Safety and Risk Assessment

The Solent coast northwest of Hill Head is of relatively low risk in normal weather conditions, but with storms and storm erosion there can be hazards. It has relatively low cliffs of sand and gravel. Some parts have a debris apron at the base and are relatively stable; other parts are undergoing active erosion and are more dangerous. The beach is of shingle with muddy sand and is accessible at low to medium tide in normal weather conditions. The main risks are as follows:

Weather: There is risk to inadequately clothed persons of hypothermia when there is gale and rain from the southwest. In such conditions it unwise to stay there long. In storms beware of being washed into the sea.

Flints: Do not hammer flints because of the danger of splinters, which can penetrate skin and could cause loss of eyesight.

Falling from Cliffs: If the edge of the low cliff is approached from above there is, in places, some small possibility of an overhang falling and injury resulting. At present the risk is greatest at Chilling Cliff which is receding fast. Keep away from the edge.

Falling debris: Beware of cliff falls and stones falling from the cliff. In good summer weather there may be only low risk from this. During storms which cause rapid coastal reatreat there can be serious hazard from this, particularly at Chilling Cliff. This was a danger in March 2008, and, in addition, a concrete and brick lookout post was collapsing onto the beach in a dangerous manner (shown in photographs below).

Soft Mud: At low tide, in places, there might be some minor hazard from this. In general the lower shore is muddy sand and there is not much danger of sinking in. Beware of soft mud, though, at the harbour entrance at Hill Head (Titchfield Haven), and possibly one or two other places.

Human activities: I am not aware of any specific problem. As always, it is preferable for students undertaking projects to work in pairs and they should have mobile phones for use in emergencies.

INTRODUCTION:

General Location, Maps and Access

Brownwich Cliff (and Chilling Cliff beyond) is easily reached by car or coach from Stubbington and Hill Head. There is parking space close to the beach (SU 531023) to the northwest of Titchfield Haven. Coaches can arrive from Stubbington and Hill Head and can park here. There is space for them to turn, but they cannot proceed on further down the narrow lane to Meon. There is a toilet block there that is usually open. Walk from here on the beach to the northwest towards Chilling Cliff and Solent Breezes. It is easy to return by a footpath on the cliff top. The upper beach is not normally affected by high tides, and there is usually no difficulty of access. The sea only reaches the foot of the cliff in storms with a high tide.

INTRODUCTION:

Features of the Coast Northwest of Hill Head

Low cliffs, about 7m. high, have been eroded on some north-eastern shores of the estuarine system where there is some exposure to waves driven by the prevailing south-westerly winds. There is a good section in the Pleistocene periglacial river gravels at Brownwich Cliff. The southeastern cliff has a debris apron at the base which is now mostly covered with vegetation. The exposure is better further on towards the northwest.

The gravels overlie Middle Eocene, Bracklesham Group (Selsey Formation). This consists here of marine sandy clays with abundant glauconite weathered to brown at the surface. It is much bioturbated, with some poorly preserved moulds of marine molluscs. Large fossiliferous calcareous nodules occur in the Bracklesham strata in the subsurface and weathered rotted examples can be found in the cliffs here.

Brickearth at the top is a brown silt deposit which in this area has clay minerals suggesting at least partial derivation from nearby Chalk outcrops.

STRATA:

Bracklesham Group - Selsey Formation at Brownwich and Chilling Cliffs

PLEISTOCENE GRAVEL

The Pleistocene Gravel - Introduction

PLEISTOCENE GRAVEL continued

Age of Gravel Terrace 2

The Pleistocene gravel belongs to Gravel Terrace 2 of the British Geological Survey. See the Southampton Sheet 315, 1:50,000 of BGS and Edwards and Freshney (1987).

Bates (2001) considered the Stone Point (Lepe Beach) peat as of the Intra-Saalian temperate stage (Marine Isotope Stage 7) and not as Ipswichian (the last Interglacial to which it had previously been assigned). He then placed the Lepe Upper Gravel (above the peat) as Late Saalian, Terrace 3. He regarded the Chilling and Brownwich Terrace 2 gravel also as Late Saalian. The Lepe Upper Gravel is very close in height to the Chilling Terrace 2 gravel and both are seen in the upper part of low cliffs. They are both unusually sandy for terrace gravels and both contain sarsen stones.

Obviously a key factor is the age of the Lepe Peat. If that should prove not to be Intra-Saalian but to be Ipswichian (Marine Isotope Stage 5e) then it is likely that both the Lepe Upper Gravel and the Chilling and Brownwich Terrace 2 gravels are early Devensian. This would be the implication if they are, as seems likely both later the Lepe temperate peat.

