogene or Tertiary strata are not quite so easy to deal with. The greatest change has been the replacement of the old "Bagshot Beds" with the name Poole Formation and an important subdivision of this into members. New maps in this webpage, use of course, the new scheme, but some parts of older maps are also reproduced (and may sometimes be more readily available because of copyright matters). There should be no problem in using an old matter in introductory terms, if the reader has some familiarity with both old and new nomenclatures. The experienced geologist will know whether an old or new scheme is being used.

[This website will be progressively updated to use the new scheme, but old terminology may persist in parts until time permits correction.]


A simplified geological map of the South Haven Peninsula and Studland, Dorset, based on modern geological maps, but completely redrawn, 2014


This simplified geological map above has been completely redrawn, with appreciable modifications. It is based partly on the data shown in the Bournemouth Sheet (No. 329) of 1991, and partly on the data shown in the Swanage Sheet (No. 342 east and 343) but does not show the Ordnance Survey data which is present on those maps. All boundaries have been shown with solid lines, unlike the BGS map, so distinction is not made between proven and postulated geological boundaries. The map is very simple in structural terms with some faults in the southernmost part and some minor synclines and a corresponding anticline. Away from the southern boundary area (i.e. at and near the Chalk) the structure is simple with overall a very low dip towards the north. Note that the map shows not just formations but also members. Some of these are very thin, just a few metres and they are variable in thickness. This particularly applies to the Poole Formation. This Eocene unit is a product of sedimentation in the hot Poole Delta. Channels within this delta were irregular and moved in position from time to time. There were lakes, and probably crevasse-splays in places. Abandoned channels in the local Eocene sediments were often filled with plant-rich clay plugs. Inevitably in such an environment, extremely reducing conditions were locally developed. Pyrite was worked economically in the past from the Poole Formation on Brownsea Island. There has been extensive oxidation of pyrite in the Parkstone Clay Member. This has resulted in brown, ferruginous cementation of the Parkstone Sand Member. The most obvious and well-known example of this is the Agglestone Rock and the nearby Puckstone. Similarly the Broadstone Sand Member shows iron-cementation at Redend Point. Here, too, there are pyritic pipes, now oxidised (above sea-level) to limonite, and coloured sands, with the colouring the result of the state and type of iron oxidation.

A special feature of the area, and shown on the map above, is the absence of the Reading Formation, with London Clay (very sandy) faulted against Portsdown Chalk.

The sand dunes and sand beach deposits of the South Haven Peninsula are discussed in the webpage: Studland - South Haven Peninsula etc.

Incidently, note that the BGS maps show "Head" associated with and mainly to the west of the dune ridges. Most Head is of Pleistocene origin, but there is a question about these particular deposits because of their close association with Holocene sand.

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1.2 INTRODUCTION - Geological Maps - older

The 2000 edition of the 1:50,000 British Geological Survey Map, Swanage, Sheet 343 and part of 342, Solid and Drift - including the Isle of Purbeck and Lulworth Cove

The British Geological Survey map, 1:50,000, Solid and Drift, 2000 Edition, Swanage Sheet, 343 and part of 342, is well worth purchasing. It can be obtained from the British Geological Survey website and is very inexpensive, costing only 12 pounds sterling. The map shown above is the new edition of the year 2000. It is different in some respects from older editions. The reader should note though that much of the nomenclature is relatively new to some extent this is just a language matter. If you already know the stratigraphical sequence in the old terminology, it is generally quite easy to translate to the new language. However, and this is the main benefit, much more detail is shown. The Tertiary strata, in particular are well-subdivided in the manner of the 1991 edition of Bournemouth Sheet, 329. A major advance, which started with that map, is the subdivision of the Eocene Poole Formation. These Tertiary stata are very difficult to correlate and the BGS has advanced their detailed mapping far beyond that shown on the older maps.

The mapping of the Chalk and other parts of the Cretaceous in the area of Harry Rocks, Ballard Point and Studland is broadly similar on old and new editions. The greatest change with regard to the junction of the Cretaceous and the Tertiary in the southwestern corner of Studland Bay. New faults are added on the new edition. The Reading Beds are not shown and the sands in the cliff are shown as a downfaulted block of Poole Formation Sands. (The topic will be discussed further when the Studland - Tertiary Cliffs webpage is revised).

If possible, compare and contrast the two editions of the map when studying a particular area. Thus you will able to see the benefit of newer, more detailed work in a historic context and be able, if necessary to enter into discussion over details of interpretation. You will also be able to grasp both nomenclatural schemes.

The old 1895 geological map of Swanage, Dorset, sheet 343, - see also the new 2000 edition BGS geological map of Swanage, sheets 342 and part of 343

Location and geology map, 1907

Location and geology map, after Braye, 1890

Geological Map of the Swanage and Studland Area, after Braye, 1890, enlarged detail

Also shown above are various old geological maps of the area. The old one from Braye (1890) is hand-painted. These provide an introduction to the geology and general topography of the area. Although the details of the town and roads have changed the geology shown here is basically correct. It is useful to obtain the current geological map of the British Geological Survey (formerly the Institute of Geological Sciences), Geological Map - Swanage, Sheet 343 and part of 342. Solid and Drift Edition. 1:50,000. There is an accompanying explanatory memoir by Arkell (1947). The present map - sheet 343 and 342 is broadly similar to the maps here but the details of the faults are different. The main feature is that the Cretaceous Chalk forms an east-west trending ridge, the Purbeck Hills.

The most suitable topographic map for the area is the Ordnance Survey, Outdoor Leisure Sheet 15, Purbeck and South Dorset. Scale 1:25,000.

Melville and Freshney (1982) have provided a good brief introduction to the area, that is less detailed and technical than Arkell's memoir, but which is very useful. The field guide by House (1993) is recommended.

Map - Geology of the Isle of Purbeck

For the sake of interest here is another old map. Here the Geology of the Isle of Purbeck is shown on part of a map modified from Damon (1884). Modern changes in the geological mapping of the area have only been of detail. Some place names have changed since Victorian times.

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2.1-1 Tertiary Stratigraphy

A chart showing lithostratigraphic schemes for the Palaeogene strata of the Bournemouth and Poole area, including Brownsea Island and Barton-on-Sea


The Palaeogene sequence of strata in the Bournemouth-Poole area, Dorset, UK, modified after Bristow et al.

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Studland Tertiary Cliffs - General

See also:

Harry Rocks and Ballard Point webpage. This is a continuation of the present webpage and considers the southern Chalk cliffs of Studland Bay, together with the coast beyond to the south.

Arkell's section at South Beach, Studland, modified

This old section is shown here with only minor modification.


Breccia of mudclasts above the Broadstone Sand Formation or Redend Sandstone, Poole Formation, South Beach, Studland, Dorset

A sequence of gently north-dipping strata at South Beach between the Chalk cliffs and Middle Beach has been given by Arkell (1947) .

An almost horizontal junction between the top of the Redend Sandstone of the Poole Formation and an overlying bed with mudclasts is visible in winter now when the vegetation has died back but was not taken into account by Arkell, so the original section might not be completely accurate. See further below some brief comments on the plant bed in the Broadstone Clay and other strata above the Broadstone Sand Formation ("Redend Sandstone").

