Romsey, Hampshire
and Visiting Scientist at:
Faculty of Natural and Environmental Sciences,
Southampton University,
Webpage hosted by courtesy of Information Systems Services, Southampton University
Aerial photographs by courtesy of The Channel Coastal Observatory , National Oceanography Centre, Southampton.
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CONTENTS:
SECTION 1 - GENERAL INTRODUCTION
1.1. 1-INTRODUCTION - Location, General
1.2. 2-INTRODUCTION - Safety
1.3. 3-INTRODUCTION - Previous Literature
1.4. 4-INTRODUCTION - Topographic Maps
1.5. 5-INTRODUCTION - Geological Maps
1.6. 6-INTRODUCTION - Route Down to the Stream
1.7. 7-INTRODUCTION - Stream Exposures
1.8. 8-INTRODUCTION - The Waterfall
1.9. 9-INTRODUCTION - The Plunge Pool
1.10. 10-INTRODUCTION - The Small Gorge (downstream from the Plunge Pool)
SECTION 2 - SELSEY FORMATION (BRACKLESHAM GROUP)
2.1. SELSEY FORMATION - Introduction to the Strata
2.2. SELSEY FORMATION - Introduction
2.3. SELSEY FORMATION - Fossils
2.4. SELSEY FORMATION - Palaeogeography
SECTION 3 - BARTON FORMATION (BRACKLESHAM GROUP)
3.1. 1-BARTON FM - Introduction
3.2. 2-BARTON FM - [for future use]
3.3. 3-BARTON FM - [for future use]
SECTION 4 - HUNTINGBRIDGE STRATA (Bracklesham-Barton Boundary at Studley Wood etc)
4.1. 1-HUNTINGBRIDGE STRATA - Introduction and Sequence -
4.2. 2-HUNTINGBRIDGE STRATA - Nummulites prestwichianus Bed at Studley Wood -
4.3. 3-HUNTINGBRIDGE STRATA - Reserve Section not in use [ was Afton]
4.4. 4-HUNTINGBRIDGE STRATA - The Huntingbridge, Shell Bed at Studley Wood
4.5. 5-HUNTINGBRIDGE STRATA - The Huntingbridge Coral Bed at Studley Wood
4.6. 6-HUNTINGBRIDGE STRATA - The Huntingbridge Coral Bed at Other Locations
4.7. 7-HUNTINGBRIDGE STRATA - Barton Clay Above The Coral Bed
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SECTION 5. - HUNTINGBRIDGE STRATA AT OTHER LOCALITIES
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SECTION 6 - PLEISTOCENE
7.2 BIBLIOGRAPHY AND REFERENCES
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1.1 - INTRODUCTION
Location - General
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The exposure is in a valley and wood only a short distance down valley. It is easy to find the stream, but the exact fossil localities are not obvious. In general it is a wet and muddy place, partly boggy, and some luck is needed to find a good exposure in the bottom of a stream bed. In winter the mud is worse but in summer the tree leaves darken the area. To see an exposure before it is filled in by the Forestry Commission is would probably be necessary to go early in the year 2016, although the filling in, of course, might be delayed. There are few good geological exposures with fossil material that can be found in the New Forest, so the place is rather unusual.
Studley Wood in the northern and highest part of the New Forest National Park and is of very easy access from the B079 main road (Cadnam to Fordingbrdge), and in particular the small car park at Bramshaw Telegraph (see location maps above). It is notable geologically for exposures of fossiliferous Eocene strata in an upper tributary of the Latchmore Brook. Generally, it is rare to find good fossiliferous exposures in the New Forest, mainly because of gentle topography and a moderate thickness of weathered ground. The exposures present in Studley Wood are notable because they are at and near the junction of the Bracklesham Group and the Barton Clay Formation. They have been described in several papers, and references are given here. Unfortunately, they may be soon covered with tipped debris and become lost for further geological study. This is because of a plan to create bogs even if it destroys geological exposures. There have been protests (not by the author here but by an environmental and geological group) but, unfortunately, they have had no effect in changing the policy of dumping gravel and hoggin and other non-local material.
More specifically, the location is at Bramshaw Telegraph, a well-known high point on the B3078 road from Cadnam to Fordingbridge. At this point the B3080 road branches off to the northwest. The map reference of the car park is 228 167. See also Google Earth - 50deg, 56mins N; 1deg 40mins W. The elevation is at 128m. (419ft), but it does not seem particularly high because the slopes across the forest to the southwest are not very steep. However the slope down to the southeast on the other side of the road is quite steep (I used to ride up and down there at one time). The Bramshaw Telegraph car park is marked on the Ordnance Survey, New Forest Sheet, and is easily found. Leave your car here and walk down an easy path, for less than one kilometre distance. The footpath is good but depending upon weather conditions, the brook and its vicinity in Studley Wood may be very muddy and in some parts a quagmire.
Bramshaw Telegraph was part of an historic communication system, used by sailors in the Napoleonic Wars. Signals were sent by opening and closing six shutters in a vertical frame and seen at a distance by telescope. The device was near Hope Cottage, on the opposite side of the road to the car park but there are no remains of the telegraph left now, as far as I know. The communication to the east was to Toot Hill (near Rownhams) and to the west to Pistle Hill at the Dorset boundary. For more information see the website:
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There are mud hazards in the Latchmore Brook eastern stream at Studley Wood, especially in winter. Within the stream bed there is in places a specific risk of becoming stuck. There is soft Eocene clay, that at certain locations can become like a "quicksand". If you remain at one of these places for more than a few seconds, you may start to sink in. If you were unaccompanied a hazardous situation could arise. There, it is best, if possible, to go in dry weather, with other people and with a mobile phone. There is also a possibility of slipping off a fallen tree trunk in the stream or adjacent banks. The location is not ideal for a student field trip, except, perhaps, in good, dry weather.
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1.3 - INTRODUCTION
Previous Literature
Older Work
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Stinton (1970)
Todd 1990
Todd's publication is quite thorough and detailed. It provides a graphic log of the succession. A modified, enlarged and clearer version of this is included in this webpage. Credit must be given to the the detailed work of
Todd (1990). .
This account of
Todd (1990) is obviously important in several respects. It has very useful introductory map, but of particular importance is his very detailed description of the succession of strata. A redrawn version of Todd (1990) log is given in this account. The original is very good and should be consulted. It is not necessarily easy to understand in detail because, unfortunately the main graphic log, has been printed in his paper at a rather small scale. The colour version here should make his work clearer.
It is also useful to see a short extract from the beginning of the paper by
Todd (1990). This summarises the history of geological work here.
Further study of Todd's paper is recommended for understanding details, fauna and correlation. Not only are the specific strata at the boundary of the Bracklesham and Barton stratal units discussed, but also the correlation and thickness of the whole Selsey Formation across the Hampshire Basin is considered. In particular note from his Text-fig 3, that the thickest Selsey Formation is present in the Ramnor Inclosure Borehole, in the centre of the basin.
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Edwards and Freshney (1987)
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Geckoella Report (2010)
British Geological Survey, (B.G.S.) - Maps and Memoirs
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1.4 INTRODUCTION -
Topographic Maps
The general introductory topographic map is the 1:25,000 Ordnance Survey Sheet, New Forest. This is on a scale of 4cm to 1km or two and a half inches to one mile. Purchase of this easily obtainable map is recommended. Larger scale, Ordnance Survey maps exist but are not very easily obtained at present. Google Earth shows detailed features of moorland very well, but, does not, in general show the stream within forest.
