[a headland predominantly of Eocene sand, former oil-sand, ironstone and clay, much of which has been disturbed by the Hengistbury Head Earthquakes of 40 million years ago]

Some Related Webpages: |Home Page and List of Webpages |Hengistbury Head - Bibliography |Bournemouth Cliffs |Barton and Highcliffe - General

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The Visitor Centre

Hengistbury Head is the best part of the Bournemouth coast for geology and geomorphology. It is an attractive area of country parkland and an archaeological site between the sea and the town of Christchurch. It provides impressive views across Christchurch Bay eastward to the Isle of Wight, and southwest to the Isle of Purbeck. Hengistbury Head has been greatly modified by quarrying for sideritic ironstone in the 19th century and also extensively by coast erosion. It retains one obvious quarry in the centre of the hill, but the remains of quarrying and quarry tips round the north and west side are now largely overgrown. The path up to the top of Hengistbury Head is over a broad quarry terrace, and the Lilly Pond on the north side is a small flooded quarry. The prominant headland is now only about half the size that it was in the 18th century (see maps which follow). After the quarrying the headland became a private estate. However, it was later opened up to the public and in due course became one of the public parks of Bournemouth. Attached to Hengistbury Head is a sandspit, Mudeford Spit, which unfortunately is no longer natural but largely covered in beach huts. It is still a pleasant place though.

Hengistbury Head is of particular geological interest because of the abundance within the sandy clays of sideritic ironstone nodules. These are in in Middle Eocene, Lower Barton Formation, strata. The nodule are not now seen on the beach in their former abundance; in fact only a small number are accessible. The reason for this is that the process of beach replenishment takes place regularly at Bournemouth and has done so for many years. The Bournemouth does not entirely stay in place but moves by longshore drift (under the influence of southwesterly winds) in an eastward direction. There is a long groyne that was built many years ago at the end of Hengistbury Head. This holds back most of the sand which is accumulating over the original beach and covering the ironstone nodules. There is now poorer ironstone rock exposure for the geologist. The nodules, though, can still be seen in the cliff.

The Eocene strata of Hengistbury Head are mainly clays and sands belonging to the basal part of the Barton Formation (details will be given further on). These marine sediments of about 40 million years ago were deposited at the junction of estuarine or deltaic conditions to the west and a shallow marine gulf to the east. The climate was warmer than would be expected for a place at about 40 degree north because of the MECO, the Middle Eocene Climatic Optimum. There has been much leaching of carbonate so that shelly fossils like those at Barton-on-Sea are not found at Hengistbury Head, only hollow moulds. Pleistocene gravels occur in the uppermost part of the cliffs above the Eocene strata.

There is the Hengistbury Head Visitor Centre near the car park and the Double Dykes (historic embankments). It is easy to walk along the beach or over the top of the hill. It is good that Hengistbury Head is protected. There is a cafe, toilets and a small road train which provides transport to Mudeford Spit.

Further down this webpage, we will discuss the geological details, with the aid of photographs, maps and diagrams.

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2.1. EOCENE STRATA - INTRODUCTION

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The strata of the Eocene (Palaoeogene)at Hengistbury Head consist of the uppermost part of the Branksome Sand Formation of the Bracklesham Group overlain by the lowest part of the Barton Clay Formation. The Branksome Sand Formation strata are seen at the base of the cliff at the western or highest part of the hill. Above them are marine clays, followed by sands (Warren Hill Sand) that are part of the Barton Clay Formation. This does not, at first sight, look similar to the Barton Clay at Barton and Highcliffe and it does not contain obvious and well-preserved shelly fossils, like those at Barton. However, fossils are present.

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In broad terms the strata at Hengistbury Head have never been deeper than in the Fermentation Zone (3), as shown in the simplified diagram below. They have, of course, been through the thin bacterial sulphate reduction zone, but not much pyrite has been formed in this zone at these strata at this locality. This is interesting because there was obviously an iron surplus in the sediments, but the sulphide reduction was much less marked than in the Eocene Poole Formation, further down. There the pyrite is so abundant that it was "mined" at Brownsea Island and Parkstone and Alum Chine and it produced a spa well at Boscombe Chine. The change in sedimentation and diagenesis at Hengistbury Head is strange. There was much iron, glauconite is abundant in addition to the siderite nodules (and probably dispersed siderite). The development of the ironstone nodules was almost certainly in the Fermentation Zone (3) and therefore a considerable development of methane should have taken place. This, of course, would be lost once the permeable strata were exposed and eroded.

Offshore from Hengistbury Head to the southwest there are oilfields of the Wytch Farm complex. These are in the Sherwood Sandstone, much deeper and older strata.

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The diagram above had been modified after Bristow, Freshney and Penn (1991). Note that the ironstone bands are renumbered. Only three bands of ironstone nodules are easily seen at the high part of the cliff. The lower two are more persistant and conspicuous.

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The photographs above, of the highest part of the cliff of Hengistbury Head, show some of the the stratigraphical subdivisions and the positions of the ironstone nodules. It is very easy to recognise the major units. The details are not so obvious.

2.2 MECO - MIDDLE EOCENE CLIMATIC OPTIMUM

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As noted elsewhere, the "Hengistbury Beds", that is the strata above the major pebble bed at the top of the Boscombe Sands, are now regarded as the basal part of the Barton Clay Formation. It is of interest that the Barton Clay is near in terms of age to the MECO, The Middle Eocene Climatic Optimum. This was a very brief hot spell, lasting only about 3 million years. In addition, the palaeolatitude in Middle Eocene times was lower (about ten degrees closer to the equator) than the present latitude of Hengistbury Head. So the palaeoclimate was generally warmer, but particularly so at this time (incidently this may favour "glauconite" formation -

In the Phanerozoic Geological Time Scale for 2012, the age of the Bartonian is given as between 41.2 and 37.8 million years. The middle Eocene climatic optimum (MECO, ~40?Ma) was a transient period of global warming that interrupted the secular Cenozoic cooling trend.

"Stable isotope data from Southern Ocean sites reveal anomalous temperature variability during the middle and late Eocene. The ca. 41.5 Ma middle Eocene climatic optimum event is interpreted to represent an important climatic reversal in the midst of long-term cooling in the middle to late Eocene, indicating that this trend was not entirely monotonic. If global in nature, the middle Eocene climatic optimum would represent one of the more rapid global warming events of the Cenozoic. Regardless of its full global extent, the middle Eocene climatic optimum is clearly an important event in the regional climatic history of the Indian-Atlantic region of the Southern Ocean. The rapidity and magnitude of warming (4 degrees C) imply that this climatic event dramatically affected both Southern Ocean biological communities and the coastal environments of Antarctica and Australia."

The above is from: Steven M. Bohaty and James C. Zachos, both from the Earth Sciences Department, University of California, Santa Cruz. In a 2003 article in Geology, entitled "Significant Southern Ocean warming event in the late middle Eocene".

2.2a BOSCOMBE SAND FORMATION (BRACKLESHAM GROUP)-

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2.3 LOWER BARTON CLAY -

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The Barton Clay succession, above the Boscombe Sands, at Hengistbury Head are greyish green to greyish-brown, sandy clays with much fine sand and some glauconite. Siderite nodules occur in the upper part, the Upper Hengistbury Beds, but not in the lower and more glauconitic part, the Lower Hengistbury Beds. They commence with a bed of large, rounded flint pebbles with obvious percussion marks, that have originated on a beach. These flint pebbles attain up to 15cm diameter. Quartz grit is abundant in the clays immediately above the pebble bed (Curry (1976). The bed with the large pebbles is, according to Plint (1983) a locally notable transgression horizon - T5 - which he considered to be the result of a eustatic rise in sea-level within the Bartonian Stage (although at the top of the Bracklesham Formation, or Group).

The lower part of the Lower Barton Clay at Hengistbury Head is generally more coarse-grained, in addition to being more glauconitic, than in the strata aboe . The small discoidal foraminifer Nummulites prestwhichianus (Jones) occurs at 5m above the base at Hengistbury Head, according to (Curry (1976), but in the leached strata is not easy to find.

The upper part of the exposed Lower Barton Clay at Hengistbury Head has four levels of ironstone nodules and also irregular beds or "balls" or fine sand. As in the case of the the lower strata, fossils are not obvious. Occasionally Bartonian gastropods and bivalves can be found in the ironstone nodules, although this is much more difficult now because of large quantities of beach sand covering fallen nodules.

In the clays there is no calcium carbonate preserved. Occasional sharks teeth have been attacked by sulphuric acid solutions from oxidation of pyrite, and the teeth are prone to have whitish encrustations. Shell moulds particularly occur, according to Curry, particularly at a level 13m above the pebble bed (T5).

2.4. BASAL BARTON STRATA AT HENGISTBURY HEAD

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A conspicuous bed of rounded and beach-battered flint pebbles marks the top of the Boscombe Sand Formation (Bracklesham and below the main beds of Hengistbury Head. About 16 metres of glauconitic clay or silty clay (pale green to brown), overlies the main pebble bed. Within this there are four bands of ironstone nodules. At about the middle of this sequence there are large subspherical and fine-grained "sand balls". These are probably slump balls resulting from sea-floor movement caused by earthquake activity (there is major slumping seen at Friars Cliff, too) (Bristow, Freshney and Penn, 1991). Two of the ironstone bands are below the slump balls and two are above.

Bristow, Freshney and Penn, 1991 discussed the problem of whether the glauconitic sandy clays at Hengistbury (the "Hengistbury Beds" of Gardner (1882) are at the same stratigraphical level as the basal Barton Clay exposed at Highcliffe.

