Beer Head to Lyme Regis

1. INTRODUCTION - References Map

Longshore transport has a net eastwards direction, in response to the dominant south-westerly or south-south-westerly wave approach. This is demonstrated most clearly by the notable eastward deflection by Seaton gravel spit of the mouth of the River Axe (Photo 3). Short-term reversals, however, are set up during periods when high-energy south-easterly winds and waves are prevalent, usually during the winter. It has been suggested that the orientation of beaches is progressively adjusting to the dominant wave direction, although in most places they are confined by cliffs so that overall coastline planform is the outcome of geological outcrop pattern determined by structural axes and lithological succession. There are several impediments (headlands, shore platforms, boulder aprons etc.) to longshore littoral transport of gravel, so that discrete beach systems such as Beer Roads (Photo 6), Seaton Beach (Photo 5), Charton Bay (Photo 9), Pinhay Bay (Photo 8) and Monmouth Beach, Lyme Regis (Photo 4) behave as virtually closed sub-systems under most wave conditions. Bypassing of sediment, however, is likely when wave energies are more intense. Some drift barriers are subject to progressive removal over time, in particular those composed of landslide debris. This can create relatively rapid "surges" or pulses of supply to downdrift beaches if breakdown of barrier effects coincide with maximum storage of sediment updrift. Thus, over longer timescales it is possible to view the beaches as a series of linked subcells gradually transferring gravel from west to east.

The geomorphological character of this coastline has evolved over a substantial length of the Quaternary, but there is no documented evidence that can provide an outline chronology of change. It is likely that the landslide complexes operated during at least the last full interglacial period, when sea-level may have been +5 to +8m. O.D. During the succeeding Devensian cold stage, sea-level fell by up to 100m and periglacial weathering/mass movement created extensive talus slopes across the contemporary nearshore and offshore areas (Gallois and Davis, 2001). Rapidly rising sea-level of the early to mid Holocene period, up to approximately 5,000 years B.P. led to marine reoccupation of the coastal slope made up of relict landslide materials. Reactivation would initially have involved the mobilisation and evacuation of landslide debris at the toes of former cliffs. Thereafter, as late Holocene sea-level continued to rise at a rate of 1-2mma^-1, coastal recession, at an estimated rate of 0.6 to 0.8ma^-1, generated new slope failures. Large magnitude events occurring (perhaps once or twice a century, created debris fans that interrupted the transfer of beach sediment eastwards. These fans, or boulder aprons, eventually broke down sufficiently to allow supply to beaches to the east. These may have constituted a barrier system that was contiguous with a proto-Chesil Beach located a little further seaward than present beaches, before it became segmented by the development of headlands during the late Holocene. Over recent centuries, the morphogenetic evolution of this coastline has featured the progressive emergence of headlands, and thus the reduction in the continuity of the longshore transport system. Isolated beaches, fed by locally substantial amounts of both fine, coarse and boulder-sized debris from landslides, and by frequent mudslides, behave as discrete transport sub systems dominated by cross-shore transfers and probable linkages with nearshore and offshore sources of sediment input. The latter, however, remain postulated rather than proven; indeed, most morphodynamic knowledge of this sector of the East Devon coastline is qualitative.

Modification of natural coastal processes by defence and protection structures is confined to developed frontages, notably Seaton (Posford Duvivier, 1994). There are short breakwaters, inhibiting longshore transport and promoting updrift beach accretion at Beer Roads (Photo 6) and the mouth of the Axe (Photo 3). The Cobb (Photo 4), at the extreme eastern end of this sector, has been attached, in its present form, to the mainland since the mid eighteenth century and has greatly modified sediment transfer process along Monmouth Beach and the adjacent updrift sector (High-Point Rendel, 1999, Jezard, 2003). Various cliff stabilisation measures have been introduced at potential hazard sites between Beer and Seaton (Lewis and Duvivier, 1975a, b, c) or where there has been some recent acceleration of retreat (Posford Duvivier, 1994). However, the scale of coastal instability is so great between the R Axe and the Cobb that stabilisation has not been attempted along this sector.