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1.5 - INTRODUCTION
Geological Maps
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The area under discussion is shown on the 1:50,000 British Geological Survey map, Ringwood Sheet, 314, published by the Natural Environment Research Council in 2004. It very near the eastern edge of the map, in the upper part. It is between eastings 22 and 23 and adjacent to the well-known, New Forest locality, "Bramshaw Telegraph". It is mostly between northings 15 and 16. It is also close to the western edge of the British Geological Survey Map, Sheet 315, Southampton, 1:50,000. A point of discussion or disagreement is the location of the boundary between the Selsey Formation (top of the Bracklesham Group) and the overlying Barton Clay Formation. If this is taken as just above the thin Coral Bed, discussed below, then the field position does not accord with that shown on the Ringwood Sheet (the Selsey Formation may be taken too high).
Based on a combination of various sources a larger scale geological map is shown below. No claim is made that this is precise, because surface exposures of the Eocene strata are very limit and no extensive resurvey has been made. Recent and specific studies, though have provided new detail.
1.6 - INTRODUCTION
Route Down to the Stream (Eastern Latchmore Brook, Studley Wood)
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The photograph above is old and was taken in 2003. The general scene has not changed much, but this image shows the scene before the Forestry Commission commenced the recent dumping of gravel and hoggin into the stream bed in this New Forest valley. Notice that there is evidence of some former deepening of the stream, probably by digging with spades. Notice the small mounds which are probably of debris dug from the stream bed.
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A short walk down from the car park at Bramshaw Telegraph leads down into small valley of Claypits Bottom. Here the very minor, eastern headwaters of the Latchmore Brook are seen. Work by the Forestry Commission has to some extent filled the small stream to create a more boggy environment. Further ahead you can see that the stream becomes more entrenched before passing into the forest, which here is the Studley Wood Inclosure.
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1.7 INTRODUCTION
Stream Exposures
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The exposures in the stream change drastically over the years. Major erosion has occurred in the area of the Coral Bed, as seen in 2016 compared to 2003. The Coral Bed exposure was high in the stream bank, at the plunge pool, near the small waterfall; it was near the northern corner of the Studley Wood Inclosure. The bank exposures have been eroded back appreciably since 2003 and in 2016 the plunge pool was much wider and the Coral Bed exposure was not found (at least, not immediately) . The peculiarly distorted trees can still be recognised in 2016, but the stream has widened out on the west side. The chances of finding particular fossil beds are very different on different occasions, and you should not be particularly optimistic, but you might be lucky!]
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As Stinton wrote:
"The next exposure to be visited was in the banks of the headwaters of the Latchmore Brook. The stream rises in swampy ground and starts to cut into substrata just before entering Studley Wood. The following descending section is seen [in 1970] as one proceeds downstream..." [see notes that follow]
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Within the wood the stream is in an old trench, about two and a half metres deep. It is apparently artificial but it seems relatively natural now. The channel is fairly straight but here and there it seems to be gradually developing small meanders. At its sides there are small, shallow ditches that are oblique in a downstream direction and can supply some water to the main trench. The water depth in the main stream is small and you can walk in it. However, it can be slippery and muddy, especially in winter conditions. Some trees have fallen partially or completely across it.
The fossiliferous exposures are at the bottom of the bank, near water level, but only at certain places. These are mainly at the northeastern part of Studley Wood Inclosure, near the place where you enter the wood from the footpath. Be careful about boggy ground here.
This is one of the few places in the New Forest where fossiliferous deposits could be seen in the past. Unfortunately and surprisingly, the Forestry Commission has plans to destroy the geological exposure by partially infilling the stream with unnatural dumped material coming from an old quarry east of the Ringwood area.
The strzat are the uppermost Bracklesham Group sediments and the lowermost Barton Clay and are in the banks of the Latchmoor Brook. The exposure is rare in effectively showing the junction between these strata units. The exposures are small and in the banks near the stream bed. Fallen trees and slippery, sticky mud are obstacles and Wellington boots are needed for practical study. The deciduous trees, particularly in summer, reduce the light for clear visibility, and in winter there may be high water-levels and high flow rates which make access impossible.
In good conditions and with knowledge of the correct locations, three fossiliferous beds can be found. The fossils are only present at or below stream level at two and half metres down. Above this level there has generally been decalcification, as a result of acid weathering (from both peaty soils and from oxidation of pyrite, producing acidic sulphate ions). In favourable conditions it is quite easy to see cream or white shelly material. The aragonitic shells though are crumbly and friable and it is not easy to obtain unbroken specimens. The good collections that have been made have probably been obtained with much care. Without doubt the shells will be in better condition at greater depth.
1.8 INTRODUCTION
The Waterfall
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1.9 INTRODUCTION
The Plunge Pool
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There are many good exposures of laminated and bioturbated clay in the Plunge Pool of the waterfall. This place has changed greatly from the year 2003 to the year 2016. It is much wider now. Some of the old fallen trees still remain, crossing the muddy pools of water. It is quite a fossiliferous locality and mainly in the Huntingbridge Shell Bed. The Coral Bed has been found by me in the eastern bank of the Plunge Pool in 2003, but not found again in 2016. Exposures here obviously vary greatly with time and erosion.
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1.10 INTRODUCTION
The Small Gorge
This is an almost straight channel, probably an old trench, extending downstream (i.e. southwest) for ten or twenty metres. It is about 2 and a half metres deep, and just a few metres wide. At the downstream end the channel suddenly widens. On the west side at this point is a "quicksand" locality, actually soft wet clay, where I almost lost a pair of boots and did lose a geology hammer. I was pulled out by friends.
Geologically, the gorge is interesting because a small variety of Clavilithes macrospira occurs somewhere in the banks here, because several specimens have been found loose. The shells are bored and the gastropod seems to have been exposed on the sediment surface back in Eocene times. Photographs of this are shown elsewhere in this webpage. At the time of writing the in situ location has not been found.
2. THE STRATA OF STUDLEY WOOD - SELSEY FORMATION (BRACKLESHAM GROUP)
2.1 - SELSEY FORMATION -
Introduction to the Strata.
The strata here are of Eocene age, in round figures about 40 million years old. The latitude was further south than at present. The climate was generally warm with sufficient rainfall for extensive forests, particularly of Sequoia trees. However, there were particular peaks of higher temperature on more than one occasion during the Eocene. The clays and sandy clays of Studley Wood originated in a shallow embayment of the sea which covered much of the New Forest area. There was the Poole Delta a short distance away to the southwest, and rivers brought much muddy sediment into the area.
It is of particular interest that the folding of the Isle of Wight and Isle of Purbeck started in Middle Eocene times, approximately coinciding with the deposition of fossiliferous clays etc at Studley Wood. In terms of petroleum geology the region is part of or adjacent to the English Channel Inversion. There was formerly a major deep basin between the southern Isle of Wight and the southern Isle of Purbeck. This is well-known as the source area of oil generation for the Wytch Farm Oilfield. This basin was "inverted" (actually uplifted) to form the Chalk and Jurassic hills of the Isle of Wight and Dorset. The area to the north, i.e. the New Forest area, had been relatively higher with shallow water deposits. In due course this became the low area (geologically) and the area to the south became the high. This is the understanding of the region as an Inversion Structure (there are other examples in northwestern Europe).