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Stratigraphical Nomenclature

History of Tertiary nomenclature in the Studland Corfe area, Dorset


Middle Eocene succession including the

There is a significant difference in stratigraphical nomenclature between that used on the new BGS 2000 Geological Map of Swanage and in previous publications. Both the new terms and older terms are used in the account which follows. Few practical difficulties should arise from this because the table shown above will indicate the approximate equivalents. In spite of the creation of the new terms, the old traditional names such as the Reading Formation (or Reading Beds) are unlikely to be completely forgotten, and its equivalent, the West Park Farm Member may as yet be a relatively unfamiliar term to many readers. Take care with the "London Clay" because this name can be used sensu stricto as was general in the past or sensu lato as the new, extended London Clay Formation of the Thames Group.

The particular problem of "Bagshot Beds" sequence and terminology is dealt with to some extent in the right-hand diagram. This is based on an attempt to relate Arkell (1947) to the new Swanage Map (BGS, 2000).


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Reading Formation

On the 2000 Edition of the British Geological Survey Map, no Reading Formation is shown at Studland Bay. The lowest Tertiary strata is considered part of the London Clay Formation. The old edition does show "Reading Beds" in the southern part of the bay. These sands and clays are now regarded as part of the London Clay Formation.

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London Clay Formation

This greyish-brown clay of marine origin is mostly covered by landslips and slumps at South Beach. Some septarian nodules from it are sometimes visible on the shore. It was estimated by Arkell (1947) to be about 30 m thick in Dorset, much thinner than in the Isle of Wight where it is three to four times this thickness. Where the base is exposed it lies on a bed of well-rounded, flint pebbles. In the Isle of Wight it is quite fossiliferous.

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- The "Redend Sandstone Member" (Poole Formation, Eocene) and the Ferruginous Pipes

[Note: Redend Point is on a synclinal axis, bringing the Redend Sandstone Member down to beach level. See the recent Geological Map]

Redend Point, Studland, 4 March 2007, with Fort Henry above which was used in the 1940s by Churchill, Montgomery and Eisenhower

Redend Point, Studland, Dorset at low tide, February 2007

Erosional changes on the north side of Redend Point, Studland, Dorset, from 1925 to 2007

The Redend Sandstone of the Poole Formation is well-exposed at Rendend Point. This is a locality which is notable for the concrete observation post of Fort Henry on top of the cliff. Here Winston Churchill, Bernard Montgomery and Dwight D. Eisenhower watched the practice D-Day landings in 1943-4. Studland was a major area for wartime practice and activities involved use of Valentine swimming tanks, five of which are sunken off the beach. At times the sea was set on fire with fuel. Numerous mines and other explosive devices were present on Studland heath. 85,000 were removed after the war (Legg, 1984). Fort Henry is not always easily seen now and may be concealed by vegetation in the summer. Recent cliff falls and the cutting down of some trees have made it visible in winter.

Notice from the photographs above the extent to which erosion has increased here since 1925. The situation is more complicated than it appears. There was an original cliff line here which extended from Redend Point to the hill in front of (east of) Knoll House Hotel. The position of this cliff is obvious to the walker. Sand accumulated in front of this from the 17 century onward, so that there was initially a phase of natural reclamation from the sea. This was probably the start of the major sand accumulation of the South Haven Peninsula. Now sand starvation is being to take effect. Eventually the coast will be lost back to the old cliff line. Already there is some limited exposure of bedrock, the lignite bed, on the shore north of the cafe and toilets (as seen in March 2007). Erosion will continue in this area, although the rate at present is not very great. It is area of interest to observe during the progressive and slow sea-rise of global warming (about half a metre a century on present estimates).

View down to south beach with Reading Formation etc

View northward from South Beach, Studland, towards Redend Point

Redend Point, Studland, Jan 2003

Redend Point with collapsed pill box

Middle Eocene succession including the

Redend Point is a small headland of brown, reddish and yellow sandstone at the northern end of South Beach, as can be seen in the photographs above. It is the first rocky headland south of the South Haven Peninsula of sand. The sandstone is, in the older terminology, the Redend Sandstone. It is part of the Poole Formationof Middle Eocene age. A new terminology and correlation of the Middle Eocene has been given by the British Geology Survey in the new edition of the Swanage Sheet and in the Bournemouth Sheet and associated memoir. The diagram above indicates the probable position of the the Redend Sandstone in the new scheme. It seems to be part of the Broadstone Sand Member according to the map and the lignite bed above is the Broadstone Clay Member according to the new terminology.

The Redend Sandstone or part of the Broadstone Sand Member is of fluvial origin, and, as noted above, it underlies a bed of lignite. At the headland the sandstone is more iron-cemented than elsewhere and it forms a relatively harder rock in softer surrounds. In the top right photograph, above, the small promontory is seen from the shore of South Beach. Notice the contrast between the area in the foreground where trees and grass are growing next to the beach, thus indication negligible erosion, and the small cliffs of the headland, showing that erosion is taking place. The headland is therefore retreating and was probably once a more prominant feature.

(Incidently, in the top left photograph, notice the dark patches of sea where the Zostera sea-grass beds are present. Compare with the sea-floor map provided below.)

At Redend Point, northern side with Middle Beach, Studland beyond

Here we see an oil company field party wading round Redend Point from the north side, Middle Beach. Erosion is much more pronounced to the north of the headland, although the land here is composed of unconsolidated sand.

Eocene sandstone, Redend Point

Redend Point with Redend Sandstone, looking south, Jan 2003

Notice, in one photograph, the north-dipping joints (towards the right). On the beach, which consists of light-coloured sand from these beds and of subangular flint pebbles from the Chalk, are blocks of harder iron-cemented sandstone. Small caves are being eroded by the sea into the small sandstone headland. A short distance south of the little headland some resistant sandstone formed in the past a small stack seaward of the cliff-line. Compare the middle two photographs and have a look at some others. The left-hand one (from a colour slide) is old, probably from about 1980 or earlier. The right hand one was taken in January 2003. The stack has now fallen and there may other minor changes. The original presence of the stack is puzzling. The stack was in front of a forested slope instead of a vertical cliff that might be expected. How can this be explained?

Coloured Sands


Coloured sands in the Redend Sandstone of the Eocene, Poole Formation, Redend Point, Studland, Dorset, as seen on the 1st April 2019


Red-stained sandstone, Redend Point, Studland, Dorset

Iron-staining in the Redend Sandstone, close-up, Redend Point, Studland, Jan 2003

Red banks in the Redend Sandstone, Redend Point, Studland, Dorset

Redend Point is interesting because of the presence of coloured sand. Iron oxides have been reprecipitated in the sandstone at various horizons in an irregular manner that does not correspond to the bedding which dips gently towards the right (north). There is liesiegang banding that has probably originated when pyrite was oxidised and iron-bearing solutions moved out from the pyrite source. It is not clear as to why in most cases the colour, yellow or brown, is typical of limonite or goethite (Fe 2 O 3 .nH 2 O), but in patches the bands are represented by a red iron oxide like hematite (Fe 2 O 3 ). At Alum Bay on the Isle of Wight similar coloured sands, on a larger scale, are a tourist attraction and are collected in tubes and bottles for ornamental use.