The Pleistocene gravels are similar to others at higher levels and to gravels occurring under the estuary. Subangular flint pebbles are dominant but there are also present some rounded pebbles with percussion marks that are derived from the Eocene strata. Scattered reddened flint pebbles are probably the result of fires on the tundra (or human activity). The gravels, which are of seasonal, braided-river origin, show scours and cross-bedding and the effects of cryoturbation and there are some ice-wedge casts.

PLEISTOCENE GRAVEL continued:

Cryoturbation Structures

PLEISTOCENE

Brickearth - Brown Silt

Above the gravel is a thin bed of "Brickearth". This is brown silt, much resembling loess. There is uncertainty about its origin and this may not be the same at all places. It is either a late-stage, quiet-water sediment of the river that deposited the gravel or it is of aeolian origin (typical loess). It commonly occurs at the top of gravel terrace deposits and can be very well seen on higher terraces at the Barton-on-Sea area.

At this locality the clay mineral assemblage is quite interesting. It resembles that of the Chalk, with a high content of mixed-layer clay. Has it been washed down from nearby Chalk regions (including Portsdown Hill?) or blown as dust from these areas?

It is not easy to prove that a deposit is aeolian, but it is quite easy to prove that it is fluvial if it contains subangular pebbles. There seems to have been at least some wash of pebbles into the Brickearth in places, but this does not mean that it is all fluvial in origin.

Important evidence on late Pleistocene fauna and environments comes from an unusually thick brickearth deposit at Salisbury ( Reid (1903) p. 66 et seq.). This deposit was worked in early 19th century brick pits at Fisherton in Salisbury. This locality is on the lower part of the spur which divides the Nadder Valley from the Avon Valley (Find Fisherton Street which is near the A36 - Churchill Way, and near the railway line. It is NW of the Cathedral and near a hospital). Here the general setting was calcareous and above Chalk. The main deposit (only part of the logged sequence) was described ( Reid (1903) p. 67 et seq.)as:
Bed c. Brick-earth, mixed with variable masses of flint and chalk-rubble, and containing bones and a few shells, chiefly in the lower part. 10ft. (3 metres) to 18ft. (5.5 metres).

This brickearth should not be regarded as typical of brickearths or of exactly the same date as that at Brownwich and Chilling Cliffs. It cannot be very different in age, though, and is almost certainly Devensian. It contains a very good fauna which gives an excellent picture of the snowy environments in the south of England during the late Pleistocene. Here is more detail:

"The main part of the brick-earth seem to have been a subaerial wash of loam and flints, derived from the Chalk and Eocene bluff above, and deposited at the foot of the slope. This view as to its mode of origin is borne out by the discovery of so many skeletons of lemming coiled up as though they had been smothered while hibernating in burrows in this talus-slope."

The Fisherton Brickearth has revealed the bones of various large mammals including:

Bos bison (the bison, probably once very common in Hampshire and the Isle of Wight - found at Southampton Docks and elsewhere and many at Newtown Estuary in the Isle of Wight)
Bos taurus, var. primigenius (the Auroch - bigger ancestor of modern cattle, survived in Poland until the 17th century)
Canis lagopus (Naali Arctic Fox)
Canis lupus (Arctic Wolf)
Canis vulpes (Silver Fox)
Cervus elaphus (Red Deer)
Elephas primigenius (Mammuthus primigenius - Mammoth)
Equus caballus (Horse)
Felix leo (Lion)
Hyaena crocuta (Hyaena)
Lepus variabilis (Mountain Hare)
Microtus nivalis (Snow Vole)
Microtus ratticeps (a Vole)
Myodes torqatus (Lemming)
Ovibos moschatus (Musk Ox)
Rangifer tarandus (Caribou)
Rhinoceras antiquitatis (Woolly Rhinoceras)
Spermophilus erythogenoides (a Ground Squirrel)
(also - Anser palustris - the Wild Goose)

This assemblage gives a good indication of the normal periglacial fauna that once lived in southern England, including the Solent area. It does not seem a strange fauna to us for a cold climate, fauna except for the presence of the lion. Elephants are expected, of course, because they are normal residents of the British region in warm times like the present as well during the longer cold phases. Their teeth and tusks are the main fossils of the Pleistocene gravels and associated interglacial deposits (e.g. at Stone Point, at the Selsey Bill Elephant Bed, at Southampton, in the Avon Valley, at the Dawlish Elephant Bed etc) It would surprising if humans did not have some role in their recent (about 10,000 years ago) disappearance from this region. Now that elephants and rhinoceras (a heavy relative of the horse) are missing from the local fauna it should be noted that places such as the New Forest can never be very natural in aspect.