Gardner , J.S. 1879. Description and correlation of the Bournemouth Beds. Upper Marine Series. Quarterly Journal of the Geological Society, London, 35, part 2, p. 209-228. [by J. Starkie Gardner].
He considered the sands with slump or seismite features at Highcliffe to lie above the clays with ironstone nodules of the "Hengistbury Beds. This old view is often ignored now, because it does not tie with in with modern correlations (as proved by the fossil fauna, found by Dennis Curry).
In other words, the siderite-bearing clays of Hengistbury Head are beneath the ground at Mudeford. The following extract from Gardner (1879) is from his page 221.
"These sands [his "Highcliffe Sands"] dip conformably with the Barton and Hordwell series, one and a half to two degrees east. The curious turn the water flowing from Christchurch Harbour has taken within the the last few years, known as the Run, has fortunately revealed the section to the very sea-level; and it is now seen that these sands rest upon another and lower series of dark sandy clay with ironstone nodules.."
[My note, 2017: thus the base of the Barton Clay Formation is not above the sands as once thought, but lower, at Hengistbury Head, and the glauconitic clays with ironstone nodules are lying, stratigraphically conformable, underneath the Haven House peninsula at Mudeford, and they have been exposed there at very low tide. If this is true, as seems likely then there is no need to involve faulting or folding. It is simply that the base of the Barton Clay is lower than was originally thought. Modern confirmation is needed, though.].
[Gardner continuing] "These [the dark sandy clays with ironstone nodules] can be almost directly traced to the headland, where they form the cliffs; for at the ferry, about midway between them, the landing place is on hard compact clay, upon and about which are alying a few indentical similar, ironstone nodules. The sands themselves, however, have not resisted denudation and, like the Boscombe Sands on the other side of the Head, have been removed from the space of a mile."
... [continues]

2.5 - STRATIGRAPHY AND SEDIMENTOLOGY - BOSCOMBE SAND FORMATION (Bracklesham Group)

[Hengistbury Head and Friars Cliff features, including Ball and Pillow Structures]

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The lowest stratal unit seen at Hengistbury Head is the Boscombe Sand Formation of Bracklesham age. This is 20 to 27 m. in thickness and underlies much of the Bournemouth area (Bristow, Freshney and Penn, 1991). The deposit is exposed in the cliffs at Boscombe but these sections are now much damaged by the Bournemouth urbanisation. Sea defences, promenade, drainage, vegetation and restrictions on access have spoilt the exposures. At Hengistbury Head, however, the sands are still very well seen, at least in part, at the base of the cliff.

The formation consist of mainly fine to medium grained sand, consisting dominantly of quartz grains, but an unusual feature is that flint grains are common at some levels (Bristow, Freshney and Penn, 1991). This may be related to the extent of flint battering that occurred on the ancient "Chesil Beach" of the eastern Bournemouth area (see above - the battered and rounded pebbles). The mean grain size varies 1 phi and 3.5 phi, with a average of 2.2 phi. Sorting is well sorted to poorly sorted with a skewness of between +0.7 and -0.5 and an average skewness of +0.1 (See Bristow, Freshney and Penn, 1991 for more data on sand statistics).

Bedding architecture is of two main types. Planar laminated beds with a few planar cross-bedded units containing flint pebble and cobble beds in the lower part, are associated with marine sands. Bi-directional cross-bedded strata in the upper part are estuarine sand. Thus it seems in general to be a regressive sequence.

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Chandler (1961) commented on the fruits and seeds of the black sands part of the Boscombe Sand Formation as seen at Hengistbury Head.

"The lowest [Eocene] beds exposed are at the southwestern end of the Headland. They consist of white, grey and black sands sands which have yielded to the writer a few fruits and seeds and would probably provide greater variety if persistent search was made. From them have come Sequoia [the Redwood tree], Caricoidea [an Eocene sedge plant], Scirpus [a sedge, like Bulrush, grows in dense tussocks], Stratiotes [the submerged aquatic "water soldier"], Brasenia [an aquatic, freshwater pond plant with roundish floating leaves], Vitis [grapevine], Cleyera? (an evergreen) and Rhamnospermum(a jasmine??). It is here that Clement Reid is thought to have obtained Nipa [the Mangrove Palm, with fossil fruits well-known from Honeycombe Chine, Boscome]." In general terms this is a Bournemouth-type, Eocene, freshwater and terrestrial assemblage. Incidently, no plant remains were found by Chandler in the next sand deposit, above, the Warren Hill Sand Member, which only contains some rare marine mollusc remains.

Plant occurrence data was given by Chandler, with regard to what was then termed the Lower and Upper Hengistbury Beds (with ironstone nodules), but now classified as just a part of the Barton Clay Formation. (see p. 196, List of Hengistbury Plant Remains). About 21 species of plants were recorded (there are also some good illustrations of fossil pine cones, Pinus dixoni etc from Hengistbury Head). The details are not repeated here. It is perhaps worth mentioning that the tropical plants - Palaeobursera sp. and Mastixicarpum crassum(Chandler) are present in what was known at the "Upper Hengistbury Beds" (actually part of the Lower Barton Clay. An almost tropical environment persisted from "Lower Bagshot" to "Lower Headon" times. This would be expected, considering the approximate palaeolatitude (round about 40 degree N) and the occurrence of the MECO (Middle Eocene Climatic Optimum) at about this time. The plants confirm the conventional theory that the hot Poole Delta had almost tropical vegetation. What is surprising is the early uplift of the southern Isle of Wight at about this time in the Eocene (see Plint and Curry etc - discussed elsewhere). So the rather hot delta was badly shaken by earthquakes from time to time. Faults with limited throw were not locking some oil in place, and hindering flow-back to the new anticline developing to the south as early Alpine compression increased (all this is discussed elsewhere).

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2.5a - STRATIGRAPHY AND SEDIMENTOLOGY -

BOSCOMBE SAND FORMATION - THE BLACK OIL SANDS (FORMERLY, BITUMINOUS SAND OR TAR SAND)

(with penecontemporaneous earthquake effects)

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[The section has been described by Dr A.G. Plint (1983) (Dr. Guy Plint) of Western University, London, Ontario, Canada. For details of the strata see:

Plint, A.G. 1983b. Liquefaction, fluidization and erosional structures associated with bituminous sands of the Bracklesham Formation (Middle Eocene) of Dorset, England. Sedimentology, vol. 30, issue 4, pp. 525-535. First Published August 1983.
Abstract: At Hengistbury Head, [near Bournemouth] Dorset, the Boscombe Sands (Middle Eocene, Bracklesham Formation) are of estuarine channel facies. A mud-filled channel is exposed, the banks and eastern flank of which have a black carbonaceous stain, the degraded remains of a bitumen. At the time of deposition, the bitumen rendered the sediment firm and it was extensively burrowed by a Thalassinoides-forming organism (crustacean). The bituminous sand on the eastern channel bank suffered brecciation and dilation as a result of liquefaction and flowage of the underlying sediments. This is thought to have been due to rapid expulsion of pore water, possibly as a result of seismic shock. The layers of bituminous sand below the surface were ruptered during water escape, resulting in localized zones of rapid flow causing fluidization and the development of dewatering pipes up to 1.2 m. long. The estuarine sediments were subsequently transgressed during which the bituminous sand was exposed on the seafloor, when it was eroded into a hummocky topography and heavily burrowed. Blocks of bituminous sand were reworked into the marine basal conglomerate, composed mainly of flints, demonstrating the remarkable strength of the bituminous cement. ]

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The above photograph shows small burrows filled with light-coloured sand into a bed of black, bituminous sandstone, uppermost Boscombe Sand Formation, Middle Eocene. Features like this were first found by Plint (1983), fig. 3, p. 528.

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2.5b - STRATIGRAPHY AND SEDIMENTOLOGY - BOSCOMBE SAND FORMATION (Bracklesham Group)

THE EXPOSURE AT FRIARS CLIFF (NEARBY), FOR COMPARISON WITH THAT AT HENGISTBURY HEAD

Friars Cliff Ball and Pillow Structures

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The Boscombe Sand Formation is seen at the foot of the cliffs in the western part Hengistbury Head, but dips down under the Barton Clay at the eastern end of the Head. However, futher to the northeast, it reappears, under the Barton Clay Formation, at Friars Cliff. This is further to the northeast and on the other side of Christchurch Harbour. Separating the two locations is is, at least in theory, a major faullt, the Christchurch Fault. This lies somewhere between Hengistbury Head and Friars Cliff, and cuts across Christchurch Harbout, but its exact position is not known because it is not visible at the surface. Hengistbury type of ironstone occur here and there almost up to Friar Cliff, according to an historic report (Osborne White, 1917, The Geology of Bournemouth, Memoirs of the Geological Survey, sheet 329, see p. 36 and 37)

At Friars Cliff there is a good exposure. The Boscombe Sand Formation, a unit which can be seen, in part, at Hengistbury Head, is characterised by Ball and Pillow Structures. These probably result from partial liquifaction of the water-saturated sediments, as a result of local earthquakes. The earthquake and liquifaction took place at a specific proven time. This was immediately prior to the deposition of the basal part of the Eocene Barton Clay. The base of the Barton Clay was exposed to the east of Friars Cliff, but is now very overgrown.

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The Boscombe Sand Formation (the lowest bed at Hengistbury Head) has been subject to liquifaction by seismic shocks (not surprising because this was the time the "Alpine" tectonics started in the Dorset area). At Friars Cliff, on the other side of Christchurch Harbour and near Highcliffe, there are conspicuous dewatering structures, in addition to general earthquake disturbance. Examples are shown in images above (some adjusted with slight emphasis applied for clarity).