Incidently, notice that the flint pebbles on the beach have not been rounded because here the wave action is limited, and the conditions are quite unlike those on the active storm beach - the Chesil Beach. Some abrasion takes place when tide and wave conditions are high and thus the foot of the small cliff of sandstone is undercut to some extent.

The more distant coast of this bay, protected from storms by a Chalk headland, consists of slopes of (underlying) Eocene London Clay of Ypresian age vegetated with small trees. Coastal retreat is slow here and if the sea cuts a small cliff in the clay, slumping takes place and a fairly even slope is soon produced again.

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Limonitic Pipes, once pyritic, in the Redend Sandstone (and offshore), Eocene Poole Formation.

Ferruginous hollow moulds left from the oxidation of narrow pyritic pipes in Eocene sandstone, near Redend Point, Studland, Dorset


Ferruginous pipes south of Redend Point

Part of a vertical pipe south of Redend Point

Pipes of pyrite south of Redend Point, Studland

A single ferruginous pipe in the Redend Sandstone, Poole Formation, Eocene of Redend Point, Studland, Dorset, February 2007

The next two photographs, taken ten years apart, show the cliff section, just round the corner, to the north of Redend Point, and the old gun emplacement. This is effectively the southern border of Middle Beach bay and near Fort Henry. The cliff has cut back in the intervening years but not to a great extent. More rocks have fallen from the cliff. Sea erosion at high tide is obviously continuing, although not at a particularly great rate. As the sea encroaches and cuts back further into the bay (if it can with sea defences), then the erosion is likely to increase further. Natural sand beach protection to some parts of the Studland coast is decreasing.

Ferruginous pipes, originally pyritic, in sandstone beneath a lignite bed at Redend Point, Studland, Dorset, February 2007

Ferruginous pipes, probably about 2 metres long, and inclined rather than strictly vertical, and  beneath a lignite bed at Redend Point, Studland, Dorset, February 2017

Pipes, formerly pyritic and up to about 2 metres in length at Redend Point, Studland, Dorset, sharper, closer view, 13th February 2017

Ferruginous pipes occur in sandstone beneath a lignitic bed, Studland, Dorset, location revisited on the 13th February 2017

Oblique, but nearly horizontal cross-sections through some ferruginous pipes at Redend Point, Studland, Dorset, 13th February 2017

An SEM scan across a small ferruginous pipe from Redend Point, Studland, Dorset, showing distribution of quartz sand grains and goethite or limonite, which results from oxidation of pyrite - modified after Fawcus 1992


At Redend Point there are numerous limonitic pipes of about 2cm up to 10 or 15cm diameter mostly extending down from the top of the Redend Sandstone, beneath the lignite bed, to the beach level. They are narrow, but straight and long. In some cases they exceed 4.6m in length (Arkell, 1947) . They are best developed north of Redend Point, the place where the lignite bed also is best-developed. Some occur south of the point but not for any distance. The coloured sand occurs in the same area as the pipes. Arkell (1947) correctly noted that the pipes they were tilted with the strata and thus antedate the folding. The origin of these pipes has been something of a mystery, and they always seemed to be limonitic, with oxidised iron.

I have always suspected that they originated by oxidation of pyritic pipes but had not been able to prove it. However, in January, 2003 some erosion of the beach near low-water mark has revealed that some consist of a pyritic core with some limonite around the outside (see photographs). X-ray diffraction of a specimen shows just pyrite and quartz (of the quartz sand). A compound pyritic pipe of two linked features is shown. There are central cylindrical cores where the pipes presumably first started.

As can be seen from details shown in the photographs, the pipes were formed early, before the sandstone was strongly lithified and before local tectonism (hence the tilt). They are witin in the Poole Formation. This not very accurately dated here but is probably about Lutetian (early Eocene). Since the pipes are pre-tectonism, this means that they are pre-Bartonian (earliest local tectonism). This implies that the pipes are roughly Auversian in age. We know that earthquakes occurred at about this time, because there is very clear evidence in the Bournemouth - Hengistbury Head area for at least three at about the Auversian-Bartonian junction. So the pipes were formed at a time when, now and again, earthquakes occurred and not long after the deposition of the sediment. Sulphide and methane were probably involved and it is not a coincidence that they occur beneath stagnant boggy, clayey peat deposits (almost a brown coal now). They appear to be a by-product of early (Auversian) fermentation diagenesis, perhaps eartquake driven, but the details are not yet clear.

There are many other examples of pipe-type pyrite in the area, offshore and onshore. Earthquake shaking of the foul, very organic-rich Poole Delta is probably responsible. So it is fairly obvious to the geologist that the pipes are about 42 million years old (could not be 50 of course and because of Bartonian tectonism could hardly be as young as 40 million!). The details of the mechanism are not such a simple matter, though. This will be followed further later.


The Underwater Pyrite Pipes of Poole Bay


The approximate locations of the main pyrite occurrences, including the pyrite pipes, in the Poole Formation in Poole Bay and adjacent land areas, near Poole and Bournemouth, Dorset, updated version 20th March, 2017


Underwater photograph of pyrite pipes that have been partially eroded out of the Poole Formation, Eocene, at Wrasse Reef, Poole Bay, Dorset, by Mike Markey in 1993

Another view of pyrite pipes, partially eroded out of the Poole Formation, Eocene, at at Wrasse Reef, Poole Bay, photographed by Mike Markey

Pyrite pipes, at the top and a broader pyritic structure beneath which  partly follows the nearly-horizontal bedding of the Poole Formation, Wrasse Reef, Poole Bay, Dorset

Pyrite, present as octahedra and seen by SEM, from an offshore pyrite reef, Poole Formation, Poole Bay, Dorset, modified after Fawcus, 1993


At Middle Poole Rocks and Wrasse Rocks (and probably elsewhere) in Poole Bay in about 13m or so of seawater there are upstanding, irregular pillars of pyrite, some more than half a metre in length. These were once regarded by divers as being part of a "petrified forest". Cutting and polishing these reveals no fossil wood and they are in fact inorganic pipes or rods of ferrous sulphide. Their origin has not been fully determined but they are similar to the pipes at Redend Point, the main difference being that they have not been subjected to oxidation, having remained below sea-level. Sand has been scoured away by currents around them leaving them projecting. There has been informal discussion about cold seeps but it is not clear whether they have originated by upward or downward movement of iron sulphide. The pipes at Redend Point although mostly oxidised to limonite were originally of pyrite and some remain so below high-tide level.


Downward, v-shaped displacement of sand sediment by formerly-pyritic rods or pipes at Redend Point, Studland, Dorset, as seen 13th February 2017


An interesting feature of these formerly pyritic structures is that at Redend Point they show evidence of small subsidence in relation to the cross-bedded sandstone in which they occur. This small subsidence was probably gravitational, although it could have been the result of compaction pressures from above.


[There are ferruginous pipes in sandstone in the Pedra Furada outcrop of Pliocene Sands south of Lisbon, Portugal (Azevedo et al., 2006). These have been attributed to upward water ascent, either from seismically fluidised beds below the Pedra Furada outcrop or to artesian water ascent.]