The offshore wave climate within central Lyme Bay is dominated by prevailing waves from the south west and south southwest (Posford Duvivier, 1998a), but Seaton Bay itself is partially sheltered from this influence by Beer Head, although the degree of shelter reduces significantly to the east of the Axe estuary entrance. Seaton Bay was one of the locations for which wave modelling exercises were undertaken as part of the DEFRA Futurecoast Project (Halcrow, 2002). An offshore wave climate was synthesised based on 1991-2000 data from the Met Office Wave Model and then transformed inshore to a prediction point off Seaton at -4.37m O.D. Results indicated that the major approach directions for waves were between 150 degrees and 210 degrees with the highest energy waves of up to 3m significant height arriving from 150-180 degrees and waves of up to 2.25 m arriving from 180-210 degrees. The lower energy of the latter would be attributable to the shelter provided by Beer Head so that waves arriving from west of 180 degrees would be refracted and diffracted around the headland. Potential sensitivities to likely climate change scenarios were tested by examining the extent to which the total and net longshore energy for each scenario varied with respect to the present situation. Results suggested that a one to two degree variation in wave climate direction could result in a 1-2% variation in net longshore energy, indicating low sensitivity to direction. Wave energy was, however, found to be especially sensitive to sea-level rise. The effect is probably due to a reduction in shoaling and wave refraction within the shallow nearshore bed as water depths increase so that slightly higher waves will approach the shoreline at rather more oblique angles.

2. SEDIMENT INPUTS - FL1 References Map

2.1 Fluvial Discharge

FL1 River Axe

The only significant source of sediment input to the littoral transport system via river discharge is the River Axe. Although its mouth has maintained its general position over the last century (and possibly for several centuries), there is evidence of a dynamic flux of both coarse and fine-grained sediment associated with inlet instability. Much of this material is likely to derive from nearshore and littoral sources (see Section 3), with occasional storm induced "pulses" of longshore and cross-shore transport that tend to block the mouth. Parkinson (1985) records a number of occasions in the eighteenth and nineteenth centuries when the mouth of the Axe was blocked completely by drift of marine gravel, and river discharge occurred by percolation. Intensification of ebb tidal current velocities due to river channel training walls, and a short breakwater on the east side of the mouth, appears to have kept the exit open in recent decades under all but extreme storm conditions due to accentuated scour. This may promote a "self-flushing" tendency, preventing any excess accumulation. It is likely that extensive reclamations of the estuary undertaken up to the 19th century (see Section 5) have reduced the tidal prism to such an extent that its ability to naturally maintain an open inlet is marginal. The strong eastward deflection of the inlet (Photo 3) is indicative of a delicate balance maintained between littoral processes operating to close the inlet and tidal exchange and flushing that maintain it.

Extensive outcrops of Greensand, fine sandstone and mudstones occupy the catchment of the River Axe. The river regime is characterised by a mean discharge of 5 cubic metres per second (cumecs), increasing to a maximum of 108 cumecs in flood (Halcrow 2002). Rendel Geotechnics and the University of Portsmouth (1996) estimate that approximately 600m³ of fine sediment, and 100m³ of coarse sands and gravels, are delivered to the estuary each year. It is uncertain how much is stored within the estuary as opposed to the quantities flushed out of the mouth. During flood discharges it is likely that considerable quantities of fine sediment and some coarse sediment can be flushed out of the estuary (Halcrow, 2002). An unknown, but probably very small, proportion of the coarse output is incorporated into the back-slope of the confining barrier spit (Posford Duvivier and British Geological Survey, 1999). Some of this sediment delivery is removed by dredging, which maintains the access channel to -1.0m. O.D. The spoil is apparently dumped below the beach crest west of the site of the Axe Yacht Club (Axe Yacht Club, 2001; Posford Duvivier, 1998b; 2001).

The regime of the inlet channel is ebb dominant (Halcrow, 2002), so that material entering the channel tends to be flushed offshore. However, it would appear that most material enters from seaward driven by wave action, so that normal tidal flushing constitutes a cycling of littoral sediment rather than an input of fresh fluvial derived material.

2.2 Cliff and Shoreface Erosion - E1 E2 References Map

Introduction

Near-horizontal unconformable and overstepping Cretaceous strata of Chalk and Upper Greensand overlie a south-easterly dipping sequence of locally folded and faulted Triassic and lower Jurassic strata. The latter are made up of sandstones, marls and clays, but with several local changes of lithology. The development of the river Axe valley has removed the Cretaceous 'cap', to the west of Haven Cliff, but it reappears westwards to form the cliffline between Beer Roads and Beer Head (Ager and Smith, 1965; Perkins, 1971; Woodward and Ussher, 1911). To the east of the Axe estuary, geological structure and rock stratigraphy combine to produce optimum conditions for larger-scale coastal slope failure occupying an "undercliff" zone over 500m in width (Photo 10). Infrequent but large magnitude landslides are promoted by the presence of strongly jointed, fissured and permeable Cretaceous strata overlying more homogenous, comparatively impermeable older rock materials. Of the latter, the Liassic strata are particularly important (Photo 8), as they occur at and above beach level and are crucial in the frequent generation of large mudslides (Gallois and Davis, 2001). Limestone bands within the Blue Lias formation are significant in determining specific pathways of ground-water movements. Seepage and basal wave erosion of mechanically weak and seasonally saturated clays and shales are key processes inducing cliff instability and shoreline retreat.