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[See also Studley Wood in the New Forest: Go to:

New Forest-Studley-Wood website. Here the Bracklesham - Barton sequence is greatly condensed [i.e thin, with much strata missing]. Uplift was taking place at Studley Wood at about the same time as earthquakes were occurring at Hengistbury Head and Friars Cliff. On the southern Isle of Wight the uplift was probably much greater. Hengistbury Head and Friars Cliff are showing the earthquake consequences of major events of the type occurring both to the southeast (i.e. Isle of Wight) and northeast (Studley Wood, New Forest).

Re the topic of palaeobotany, note that Miss Chandler (1963) obtained more than 50 species of plants from the Boscombe Sands. In terms of marine macrofossils, there are a few brackish and marine bivalves present, but it is not easy to find molluscan fossils in these strata. Dinoflagellate cysts indicate the intricata Assemblage Zone ( Costa et al. 1976).

[CONTINUES WITH HENGISTBURY HEAD]

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2.6 EOCENE - PEBBLE BED AT THE TOP OF THE BOSCOMBE SANDS, HENGISTBURY HEAD

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At the top of the Boscombe Sands at Hengistbury Head there are two pebble beds. The pebbles are of characteristic "Chesil Beach" type. They are very rounded and they all have percussion marks resulting from pebble-to-pebble impacts on a well-sorted pebble beach. Such percussion marks or impact marks are actually small conchoidal fractures and are formed when a pebble has literally been thrown up on a clean pebble beach (without sand) by the action of large storm waves.

Confirming the former existence of a major storm beach, like the Chesil Beach, is the presence of a Maastrichtian flint pebble in the Boscombe Sands at Boscombe (Curry). The Maastrichtian is not not present on the land area of southern England, and the pebble could only have come from the English Channel area to the south. Also compatible with the occurrence of a "Chesil Beach" is the fact that there is much minute flint debris in the Boscombe Sands (Edwards et al.). The pebbles have been shaped by the impacts and the minute conchoidal fractures. The flint debris has been deposited in the sands.

The existence of such a storm beach is not surprising, but the evidence of substantial wave height is odd. The Chesil Beach in Dorset has a very great fetch, and the nearest land opposite to the beach at Chiswell is Venezuela. Thus very large storm waves occur from time to time. The Eocene "Chesil Beach" of Poole Bay seems to have been facing the southeast (because there is evidence of land to the west). It is surprising that the wave fetch was sufficient. Perhaps the Middle Eocene weather, know to have been very hot (Middle Eocene thermal maximum) was also prone to great storms or hurricanes in this region (about 40 degrees north).

The pebble bed at Friar Cliff is above Ball and Pillow Structures and unaffected by them. It is later than Boscombe Sands Formation earthquake, although preceding the early Barton Clay earthquake.

2.7 STRATIGRAPHY AND SEDIMENTOLOGY - LOWER BARTON CLAY - GENERAL.

The lowermost Barton Clay at Hengistbury Head was formerly described as the "Hengistbury Beds". It consists of greenish-grey, glauconitic sandy clay. The distinctive ironstone (siderite) nodules occur within it. They are present at three or sometimes four levels. The sandy clay is not conspicuously fossiliferous to the eye. Shell moulds occur within it but are not easily found. Actual shells or aragonite or calcite are absent because of some phase of weathering that has not taken place in the fossiliferous Barton Clay of Barton-on-Sea.

2.8 STRATIGRAPHY AND SEDIMENTOLOGY - LOWER BARTON CLAY - Nummulites prestwichianus Bed.

The distinctive, small fossil nummulite in the basal part of the Barton Clay at various localities is the minute, almost flat microfossil - Nummulites prestwichianus (T.R. Jones). It is about 3 mm. wide. [data to be added]

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2.9 STRATIGRAPHY AND SEDIMENTOLOGY - LOWER BARTON CLAY FORMATION - WARREN HILL SAND MEMBER.

The Warren Hill Sand Member is a part of the Lower Barton Clay Formation, but which is only seen at Hengistbury Head. It is a thick yellow, medium grained, sand unit, about 10m. thick and with parallel bedding and with low-angle cross-bedding.

Notes: The sand formation at the top of the cliff at Hengistbury Head (western part) has been known as the Warren Hill Sand Formation. It was named, of course, after the Warren Hill name for Hengistbury Head. The numerous rabbit burrows are in this sand. It is present at the western and high part of the Hengistbury Hill or Warren Hill.

Above the glauconitic clays of the Hengistbury Beds in the cliff section at Warren Hill, Hengistbury Head, and also in the high sea cliff (danger - do not approach the cliff edge!), there are 10 metres of very fine grained, buff and yellow, mostly unfossiliferous, cross-bedded sands. They are overlain by the Pleistocene river gravel (Bristow, Freshney and Penn, 1991). The sands were first noted by Sir Charles Lyell (1827). In 1879 Gardner referred them to the Highcliff Sands, because they were thought to be the equivalent of the Sands at Friar Cliff, Highcliffe, which underlie the Barton Clay. The dip of the strata at Hengistbury Head is such that they appear to correspond in structural terms with that unit. However, much more recently, Curry (1977) correlated the Hengistbury Beds with the Barton Clay, as mentioned above. If that correlation is correct (and the faunal evidence is quite good) then these sands correspond to the uppermost part of the Lower Barton Clay and to almost all of the Middle Barton Clay (the well-known, fossiliferous Barton Clay). These sands were then renamed the Warren Hill Sand by Freshney et al. (1984, p.46).

Now a fault has been recognised as running through Christchurch Harbour (Bristow, Freshney and Penn, 1991), and some penecontemporaneous movement (possible in Bartonian times) might have caused changes in lithology on either side of it. However, it remains, to say the least, rather surprising that the fossiliferous, gastropod-bearing Barton Clay of Barton and Highcliffe is apparently replaced here by a yellow sand with burrowing bivalves such as Pinna, Solen and Panopea Curry (1977). If these are lateral equivalents then the sand is the shallower facies from the near the lower intertidal zone. It was a very hot beach, having been deposited at close in time to the MECO - Midde Eocene Climatic Optimum!

Observe, that unlike some other Eocene strata in the Hengistbury Head area, the Warren Hill Sand does not appear to have been affected by earthquakes). All the strata in the cliffs, below the Sand unit have been affected by severe earthquakes in this area (that is at Hengistbury Head and at Friars Cliff).

The Warren Hill Sands at the upper part of the cliff near the Coastguard lookout contain holes made by Sand Martins, Riparia riparia. The photograph shows these flying around near their burrows in the hot weather of June, 2010. They were seen from above, but the cliff edge is not safe enough or stable enough to be approached in this area.

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2.10 STRATIGRAPHY AND SEDIMENTOLOGY - SUMMARY SEQUENCE, Lower Barton Clay - Hengistbury Head Succession

The sequence of strata at Hengistbury Head, arranged in order of height, is as follows:.

5. Pleistocene Gravel Terrace 10 (a small exposure at the highest part of Warren Hill, around the Coastguard Lookout Hut, older and higher than Terrace 4).
4. Pleistocene Gravel Terrace 4, (eastern end of the hill) lying unconformably on the Eocene strata.
3. Barton Clay Formation: the Warren Hill Sand Member
2. Barton Clay Formation; lower Barton Clay (up to and some way above the Prestwichianus Bed). 2. Basal Barton Clay Pebble Bed. With medium and large rounded flint pebbles. (might be regarded as top Boscombe Sand Fm., but it is transgressive beach deposit)
1. (at the base) Part of the Boscombe Sand Formation (at the beach level, western Hengistbury Head). Oldest strata present.

2.11 STRATIGRAPHY AND SEDIMENTOLOGY - Lower Barton Clay - Seismites (Ball and Pillow Structures>

Disturbed strata with evidence of slumping or convolution and that has originated from earthquake activity are known as seismites. A contorted bed of this origin is particularly conspicuous in the basal part of the Boscombe Sand Formation (Eocene) between Boscombe and Bournemouth Pier. Similar contortion is also seen in the sands beneath the Prestwichianus Bed at Friars Cliff, Mudeford. [text to be added]

2.12 STRATIGRAPHY AND SEDIMENTOLOGY - Lower Barton Clay - Clay Mineralogy

First the general clay mineralogy of the Barton Clay will be considered broadly. The information comes from a thesis by Bale. [new text follows]

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2.13 STRATIGRAPHY AND SEDIMENTOLOGY - Lower Barton Clay - Geochemistry

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Geochemical data is also mainly from the work of Bale. He did not specifically study Hengistbury Head but worked on the Barton Clay succession at Barton and Highcliffs, and also on the Isle of Wight. Some brief notes based on his work are added.

A very large amount of data on Barton Clay geochemistry has been been provided by Bale (1984). Some of this is relevant to Hengistbury Head, even though mollusc shells are not preserved here in their original condition as is the case in the Barton-Highcliffe cliff section. The Barton Clay at the type locality provides the background situation. This is relevant to Hengistbury Head, in that dissolution of fossil shells has taken place there. We do not see the well-preserved fossil molluscs of Barton-on-Sea, only moulds in sideritic ironstone or in clay.

The Barton-Highcliffe data shows the composition of the shells prior to weathering. A striking feature is that the original mineralogy is preserved. Oysters (Ostrea etc) are, of course, naturally composed of calcite, whereas most marine molluscs at the present day are of aragonite. Common molluscs of the Barton Clay, such as Corbula pisum, Crassatella sulcata or Clavilithes are still 100 percent aragonite. There has been no calcitisation of the shell whatsoever. The strontium values are very high: Clavilithes spp. - 1705 ppm Sr., Crassatella sulcata - 2450 pp Sr, Corbula pisum - 2410 ppm. Sr. (figures for Headon Hill Formation mollluscs are rather lower).