For comparison, see particularly the pipes in the Carboniferous, Witt Springs Formation. These are in the Arkansas Sandstone. These are very similar to those in the Eocene strata of Dorset, England.

Go to: Arkansas Sandstone Pipes.

See the photographs that are online.

Brief extract from the text:

"This is a "sandstone pipe" in the Witt Springs Formation of north central Arkansas. At first glance, it seems that someone has managed to insert a pipe into the outcrop (either that, or someone had fairly sophisticated plumbing 320 million years ago). Actually, these naturally occurring features result from iron minerals precipitating out of ground water as it moves through rock. When minerals precipitate from a solution, they do so in concentric bands known as liesegang bands. They were named for Raphael Liesegang: the chemist that first produced them in the laboratory. Once the band of minerals has formed, it makes that part of the rock harder, and, as the rock erodes, the iron-fortified band stands out in relief. Typically liesegang bands form in organic shapes like the ones that surround the pipe above. When they form a cylindrical band, however, they look almost identical to iron pipes."

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[Note: Hermit's Cave in the Redend Sandstone

"From the cross [Studland Cross near Studland church] to the beach we pass through the ancient and very picturesque Water Lane, which is supposed to have been the main road to the shore before that to the Coast Guard station was made [the coast guard station is located at northeastern corner of what is now the main National Trust car park]. About halfway down Water Lane a junction is passed leading to the north, and by the Bankes Arms; and further on when the first bend was diverted to the north-west, it passes by on the west of the Manor House, whereas formerly it passed east of this old house. We pass down a deep narrow lane called Kit's Lane, at the end of which we arrive at another lane or gorge running east and west called Bishop's Lane, which leads to the shore. This lane was so named after a man called Christopher Bishop who lived as a hermit in a dug-out cave in the sand rocks in the early part of the 19th century. " (Hardy, 1910, p. 230) [Am I correct in assuming that Bishop's Lane is the little chine leading to the shore just north of Redend Point and starting at the southern end of the National Trust car park. If so the Hermit's Cave would probably have been excavated in the Redend Sandstone on the north side of Redend Point, just below the lignite bed. Otherwise the hermit would have had to round the point. The Hermit's Cave was probably not the existing cave at the point because it is often flooded at high tides.]

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Limonitic Pipes in Eocene Sand, Hartsnole Hill, Middlebere Heath

Labelled and modified version of a topographic map of the area around Middlebere Heath and part of Wytch Farm Oilfield, Isle of Purbeck, Dorset

Egdon Heath type of country - Middlebere Heath and Hartland Moor, on Eocene Poole Formation, near Wareham, Dorset

Mark Ordish at Hartsnole Hill, Middlesbere Heath, Dorset, where he found the ferruginous pipes, 10th August 2011

A view from  Hartnole Hill on Middlebere Heath southward to Corfe Castle, Isle of Purbeck, Dorset, 10th August 2011

Mark Ordish has found unusual ferruginous pipes on a hill in the Hartland Moor Nature Reserve. They consist of limonite-cemented, quartz sandstone. Mark reported that this part of the Isle of Purbeck used to be well-known for deer and there was apparently a hunting lodge at Slepe, on the edge of this heath. Thus the word "Hart" is involved at this locality. Apparently, Hartland Moor was called Hartsknolle in 1545. Hartsnole Hill is listed in 1632. This seems to be the old name of the hill with the ferruginous pipes according to Mark Ordish (based on information from Mills, 1977, Glossary of Dorset Place Names). Middlebere comes from the name of the farm which is situated on Middlebere Lake (an inlet of Poole Harbour) and now near the centre of the Wytch Farm Oilfield.

An iron-cemented, natural pipe from the Parkstone Sand Member, Poole Formation, Middlebere Heath, near Wareham, Dorset, 10th August 2011

Pipes with irregularities including a flange, Poole Formation, Hartsnole Hill, Middlebere Heath, Dorset, 10th August 2011

A subhorizontal pipe, one of many in the Parkstone Sand Member, Poole Formation, Middlebere Heath, near Wareham, Dorset, 10th August 2011

Multiple-type, iron-oxide-cemented pipes, Parkstone Sand Member of the Poole Formation, Middlebere Heath, near Wareham, Dorset, 10th August 2011

A complex type of pipe in the Parkstone Sand Member of the Poole Formation, Middlebere Head, near Wareham, Dorset, 10th August, 2011

Quartz sand grains in a section of a pipe, Parkstone Sand, Middlebere Heath, near Wareham, Dorset, 10th August 2011


An isolated pipe found by Mark Ordish on Middlebere Heath, south of Poole Harbour, and near Wareham Dorset, November 2016


[Foreword - Stratigraphical Note. The British Geological Survey Sheet 329, Bournemouth, 1991 edition, and the BGS Sheet, 324 (East) and part of 343, Swanage,2000 edition both show some of the Middlebere Heath area discussed below, i.e. there is a small overlap. The mapping is different. The flat-topped hill with snakes in Middlebere Heath is on Oakdale Clay according to the Bournemouth Map but on Parkstone Sand according to Swanage Map. On the old editions of the Swanage Sheet they were listed as "Bagshot Beds". Do not be too confident about the mapping of subdivisions within the Poole Formation. It is a deltaic sequence with much lateral variation and with only limited exposures on the heaths. The Poole Formation is a reliably recognised unit, but the subdivision classification may be open to debate in some areas. This is not to suggest that it is incorrect; simply that the subdivision schemes on the Dorset heaths should be treated with caution. Cliff sections like those of Brownsea Island and the Bournemouth Cliffs are interpeted with more certainty.]

Mark Ordish, while exploring the "Egdon Heaths" of the Isle of Purbeck, south of Poole Harbour (part of "Egdon Heath" of Thomas Hardy) discovered numerous strange, iron-oxide-cemented pipes in the Parkstone Sand Member of the Poole Formation. Mark, who is the son of Geoffrey Ordish, the famous photographer and painter of Cornish mines, is a regular explorer of the south Dorset heaths. He found these peculiar pipes of limonite-cemented sand on the top of a hill of low-dipping Parkstone Sand.

The pipes are of limonite-cemented sand within grey sand of the Parkstone Sand Formation. They are not vertical like those at Redend Point but are subhorizontal with a slight dip. They are all roughly parallel and associated with sheets of limonite-cemented sand. They occur at the brow of a hill where there has been some erosion. Their lateral extent is not known because of lack of exposures elsewhere on the hill and because no trial pits have been dug. The impression given is that they occur within a roughly horizontal stratum almost parallel with the flat top of the hill. The pipes vary in diameter from a about a centimetre up to about 10 centimetres. They are not uniform in size. In some cases two or more pipes seems fused in a parallel manner. Pipes may be complex with several small tubes within them, and cross-partitions may occur. These features are shown in the photographs. It must be stressed the pipes are not initially empty by contain sand. Thus they only appear as true pipes once the sand has been removed by natural processes or scrapped out by humans.

The pipes trend 136 degrees, that is southeast, with a very low and gentle dip of a few degrees from the horizontal and in that direction.

Various explanations are possible and until further research has been undertaken, there is no certainty about their mode of origin. The following are possibilities:

1. The pipes are an unusual variety of iron pan at the base of a podzol soil profile. However, a conspicuous, leached podzol soil profile above was not observed, although it would be quite possible in an environment like this, and exposures are very limited.