Returning more specifically to the Solent area, no vertebrate assemblage, as good as that at Salisbury has not been found as yet in the Brickearth at Brownwich and Chilling Cliffs. However, bison bones etc occur in some abundance in late interglacial deposits of the Newtown Estuary across the West Solent, and as mentioned elephant and other vertebrate remains are present in strata of about the same age at Stone Point (Lepe Beach) and at Selsey Bill. Bones (probably bison etc) are also known to occur further up the east side of Southampton Water but the details have not yet been revealed by the finders.

The absence of bones in the brickearth at Brownwich and Chilling Cliffs is probably mainly because the sediments are not now calcareous (chalky) and are very leached. The assemblage, however, is a good indication of the normal vertebrate life that lived in this region when it was in the periglacial conditions. The fauna was probably similar when the gravels were deposited.

GRAVEL TERRACE 2 - SARSEN STONES

Unworn Sarsen Stones (Tertiary Quartzite)
(from both the cliffs and nearby gravel pits)

(see also: Erratics of the Wessex Coast webpage.)

(For more on the Stiperstones go to:
Geology of Britain - Introduction.)

PLEISTOCENE:

GRAVEL TERRACE 2 - LATE SAALIAN

Sarsen Stone of Nodular Form

The nodular silcrete or sarsen stone shown above is from a gravel pit in Terrace 2 at Hook. It resembles in morphology the common nodules of siderite found in local Tertiary deposits, as in the Eocene of Hengistbury Head and Hordle Cliff. Silcretes of nodular form have been described in the Upper Eocene to middle Miocene, Cypress Hills Formation in southern Saskatchewan, Canada (Leckie and Cheel, 2006).

Sarsen stones are common in the Brownwich Cliff and Chilling Cliff, northwest of Hill Head, and were mentioned briefly by Nicholls (1866). They are also common in gravel pits of this region. They consist of orthoquartzite, that is quartz sandstone, cemented by quartz. They are quite hard but not completely solid quartz, so they can broken to some extent by a hammer without difficulty. They may show some bedding. Sarsen stones sometimes show evidence of rootlets. They are derived from some Tertiary strata above the Chalk and are not normally found in situ. The source of the particular examples here is not known. Sarsen stones, often quite large, occur in quantity on Chalk surfaces such as Marlborough Downs in Wiltshire and at Portesham in Dorset and at various other places.

Some of the sarsens are large slabs with angular, joint-bounded margins. Others, as in the photograph above, are smooth and ovoid and resemble in shape the common siderite nodules or other carbonate concretions of sandstones and sandy clays.

The sarsen stones have probably been transported during deposition of the gravel by floating ice. There is no evidence of Pleistocene marine conditions within the gravels and thus this might have been the result of floating ice on the periglacial rivers during times of flood. The gravels show some cryoturbation features and ice-wedges compatible with the melting of ice. It has to be noted, though that interglacial estuarine deposits occur beneath similar gravels both at Stone Point, Lepe Beach, on the West Solent and at Selsey Bill. At the latter locality there are variety of erratics and also evidence of marine rounding of flint pebbles in the gravels. See the Erratics Webpage for more information.

Sarsen stones rarely show stratches or striations, but some small examples with a regular orientation are present in two places on the large block shown above. It cannot be proven that these are associated with the action of ice, although this is quite probable, because the block might have become scratched when sliding out of the cliff.

COASTAL PROCESSES:

Hook Spit at the Mouth of the Hamble River

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COASTAL PROCESSES:

Hook Spit to Solent Breezes Holiday Park

COASTAL PROCESSES:

Chilling Cliff at Solent Breezes Holiday Park

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COASTAL PROCESSES:

Erosion at Chilling Cliff, Southeast

Erosion of the cliff at Chilling seems to have been fairly limited for many years. However, on the 10th March, 2008 there was major storm surge that raised the sea-level by about a metre. This caused much increased erosion, and the cliffs have continued to collapse for months afterwards.

Details of the storm surge were given by Dr. Neil Wells in the Online Newsletter of the CCPM. This organisation, at Southampton University, is: The Centre for Coastal Processes, Engineering and Management. Some relevant extracts of Dr. Well's article are given below:

"Storms and surges at Southampton Monday 10th March 2008:

A very intense storm event (central pressure of 965 mb) coincided with high spring tides at lunch time on 10th March 2008 (12.20 GMT) resulting in a very high sea level at Southampton. The water level at Dockhead was 5.6 m above the chart datum at 12.10 GMT, whilst the predicted high water level from the tide tables was 4.7m. The surge of 0.9m was quite extreme for this area of the coast. The storm intensity and track itself was well predicted 24 hours ahead, together with the winds on the south coast. The storm surge also appears to have been well predicted by the environment agency at Southampton and Portsmouth. The unusual coincidence of a very deep depression and extremely high winds in the English Channel, with high spring tides is the cause of the high water levels...
High spring tides are not unusual particularly as we approach the equinox (21st March). Intense wind storms in early March again are not unusual for the UK, but the coincidence of very low pressure, high winds and high spring tides is unusual.... The effect of global warming on the intensity of the storm systems is still debated."