The implication of these high figures (like present day data) is that no significant carbonate diagenesis has taken place within much of the Barton Clay. On the other hand, the formation of septarian nodules shows that diagenesis has occurred, almost certainly in the Fermentation Zone.

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4.1 FOSSILS OF HENGISTBURY HEAD - GENERAL

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There are abundant fossils present at Hengistbury Head, but they are not conspicuous and therefore not often found by the briefly-visiting geologist. Dedicated fossil collectors and palaeontologists can find the fossils. Sharks' teeth are the most commonly found in the Lower Barton Clay here (I have probably found 10 or 12 of these, although I am not a serious fossil collector. They are often found in damaged condition, having been affected by the acids from the oxidation of pyrite.They may be as common at Hengistbury Head as they are in the Barton Clay at Barton and Highcliffe. These can be found on the weathered surface of the so-called "Hengistbury Beds" or Lower Barton Clay simply by regularly searching for several days. More information on fish teeth is given below. There are numerous other fossil bivalves and gastropods present but they are not easily seen. Many of these are listed below.

Erosion of the cliffs now is very limited because of a wide beach, so the chances of finding fossils are actually very small. The place was in the past subjected to more rapid erosion. I am afraid that the general visitor on a short trip to Hengistbury will usually find no fossils.

The ironstone nodules contain fossil shell moulds and sharks teeth only rarely. At the present only few ironstone nodules are present on the shore, whereas up to about the 1960s they were still abundant. This increases the difficulty in finding fossils within them. Moulds of gastropods are present. They include small examples of Turritella, as shown above, and the bivalve Cardita. Other species of molluscs that may be present in the nodules. Sharks teeth and have been found occasionally in the ironstone, but they are rare. Many fossils occur in the clays but they are not conspicuous.

Hengistbury Head is quite an important fossil locality and hundreds of specimens have been found over one and half centuries. This is a place, though, only really of interest to the specialist because the fossils are very difficult to find and they cannot be extracted as shells, only as moulds on a friable slab of clay. It is not like Barton or Highcliffe where there are obvious white fossil shells of aragonite or calcite. It is better for the general fossil collector to go to the cliffs between Barton and Highcliffe.

There are various reasons for the relative difficulty in finding the thes fossil contents of Hengistbury Head. Firstly fossils are just not widely distributed in the strata. If this was the case then they would be seen in more of the siderite (ironstone) nodules, although it must be accepted that there can be loss during diagenesis. Fossils do occur in the nodules (and I have a collection from them) but they are exceptionally rare. Most nodules show none. Unfortunately now, very few nodules are visible now because the beach has built up with sand and shingle, and because of sea defences. Only a few are visible in the old quarry. Hengistbury Head now does not look the same as in the past and the exposures are not as good.

In the clays the shells are preserved as moulds, not as shells of aragonite or calcite, as at Barton-on-Sea. The calcium carbonate has been dissolved away, although it is not quite as to just when this happened. Furthermore at the present (2013) the Head is not undergoing its usual erosion (because of a wide beach) and it is not as rapidly retreating a coast as at Barton-on-Sea.

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4.2 FOSSILS OF THE BARTON CLAY AT HENGISTBURY HEAD - MARINE SHELLS

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There are older reports of fossil content in the Eocene strata of Hengistbury Head, discussed briefly by White (1917). Sir Joseph Prestwich (1848) looked for fossil at Hengistbury Head. He stated that he found a few Eocene species above the "lower part of the clay" at Hengistbury.

A note on sheet 16 of the original Geological Survey map records, without giving their precise positions:
Cardium semigranulatum,
Cytherea obliqua,
Pinna affinis,
Thracia sp.,
"Lamna elegans" [shark's tooth], [quite likely to be Stratiolamia macrota - see below]
Otodus appendiculatus [shark' tooth]
leaves of dicotylodonous plants [plants are listed further below].

There was some successful later work. Dr. Cowper Reed, a notable geologist, was assistant to the Woodwardian professor of geology at Cambridge University in 1892, and was the curator of the Woodwardian (later the Sedgwick) Museum at Cambridge. He came to Hengistbury Head to search for fossils in about 1913. He went to Holloway's disused quarry in the centre of Hengistbury Head which at that time would have been a good exposure (it was still good by the 1950s). Reed (1913) found a number of fossils between the highest and the second-highest band of siderite concretions (approximately 2 to 4 metres below the base of the Warren Hill Sands). These were probably just moulds. Actual shell material does not survive the very acid conditions resulting from the oxidation of pyrite at Hengistbury Head. Even sharks teeth are attacked to some extent by the acid.

Six of these fossil, the good specimens, found by Dr. Cowper Reed were identified by him as:

Nuculana (Leda) minima,
Protocardium turgidum,
Corbula pisum, [this is a very common small bivalve of the Eocene, only 3 or 4mm in size, i.e. pea-sized, and fairly robust. It ranges from Bracklesham Group, through the Barton Clay and up into the Headon Hill Member.]
Crassatella sulcata (Solander), [a very common Barton Clay bivalve]
Panope (Glycimeris) intermedia
Calyptrea aperta Solander" [this has a range from Woolwich Beds to Headon Hill Formation ].

Cowper Reed then listed another 14 species, less well-preserved, with more or less uncertainty. These are the species listed as with uncertain identifications:

Anomia lineata?
Arca duplicata?
Pectunculus (Axinaea) dissimilis?
Cardium cf. formosum?
Cyrena cf. crassa?
Meretrix (Cytherea) cf. incurvata?
Callista (Cytherea) sp.
Cardita sulcata (Solander)?
Cardita sp. (small)
Corbula ficus?
Corbula cuspidata?
Tellina sp.
Turritella sp. (the gastropod, see also photograph above, which probably shows the common, Bracklesham to Barton, Turritella (Haustator) imbricateria Lamarck)
Callianassa sp. (a shrimp)

About 8 or 9 feet [about 3 metres} below the second ironstone band down Dr. Reed obtained " Mytilus affinis and Tornatella nysti" from dark chocolate clay with grains of glauconite. At the base of the cliff at the north-eastern corner of the headland he found, surprisingly, an example of Schizaster d'urbani [an irregular echinoid and not a common fossil].

The fossils in the Lower Barton Clay of Hengistbury Head occur in patches, and Osborne White (1917) when writing the old Geological Survey memoir on Bournemouth said that could only discover rare and faint impressions of shells at the horizons indicated. Internal casts of a small Corbula (Corbula pisum?)were said to be common, and with remains of other bivalves, in a band 2 feet above the lowest level of ironstone nodules in about the middle of the southeastern cliff of Hengistbury Head.

Hengistbury Head was visited by the first Australian Commonwealth Palaeontologist, Frederick Chapman, in about 1913. He discovered foraminifera there. See his paper in the Geological Magazine - Chapman (1917).

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4.3 FOSSILS OF HENGISTBURY HEAD - SHARKS TEETH

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Fish Teeth - the Sharks' Teeth of Hengistbury Head

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[PART OF 4 PALAEONTOLOGY]

Fossil shark's teeth are common in the Barton Clay of the cliffs of Hengistbury Head, as they are in the Barton Clay of Barton and Highcliffe, further east along the coast. Mostly the teeth probably belong the species Striatolamia macrota Agassiz. This common fossil is well-known to collectors from the Barton Clay of here and at Barton and Highcliffe as "Odontaspis macrota" (a synonym). It is the most frequently found of the Palaeogene odontaspids, but, of course, not all sharks' teeth found at Hengistbury Head are necessarily of this species. The Eocene Odontaspids were probably, as at the present day, large-bodied sharks with conical snouts. The teeth were not identified in detail in the past and in the old literature they may sometimes have been referred to "Lamna elegans" which was a rather general name for fossil Eocene sharks' teeth. For more information, although largely regarding the Bracklesham Group, see the work of: Kemp (1977) and Kemp, Kemp and Ward (1990) for identifying Eocene vertebrates, particularly sharks' teeth.

About 10 metres above the pebble bed (i.e. just below band 3 ironstone nodules in the diagram above) a seam with fish teeth was found by Dennis Curry. The teeth were identified by Mr. F.C. Stinton (Fred Stinton the Eocene otolith specialist of Bournemouth). The seam yielded at least 15 species, including:

Eugalus minor (Ag.),
Physodon secundus (Winkler),
Scyliorhinus minutissimus (Winkler) [cf. Scyliorhinus canicula, the common Catshark of the coastal waters of Europe - a nocturnal fish of the continental shelves],

and also representatives of the following genera:

Odontaspis [i.e. Stratiolamia, discussed above],
Myliobatis [the combe-like teeth of this Eagle Ray, Myliobatis are very common in the Barton Clay at Barton-on-Sea, probably as numerous as the teeth of Odontaspis],
Rai,
Dasyatis,
Rhynchobatis,
Trichiurides
Cymbium
Sphyraena and
?Labrus.

"Mr. F. C. Stinton, who kindly made the identifications, states that the assemblage can be matched in the Lower Barton Beds but that it includes no species which are exclusive either to the Bracklesham Beds or to the Barton beds. Chandler (1960) studied a series of plant remains from the Hengistbury Beds [see listing above], but these also (p. 197) yielded no definate evidence as to the age of the Hengistbury Beds" [extract from p. 402 of Curry (1977).]

4.4 FOSSILS OF HENGISTBURY HEAD - PLANT FOSSILS

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Hengistbury Head - Fossil Plants

See particularly Chandler on Hengistbury fossil plants.
Chandler (1960).