2. The pipes are artificial and perhaps of former military or of archaeological origin. Parallel elongate objects of iron or steel and different widths might have been present in sandy soil and have become oxidised. It is difficult to explain why such objects should have been there, but it is possible that the hill has been used for some military or firing practice in the past.

3. The pipes are the result of artificial pyrite oxidation processes, i.e. the production of copperas, as on Brownsea Island. Oxidation of pyrite is involved and the acidic and ferruginous fluids can cause iron cementation.

4. The pipes are the result of natural oxidation of very elongate, rod-like pyrite nodules in the Parkstone Sand. This would be analogous to the formation of vertical pipes in the Redend Sandstone at Redend Point, but there is no obvious reason to explain the near parallel and subhorizontal orientation. However, at present, in view of the occurrence of limonitic pipes from pyrite oxidation elsewhere in the Poole Formation, this, at the moment seems the most likely explanation.

However, nothing more than a cursory examination has been made. Excavation elsewhere on the hill would be needed to obtain further evidence as to their origin. It would also be helpful if similar pipes were found elsewhere on the neighbouring Dorset heaths.

At the moment, they are a newly discovered curiousity of "Egdon Heath" and found by Mark Ordish.

A modified and small section of the BGS Geologicl Map for Swanage, Sheet 342 (East) and part of 343, showing details of Middlebere Heath, and in particular a possible origin for the ferruginous pipes

The extract of the BGS map above provides a good possible explanation for the ferruginous pipes. Notice that the Parkstone Clay seems to wedge out northward on Middlebere Heath. This is not observed in other areas of this map and is an interesting feature. The ferruginous pipes are occurring just north of this wedge-out. This mapped distribution strongly suggests the ferruginous pipes may be an oxidised relic of a thinned version of the pyritic beds of the Parkstone Clay, that were worked for Lord Mountjoy on Brownea Island in the 17th century. In other words they are oxidised "copperas".

A mass of pyrite of the type probably used for copperas manufacture in historic times, South Shore of Brownsea Island, Poole Harbour, Dorset, UK, photo 2007

An elongate limonitic concretion in the soil on Middlebere Head, Isle of Purbeck, Dorset

Pyrite nodules occur on the South Shore of Brownsea Island, although they were probably more easily found in the past. This have been collected in historic times and used for production of copperas or ferrous sulphate (melanterite). The elongate nodules come from the Parkstone Clay Member of the Poole Formation on Brownsea Island (see the webpage: Geology of Brownsea Island - Pyrite.). The shapes of the limonitic features of Middlebere Heath are varied, but tend to be elongate, sometimes tubular, sometimes irregular or more sheet-like. Comparison of the images above shows that it is feasible that the limonitic concretions are the result of oxidation of pyritic concretions.

The probable stratigraphical position and the development of cylindrical pipes (as at Redend Point, although of different orientation) does suggest a pyritic origin. It is very probable that the Middlebere pipes are the result of oxidation of pyrite nodules similar to those in the Parkstone Clay of Brownsea Island. Further research would be needed for definate proof of this hypothesis, though. In particular, trial pits elsewhere on the hill might be informative; some examination of the Parkstone Clay at localities in the vicinity of Middlebere Heath would also be useful.

The geomorphology of the flat-topped hill (notable for reptiles, including the Smooth Snake) may be influenced by the preservation of the limonitic concretions. Fragments suggest that they extend over much of the hill top, but there seem to be few satisfactory exposures.

Ian West on lower ground on Middlebere Heath, Dorset where white quartz sand is probably derived from the Parkstone Sand, Eocene, 10th August 2011

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Plant Bed above the Redend Sandstone

Lignite Bed at Studland, Dorset

Above the Redend Sandstone there is interbedded sandy clay and sand, which Arkell (1947) found to attain about 6m of exposed sediment. It can be seen in the eroding corner between the point and Middle Beach. The dip is 20 degrees rather west of north. The lower part of this sand and clay succession is very light-coloured and seems to contain mud-clasts (see Introduction - above). The upper part is very dark grey because of lignitic material and has some quite well-preserved plant remains, examples of which are shown above. Ferruginous springs occur in the cliff and a little water with iron hydroxides, which no doubt originates from the oxidation of pyrite, trickle down the cliff, partly obscuring the plant bed. Usually this bed is not directly accessible in situ, being rather high in the small cliff. However, there is often fallen debris on the ledge of Redend Sandstone beneath.

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Ball Clays or Pipe Clays of the Early Eocene Climatic Optimum

An old, abandoned ball clay or pipe clay mine, hidden in the woods north of Creechbarrow Hill, Dorset, as seen in about 1950

Ball clay or pipe clay in the Poole Formation of Eocene age at Dorey's NW pit, near East Holme, Wareham, Dorset, 27th June 2009

A palaeosol with hexagonal oxidation marks at the top of a ball clay bed, Dorey's Pit, near East Holme, Dorset, worked by Imery, the major ball clay company, photo - 27th June 2009

Ball clay or pipe clay and a palaeosol of the pseudo-tropical, Poole Delta, Dorset, deposited in the EECO - Early Eocene Climatic Optimum

In the drying and crushing sheds of the Imery ball clay company, at Furzebrook, near Wareham, Dorset

Clay mineral distributions in the Hampshire Basin, based on the work of Gilkes (1968), with some further palaeoenvironmental interpretation

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Reading Formation

View down to south beach with Reading Formation etc

The Reading Formation in Dorset was considered by Arkell to be between 12 m and 30 m Arkell (1947) . He considered the total thickness of Reading Formation and London Clay at South Beach Studland to be about 44 m, as estimated from the outcrop width and the dip.

The junction of the Chalk (Upper Cretaceous - Campanian) and the Reading Formation (Palaeocene) above is clearly visible at the south corner of South Beach. The true K/T boundary is not seen. That is to say that the upper most Cretaceous of the Maestrichtian Stage is absent and so too are the lowermost Tertiary strata. Thus this is not a place to see the boundary clay with its iridium! There a substantial gap in time between the highest Chalk and the lowest Tertiary. The major reason for this is probably erosion of the Chalk in Palaeocene times. The early Tertiary strata lie on different zones of the Chalk in different places; this is the result of some early Tertiary folding of gentle type and erosion, weathering and solution of the uppermost Chalk. In the English Channel to the south there is Maestrichtian Chalk present, and it probably once occurred here.

The dip of the Chalk is at 9 ° in a direction N. 6° W according to Arkell (1947) . Its upper surface is undecayed but undulates owing to the early Tertiary erosion, before the Reading Formation was deposited. A hummock of Chalk rises above the beach some metres to the north of the main outcrop, surrounded by Palaeocene strata. The hollows are filled with up to 1.2 m of dark brown ironstone and black flints, forming the basement bed of the Reading Formation. According to Arkell (1947) , between the hollows the same band exends more or less continuously but is thinner. In places it consists of a 20 cm band of black flints in a a ferruginous matrix overlain by about 20 cm of boxy ironstone with a few flints. Above comes about 1.8 m of buff and greyish mottled clay, passing up into cross-bedded red, yellow and white sand. The general dip of these beds is 10 ° rather west of north.