So the New Forest area was not greatly tectonised and the strata dip at only very low angles. The Bracklesham Group and the Barton Clay (above it) are Eocene strata that are richly fossiliferous. They are well known from coastal exposures at Bracklesham Bay and at Barton-on-Sea, and on the Isle of Wight. These strata underlie a large part of the New Forest. Exposures of the strata in the New Forest are rare because of subdued topography and the fact that the sediments are soft, not hard rocks, and are often covered with Pleistocene gravels, with weathered soil and heather and forest. You will not see much of them. At Studley Wood, however, there is an unusually deep stream, probably partly an old artificial drainage trench, and in this there is a remarkable abundance of fossils from at and near the Bracklesham - Barton boundary. Most notable is the Studley Wood coral bed. So this is place in the New Forest with fossiliferous Eocene strata. The particular sequence at Studley Wood can now be discussed.
The Bracklesham strata underlie the Barton strata, so we commence with the Bracklesham Group. Only the top part of this, a portion of the Selsey Formation is present in the Studley stream exposure.
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2.2 - SELSEY FORMATION
Introduction
The Bracklesham Group of Middle Eocene strata take their name from Bracklesham Bay at the Selsey Peninsula, West Sussex. A notable early description of the strata there have been given by
Fisher (1856). The Selsey Formation is the uppermost part of the Bracklesham Group strata. It is Lutetian in age. In general it consists of glauconitic sands and clays with many marine fossils. The latter include large bivalves, gastropods and less-commonly corals and also sharks' teeth. At Studley Wood the uppermost part of the Selsey Formation is seen. The Huntingbridge strata are the units at the boundary between the Selsey Formation and the overlying Barton Clay.
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2.3 - SELSEY FORMATION
Fossils
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Shelly material is found in bluish-green, sandy clays, downstream from the Coral Bed locality in the tributary of Latchmore Brook, Studley Wood. Fossils are common here, both in situ, in the bank, and also as washed-out material in the stream bed. This is almost certainly strata of the Bracklesham Group. The fossils are common Bracklesham species, probably from the Selsey Formation, at no great depth, stratigraphically below the Barton Clay.
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Many worn fossils are present, loose, in the stream bed at Studley Wood, downstream from the Coral Bed and the Nummulite Bed. These are mainly worn and broken gastropods and bivalves from the Bracklesham strata. They are probably from the Auversian, Selsey Formation. As shown in photographs here, Turritella imbricateria is common and so too are pieces of the large bivalve Cardita planicosta. There are several other species present too. About forty shells or shell fragments were found in about an hour. some of these may be of Barton Clay origin, but most seem to be from the Selsey Formation of the Bracklesham Group.
2.4 SELSEY FORMATION OF THE BRACKLESHAM GROUP
Palaeogeography - European
A palaeogeographic map of the English Channel and broader European area in the Middle Eocene, Lutetian (about 41 million years ago) is shown below. Notice that a precursor of the English Channel was already present at this relatively early date.
The palaeogeographic map above is based on
Diedrich (2012). It is generalised but it sets the scene. The New Forest and the Hampshire and Dorset coastal exposures and those of the Isle of Wight contain deposits that originated in a warmer precursor of the English Channel. Regard the comments about beach pebbles with caution at the moment. It is not impossible that the wave action responsible for these "Chesil Beach" type clasts may have been coming from the southwest, even in spite of early uplift of the Isle of Wight structures. The map may be adjusted.
3. BARTON
BARTON FORMATION - INTRODUCTION
The Barton Clay is, of course, particularly well-exposed on the Hampshire-Dorset Coast at Barton-on-Sea. The stratigraphy of the upper part of the succession is well-established an not a subject of dispute. The geology of the lowermost parts in the area of Highcliffe-on-Sea, at Hengistbury Head and eastwards are not, however, straightforward and easily classified into easily recognised units. This Bournemouth region is just west of the Eocene Poole Delta. There is lateral change from marine strata in the east to deltaic facies in the west. This has caused complications of correlation. The real base of the Barton Clay may, in fact, be lower than has been generally recognised in the past.
3-BARTON-2 - SEQUENCE BARTON FORMATION - INTRODUCTION
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3-BARTON-3 - SEQUENCE BARTON FORMATION - New part to be added
(Bracklesham-Barton Boundary Strata at Studley Wood)
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4.1 HUNTINGBRIDGE STRATA
Introduction and Sequence
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The above diagram shows the succession of Eocene clays and sandy clays near the Brackllesham Group - Barton Formation boundary. This is largely based on
Stinton (1970) with comparison made with data from
Fisher (1862). The Coral Bed was seen seen by Fisher in a shore section near Stubbington (Lee-on-the-Solent) and he measured the associated sequence. Thus it was known about 100 years before its re-discovery in the New Forest. The bluish-grey clay with scattered corals is a conspicous marker if it is exposed. As noted above, it was studied by
Stinton (1970)
and he had collected other fossils from the Studley Wood stream section. More recently,
the present author (with grandson Daniel Bentley, then very young, and shown in the photographs) in about 2003 or 2004. I had no difficulty finding it or collecting corals. However,
Todd (1990) described the section, with some good detail, but did not find the coral bed. This is unfortunate because his graphic log cannot easily be tied in with a log shown above, based on
Stinton (1970) and on Fisher (1862). I have not personally logged the section systematically and I would have liked to have linked
Todd's (1990)
data to the older records. I have not yet done so and I need to follow further the work of Todd and of others. This online account must be regarded as incomplete, but it should give introductory guidance to those wishing to study the matter further. See
Todd's (1990) Text-Fig 3 for his correlation of the uppermost Selsey Formation (Bracklesham Group) strata across the Hampshire Basin. His diagram is detailed but there was some uncertainty about the position of the Coral Bed.
A redrawn and modifed version of Todd's vertical section is given below.
4.2 HUNTINGBRIDGE STRATA
Nummulites prestwichianus Bed in Selsey Formation at Studley Wood
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The Nummulites prestwichianus Bed is an important marker horizon, that is just below the Bracklesham-Barton boundary. It is bed SW1b of
Todd (1990).
Its relative position in the Latchmore Brook and at Stubbington is shown in an associated diagram here. It must not be confused with the Nummulites variolarius bed, which is lower in the Bracklesham sequence.
Only a limited fossil content of the bed seems to have been reported for Studley Wood.
Stinton (1970) commented on it very briefly as follows:
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The grey sandy clay of this bed contains many small nummulites, resembling Nummulites variolarius . With these microfossils are minute bivalves, even smaller than the tests of the protozoans. These bivalves are probably a species of Corbula.
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[Reserve Section - not in use at present]
4.4 HUNTINGBRIDGE STRATA
Bed C - The Huntingbridge Shell Bed of Studley Wood
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This is a very fossiliferous unit of burrowed, partially glauconitic, very sandy clay, with shells. It is easily seen in the banks of plunge pool area, just down from the waterfall and about two metres deep. This plunge pool is rather hazardous in wet weather conditions, very muddy and slippery with irregular tree trunks and branches. It is all too easy to slip off a tree trunk into soft mud, and if you were alone, it might be a long time before you were seen in this broad dark hole.
The dark, nearly horizontal beds of fractured clay contains numerous bivalves. However, they are rather fragile and difficult to extract whole. There are also abundant small calcareous tubes that may be the scaphopod - Dentalium. Many of the fossils are very fragile and may be too easily broken to extract from the clay, at least in the field. Shelly, sandy clays are also present in the small, straight, gorge-like part of the stream that extends down from the irregular plunge pool. Shells are present in this section too. The gastropod Clavilithes is found washed out at the sides of the stream down here.
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Since 2003 when the earlier photographs shown here were taken the general plunge-pool area, just downstream from the waterfall has expanded. It is very irregular, with fallen tree trunks and requires some clambering around in a slippery, wet and muddy environment. The banks are of bluish clay and of sandy clay and are quite fossiliferous. Unfortunately, probably because the exposure is at shallow depth and has been affected by weathering (or Pleistocene periglacial fracturing) the shells are not usually extractable whole. They break if you attempt to get them out. They are mostly Turritella, with scaphopod-like, tubes, that may be Dentalium. The fossil content and general relative position confirms that the clay here is part of the Huntingbridge Shell Bed. In the sandy clays in the vicinity there are also many paired bivalve of an elongate species.