This listing below is from the Palaeobiology Database online, with some additional notes of mine. Palaeobiology Database - Hengistbury Head.
The following plants from Hengistbury Head are listed

TAXONOMIC LIST:

Pinopsida - Pinales - Araucariaceae

Araucarites sp. leaf, Presl 1833 [related to the Monkey Puzzle Tree and Norfolk Island Pine]

Pinopsida - Pinales - Pinaceae [the pine trees]

Pinus dixoni (Seed/fruit) [Note that succinite - amber, which comes from Pine trees occurs is present in the Bournemouth cliffs.]
Pinus sp. Leaf Linnaeus 1753. [ Ord (1914) records having twice found the remains of pine cones at Hengistbury Head. Incidently, pine trees were millions of years ago native to the Bournemouth district, although the pines there now were brought in artificially in Victorian times!]

Magnoliopsida - Theales - Pentaphylacaceae
Cleyera ? variabilis (Seed/fruit)

Unclassified

Daphne sp. (Seed/fruit)
Epacridicarpum mudense (Seed/fruit)
Mastixicarpum crassum (Seed/fruit)
Symplocos sp. (Seed/fruit)
Rhamnospermum bilobatum (Seed/fruit)

Magnoliopsida - Rhamnales - Vitaceae

Vitis sp. seed/fruit Linnaeus

Perissodactyla - Lophiodontidae

Lophiodon cf. lautricense Hooker 1977, (1 specimen; fragment of mandibular symphysis with five roots)

Unclassified

Sequoia couttsiae Heer. Wood. [Big tree, Redwood Tree etc - i.e. an Eocene tree related to modern descendents - the Californian Sequoias. It once formed great forests in Europe. Locally it covered Dartmoor.][See Chandler, M.E.J. 1922. Sequoia Couttsiae, at Hordle, Hants: A study of the characters which serve to distinguish Sequoia from Arthotaxis. Annals of Botany, os-36, (3), pp. 385-390. This is a record from the Headon Hill Formation. It is very abundant in the Hordle Leaf Bed. Available online as a PDF file, for a fee.]

Limnocarpus headonensis. Seed/fruit
Stratiotes hantonensis Seed of a water plant. [Stratiotes is a perenial aquatic plant, floating in summer and submerged in winter. The leaves are similar to pineapple leaves.]
Scirpus lakensis. Seed/fruit [sedge or bulrush]
Caricoidea obscura. Seed/fruit
Caricoidea sp. Seed/fruit
Palmophyllum sp. leaf [palmelloid green alga]

Nipadites burtini. seed/fruit [the Vietnam Swamp Palm, a notable fossil from Honeycombe Chine, Boscombe, Bournemouth. It is well-known from the Lower and Middle Eocene, including the London Clay of the Isle of Sheppey]

Hantsia pulchra. Sseed/fruit
Brasenia ovula. Seed/fruit
Palaeobursera sp. Seed/fruit
Carpolithus cornutus. Seed/fruit
Carpolithus sp. Seed/fruit. Linnaeus, 1768

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Some further brief information on plant remains at Hengistbury Head has been given by Ord (1914). He commented on fossil remains within the siderite nodules, which at that date, were visible in much greater numbers than they are at present. He said that "The ironstone concretionss contain sharks' teeth and vertebrae, both Otodus and Lamna being represented. Compressed tree-stems frequently traverse them; these are of considerable size, occasionally 5 feet in length. The bark is sometimes preserved having a black shiny appearance like coal, and the wood is usually riddled with teredo-borings [Teredina]. Fragments of lignite and vegetable debris are common and I have twice found remains of pine cones."

St. John Burton in 1931 (Burton, 1931) commented on coniferous wood in the "Lower Hengistbury Beds" (now classified as basal Barton Clay Formation) at the northeast corner of Hengistbury Head. In dark green, glauconitic clay, of which only 3 feet (about 1 metre) were seen down to beach level, he reported abundant fragments of coniferous wood, 2 feet (0.6 m.) in length. He also found tree trunks up to six feet (1.8 m.) or more in length in length. They were, of course, in the Eocene sea and as a consequence they were bored by xylophagous molluscs. So there was the washing out to sea of tree trunks from nearby land into seawater. Lignitic wood occurs in the Barton Clay at Barton-on-Sea but not usually as such large trunks. Lignite also occurs at about the Bracklesham-Barton junction at Studley Wood in the New Forest.

4.5 FOSSILS OF HENGISTBURY HEAD - ADDITIONAL NOTES

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Hengistbury Head - Later Fossil Discoveries

Curry (1977) in an important paper on the age of the Hengistbury Beds, reported finding new fossils. At about 13 metres above the pebble bed (probably this is a reference to the basal pebble bed, occurring just above the Boscombe Sands in a diagram above), Curry made a collection of clay moulds. He did not give the full list but reported those which had not been found by Cowper Reed or by Hooker, were therefore additional. The list of these newer discoveries follows:

Nucula cf. ampla
Mactra 2 spp.
Phorus cf. agglutinans
Euthriofusus regularis
Surculites errans
Sconsia ambigua
Athleta cf.nodusus
Akera striatella
Turris spp.

Breakdown of the clay in water yielded to Curry several species of smaller molluscs. Those discovered include

Lutetia pisiformis (Charlesworth)
Marginella pusilla Edwards
Conomitra parva (J. de C. Sowerby)
Roxania coronata (Lamarck)
Volvulella lanceolata (J. de C. Sowerby)
Crenilabium crenatum (J. de C. Sowerby)
Pteropod (free-swimming gastropod) - Skaptotion bartonense Curry

There were also pyritic internal moulds of the foraminifer Globulina.

Four of the mollusc species are especially significant for dating according to the late Dennis Curry. Venericardia sulcata (Solander), Crassatella sulcata (Solander), Sconsia ambigua and Akeria striatella are well-known from the Barton Beds but not from the Bracklesham Beds. In contrast a single mould of an umbo of Venericor planicosta was found by St. John Burton "a third way up Hengistbury Head". V. planicosta occurs throughout the Bracklesham but has never been found in the Barton Clay elsewhere. It could have been reworked, of course, particularly since there is evidence of reworking in the Boscombe Sand at Hengistbury Head (Bristow, Freshney and Penn, 1991) and there is obvious slumping in the Lower Barton Clay. Bristow, Freshney and Penn, 1991 discussed the matter in general and accepted the Hengistbury Beds as equivalent of part of the Lower Barton Clay taking the pebble bed at the base (after Plint 1983) as the lower boundary.

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6.1 - BEACHES - INTRODUCTION

The beach material at Hengistbury Head is prodominantly of four types. The large ironstone nodules are major features and this ironstone is discussed elsewhere in this webpage. As discussed they have come from the sandy clays of the Lower Barton Clay Formation within the cliffs of Hengistbury Head. They do not occur in the beds of soft sandstone (the Warren Hill Sand) at the top. Far more nodules were present on the beach even in the 1960s but on the south side they have been covered by new beach sand. On the far end of Hengistbury Head there are now sea defences and the original shore of countless nodules is largely concealed. Some can be seen, but in comparison with the past the number is small. Before the quarrying in the 19th century there would have been even more nodules. It is a pity that so few are visible now.

The beach sand was originally derived from the cliffs of Hengistbury Head, with additional material moving eastward by longshore drift from the cliffs of Bournemouth (particularly from the Branksome Sand Formation). Now the matter is very complicated. Major beach replenishment of beach sand from other areas (such as off the Isle of Wight) takes place every few years. A huge amount of sand and some gravel is artificially deposited on the Bournemouth beaches. Much of this moves eastward by longshore drift because of the prevailing southwesterly winds. In terms of beach material, Bournemouth's loss is Hengistbury's gain. As long as there is adequate funding for Bournemouth to periodically dump sand on the shore and then lose much of it again, then Hengistbury Head (and Southbourne) will not be short of beach sediment. In the 1950s this was not the case, and there was major erosion at Southbourne and at Hengistbury Head. The book "Hengistbury Head" by W.A. Hoodless is recommended for further information, and gives specific details about the situation at the Double Dykes.

Gravel is eroded from the Pleistocene gravels at the top of the cliffs at at least three different height. This is brown, iron-stained, subangular flint gravel. Extremely well rounded pebbles (like those of the Chesil Beach) occur in the basal pebble bed of the Barton Clay. They are easily seen in the lower part of the high cliffs of Hengistbury Head. These are eroded out and added to the other pebbles on the beach. They are very easily recognised. Following their history back further they have come from the Chalk of the Isle of Wight to Isle of Purbeck area which was uplifted in Bartonian times. Some at Boscombe are Maastrichtian in age and thus remarkably young for Chalk flints (there is no Maastrichtian Chalk in the region at the moment; it has been eroded away). See the work of Curry and of Plint for more information

6.2 BEACHES - THE BEERPAN ROCKS

The Beerpan Rocks are an accumulation of ironstone nodules that were once at the foot of Hengistbury Head. They had fallen from the cliffs. The ironstone quarrying of the 19th century resulted in the removal of the easily accessible ones. Only those below low tide level now remain.

6.3 BEACHES - DEPOSITION, EROSION AND FLOODING

(This section is not in use at the moment but is available for further information on the beaches in the future.)

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7.1 LOCATION 1 - THE THREE PORTLAND STONE GROYNES

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[Eastern Portland Stone Groyne]

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[Three Portland Stone Groynes]

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[Westernmost Portland Stone Groyne]

[note that for future recognition this eastern Portland Stone groyne has a tilted warning post on the seaward end, and some sand dunes on the landward end]

Between the eastern end of the estate of houses at Southbourne and the first part of the high cliff of Hengistbury Head there are several groynes. This low stretch has been an area of potential erosion of beach material and more seriously of the low cliff. The possibility has been considered that in an extemely severe storm, a hurricane, the sea could break over some part of the low stretch and run through to Christchurch. This is a genuine risk but only in unusual circumstances. Obviously, there is in general an apparent benefit by maintaining a good, wide beach in front of this low stretch (and elsewhere, of course). There are several groynes which retain beach sand, mostly coming from the beach replenishment schemes of Bournemouth sea front. Longshore drift is from west to east because of the prevailing southwesterly winds. The pebbles on the beach can less easily move and many of those in this low area may be derived from the local cliffs. If you examine the beach pebbles and the cliff pebbles you will notice this. Particularly easily recognisable are the very large Eocene pebbles (these occur in the cliffs at Boscombe, Hengistbury Head, and in the Pleistocene gravels between these two area. Probably the pebbles do not move easily past the groynes.