In addition to the erosion hollows of early Tertiary age, there are some large solution pipes of subsequent date. One pipe 1.5 m in width was seen by Arkell (1947) to pass throught the basement bed and the Chalk alike and was seen to be filled with mottled clay and sand to a visible depth of 2.4 m, when it disappeared beneath the beach undiminished in width. The upper part of the Reading Formation is concealed by slips.

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South Beach - Sediment and Debris

Dead squid on South Beach, Studland, Dorset

There is sand in the northern part of South Beach together with some pebbles. Further south the proportion of beach pebbles increases. These pebbles are mostly subangular Chalk flints, grey, white or black in colour and with very little rounding. Most have come directly from the Chalk at the southern end of the bay, although some may have been reworked though the Reading Formation. They differ from the pebbles on most beaches in the region. At other places flints have mostly been derived from the Pleistocene gravels and these are iron-stained and brown. Flints eroded directly from the Chalk are rarely brown and may be quite large. Conchoidal fractures showing black flint are common. In the southern half of this bay there are some clasts of chalk.

The beach usually shows much debris from the beds of Zostera sea-grass that lies just offshore. There is also some algal seaweed. The photograph above shows an unusual find on South Beach. It is a dead squid, discovered near Redend Point (by Lynda of the Open University Geological Society). Later the ink sack burst revealing the typical black ink.

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Offshore Sediments

Areas of sea-grass and maerl offshore from Studland

Most of the sediment offshore from Studland is sand, but there are certain unusual features. Marine biology surveys for the Hook Island Environmental Study (BP Exploration, 1991) have established the presence of a Maerl community near Handfast Point. This is an assemblage of free living calcareous algae (red algae) Phymatolithon and Lithothamnion. Carbonate from these has accumulated on the sea floor. It is interesting that there should be Recent carbonate sediments fairly close to the South Haven Peninsula which is notable for being almost totally carbonate-free. The carbonate sediments though are actually closer to the headland of carbonate rock, the Chalk which can provide cleaner, clearer water. The algal clasts are transported southward by tidal currents beyond the town of Swanage and small accumulations can be found on the beach in Durlston Bay immediately north of Durlston Head. They are not usually seen on the beaches of the South Haven Peninsula though. Maerl is known elsewhere particularly off the north coast of Brittany, as at Paimpol, where it has been dredged for fertiliser. It is also present at Falmouth and has been used for fertiliser there too, and is common off the west coast of Ireland. Some Lithothamnion occurs in the carbonate (mainly shell) sediments of the beaches of north Cornwall and Devon. It is favoured by clear water with a low content of suspended clay and often associated with shell debris.

The sea-grass Zostera mainly grows in the southern part of Studland quite close to the cliffs of Chalk. Accumulations of dead sea-grass are washed up on the beaches here.

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Doline south of Studland Village

(since filled in - as when seen in July 2009)

Location of doline, south of Studland village

Doline that appeared in late November 2002

Roots in the soil at the top of the doline

Downhole video of doline

Doline fenced, as seen in Jan 2003

A new doline or solution pipe appeared at Glebe Farm south of Studland village in late November, 2002, after heavy rain. It is in a field just east of the road to the Glebeland Estate and near to a large barn. The map reference is SZ 037821. It is on the outcrop of the Reading Formation just north of the Reading/Chalk boundary. It is close to the centre of a small valley descending from the southwest (from just west of the Glebeland Estate), and it is also close to a well near the barn and this well was in the past pumped so extensively that on occasions it yielded saline water coming through the Chalk from the nearby coast (saline intrustion).

The hole in the field was first observed by farm staff and then by Geoff Han of the National Trust on 22 November. I visited it at the invitation of Mr Han on the 29 November and advised against anyone descending into the hole, because of serious danger of it falling in. The doline is a hole of collapsed Reading Formation over low-dipping Upper Chalk. The chalk has been dissolved away beneath to form a solution pipe, like a small version of Red Hole, near Lulworth Cove. The Reading Formation which has been collapsed in and been washed down. It is unusual to see such a doline in its early stages. It is expected that the hole will eventually collapse into a conical or crater-like shape like Culpepper's Dish and the other large dolines near Bere Regis in Dorset. The doline hole at the surface was measured on 29 November 2002 as 1 metre from east to west and 1.29m from north to south. There was overhang at the sides up to 0.6m. Later the overhang was removed by machine for reasons of safety and the danger area fenced off. A video was made by lowering a camera on a trolley down the hole. A cave in the sand of the Reading Formation was found to extend about 5m towards the southeast. Sooner or later this will collapse. I am very grateful to Geoff Han and the National Trust for the opportunity to examine this doline.

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Doline - Resurgence on Beach, 2007.

Resurgence from the top of the Chalk at the southwestern corner of South Beach, Studland, Dorset, probably connected to the doline and cave system

After heavy rain a resurgence was seen in the southwestern corner of South Beach, Studland. This is precisely where the water from the doline and cave system, discussed above, would be expected to appear. Confirmation comes from an enlarged joint in the cliff (just to the south of this) which has a clay fill with clasts and is clearly part of a solution pipe or cave system. Water from part of Ballard Down is clearly entering a cave system at the doline and flowing southeast to the nearest part of the coast. The piezometric head is above the level of the top of the north-dipping Chalk beneath the Reading Formation clay. Being at the top of a permeable formation, this can be classified as an overflow spring.

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Studland Village Cross

Studland village cross, with Concorde

If you visit the Bankes Arms or adjacent car park you are only a short walk from Studland village cross which is near the Church. It is worth seeing if you have time. This is an unusual carving, perhaps in Portland Stone from the Isle of Purbeck. Amongst other surprising features it includes a carving of the Concorde supersonic aircraft. It has the inscription of the name of Trev Haysom, a well-known Purbeck quarry owner and Marbler. Mr Haysom has a quarry in Portland Stone at St. Aldhelm's Head.

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Introduction -Access

The Agglestone Rock in 2004, now tilted, Studland, Dorset

There is no direct road access to the Agglestone, but there is a pleasant walk to it. Consult the Ordnance Survey map - Purbeck and South Dorset - Outdoor Leisure Map 15, 1:25,000. The location of the rock is northwest of Studland village at map reference SZ 023828. There are several paths from the village and also one from Dean Hill. Park a car at one of the two National Trust car parks at Studland or at Knoll Beach. One route is to walk to the Knoll House Hotel on the road north of Studland village. There is a black gate on the west side of the road just south of the Hotel (mentioned in the old account in the footnote below). Pass through this, cross a field, past a house and then down a farm track to the ferny valley, thence westward, and then southwest onto the heath, where the rock stands out conspicuously on a hill. It is really not far from the village but the place seems quite remote, and much like a tor on Dartmoor.