During this particular field trip, the exposure of the Coral Bed was not seen. It has been seen near here in the past. Howevever, conditions vary here from time to time with occasional collapses of the banks and occasional new exposures. Diligent search in dry weather may reveal it again.
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A fault is present, running almost along the direction of the stream, according to Todd (1990) . This fault is not visible but has been detected by augering and detailed studies of the stream. It results in the apparently anomalous occurrence of the Nummulite Bed, discussed below, just downstream of the Coral Bed. In fact the Huntingbridge Shell Bed ought to occur next but part of it is seen a little further south on the east bank. It occurs at the bottom of a little meander cliff. As in the case of the other beds it is decalcified in the bank except at the bottom near stream level. Fragments of common Eocene mollusc shells such as Turritella can soon be recognised. The little exposure resembles a rather weathered bank of the familiar shelly Barton Clay at Highcliffe. It is obvious that a good range of fossil material is present, but good specimens are not immediately found and those seen are fragments in rather crumbly, clayey sand. The present writer has not sytematically collected from here, and thus refers below to the literature regarding species found in this bed. What is shown in the photograph may not necessarily be the best part for shells and better material may be present elsewhere in the stream bed. Note that when the stream level is high access to the bed might be impossible. Like the other exposures, this is a rather dark locality within the wood.
Stinton (1970) described this bed as follows:
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The bed was referred to as the Hunting Bridge Bed by
Fisher in 1862. It was originally studied in an artificial watercourse, round about half a kilometre to the east of Fritham and in the Linwood Inclosure or Lynwood Coppice.
Edwards and Freshney (1987)
5.1. HUNTINGBRIDGE OTHER LOCALITIES - Lee-on-the-Solent
5.2. HUNTINGBRIDGE OTHER LOCALITIES - Hunting Bridge near Fritham
5.3 HUNTINGBRIDGE OTHER LOCALITIES - (Other New Forest localities)
5.4 HUNTINGBRIDGE OTHER LOCALITIES - Ramnor Inclosure
5.5 HUNTINGBRIDGE OTHER LOCALIITES - Alum Bay, Isle of Wight
5.6 HUNTINGBRIDGE OTHER LOCALITIES - Whitecliff Bay
5.7 HUNTINGBRIDGE OTHER LOCALITIES - Afton Brickyard, Isle of Wight
5.8 HUNTINGBRIDGE OTHER LOCALITIES - MECO Time Plane, Discussion
6.1 PLEISTOCENE GRAVELS - Description
6.2 PLEISTOCENE GRAVELS - Discussion
6.3 PLEISTOCENE CRYOTURBATION
7.1 ACKNOWLEDGEMENTS
The Studley Wood section is in the northern part of the New Forest National Park, very close to Bramshaw Telegraph or Telegraph Hill, one of the highest points in the forest.
It is very near the main road, the B3078, from Cadnam to Fordingbridge. There is a free car park on south side of the road. It is rather small and can take only about a dozen cars (but there are other car parks a short walk away). From here you only have to walk down into a nearby stream valley; it is less than a kilometre down. Except in very dry weather you will probably find the route rather muddy. Full height Wellington boots are advisable, and essential if you intend to explore the stream exposures. Whether or not it is needed elsewhere a treking pole can be helpful in the muddy stream valley. If you are not actually going into the stream, the walk is just a normal New Forest walk on a rough footpath with a little boggy ground here and there, and easily done by most people. Going down into the northern, narrow part of stream bed (i.e. below the little waterfall) is best avoided, except by a researcher. The clay can be very slippery and muddy and with various fallen tree trunks, and there is some "quicksand" in places. Significant physical effort would be necessary in places, and it would certainly not be a good place to become stuck on your own.
There are some other possible hazards that are less likely to be a problem. Be cautious with regard to animals, and do not disturb New Forest ponies. Pigs which might be present in the acorn season and on rare occasions (with young) might be aggressive. Adders (poisonous snakes) can be present in the New Forest but they are very rarely seen, and not aggressive unless handled. At the road, of course, there are the usual road traffic risks, and you should drive slowly and look out for the animals (ponies, donkeys, cows and pigs that are common here. Note that this website is descriptive and is not a digital guide-book; it does not advise you to go to any particular place or take any particular risk. No liability is assumed regarding field work here or anywhere else.
Early work on the Bracklesham strata by
the Reverend Osmond Fisher (1862) provided good bed-by-bed descriptive information for some important localities in the region. He studied strata at Lee-on-the-Solent equivalent to that at Studley Wood. He is well-known, amongst other work, for having provided a good early description of Bracklesham strata of Bracklesham Bay, Sussex. In 1862 he reported that a fossil bed was discovered in an artificial watercourse near a place called Hunting Bridge in Lynwood Coppice of the Ordnance Survey Map. This location is now termed the Coppice of Linwood and it is about half a kilometre east of Fritham. This was presumably in the King's Garn Gutter or a tributary of it. He reported a six inch [15cm} thick bed of "Bluish-green clay, full of large Dentalia (sp. nov.) and corals. He provided a list of fossils collected, including nummulites. Much later, in 1956, "Huntingbridge Bed" fossils were found again. Curry reported them in a 1968 French account. Then came Stinton's work.
Stinton (1970) [Mr Fred Stinton of Bournemouth and Bournemouth Natural Science Society] wrote a report of a geological field meeting in the New Forest in 1969. He provided some details regarding the Studley Wood exposures. Some notes based on his observations are given below. There is later, more detailed, work by
Todd (1990). A recent report by Geckoella (2010) gives some further details and some good illustrations. See also the correlation diagram of
Kemp et al. (1979).
"The stream of Latchmore Brook flows south-westwards into the River Avon which delimits the western boundary of the New Forest. In its upper part, it cuts a valley through Pleistocene Plateau Gravel, Eocene Barton Clay Formation and Selsey Formation sediments. Due to rapid downcutting the last two are exposed in banks of up to 3.5m in height. From the southern half of Claypits Bottom south-westwards through Studley Wood Inclosure, where the fossiliferous sections occur, into Islands Thorns Inclosure, the bank sections decrease in height with the shallowing stream gradient (Text-fig. 1).
Rather suprisingly this site was unknown to Keeping, Fisher and other nineteenth century workers who discovered the famous fossiliferous New Forest sites. However the 2.5 to 3m of rock [i.e. clay, silt or sand] underlying soil level is decalcified, except in a few small pockets, and the stream may have only comparitively recently exposed unweathered sediments. This may account for the late discovery of typical "Huntingbridge bed" fossils at "Claypits Bottom" by J.G. Turner sometime before August 1956 when they were presented to the British Museum (Natural History) [i.e. the Natural History Museum]. A short account of the stratigraphy was published in French by Curry (1968) and a similar summary in English by
Stinton (1970).
Kemp et al. (1979) gave a correlation diagram with sections of similar age which superseded that of
Murray and Wright (1974)."
[section to be added]
Geckoella Environmental Consultants of Taunton Somerset produced an excellent report on Latchmore Brook that was commissioned by the Forestry Commission. It is entitled:
Geckoella (2010), 2010. Geological Survey of Latchmore Brook, Claypits Bottom (Studley Wood GCR Site) New Forest, Hampshire.