The erosion at Chilling Cliff seemed to much greater than elsewhere. It was obvious that the cliff had been much eroded, but the extent of erosion would not normally be obvious to the visitor because the ground above is mostly agricultural fields without conspicuous markers. However near the Brownwich Valley there were lookout buildings, perhaps dating from the years of the Second World War (1940s). One of these building had remained for years hardly affected by erosion. The March 10th storm surge, however, caused so much erosion here that the building started to collapse. This continued long after the storm. The sequence of collapse is shown in a series of photographs below. The erosion here is now being monitored by Southampton University student - Scott Mills, who has also been working for Fareham Council.

The lookout building are useful markers which may make it possible to estimate the extent of erosion over time. There are actually two old brick buildings here. In addition to the one shown above, there is another on the cliff top. Both seem to be lookout or gun emplacements from World War II, although I have no proof of the date of origin and could be wrong. If they are from the war then the overall average rate of erosion is low, to judge from the retreat of the cliffs at a lookout from the seaward end of the building. The rate would only be round about 6cm a year.

However, if you compare the situation in July 2005, as shown in a photograph above, with that in October 2007 you will note that the change is drastic. The cliff has retreated by about 4 metres in this time. However, the greatest change was in the storm surge of the 10th March 2008. There is little doubt that a further storm surge of this type would destroy the remains of the building and bring the second (cliff-top) lookout close to the edge. Scott Mills is monitoring the situation here.

COASTAL PROCESSES continued:

Beach Sediment at Chilling Cliff, Southeast

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COASTAL PROCESSES continued:

The Mouth of the Brownwich Valley

In the summer of 2011, the stream at the mouth of the Brownwich Valley was found to be flowing directly to the sea. Previously it had been deflected to the southeast by longshore drift of shingle and the formation of a shingle spit. Breakthrough of larger shingle spits deflecting rivers or streams is a fairly common event usually happening during winter storms.

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COASTAL PROCESSES:

Brownwich Cliff

(notes to be added)

COASTAL PROCESSES:

Titchfield Haven

The River Meon originally flowed southwestward straight out into the Solent and Titchfield Haven was a relatively open estuary. A shingle spit subsequently built out towards the southeast across the mouth of the river. The material for this has come from Chilling and Brownwich cliffs. The spit is shown to be present on the 1787 map of John Carey, part of which is reproduced above. This map is fairly accurate.

An earlier map by Norden in 1595 does not show the spit but it is not very accurate. It shows the Hamble estuary and the Meon Estuary as rather similar. It is not clear whether the spit was present at this time (local historians may have more information on this). A possible phase of spit development or enlargement is that of the great storm of 1703, as described by Daniel Defoe. Thousands of people, largely sailors, were killed in this terrible November hurricane. It was very similar to the destructive November hurricane of 1824 but worse. Both of these caused the sea to break over Hurst Spit and in both cases storm surges caused extensive sea-flooding. These approximately 1 in 250 year hurricanes can change the coast quite appreciably (obviously we do not know when it will next happen, but it certainly will happen again). The 1703 event has drastic effects on shipping in this region, and a ship was driven by the storm from Cowes onto the land at Stokes Bay, not far away. It would be interesting to know just what effects it had in the Hill Head - Titchfield Haven area.

LOCATION:

Hill Head

ACKNOWLEDGEMENTS

I am very grateful to Professor Dorrik Stow and to the many students who have participated in field trips to the cliffs northwest of Hill Head. I much appreciate the help of Robert Howe of Stubbington in drawing my attention to some corrections that were needed for an early draft. I very much appreciate the kind help and cooperation of the Channel Coastal Observatory in making available excellent aerial photographs of the region of study. I particularly thank Scott Mills of Warsash for helpful discussion in the field on erosional features of the Chilling cliffs. I thank Mark Turner for kindly informing me about collapse of the lookout building at Chilling Cliff. Mrs. G.A. Holloway has kindly informed me about the present and past locations of the "Three Stones", sarsen stones of Titchfield, and sent photographs for which I am very grateful. I am very much obliged to Gary Manning for a photograph of a sarsen stone emerging from Chilling Cliff.

BIBLIOGRAPHY AND REFERENCES

Please go to the:

Solent Bibliography.

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

Webpage - written and produced by:

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

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at his private address, Romsey, Hampshire, kindly supported by Southampton University,and web-hosted by courtesy of iSolutions of Southampton University. The website does not necessarily represent the views of Southampton University. The website is written privately from home in Romsey, unfunded and with no staff other than the author, but generously and freely published by Southampton University. Field trips shown in photographs do not necessarily have any connection with Southampton University and may have been private or have been run by various organisations.