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The Agglestone - General Introduction

The Agglestone, Studland, Dorset, from the south

The Agglestone was until recently a type of pedestal rock, but it has since fallen towards the southeast. It was an anvil-shaped block of about 400 or 500 tons weight, perched on a conical hill which the stone has protected from the weather. It is an eroded relic of iron-cemented, Tertiary sandstone, the Agglestone Grit. This is a coarse, cross-bedded and pebbly grit of Eocene age of about 11 metres in thickness,and it takes its name from the rock. The ferruginous sandstone, or heathstone, is not confined to the Agglestone but also forms the Puckstone nearby and, in addition, pieces of this hard irony sandstone litter the heath and have been used for building walls, barns and houses. The Agglestone rock, is, needless to say, not a sarsen stone nor something put in place by man. It is, nevertheless, a rather unusual and interesting hill-top tor. However, although mainly natural, as discussed below, its shape has probably been modified in historic times by human activity. The photographs above show its present condition. I have also provided a Victorian photograph from Climenson (1906) , showing the rock in its earlier anvil-shaped condition.

A Victorian view of the Agglestone Rock, Studland, Dorset

The Agglestone Rock, Studland, Dorset, as shown by Brannon in 1862

A old view of the Agglestone, when still in place, probably in the early 1950s, Studland, Dorset

An etching of the Agglestone, near Studland, Dorset in 1766

The history, in terms of human history, of the Agglestone is not well-known, but it has clearly been modified in form. The hill is natural and the strata was in place until it collapsed. However, some type of quarrying or carving operation has converted it into a more perfect inverted cone. In 1766, as shown by the etching, above it had a neat flat platform cut around it (which still exists in rougher condition) and about eight rectangular and shaped blocks, presumably of Agglestone Grit, standing on the platform. The rock type is, as mentioned, a type of heathstone, similar in general to that which has been used in the construction of the Church at Studland. This heathstone, a ferruginous sandstone occurs fairly widely over the Tertiary heaths from Studland to the Corfe Castle area and beyond and is not confined to the Agglestone. It probably originates from cementation by goethite or limonite of fluvial, channel sandstones of the Poole Formation. The iron oxide most probably comes from oxidation of pyrite, which is particularly abundant in the Parkstone Clay Member.

It is not known as to why the rock was (partly) shaped in this peculiar manner by some quarrying process. If the Agglestone was simply regarded as a source of stone, then the quarrying would not necessarily have been so symmetrical. A small quarry would problem enter from one side and remove stone in a cruder and less systematic manner. Why have a neatly circular quarry? Why leave blocks almost encircling it. Why not leave a pile or a specific accumulation as has happened on the Isle of Portland? Why were the rocks squared off as freestone? Have any of these squared-off block remained on the heath in the adjacent area, or have they been used in nearby building. There are some interesting problems that are not geological.

A more specific reason for the shape has been postulated by Hardy (1910) . He argued for quarry on a larger scale than that suggested above. From an introductory point of view, he noted that the rock is of sandstone resting on its natural bed and is on the northeast of of a 0.8 km ridge of "Bagshot" sandstone. It stands on a steep, semi-circular mound about 27m above the bog below. The depression has formed a natural receptacle for the dbris was has been washed or fallen from the sandstone ridge. He considered that this ridge was once a vast quarry, especially at its east end and the present Agglestone rock is a relic left after the excavations had terminated. The ancient masons cut doorsteps, walling stones and handmill stones etc from the Agglestone Grit. He had found a fine example of an Agglestone Grit doorsill under the foundations of Studland Church during restoration. It was rebated and had one square hole for a jamb and two or three for iron bolts. Hardy considered that the Agglestone Rock waqs undoubtedly once much larger than it is now, perhaps about four times its present size when it was left by the quarrymen. The top crust consists of very hard, ferruginous sandstone, about 2 m thick with natural joints running perpendicularly through it at varying intervals. The bottom strata is softer and kept moist by rain, mists and drippings from the rock above. After the quarrymen had left it natural weathering operated on it, including the effects of frost-wedging. Rains wash portions of the softer substratum away and in addition when a dry wind blows the chipped rock is blown off. Pedestal rocks in deserts have in many cases been attributed to wind deflation and abrasion. The Agglestone does not seem to directly affected by the blown sand abrasion because although the sand dunes of the South Haven Peninsula are not close to the rock which has boggy moorland adjacent. The Agglestone has been undermined by up to 1.2m on the north side and 3.7 m on the south side. Hardy made comparison between this rock and the rocking and logan stones of Cornwall and elsewhere. He noted that frost cracking of the hard top part has forced off lumps of rock from 5 to 15 tons weight and found 23 large pieces around the mound when he examined it. Hardy predicted its collapse, which has since occurred.

It remains, though, a matter of opinion as to whether the Agglestone is the relic of a large quarry, or is a natural rock exposure, modified by small-scale quarrying and a peculiar and specific type. It is the relic of an industrial quarry, like the stone monolith at St. Aldhelm's Head or Nicodemus Knob on the Isle of Portland, or has it been shaped for some special purpose?

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The Agglestone Grit of the Agglestone Rock, Studland, Dorset

Middle Eocene succession including the

The characteristics and lateral relationships of the Agglestone Grit has been discussed briefly by Arkell (1947) . It is not only exposed in the Agglestone. It also has been seen in a sandpit near the golf course and in pipe-clay workings at Newtown. Arkell commented that westward it and the upper part of the Pipe-clay Series contain an increasing amount of pebbly beds, composed of flint, Upper Greensand chert, vein-quartz, and far-travelled Palaeozoic detritus (of Cornubian type), together with small pieces of silicified Purbeck limestone. In this condition the strata are the typical "Bagshot Beds" of the Moreton and Warmwell district. Westwards they overlap the two lower members of the "Bagshot Beds" and the London Clay until between Warmwell and West Stafford they rest unconformably on the Reading Formation (of the Thames Group). Finally in the outliers south and southwest of Dorchester they consist mainly of shingle and coarse cobble gravels, in a matrix of typical Agglestone Grit, let into huge solution pipes let into the Chalk.

Thus the detritus indicates a Middle Eocene river flowing east from Cornubia (the old Devon and Cornwall upland) onto the Bournemouth delta. The westward overstep shows that eastward tilting was taking place, and this was at about the same time as the earliest "Alpine" movements were produced by a north-south compressional regime. The pebbly grit of the Agglestone is likely to be a channel deposit of the river situated on the delta. The river was flowing sufficiently fast to move this fairly coarse material and, furthermore, it was also carrying Fe from the chemical weathering on the uplands (to be expected from the Eocene palaeoclimate). The current cross-bedded channel debris was, in due course, cemented by hydrated iron oxide - limonite or goethite. The cementation was greater at this particular point, for a reason not known, and the relatively resistant rock material was produced. In relatively recent times there has been erosion and the softer, more less-resistant sediment around the Agglestone was washed away, leaving a prominant rock.

Sundew or Drosera near the Agglestone at Studland, Dorset

There is a complete lack of carbonate in the Eocene strata in the vicinity of the Agglestone. Water is held up in places by clays. The result is the occurrence of acid and peaty bogs like those of much of the New Forest. The bogs are treacherous and walkers should stay on the footpaths. Within the soft, wet ground of bogs the small, insectivorous plant Sundrew or Drosera, occurs as in the New Forest bogs. This obtains nitrogen from flies. Some of the other plants of the Agglestone walk are mentioned in the old account given in the footnote below. Most of these are still there, although the Osmundia ferns did not seem very tall at the time of my recent visit. Please take care not to disturb or remove any plants, so that the Agglestone geological and botanical walk is still as good in another 100 years time!