This survey was commissioned by the Forestry Commission as part of their investigations relating to proposed mire restoration works at Claypit Bottom. The proposed work involves effectively filling in the stream channel with various materials including a peculiar mixture of very coarse flint pebbles (quarry reject?) and sands, silt and clay. This material would come from a quarry near Ringwood in Tertiary strata, overlain by Pleistocene gravel [more details will be given later]. So the stream channel which has yielded important geological exposure may be filled and leveled out so as to create yet another bog within the New Forest. It would seem that the stratotype exposure of the Studley Wood Member of the Selsey Formation (Bracklesham Group) may be covered and converted and conealed under bog. Geckoella, referred to below has produced a geological report, and more information relating to this will be provided later. The most important geological publication on the exposures, strata and locality is that of
Todd (1990) . More information from Todd is given elsewhere in this webpage (which is still in process of being written. The particular site has been visited by several people, and the present writer particularly thanks two local experts for guidance at the site and discussion of the stream-filling scheme. The writer thanks Professor John Shephard for drawing attention to the problem, here. [These are preliminary notes and more information will be provided, and the account re-structured].
The following brief extract regarding previous work at the Latchmore Brook and Studley Wood stream exposures and fossil localities is from
Geckoella (2010):
"A useful overview of previous work undertaken at this site, especially regarding its stratigraphy, can be found in Daley and Balson (1999). It has been estimated that a thickness of approximately 10.5 to 11.5 metres of clays, silty and sandy clays and glauconitic muds are present in the Latchmore Brook/ Studley Wood sections (Daley and Balson, 1999). Although the precise stratigraphical assignment of the strata is still not agreed, it is clear that the sediments occupy a position adjacent to the Selsey Sand Formation/ Barton Clay Formation boundary, and provide a fossiliferous sequence across the Lutetian/Bartonian stages of the Eocene. As Todd (1990) mentioned, this site was rather surprisingly unknown to 19th century geologists (such as Keeping and Fisher) who discovered other fossiliferous locations in the New Forest, including Shepherd's Gutter. J. G. Turner discovered fossils at the north-eastern end of the site before 1956, although it was C. King who re-discovered much of the section following his consultation of notes made by Wrigley who recorded fossils in the banks of Latchmore Brook in the 1930s.
The geology and stratigraphy at various locations along Latchmore Brook is illustrated in Figure 4, which is a composite map based on Todd (1990), 2010 survey work and various observations by others. The geological sequence is complicated by a fault striking 230 degrees with a downthrow of 4 metres to the southeast ( Todd,1990). Latchmore Brook exploits this fault line for a short distance close to the northeast inclosure corner of Studley Wood, and immediately downstream this fault causes the Studley Wood Member to outcrop in the west bank of the brook, whilst the opposite east bank exposes the Elsmore Member (Unit 3a).
Apart from Todd's (1990) paper on the site, few detailed stratigraphic descriptions have been published. Brief summaries appear in Curry (1968), Stinton (1970) Kemp et al. (1979), and Edwards and Freshney (1987). Stinton recognised three beds (in ascending order - the Nummulite Bed, the Huntingbridge Bed and the Coral Bed). Todd (1990) recognised six 'units' at the locality: his lowest units (SW1a and SW1b) comprise the Studley Wood Member (equivalent to the Nummulite Bed of Swinton) for which the Studley Wood is the stratotype. Todd's remaining units area are assigned to the Elmore Member, with Units SW2, SW3a and SW3b representing the 'Huntingbridge (Shell) Bed', and his Unit 4 including, at its base, the 'Coral Bed'." [continues]
For the general geology of the region around Studley Wood the British Geological Survey Geological Maps and Memoirs are very useful . See Edwards and Freshney (1987) on the Southampton area, including part of the New Forest. See also
Bristow, Freshney, and Penn (1991). for the geology of the the Bournemouth area. This is relevant. The Ringwood Geological Map (Sheet 314) just covers the Studley Wood area. Unfortunately, there is not a substantial sheet memoir for this map. There is only a very brief descriptive explanation of the Ringwood District by Barton, C.M. et al. (2003).
(driectly downstream from the Plunge Pool)
"Nummulite Bed [i.e. prestwichianus nummulite bed]. Dark grey, very sandy clay with numerous Nummulites cf. prestwichianus T.R. Jones and frequent well-preserved small molluscs, fish remains and other fossils. [0.45m.thick]"
"B. Huntingbridge Bed. Dark green, glauconitic, very sandy clay, unfossiliferous above but becoming very fossiliferous below with an abundance of large specimens of Turritella sulcifera Deshayes, Thylacodes ornatus J. de C. Sowerby, Dentalium grande Deshayes and numerous other molluscan species including Bicorbula gallica Lamarck and Spondylus rarispina Deshayes. Thickness - 2 metres. "
Stinton described the bed and the following notes are based, with additions, on his description.
Dark green, glauconitic, very sandy clay, unfossiliferous above but becoming very fossiliferous below with and abundance of large specimens of Turritella sulcifera Deshayes. Incidently, Geckoella (2010) figured three specimens of this common gastropod, which like other fossils from this locality, have many small boring into the shell. Thylacoides ornatus J. de C. Sowerby, the scaphopod, Dentalium grande Desshayes and numerous other mollucan species including Bicorbula gallica Lamarck and Spondylus rarispina Deshayes occur.
Stinton referred to the bed at Studley Wood as being 2 metres in thickness.
Elwes (1887) found 60 species at Huntingbridge, of which 25 were different from species found in the Brook Bed.
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Amongst much bivalve material, difficult to separate from the sandy clay of the Huntingbridge Shell Bed at northwest Studley Wood plunge pool, is a minute Crassatella, only 12mm in length with extremely small, close-spaced concentric ridges.
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The Huntingbridge Coral Bed is a small but notable unit within the basal part of the Barton Clay Formation of the New Forest. It was observed, long ago in the 1890s, at a stream section in Kings Garn Gutter, also in the New Forest, about one kilometre ENE of the main road at Fritham [Keeping's summary log of the section is recorded in Wise, J.R., The New Forest, its History and Scenery, p. 112]. The succession could be followed down into the basal part of the Barton Clay sequence. At the Kings Garn Gutter ( the coral bed is 15cm thick and contains the crushed Dentalia and Serpula in addition to the coral, referred to as Paracyathus caryophyllus in the equivalent bed where it is exposed on the shore at Stubbington.
[See this extract from Keeping.
"These beds were discovered by Mr Fisher in 1861, and for the following measurements I am indepted to Mr Keeping. We find, about one hundred yards in south-eastward direction from the point where the footpath from Brook to Fritham crosses the stream (1) the Coral Bed, the equivalent of that at Stubbington, full of crushed Dentalia and serpula, six inches [about 15cm.] (2) Sandy light blue clay with very few fossils, seven feet [2.1m.] (3) Verdigris green [i.e. glauconitic] and slate-coloured [i.e. grey] clay characterised near the top by a new species of Dentalium, Serpulorbis Marchi(?), and Spondylus rarispina. The other typical shells are Voluta Maga, several species of Arca and Corbula gallica, five feet [1.5m.]. It is in this bed that large roots of trees and ferns are found. No person, however, I should suppose, would think of examining any of these beds without first consulting Mr. Fisher's most valuable paper on the Bracklesham Beds in the Proceedings of the Geological Society, May 1862." ]
In Studley Wood the bed looks much as described at Kings Garn Gutter. The section is not so clear but it may well be about 15cm thick; there is nothing to suggest that it is greatly thicker. Sometimes this thin bed is difficult to find. The probable reason is that the Studley Wood exposure is very likely in a sequence disturbed by solifluction and camber during the late Pleistocene. Some photographs are now shown, but these were taken in 2003 and the bed is not obvious in 2016 (but conditions in the stream may change and it may be clearly revealed again.