Three of the groynes at the low stretch discussed here are of white Portland Stone blocks. This local rock type tended to be popular for this type of use in the region (but later, blocks of Carboniferous Limestone became common, and then the dark-grey larvikite from Norway). The Portland Stone rock armour is not too obtrusive, although of course, not natural to Hengistbury Head. The blocks from Portland quarries are quite interesting. In more detail, there is Portland Cherty Series, some Portland Freestone, and some basal Purbeck debris. A photograph below shows a block of Portland Stone from adjacent to a major joint or fissure. Calcite has been commonly deposited on the surfaces of these major joints. Some, as shown in the photograph here, reveals previous water levels, as seen from travertine (calcite) precipitation levels.

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The last [or first] groyne at the western end of the beach between Southbourne and Hengistbury Head is of traditional type. In 2018 the beach is well-developed because of the drifted beach sand from Bournemouth and the groynes may not be essential.

7.2 LOCATION 2 - THE SHORE OF CHRISTCHURCH HARBOUR (N. OF THE HEAD)

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[Subsection - Introductory - re Mudeford Spit]

[8.1b - extra run photos - Subsection - Photographs of the Run]

On the north side of the entrance to Christchurch Harbour, the Run, there is a shorter sand and gravel spit, Mudeford Quay, now mostly, but not entirely, covered with concrete and tarmac. Here is the Haven House Inn, a car park, a cafe, a fish shop and a few other buildings. It is a centre for sailing activities.

This smaller peninsula is an interesting place because much of it is only a short distance above high tide level. The original sand and gravel spit would have been a consequence of currents, wave action and long-shore drift and its top would have been at the upper limit of normal wave action (unless having an addition of blown sand). The sea-wall, concrete and tarmac has "petrified" this spit, at some time in the past, perhaps in the 1940s. It receives no natural addition of sand or gravel, and remains as a marker of safe ground in relation to a past sea-level. It is thus good for the observation of the general sea level rise in the region and any further increased rate resulting from global warming.

The general rate of sea-level rise during the last few thousand years has been between 1 and 2 mm per annum. This is shown by dated estuarine deposits at Fawley at the southern end of Southampton Water (Hodson and West, 1972). Later studies have shown that it has been rising at the increased rate of about 3 to 4 mm per annum since the 1940s. It will flood, of course, at high tide within about 100 years. However, this is not the current risk; more serious is a return of the 1824-type hurricane which caused a storm surge in the central to western English Channel. Such a hurricane (like Hurricane Katrina) can raise sea-level by 2 or 3 metres above high tide level, but fortunately this is so rare that it has not happened since 1824 (for more on the effects of this storm, which flooded Christchurch see Chesil Beach and English Channel Storms Webpage). The average return period is not known, but such a storm is something like a 1 in 250 year or 300 year event, and, of course, it will happen again sooner or later.

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On the north side of the entrance to Christchurch Harbour, the Run, there is a shorter sand and gravel spit, Mudeford Quay, now mostly, but not entirely, covered with concrete and tarmac. Here is the Haven House Inn, a car park, a cafe, a fish shop and a few other buildings. It is a centre for sailing activities.

This smaller peninsula is an interesting place because much of it is only a short distance above high tide level. The original sand and gravel spit would have been a consequence of currents, wave action and long-shore drift and its top would have been at the upper limit of normal wave action (unless having an addition of blown sand). The sea-wall, concrete and tarmac has "petrified" this spit, at some time in the past, perhaps in the 1940s. It receives no natural addition of sand or gravel, and remains as a marker of safe ground in relation to a past sea-level. It is thus good for the observation of the general sea level rise in the region and any further increased rate resulting from global warming.

The general rate of sea-level rise during the last few thousand years has been between 1 and 2 mm per annum. This is shown by dated estuarine deposits at Fawley at the southern end of Southampton Water (Hodson and West, 1972). Later studies have shown that it has been rising at the increased rate of about 3 to 4 mm per annum since the 1940s. It will flood, of course, at high tide within about 100 years. However, this is not the current risk; more serious is a return of the 1824-type hurricane which caused a storm surge in the central to western English Channel. Such a hurricane (like Hurricane Katrina) can raise sea-level by 2 or 3 metres above high tide level, but fortunately this is so rare that it has not happened since 1824 (for more on the effects of this storm, which flooded Christchurch see Chesil Beach and English Channel Storms Webpage). The average return period is not known, but such a storm is something like a 1 in 250 year or 300 year event, and, of course, it will happen again sooner or later.

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The Run is the outflow channel from Christchurch Harbour, carrying the waters of the Avon and Stour and tidal water. It seems to have remained fairly stable in terms of position in recent years flowing out to sea over a submerged sand bar near the well-know, former residence of poets - Gundimore. In the past, though, Mudeford Spit (that is the Hengistbury side) has extended much further towards the northeast, having gone beyond Steamer Lodge to Cliff End. It has almost approached Highcliffe Castle. From time to time the extension has been breached, somewhere near the present termination. The remains of the channel have become a temporary lagoon. A good record of events, from the study of old maps and other records, has been given by the late Mr St.John Burton (1931) of Barton. Some aspects of his records are summarised here, but it is recommended that you read his paper in full, because there are many interesting points regarding the history of Mudeford Spit, the Run and Mudeford Quay.

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The eastern end of Hengistbury Head was in relatively natural condition in the 1950s. The long groyne was already in place and it was restricting to some extent the movement of sand from the Bournemouth area eastwards and round to the spit. Nevertheless the spit was stable. The end of Hengistbury Head near the spit was undergoing erosion with many ironstone nodules on the beach.

In the 1960s or early 1970s Mudeford Spit had not changed much but there were more beach huts.

Mudeford Spit is the sand spit extending northward from Hengistbury Head and partially blocking the entrance to Christchurch Harbour. The waters from the rivers Avon and Stour and tidal water from Christchurch Harbour flow out via the Run, which the narrow channel at the end of the sand spit.

The spit largely consists of sand, especially on the seaward (southeast) side with some gravel on the shore on the Christchurch Harbour side. It has some sand dunes which are better developed towards the distal end. These were originally higher and been trampled and damaged. Some Marram Grass grows on these. Much of the spit is covered with beach huts. These are usually raised on timber posts or platforms to reduce problems of flooding. Sheltered from the southwesterly winds and waves by Hengistbury Head, they seem to withstand the usual storms quite easily. Fortunately, they have not yet had to encounter the 1 in 250 year type of storm. In 1824 the sea rose several metres in a storm surge associated with a hurricane and parts of Christchurch were flooded. The spit, relatively free from buildings at that date, survived this, although possibly with a much widened Run (more information is given below in the section on historic records). At the northern end of the spit is the Black House, a conspicuous old brick building covered in tar.

Access to Mudeford Spit is easy, even in winter, with frequent motor ferry from Mudeford Quay and road trains from the car park at the western end of Hengistbury Head. It is much more heavily used by visitors now, even in winter, than when I knew it 50 years ago. At that time there was no road train and the ferry was a small, open, wooden boat that could not always cross the Run easily in a strong ebb current. It was a rather more remote place at that time.

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[Mudeford Spit continued - Erosion and Sea Defences]

Mudeford Spit is sheltered by Hengistbury Head and does not face major storm waves of long fetch arriving from the southwest. Waves coming from the southeast are to some extent limited in size because of a small fetch; there is protection by the Isle of Wight. Its protection depends on the headland and its sand supply has always come round the head. However, it is now sediment starved because of the Long Groyne at Hengistbury Head and a more recent range of rock armour groynes. It will, of course, continue to lose sand and there is no natural resupply now.

Obviously this is a spit which without further intervention should decline and reduce to a small sea-washed sandbar in a few decades. However, there is a 50 year plan for its survival. Few, Brown and Tomkins (2004) in an astute viewpoint and well-referenced paper have summarised the situation:

"The Poole and Christchurch Bays Shoreline Management Plan,... recommends a continuation of 'hold the line' defences for Mudeford Sandbank, a low-lying spit across the entrance of Christchurch Harbour (Halcrow Group, 1999). The presence of the spit reduces wave attack in the harbour and attenuates tidal range by narrowing the harbour entrance (Christchurch Borough Council, 1997). Christchurch Borough Council decided to upgrade the defences, opting for a set of new rock groynes and a rolling programme of beach nourishment. The scheme is intended to cope with changing conditions over its design life of 50 years....

Christchurch Harbour might seem well defended at its mouth, but agency and local level officials expressed concern about the potentially severe impacts of combined river/tidal flood events on Christchurch town, the prospect of sea level rise disrupting urban drainage systems, and the possibility of a catastrophic breach to the south across the low-lying portion of Hengistbury Head. Mudeford Sandbank itself has been vulnerable to past breaching during high seas, which caused extensive flooding around the harbour (Christchurch Borough Council, 1997). Engineers interviewed predicted that natural or artificial sedimentation processes will enable the sandbank to maintain its height vis-a-vis a rising sea level, but pointed out that this assumption depends heavily on the assumption that present beach recharge will continue along the beaches further to the west."