Footnote: A Visit to the Agglestone in Victorian Times?

A  Victorian view of the Agglestone Rock, Studland, Dorset

Victorian map of the Isle of Purbeck, showing the Little Sea and the Agglestone location

This is a fictious account from Climenson (1906) - giving supposed extracts from the diaries of Miss Eva Cheeke and Mr. Jack Needham, staying at the Manor, Studland. However, the detail and the photograph strongly suggests that it is partly based on a visit to the Agglestone by Emily Climenson in Victorian times:

Miss Eva Cheeke, daughter of Sir John Cheeke, writes of speaking to Dr. Hardy while staying at the Manor House at Studland.

"But now, Doctor, will you tell me why, when the 'little maid' as they called her, talked of taking me to the 'Agglestone,' the old man laughed so?"

"Well, my dear young lady, the tradition is this: if you have a lover any keep tryst at the 'Agglestone,' a happy union is sure to follow.."

"What is the story of the Agglestone, Doctor?" said I.

"Well the legend is that the Devil was sitting on the Needles Rocks, in the Isle of Wight, one day and he was annoyed at seeing Corfe Castle towers shining in the sun, so he took off his nightcap and threw it at the Castle, and it fell there and turned into the Agglestone. The real truth is, that it is a huge piece of red sandstone, and from the denundation of the soil around, it has become isolated on a high mound. It is said but how true or not I cannot say, to have been used by the Druids, has some curious marks on the summit, and faces east to the rising sun. The name, some say is from 'Heilig' (holy), and 'Stan' (stone); others say from 'Hagge' (Anglo-Saxon for witch), and 'Stan' (stone). There is an ancient barrow near the sea and a smaller stone called Puck Stone, a little way north of it.."

Later - Mr. Jack Needham, Barrister at Law, writes -

- "So I then inquired of Mrs. Harper [the housekeeper of the Manor House] the way to the Agglestone.

"Oh, it is only about a mile off. Keep to the road past the Manor towards Poole Harbour and bear to the left through a gate; 'tis a beautiful sight the country round, sir, from it, but you must look out for the bogs."

"So shaking hands with the old woman, who made a dignified curtsey, Eva and I started on our walk to the mysterious stone. Arrived at the gate that Mrs. Harper had told us of, we emerged from the beaten track on to a slight eminence, a mass of glorious purple and crimson heather, where we followed a small white track; in front of us lay a superb view, the ground, after the first rise, trending in a gradual slope which prolonged itself into a triangular promontory, whence the entrance to Poole Harbour could be discerned. To the left lay slopes of heather and gorse, to the right the bay with a wide line of gleaming whitish sand, on which the waves fell with a peaceful swish. In front we could perceive the mound, crested with a stone which from the distance looked insignificant. Exquisite was the day, blue sky above, with little fleecy white clouds scattered about it promiscuously; bees hummed in the heather, and brilliant butterflies and moths hovered over the floral treasures around. The bog myrtle, or sweet-gale, which flourishes here, exhaled a delicious penetrative odour as our feet crushed it, tall Osmundia ferns reared up in vigorous clumps at intervals, whilst numerous other ferns peered from crannies in banks and dykes along the track.

We soon descended the slope and then the "Agglestone" assumed a very different proportion. It was set on an insulated mound or rock, some ninety feet high, a huge block of red sandstone, beneath the mound stretched a succession of bogs, in which waved the silky white heads of the cotton grass, varied with spikes of yellow red-tipped Bog Asphodel. A rough, miry track led to the mound, and seeing Eva's dainty little shoe sinking into the mud, I laughingly caught up the darling and carried her across to the mound, where I set her down laughing, saying I was a dear old elephant to do it; hand in hand we ascended the mound, and stood under the huge mass, which appeared to be some nineteen feet high, having explored all round it, and found that the overlying mass afforded a shelter on either side, I scrambled to the top, not an easy matter; on the face of the stone are three curious circular indentations, one has evidently been used as a nest, returning to Eva's side she informed me that one of the superstitions regarding the "Agglestone" is that it had formed a Druidical altar, on which sacrifices had been offered, as it faced the East, that quarter equally respected by pagans as well as Christians. It seems quite probable, but anyhow the view from the mound is one calculated to make the most insensible heart turn with gratitude to the Creator of such a fair world. Below the Agglestone at some little distance, we espied a small sort of lake of salt water, which Eva told me was called "Little-sea," to our right one or two salterns and a barrow or two were perceptable between us and the shore. Over the inland sea were a vast number of birds of various sorts, gulls, ducks etc, swooping fishing and bathing forming a delightful spectacle. Eva, however, now turned to me and said "Jack, you are to plight your troth to me afresh, you are to say after me, this - 'I Jack, promise to take you, Eva Cheeke, to be my wife, and to love you as you live.' This I readily enough repeated, and Eva then said 'And I, Eva Cheeke, promise to be your wife, Jack Needham, and to love you as long as you live.' This compact was, as may be readily supposed sealed with a kiss, then we seated ourselves under the shade of the old red stone.."


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Beyond to the South

See also:

Harry Rocks and Ballard Point webpage. This is a continuation of the present webpage and considers the southern Chalk cliffs of Studland Bay, together with the coast beyond to the south.

Harry Rocks

Chalk extends from the Needles to Harry Rocks

Studland gives good views to the south of the Chalk Cliffs, extending east to Harry Rocks. The Chalk cliffs are described in the guide on Harry Rocks and Ballard Point. Beneath the sea the Chalk outcrops from the Needles on the Isle of Wight to Harry Rocks, although not in quite the straight line that you might expect (there is an en-echelon type displacement in the middle of the sub-sea outcrop). Note that at the Needles and Scratchell's Bay (the white cliffs are those of this bay) the Chalk is very steeply dipping to the north (left) but at Harry Rocks the dip is very low to the north, the strata being almost horizontal. The Ballard Down fault is responsible for the anomalously low dip in this east Dorset area.

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BIBLIOGRAPHY and References

Please go to the main Studland; Bibliography and References webpage for literature references and a list of publications relevant to the area.

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I am very grateful to Ken Collins and Mike Markey for underwater study and photographs of pyrite pipes at Middle Poole Patch and Wrasse Reef and information from other studies in Poole Bay. I particularly thank Mark Ordish for drawing attention to the unusual pipes of Middlebere Heath (also of pyritic origin), and for showing them to me in the field. I thank the many students and others who have accompanied me in the field to Studland Bay and adjacent area. Roger Fawcus is thanked for providing data in his undergraduate research project on the ferruginous pipes of Studland. I am, of course, very much obliged to the Head of and Staff of the School of Ocean and Earth Science, National Oceanography Centre Southampton, Southampton University and to iSolution, Southampton University for supporting and running this website on the server. My late wife and my family supported the geological work. I much appreciate the advice and help of my daughter, Tonya Loades of Bartley West, Chartered Surveyors.

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Copyright © 2019 Ian West, Tonya Loades 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 cancel 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 does not necessarily represent the views of Southampton University. The website is written privately from home in Romsey, unfunded and with no staff other than the author, but generously and freely published by Southampton University. Field trips shown in photographs do not necessarily have any connection with Southampton University and may have been private or have been run by various organisations.