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The above photograph of 2016, shows the general location of the Coral Bed exposure in the stream. It is near the northern entrance to the wood and a just down from a small waterfall, almost the start of the entrenched section of the brook. It is not necessarily easy to find. The forest is bright in winter, but then the stream is very muddy. In summer the leaves on the trees make this rather dense part of the forest quite dark. Major changes take place within the stream, so that on occasions it may not be exposed (see, for example, Todd (1990) , who could not see the Coral Bed at the date of his investigations). Palaeontologist might wish to check from time to time [if the stream is not filled in by Forestry Commission works].
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This coral bed is at the top of the three main units described by Stinton (1970). His summary includes as follows:
"C. Coral Bed. Blue sandy clay with many specimens of an eupsammid coral and large calcareous annelid tubes. - 0.45m"
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The highest of three exposed fossiliferous beds at Studley Wood is the Coral Bed, placed by Todd (1990) in the Elmore Member of the Barton Clay Formation. This bed, as shown above, consists of very sandy clay or argillaceous sand with much glauconite in the sand fraction. The colour varies according to the wetness or dryness of the sediment, the light conditions, the extent of weathering. In the field it seems to be bluish, as shown in the picture, but drying material from the bed seems quite green. A distinctive feature are the large calcareous worm tubes, usually crushed. The corals are surprisingly abundant and may be seen in the field, but the dim light and muddy conditions of the stream bed may not necessarily make this easy. Other shell material, such as remains of bivalves, are present but not conspicuous. This shell debris, as in the associated beds, is still aragonitic. Nearer to the surface the bed is weathered and shell material disappears. The best samples are from about or just above water level of the stream in dry weather when the stream flow is low.
This bed has been briefly described by Stinton (1969) as follows:
"[Unit] C. Coral Bed. Blue, sandy clay with many specimens of an eupsammid coral and large calcareous annelid tubes. 0.45m."
Todd (1990) seems not have seen a good exposure of the Coral Bed. He commented:
"Units SW 2 and 3 [of the Elmore Member of the Barton Clay Formation] represent the 'Huntingbridge Shell Bed', Unit B of Stinton (1970). His 'Coral Bed', unit C was not confidently identified. Notes on the specimen labels from this locality in the British Museum (Natural History) show that at one time he considered it to be merely the upper part of the 'Huntingbridge Bed'. From this and details of the location (Hooker, 1988 pers. comm.) it is probable that the Unit C lies within SW 3B."
Exposures in the stream bed obviously vary from time to time, and back in Victorian times it seems not to have been seen here. It was visible to Stinton in 1970, but may have been obscured when Todd did detailed work there in about 1990. It was easily found at the time of writing (summer 2003), but this is after a prolonged phase of dry weather. In wet weather it may be under water, and almost certainly of difficult access. To see it closely it is in any case necessary to stand in water and soft mud, looking at the east bank, and you are warned of the risk of becoming stuck. You can, however, observe the location of the bed in safety from the top of the west bank of the stream where this brook first enters the wood (adjacent to an old woodbank).
The Huntingbridge Coral Bed, Bed C of Stinton, at Studley Wood is notable. It is just above the junction of the Bracklesham strata and the Barton Clay.
Coral remains from what is probably the equivalent bed in the old Marchwood to Fawley railway cutting (1924) have been identified by Burton (1935) as Paracyathus crassus Milne Edwards and Haime, 1851. Fisher (1862) referred to the coral, seen at Stubbington, as Paracyathus caryophyllus.
The bed of an upper branch of the Latchmore Brook, has, in the past, been deepened in a trench-like cutting in the Studley Wood Inclosure, near Bramshaw Telegraph, New Forest National Park. Fossiliferous beds, including a unit with corals, have been exposed here. There has been some confusion about the stratigraphy because it is an isolated exposure and not easily seen in geological context.
Important work by Edwards and Freshney (1987) put this exposure into perspective. See their Fig. 33 on p. 62 of the British Geological Survey Memoir on the Southampton area (Geological Survey Sheet, 315). The Ramnor Inclosure Borehole (near Brockenhurst) has shown the positions of the coral bed and Huntingbridge Bed at the base of the Barton Group. Note this is not the base of the more-restricted Barton Clay as at Barton-on-Sea, but it is lower and near the base of the lateral facies, the Boscombe Sand. [do not confuse the Barton Clay Formation with the larger Barton Clay Group]. So the broad picture is now understood.
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More specifically, Stinton (1970) found an isolated exposure of this coral bed in Studley Wood Inclosure, at a date when the lateral correlation, referred to above, had not been established. The particular stream, one of two upper tributaries of the Latchmore Brook flows, initially in marshy or boggy conditions in Claypits Bottom. If you walk down towards the corner of Studley Wood Inclosure, the small stream drops into a deeper trench (probably artificial) just before the Inclosure is reached. The Coral Bed is the first fossiliferous bed to be encountered in the entrenched stream near the Inclosure corner.
The exposure is of blue sandy clay with many specimens of eupsamid coral and large calcareous annelid tubes. Thickness 0.45m. This was referred to by Fisher (1862), after notes by Keeping, with regard to the Hunting Bridge locality, Linwood Inclosure, east of Fritham reported as follows: "Bluish-green clay full of large Dentalia (sp. nov.) and Corals. 0.6 inches." He stated that beneath this bed at Hunting Bridge (or Huntingbridge) there is 20 feet [6m.] of dark green sandy clay with fossils scattered throughout.
This coral bed (C) is found on the foreshore at Lee-on-the-Solent Stinton (1970).
The following details of Coral Bed at Studley Wood are by Stinton (1970)
"Blue sandy clay, with many specimens of a eupsammid coral and large calcareous annelid tubes." [might these really be scaphopod tubes?]
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There is also data on the Coral Bed at Ramnor Inclosure Borehole by BGS.
There is limited and rather general data on the same Coral Bed of Studley Wood, encountered in a borehole at Ramnor Inclosure is given by Edwards and Freshney (1987). The borehole is important stratigraphically but does not seem to give sufficiently precise data on the Coral Bed. (perhaps it comes from a mud-logger's report).
"Paracyathid corals". (species not specified - but see Fisher (1862) p. 78 where the coral bed at Stubbington (Lee-on-the-Solent is seen; he reported it as Paracyathus cariophyllus.)
Go also to the website:
Bracklesham Beds Foraminifera, Bryozoans, Corals, Worm-Tubes, Sea Urchin, Starfish, Crab to see excellent clear photographs of Paracyathus cariophyllus Edwards and Haime, from the collection of Alan Morton. It is listed as from the "Upper Bracklesham Beds, New Forest. Perhaps it has come from Studley Wood.
"?Opisthobranch gastropods"
(this is a very large branch of gastropods, so it does not have precise significance)
"Turrid gastropods" (i.e. Turritella?, a common Barton fossil)
"Scaphopod"
(Scaphopods are the only class of marine molluscs that are completely infaunal. They are of curved tube shape; the large apperture is anterior. The common form in the Barton Clay cliffs at Barton is Dentalium bartonense Palmer. At Barton, it used to be called
Dentalium striatum. Dentalium occurs in both Bracklesham and Barton strata.)
"Bivalve Barbatia." Species of Barbatia are known to occur in both Bracklesham and Barton strata. Without the species name this is not particularly significant.
"Calpitaria." (The bivalve Calpitaria sulcata Deshayes ranges from the London Clay to the Barton Beds, and is not therefore of much stratigraphical significance.)