This is probably a good general assessment of the situation. As you may have noticed, there is, however, some concern about the eventual recurrence of an 1824 (Hurricane Katrina - type) "Great Gale" which may affect much of the low ground just above sea-level in the region. Consider also that there is a need of financial support for the continuation of any future sea defence work. That funding could be affected by a major recession or a different fashion or political viewpoint. A possible problem is that there might be need at some future date to divert funding to the vulnerable and low parts of the east coast of England which may be more seriously affected by rising sea-level.

Of course, in geological terms of millions of years a sand spit is a temporary feature that is extremely mobile. It will move back inland as the coast recedes and vary in length, width and details from time to time. Like Christchurch Bay in general Mudeford Spit will race inland at the high velocity of about one kilometre every two thousand years or so (or even more with global warming!). This rate of retreat is quite abnormal in geological terms but has happened at intervals during the last few million years because of glacio-eustasy (melting of ice and warming and expanding of seas).

However, note that this an average rate of average rate under consideration. For very short intervals of time such as one or two hundred years or maybe a thousand years nothing much may happen. Unfortunately, this can suggest to some people that present coast is a permanent feature. Indeed, at the time of writing (2007) Mudeford Spit appears very stable and there is almost no sign of drastic change. It is well protected by rock armour and has adequate sand and shingle. It is very suitable for public enjoyment.

However, it is not permanently stable. A 1 in 50 year storm event will happen sooner or later but it might not produce very serious damage. The 1 in 200 or 250 year event also certainly will. One day, the next "Great Gale" (as of November 1824) will arrive and it will change Mudeford Spit (and other coastal areas) quite drastically by high storm-surge flooding, probably all within 12 hours. Later the spit may stabilise again, but if it does it will be further inland. It will look much the same but it will not be in exactly the same place. The hurricane event may not happen this year, it may not happen in your lifetime, but one day or night the great storm will come. It is obviously sensible to expect it and plan for it.

8.2 MUDEFORD SPIT AND THE RUN - HISTORY

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The Run is interesting because although it is usually northeast of the Black House and the present position of Mudeford Spit, it changes from time to time. For some years it may extend much further to the northeast, approaching Highcliffe. Then it can break and return to a situation like that at present (2007). Here are some records of its history.

Early Records

1366 - Erosion at Highcliffe

To judge from the following historical record in Samuel (undated), there seems to have been great land loss in the 14th century.

At Highcliffe, adjacent to the Chewton Bunny, Christchurch priory provided 40 acres compensation for land loss to local villeins. The loss must have been at least 40 acres within an easily memorable time. An acre is about 4000 square metres. If a strip 2 acres wide and 20 acres long was lost then the erosion would have been about 126 metres landward. If the strip was one acre wide and 40 acres long then the erosion would have been about 63 metres. These would be minimum figures. If the time was say 10 years then the erosion rate would have been at least 6 metres per annum, which is about 6 times the figure for the maximum erosion rate in Christchurch Bay in recent times. It could have been more than this. A summary of the information is quoted below. The full document is a manuscript in the British Library - T16, part II, Folio 38a. It is in Latin, but a historian might be able to obtain from it a clearer picture of the ravages of the sea at that time.

[Because of major loss of land around Highcliffe by coastal erosion of Barton Clay -] "Christchurch Priory has granted its villeins of South Chewton forty acres in lots to the west of Chewton Mill in the thirty-first year of King Edward's reign (1366), in return for which the men have paid two marks as entry fee and are renting each acre at two-pence payable annually at the Feast of St. Giles: therefore they are not to be charged because of these acres, but neither are they to be excused from services which they did before this present concession; they may never claim compensation from the Priory for any of their land waste by the sea, nor relief from gifts previously owing by custom to the Priory: and if it is necessary to move their homes owing to marine devastation the men agree to rebuild at their own expense on the forty acres."

Sea level rise at about this time had major effects elsewhere. The Norfolk Broads were peat (turbary) diggings that were abandoned by the end of the 14th century (i.e. about this time) because of increased flooding resulting from a rise in sea-level (Lambert, J. et al. 1960)

1654 Old maps of this date were seen by Burton (1931). The end of Mudeford Spit was opposite the ferry at Mudeford Quay.

1703 - Daniel Defoe's Storm

On 26 November 1703 there was a famous storm that destroyed most of the windmills in England. This was a serious event, like the 1824 hurricane. It is considered to have changed the mouth of the Beaulieu Estuary in the relatively sheltered waters of the Solent by forming a new spit. According to Legg (1999) this had been recorded in parish registers as: "The great storm, both at sea and land, the greatest man knew in England was on the 26th day of November in the year 1703". For more on this see the Chesil Beach Storm and Hurricane webpage. See also Defoe in the Chesil Beach Bibliography. If it affected a spit in the Solent it would be surprising if it had no effects at Hengistbury and Mudeford Spit, but no details are known.

1717

Maps by Bowen. The end of Mudeford spit was in a similar situation to that in 1645.

1759

The Admiralty Chart of Lt. Murdock Mackenzie, two inches to one mile, 1785, was discussed by Burton (1931). The end of Mudeford Spit was within a hundred metres SE of the Haven Houses, Mudeford Quay. The width of Run was 90 yards at high tide. There was a considerable expanse of sand on both sides of the entrance, and stretching seaward for as much as 260 yards at the widest point. The opening at low water has a width of 300 yards. The sand on the north side extends only half-way to Steamer Lodge, but on the south it extends not only as far as Hengistbury Head but actually round its southeast corner. Probably there was active sand supply at the time from the eroding, Bournemouth sand cliffs.

Two smuggling luggers, loaded with tea and brandy, were approaching Christchurch Harbour at Mudeford. The sloop-of-war HMS Orestes arrived off Beerpan Rocks, Hengistbury Head at 6am. About 300 people were involved bringing the goods ashore at Mudeford and transporting them away on waggons drawn by 300 horses. There was a fierce battle from 6 in the morning until 9 in the evening. Many shots were fired from small arms and cannon. The smugglers scraped out a breastwork in the sand-dunes for defence (Morley, 1994). It is quite likely that much sand was available there at that time because extensive shoals of sand are shown near Steamer Point on the map of Isaac Taylor (1759) and much sand is recorded, as mentioned above, on the Admiralty Chart for 1785.

1811

- 1 inch Ordnance Survey Map. No lengthening of Mudeford Spit beyond Mudeford (i.e. entrance still near Gundimore).

1824 - "The Great Gale" - A Severe Hurricane

A major hurricane, known as "The Great Gale", with disastrous effects, including fatalities, in the Portland and Weymouth area. Sea-level rose in the Dorset region in a storm surge of 2 or 3 metres above high tide level and parts of Christchurch (Bridge Street etc) were flooded. It is not clear, though, whether the Christchurch flooding was sea-flooding or river-flooding or some combination of both. Burton (1931) noted some washover gravel deposits at the back of Mudeford Spit but these are not dated, and may or may not be the results of this storm. Since Hurst Spit was driven back about 40 yards it is not likely that Mudeford Spit was unaffected (although it has protection from the southwest waves by the Head). It does not, however, seem to have been broken through near Hengistbury Head, and major washover effects are not obvious (see the following comments regarding the Run).

1825-1826 - Greenwood's Map. A wide opening to the Run is shown on a map of Greenwood according to (Burton, 1931). I have not seen this map and do not know how reliable it is. It is interesting that the entrance to the Fleet Lagoon, near Weymouth, at Smallmouth became four times its normal width after the 1824 hurricane because of the subsequent outflow of the storm surge and the overtopping waters which had been pushed into the lagoon. Could something similar have happened with regard to Christchurch Harbour and Mudeford Spit; in other words was the run temporarily widened by the hurricane flood water outflow?

(Supplementary notes on the exceptionally rare conditions of hurricane flood outflow:-
The Fleet Lagoon received a huge quantity of water during the 1824 hurricane because of the overtopping of the Chesil Beach by very large waves coming from the southwest, in addition to a storm surge of 3 metres or more. The Fleet flooded deeply with a maximum of up to 9 metres at East Fleet Church. This stock of water moved down to the outflow channel - Smallmouth, the local equivalent of the Run, and flowed out in a torrent, widening the mouth, destroying the ferry house and drowning the ferryman. See Chesil Beach Storm webpage for details.
Christchurch Harbour may not have received this large amount of water, although no data is available. Mudeford Spit is much lower than the 14m high Chesil Beach but it is also much more protected, particularly from southwest storm waves. However, unlike the Fleet Lagoon, Christchurch Harbour is fed by two rivers, the Avon and Stour both of which are prone to flooding and these rivers may flood from rain during a hurricane. It would of course be expected that the sea flooded over Mudeford Spit, because of course it did that at the larger spit of Weymouth. Input of seawater elsewhere is less likely. Normally seawater cannot get over the low cliffs between Southbourne and Hengistbury Head and there are sand dunes on the cliff top which suggest that it not happened in very recent times. In the exceptional conditions in November 1824 a storm surge coincided in part with a high spring tide and with severe wave action. Sea level was effectively raised up to several metres above normal levels, although we not know just how much at Hengistbury, and this was probably less than at Lyme Regis for which there is data. If much seawater really was able overtop the low cliffs then it could have run down the supposed river channel and thus could have fed to Christchurch Harbour and added to the flood water from other sources. This is a "worst case scenario" though and it may not have happened, as yet. Local historians may discover old records regarding Christchurch which provide useful information. Look for data on the night of 22-23 November, 1824)

1829 - A steamer was wrecked and pushed into the cliff at Steamer Lodge (see photograph of notice above) apparently in about 1829. Is it possible that the wreck happened earlier and in connection with the 1824 hurricane? That had a storm surge of 2 or 3 metres or more and this would have easily enabled a steamer to be beached up at the cliff (in this particular storm a ship was washed onto farmland at Parkstone, near Poole Harbour). However, there may have been other storms in the early 19th century that caused a major storm surge.
It is worth noting that if a steamer can be driven into the cliffs at Mudeford, then at times, albeit rare, Mudeford Spit must be flooded over with seawater as has happened to the larger Melcombe Regis sand spit (Weymouth sea front).