"A Carditid" (insufficient information. The Carditid Venericor planicosta (Lamarck) is well-known from both Bracklesham and Barton strata.)
"Chlamys" (too vague)
"?Nemocardium" (too vague)
"Nucula" (vague, perhaps the common Nucula similis J. Sowerby, of the Barton Beds
"fish scales".
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The Huntingbridge Coral Bed at Other Locations
4.6. HUNTINGBRIDGE STRATA
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The diagram above shows what is probably the most likely correlation of the Coral Bed, Shell Bed and Nummulite Bed of Studley Wood, with Hunting Bridge, Lee-on-the-Solent and Afton, Isle of Wight. The general scheme is self-explanatory and it shows reliance on the stratigraphical location of corals and nummulites and a particular gastropod. Some minor additions have been made, mainly in relation to the occurrence of fossiliferous Bracklesham, Selsey Formation strata at Studley Wood. Fragments of Cardita planicosta occur very commonly a short distance downstream from the coral bed location.
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Fisher (1862) p. 78, as mentioned above, commented on the coral bed at Stubbington, near Lee-on-the-Solent. This is useful for understanding the bed in Studley Wood. It also shows the considerable lateral extent of this horizon. [incidently the Reverend Osmond Fisher was a very good geologist, ahead of his time. He also described the Purbeck section at the Upwey Cutting Weymouth, and his work is better than recent efforts with regard to the parallel road cutting of the Weymouth Relief Road.]
"Commencing from a point in a line with two large boulders on the shore, and opposite a hut upon the cliffs at the eastern end of Stokes Bay and going westward, we have the following descending section ......
Bracklesham Beds:-
21. [numbering upwards stratigraphically].
Light-greenish-blue sandy clay, laminated. 14 feet 6 inches [4.4 metres]
[this is the basal Barton Clay, in comparison with Studley Wood, particularly at Claypits Bottom]
20(a). Light-greenish sandy clay, containing rather abundantly a coral like Paracyathus caryophyllus (see Palaeontographical Society Monograph, volume for 1850, part 1). and crushed Dentalia [i.e. the scaphopod], with a few bivalves, species undistinguishable. (The equivalent bed is found at Hunting Bridge [east of Fritham] in the New Forest). It ends not far east of some rails on the cliff. 8 paces [of outcrop at low dip] 6 inches [thickness of 15cm, i.e. very thin].
19. Greenish-blue sandy clay; no fossils seen. 22 ft, 4 inches [6.8 metres, quite thick].
18. The same, [greenish-blue sandy clay], rather more laminated. 7ft 6 inches [2.3metres]
17. The same, [greenish-blue sandy clay], with Pleistocene weathering and roots of trees, opposite the mouth of a small valley. 2ft 9inches [0.84 metres]
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The Coral Bed (C) on the foreshore at Lee-on-the-Solent, Hampshire, described by Fisher has subsequently been studied by later workers and referred to as part of the Elmore Formation. See also Stinton (1970).
In summary, the Studley Wood coral bed is known at Hunting Bridge, at the Ramnor Borehole, at the Marchwood-Fawley railway line, at Stubbington (near Lee-on-the-Solent) and at Whitecliff Bay, Isle of Wight (details are given elsewhere in this account). At these places it is probably at the top of the Bracklesham Group and is in a normal Eocene, shallow marine setting.
The bed is not seen in the Bournemouth area, where the facies are different because of the proximity of the Poole Delta. There is a correlation problem in relation to the more typically marine strata further east. The bed is not seen in the Barton - Hengistbury Head cliff sections. It should be lower than the typical "Barton Clay" of Barton-on-Sea and broadly corresponds to the lowest strata of Hengistbury Head. Note that if the Barton Clay is regarded as a purely lithological unit then it probably has a diachronous base (higher in the Bournemouth area).
In terms of stratigraphical correlation see Edwards and Freshney (1987); Geology of the Country around Southampton, Memoir for BGS Sheet 315. Refer particularly to Fig. 33, Stratigraphy and correlation of selected sections in the Barton Group of the Hampshire Basin. In this figure see the details of the Ramnor Inclosure Borehole [Ramnor Inclosure is near the Hollands Wood Campsite; it is about one kilometre east of New Park, the New Forest Show location, on the Lyndhurst to Brockenhurst Road].
The summarised borehole log in Fig. 33 (p. 62) places the Coral Bed near the base of the Barton Clay in its thicker development as seen at Whitecliff Bay, Isle of Wight. It is below the typical Barton Clay of Barton-on-Sea and Highcliffe. It is within the broader, Barton Group and equivalent to a low (almost) basal part of the Boscombe Sand Formation and below the level of the Nummulites preswichianus Bed.
Another occurrence of the bed seems to have been found in a section of the Totton to Fawley railway line under construction in 1924. Burton (1935) reported that the coral Paracyathus crassus was found in a section of the Totton to Fawley railway line, constructed in 1924. It is within a shelly seam of Upper Bracklesham strata with numerous examples of the bryozoan Orbitulopora petiolus. This is very likely another occurrence of the Studley Wood Coral Bed.
Scattered coral fossils occur in the British Eocene but are not abundant. Burton (1935) listed ten species from the Barton Clay Formation of Barton-on-Sea. There are six species of Turbinolia present, only one of which, Turbinolia humilis Edwards and Haime is "very common". The only form, closely related to that at Studley Wood is Paracyathus crassus Edwards and Haime. This is "very rare" in Bed F at the top of the Barton Clay Formation.
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4.7. HUNTINGBRIDGE STRATA -
Barton Clay Above the Coral Bed
This is present in Claypits Bottom, upstream from Studley Wood. It is not exposed. The BGS geological map, Ringwood Sheet, does not show this correctly in relation to the exposures in Studley Wood.
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[End of Huntingbridge Strata, Studley Wood section]
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5.1. HUNTINGBRIDGE STRATA AT OTHER LOCALITIES -
Lee-on-the-Solent
See Fisher for early work.
See Kemp etc for Elmore Formation
5.3. HUNTINGBRIDGE STRATA AT OTHER LOCALITIES -
Other New Forest Huntingbridge Localities
5.4. HUNTINGBRIDGE STRATA AT OTHER LOCALITIES -
Ramnor (New Forest) Borehole
The British Geological Survey drilled into strata corresponding to the "Huntingbridge Beds" etc. at Ramnor Inclosure, near Brockenhurst.
5.5. HUNTINGBRIDGE STRATA AT OTHER LOCALITIES
Alum Bay, Isle of Wight
5.6. HUNTINGBRIDGE STRATA AT OTHER LOCALITIES
Whitecliff Bay, Isle of Wight
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More information on the Nummulites prestwichianus Bed comes from other localities, useful for comparison. It is a notable horizon, once seen at Afton Brickyard, near Freshwater Bay on the western part of the Isle of Wight. This brickpit originally belonged to the Pritchett Family but was bought by Samuel Saundes in the 1920s. [see: The Brick Directory Blog.]
The Nummulites prestwichianus bed has been described as a "one foot", i.e. 0.3m., bed of abundant Eocene nummulites. At the old Afton Brickyard it was seen in vertical strata (of the Isle of Wight monocline). It was described by the late, well-known palaeontologist (and owner of Curry's stores), Professor Dennis Curry in 1941.
It is interesting that the nummulite bed is present there in similar condition to that of Studley Wood. This demonstrates that there was no major anticlinal uplift at Afton by this date at the end of Bracklesham and just before Barton times. The reason that this is a problem is because previous work on the Boscombe Sand Formation [of about this age] suggests uplift and erosion in the Isle of Wight (see the important work of Plint). It was likely that there was uplift in the Isle of Wight area but to the south of Afton, not specifically at Afton.
"The Nummulites prestwichianus bed which follows [placed within the Barton Beds by Curry], is literally crammed with fossils, which are moderately well-preserved. It is a thin sandy seam, in which myriads of tests of Nummulites are seen to be crammed together, lying at all angles to the plane of bedding. The bed contains occasionally rounded quartz grit, about 1 mm. in diameter and occasional large and unabraded flints, which may be covered in oysters [these flints are important because this is about the time when the Chalk of the Isle of Wight area was beginning to be uplifted and eroded. This, while obviously not just here, was nearby, probably updip. Thus freshly eroded flints were encrusted on a locally new, transgressive sea floor. See Plint (1980, 1983 etc.) with regard to Chalk erosion in Bartonian times]. Molluscs are fairly common, but soft and cracked, and very difficult to extract entire. The fauna recorded below, includes a mixture of Barton and "Bracklesham" species.
At Afton Brickyard three specimens of the coral ?Paracyathus, a genus well-known from the Coral Bed of Studley Wood were found by Curry. He did not find the coral bed, but this occurrence is important because the prestwichianus nummulite bed is only a very short distance beneath the Coral Bed.]
? Paracyathus sp. [coral]
Ostrea plicata (Sol.). A fragment.
Ostrea dorsata Desh. A few social masses attached to flints. Portion of an upper valve shows characteristic radiating striae.
Amussium corneum J. Sow.
Glycymeris sp.
Nuculana cf. minima (J. Sow.)
Nemocardium turgidum (Sol.)
Corbula pisum (J. Sow.)
Corbula sp. (? juvenile C. costata J. de C. Sow)
Dentalium striatum J. Sow. [the scaphapod, very common at Studley Wood in the New Forest]
Natica sp. cf. caillata Desh. Occurs also in the Chama Bed at Barton.
Solariaxis plicatulum (Desh.) (dumonti of G.K. & M.)
Tuba sulcata (Pilk.)
Rimella rimosa (Sol.)
Sconsia ambigua (Sol.)
Ficus sp.
Daphnobela juncea (Sol.)
Pseudoneptunea ? brevicauda (Philippi)
Sycostoma pyrum (Sol.)
Surculites errans (Sol.). Two rather doubtful fragments.
Clavilithes cf. scalaris (Lamk.)
Fusinus porrectus (Sol.)
Conomitra cf. fusellina (Lamk.). Stouter than the typical C. fusellina. It is also frequent at Alum Bay in the N. prestwichianus bed.
Volutospina cf. solandri Edwards.
Volutospina ambigua (Sol.) var. compressa (Edw.) Frequent.
Volutocorbis scabricula (Sol.)
Marginella edwardsi Desh.
Surcula transversaria (Lamk.)
Bathytoma turbida (Sol.) var hemileia (Edw.). I [Dennis Curry] agree with Mr. Wrigley in regarding hemileia as merely a variety of the common Barton fossil. This variety is common in the Lower Barton Beds at Alum Bay, from which the type material probably came.
Drillia cf. fisheri (Edw.). This specimen is close to certain Barton A3 specimens.
Gemula plebeia (J. de C. Sow.) (very long range)
Europleurotoma varians (Edw.)
Physodon secundus (Winkler)
Myliobatis sp. [ray fish tooth, common in the Barton Clay]
Raja sp.
cf. Arius sp.
[end of Curry's list]
He noted that: the above list of fossils has a higher percentage of Huntingbridge and other Auversian [i.e. high Bracklesham] species than of any bed at Barton [Barton-on-Sea cliffs, Hampshire].
[END OF AFTON BRICKYARD NUMMULITES BED SECTION]
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5.8. MECO TIME PLANE - DISCUSSION
Middle Eocene Climatic Optimum - at Studley Wood, Bournemouth etc.
[Discussion - to be added]
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Go to the Alum Bay webpage for details of the Middle Barton pebble Bed with its evidence of early erosion of Upper Greensand Chert.
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6.1 PLEISTOCENE GRAVELS -
1 - Description
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The Pleistocene flint gravels at Hope Cottage and Bramshaw Telegraph, adjacent to Studley Wood are of particular interest. The high river gravel terraces are generally referred to as Plateau Gravel. However, they were named as "Older River Gravels" in Edwards and Freshney (1987); Geology of the Country around Southampton, Memoir for BGS Sheet 315.
Upslope from Claypits Bottom, near Studley Wood, and occupying the highest ground of the New Forest at Bramshaw Telegraph is the high gravel terrace 10. It does seem well-exposed at present in this area. It is responsible for high, flat ground here at about 110 metres above sea level. It is a gravel of hard, subangular flint pebbles with a certain proportion of rounded, former beach pebbles derived from the underlying Eocene strata. These rounded pebbles are very distinctive and have numerous percussion marks from impacts on the former "Chesil Beach" of this Eocene sea embayment. The New Forest bay or gulf faced eastward and therefore the implication is of very severe wind storms or hurricanes coming from the east, at about 41 million years ago. There is no possibility that the waves came from the southwest, as in the case of the modern Chesil Beach. Pebbles are usually larger than those on the Chesil Beach except at the extreme southeastern end (at Chiswell).
In particular, the rounded, beach-battered, flint pebbles seen here (derived in Pleistocene gravels) closely resemble those in the pebble bed at the top of the Boscombe Sand Formation at Hengistbury Head.
Go to
Hengistbury Head webpage. About a quarter-way down the pebble bed at Hengistbury Head is discussed.
Two illustrations from it are shown below for comparison.
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6.2 PLEISTOCENE GRAVELS -
2 - Discussion
6.3 PLEISTOCENE CRYOTURBATION -
General
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he beds of Eocene sandy clay in the banks of the Latchmore Brook in Studley Wood are not entirely uniform. In general they show a very low dip, and are almost horizontal. This area has been subjected to periglacial conditions in the past and the last phase was in the Devensian (at the end of the Pleistocene). The Eocene beds seem at at least one place to show minor deformation. It is quite likely that there has been much cryoturbation here, but the exposures are not sufficiently good to see much detail. A fault is supposed to be present in the valley, and even this could be the periglacial activity, rather than tectonism. Not much clearly defined evidence has been seen, as yet. Further search will be made.
I am grateful to many people, who over the years, have helped me with regard to the geology of New Forest. I particularly thank those who have helped me with regard to Studley Wood and the Latchmore Brook. I thank Ailsa Farrand and two other people, not named here, who kindly drew my attention to Studley Wood matters again recently. I initially studied this locality many years ago as a result of general studies of New Forest geology, and interest was later encouraged by much horse-riding in the area. I knew the dedicated fossil collector, Fred Stinton in the 1950s and 1960s and he described the section in the PGA for 1970. About thirty-fours later I was by chance riding horses around Studley Wood. I then decided to look at the section on foot and so added some photographs and description on my website in 2003. A little later, in 2016, a dispute arose regarding planned destruction of the fossiliferous exposures here by infilling, as planned by the Forestry Commission. Professor John Sheppard suggested a further study of the section. Two other people, to whom I am particularly grateful assisted me in commencing further study for the website, and this is still in progress. I am very much obliged. Ailsa Farrand is thanked for her help. The guidance of the unnamed expert is much appreciated. Descriptions and photographs in this webpage are prelinary and more will be added.
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Please go to the New Forest Geology Bibliography .
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Webpage - written and produced by:
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Ian West, M.Sc. Ph.D. F.G.S.
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