1847 - Admiralty Chart of Captain Sheringham. The Run now extends at low tide to halfway between Haven Houses and Gundimore. Very shallow bar, only 1 foot of water at low tide. The general pattern was as previously. However, there was new accumulation of sand and shingle south of the Haven Houses.

1849-1852 - Removal of loose ironstone, a natural rock armour, from the shore at Hengistbury Head (Powell, 1995).

1870 - Ordnance Survey Map, Sheet 87, Hampshire.
Mudeford Spit has now extended nearly to Cliff End. This may or may not have been the first extension of the Spit following the removal of ironstone at Hengistbury Head.

1880 - Mudeford Spit extended to about halfway between Steamer Lodge and Highcliffe Castle, as shown on the map below.
A party from the Geologists' Association viewed the extended Run on 29 March, 1880 (Gardner, 1880):
"The Members then drove to Mudeford, and thence found their way along the base of the cliffs to Highcliff. The new channel recently created by the Stour and Avon for a mile along the base of these cliffs caused much surprise when the rapidity with which it had been formed became known."

Round about 1880 the problems of the Run extending to Highcliffe concerned the Marchioness of Waterford who owned the Highcliffe Estate. It is recorded that Louisa, Marchioness of Waterford, living at Highcliffe Castle, attempted to reduce the perennial problem of the Highcliffe Estate - the erosion of the cliff by the sea (Dale, 1914). A major factor was the Run, the river outflow from Christchurch Harbour. This was running close to the cliffs increased the rate of erosion. Lady Waterford thus ordered the placing near the Castle of blocks of limestone, and even "granite-porphyry", with the addition of slabs of the "Shell Bed" or "Stone Bed" from the base of the Becton Sand (Barton Sands) (Burton, 1931). The blocks were there in 1880. This was an early use of "Rock Armour". The objective was to turn the extended course of the Run outward rather than directly restraining the action of the sea (West, 1885). The groyne was eventually destoyed and by 1931 only a few of the stones were visible at low tide (Burton, 1931).

1883
- Mudeford Spit broke through near Gundimore

1893 - MS Geological Survey Map, Sheet 87, 1893 - Mudeford Spit extended to opposite Steamer Lodge

1895 or 1896? - Mudeford Spit probably broke through again near Gundimore (Burton, 1931)

1898 - Geological Survey Sheet 87 of 1898 - Opening of the Run is opposite Gundimore (no change)

1911
The Run extended past Cliff End

1911 - November
Breakthrough of the Run southeast of Gundimore (White, 1917)

1913
Two and half years after the opening in 1911, the end of the spit was a quarter of a mile further east (Ord, 1914).

After 1913
The rate of extension, if uninterrupted, would have taken the end of the spit almost to Highcliffe Castle by the 1930s. However there may have been another break, although Burton is not specific about this.

1929 - Winter
Some erosion took place on the main part of Mudeford Spit. The sand dunes here were originally 16 feet (4.9m) to 20 feet (6m) high but had already been reduced by trampling by summer visitors. In 1929 prolonged and severe gales swept the coast and erosion of dunes took place on the harbour side. Many dunes were cut in half, leaving vegetation hanging from them (Burton, 1931).

1930 early January
A southeasterly gale took place. This did not affect the position of the end of the Run, which was probably then in extended situation. Erosion, however, took place of a 200 yard long and 10 yard wide line of sand dunes at Cliff End. The height of the shore at the base of the cliff was lowered by 6 feet. The roots of the Marram Grass were washed out and spread along the margin of the lagoon. Sand was driven into the lagoon Burton (1931).

1930, September 18th -

The end of Mudeford Spit had reached a point at high-water mark almost due south of Steamer Lodge (Burton, 1931). A lagoon, still present there at that time , is a relic of a former channel of the Run (see map above).

1930 September 19th
There was a southeasterly gale accompanied by a very high tide. The wind, however, veered southwest after several hours. The only effect was a shortening of the spit at low tide by about 100 yard. The Run turned in towards the low (20 feet) cliff near Steamer Lodge, and Burton (1931) thought that the coming winter it would invade the lagoon still present at the base of the cliff, unless a breach takes place at Mudeford.

1931

Burton (1931) commented that (on page 161): "The recent chart shows the sandspit extending to about halfway between Steamer Lodge and Highcliffe Castle and the entrance below this and immediately south of it. The length of the spit is that attained in 1880."

1940s to 2006

A breakthrough near Gundimore must have occurred after the publication of Burton's (1931) paper and before 1939, but I do not know exactly when this happened.

Here is an account of the breakthrough by Herbert (1947):

The Future

Obviously consideration of the future of Mudeford Spit is mostly a speculative discussion point, but it is also a matter of real interest. Most spits in the region are undergoing erosion, as discussed in the next section, particularly in they are situated such that sea defences have cut off the sediment supply source. Only one, however, Hurst Spit, has been almost destroyed.

The construction of the Long Groyne and a promenade and other sea defences at Hengistbury Head have greatly limited supply of sand from the west. With the supply cut off it is very unlikely that Mudeford Spit will extend once more towards Cliff End. There is already now a sand-starvation problem, which has already necessitated some replenishment by dredged sand. Global warming and increased rate of rising sea-level will not help. The question is not whether it will extend again, but whether it can survive without a serious breach further to the south and nearer Hengistbury Head. Sea defences to the south and east mean that there is risk that Mudeford Spit will eventually follow the artificially-reconstructed Hurst Spit in becoming a type of engineered harbour wall.

Of course, no-one can be sure exactly what will happen, and there may be surprises in store. When the next major hurricane of 1824-type (a Katrina style hurricane with 2 to 3 metre storm surge) strikes the coast here it is, of course, bound to be damaging and it might cause flooding up to Christchurch, as seems to have happened in the past. It is not known just how much it would damage the spit or whether it may just break some sea defences further west and release a sand supply from Hengistbury Head to the spit again. Thus it is not known whether the final effects of the next one in 300 year hurricane would be a destructive or constructive process regarding the sediments of Mudeford Spit, but a destructive result is more likely. For further discussion on the sea defence scheme for Mudeford Spit see Few et al. (2004).

To obtain some idea of the future prospects it might be useful to make comparison with other spits.

Similar Sand Spits

Mudeford Spit has many similarities to Dawlish Warren, a sand spit on the southwest side of the Exe Estuary. Although Dawlish Warren is larger and wider, it has similarly been naturally supplied by sand from the west. In Victorian times Brunel built the coastal railway to Dawlish which isolated the cliffs of sand from the beach. This railway and associated sea defences have now cut off the sand supply from the west (cf. effects of Bournemouth promenade and the Long Groyne at Hengistbury Head). Of course, there may have undoubtedly been other complicating factors, but since then the coastal protection to the west has been major erosion at Dawlish Warren. A large part of the spit which had beach chalets in the 1930s has disappeared, and what remains is now a nature reserve. The narrower spit that has been left is still undergoing erosion on the seaward side, so that sand dunes are cut by small sea cliffs, as shown in the photograph above.

Mudeford Spit has some similarities to the east-facing sandspits at the entrance to Poole Harbour - Sandbanks and the South Haven Peninsula (although this is much larger). These Poole Harbour entrance spits have also received their sand from the Bournemouth Cliffs. The supply is now cut off by sea-walls and sea defences. However, there has been some offshore reserve in Hook Sand. Both Sandbanks and the South Haven Peninsula are undergoing some erosion although neither are seriously threatened as entities by this.

The Melcombe Regis or Weymouth Sand Spit, which is now the holiday resort of Weymouth has been extensively built over. It has not been breached or seriously eroded in recent times, but has been almost completely flooded over in the 1824 event. The solid Georgian Houses have survived this.

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Mudeford Spit might be compared to some extent to the spit at the other end of Christchurch Bay, that is Hurst Spit. This, however, is much larger and it is a gravel spit rather than a sand and gravel spit. These are both the consequences ot it being much more exposed to southwesterly storm wind and waves. The castle and adjacent area has survived because it the accretion area (the southeastern "natural tip heap")of the spit. The main beach between Milford-on-Sea and the castle, however, has suffered from the cut-off of shingle supply because of the unfortunate existence of sea-defences to the west. The result is that it has been flattened in storms and almost destroyed. However, the local authorities saved it by being rebuilding artificially from gravel dredged from the Shingles Bank. This has been done so effectively and neatly that it is not at all obvious to the casual observer that the bank has been destroyed and reconstructed. However, most of it is still gravel and to some extent vulnerable to extreme storms. It is now holding for the present, but has not yet been subjected to a real hurricane. For more on this see the Hurst Spit webpage.

The best surviving spit in the region is Calshot Spit of mainly shingle at the entrance to Southampton Water. Henry VIII's castle survives on the end and the spit has an ancient history. The reasons for this are (1) it is in a relatively protected area, the Solent, and (2) it has not been seriously affected by any major construction of sea defences to the west. There are still small gravel cliffs at the western end of the Spit keeping it supplied.

The Chesil Beach is not a good comparison because it is much larger, it is of gravel, it is part of a tombolo rather than a spit and it faces the southwesterly storm waves. However, the Chesil Storm webpage might be of interest because it contains a record of major storm events in the region, and detail regarding the disastrous 1824 hurricane.

Readers with further interest in comparisons should read about the East Coast spits such as Spurn Head and Orford Ness. See also Mosby (1939) on breach of a sand spit at Horsey on the east Norfolk coast.