Basal marine cliff morphology is highly variable, with some sectors consisting of steep slopes cut into insitu bedrock lacking weathered debris (Photo 2 and Photo 8), and others of substantial accumulations of mixed coarse and fine material derived from the repeated failure of the entire coastal slope (Photo 9). In places, large displaced blocks of Cretaceous materials are undergoing direct marine erosion having slipped from the cliffs above (Photo 10). The spatial distribution of contrasts in the size and geometry of the marine cliff between Axemouth and Lyme Regis is subject to temporal change, as slope mass movements, surface gullying and wave erosion selectively modify site-specific variations in the balance between bedrock exposure and rock talus overburden. Further variation is provided by the presence or absence of protective shore platforms and beaches. In places foreshore reefs run out to sea where limestone bands have curving outcrop patterns imposed by local anticlinal structures (Photo 8).

E1 Beer to Seaton (see introduction to cliff and shoreface erosion)

The Chalk cliffs between Beer Head and Beer Roads are significantly lower than they are to the immediate west, partly due to reduced basal wave attack resulting from the change in shoreline orientation. The cliff profile is characterised by an upper convex slope segment succeeded by a basal facet that is near vertical. The main control of the latter is likely to be one or more structural surfaces as vertical joints have influenced the development of several narrow but deeply penetrating recesses (Lewis and Duvivier, 1975a and b).

Debris falls are relatively common, but usually involve only small quantities of material. Exceptions occur, e.g. at Tom Tizzard's Hole in 1932, when a toppling failure along a fissured joint plane removed 10,000m³ of chalk; at Pound's Pool Beach in 1995, when the same mechanism contributed an estimated 7,000m³ in a single event; and over 15,000m³ in January 2001 following several weeks of almost continuous rainfall (David Roche Geoconsulting, 2001). Between the mid 1930s and mid 1990s, these cliffs were relatively inactive, though protection measures against superficial debris slides from their upper profile have been necessary (Photo 6). David Roche Geoconsulting (2001) state that, for this entire length of cliffed coastline, there has been near stability of Mean High and Low water positions since the late 1890s. This conclusion is derived from analysis of successive Ordnance Survey map editions. Apart from the localised falls referred to above, the main change during this period would appear to be some loss of basal rock debris.

Relict landslides occupy the Chalk and Upper Greensand cliffs between Beer Roads and Seaton Hole, but have not been analysed for their morphology and potential activity. The slip surface at Seaton Hole is apparently related to the presence of a north to south-orientated fault that throws Upper Greensand (permeable) against Mercia Mudstone (relatively impermeable). Toppling failures have occurred here (Lewis and Duvivier, 1975c), the most recent of which occurred between January and March 2001 and involved 3,000 to 5,000m³ of Upper Greensand (David Roche Geoconsulting, 2001).

Posford Duvivier (1994, 19997; 1998a) calculate mean erosion rates for the cliffed coastline between Beer Head and Seaton Hole. For the period 1903 to 1933 this was 0.3m.a^-1, accelerating to 1.0m.a^-1 between 1940 and 1990, with some significant reduction (possibly as low as 0.2m.a^-1) since 1995. These figures refer to cliff top recession, and they generalise local differences due to contrasts of rock lithology and structure. In a separate analysis of erosion of the red mudstone cliffs between Seaton Hole and the start of West Walk Promenade, Seaton, Posford Duvivier and British Geological Survey (1999) calculated a contemporary yield of approximately 6,000m³a^-1 (all fine sediment) from this 380m frontage of 20m high cliffs. Yield from the Chalk cliffs was not calculated. A further 12,000m³a^-1 of fine material was calculated as being supplied from erosion of the shoreface (Posford Duvivier and British Geological Survey, 1999).

E2 Axe estuary to Lyme Regis (see introduction to cliff and shoreface erosion)

Details of the morphology of the coastal slope are provided in several papers describing the mechanisms of landsliding. The section between Axemouth and Lyme Regis has been examined by several authors (Arber, 1940, 1973; Grainger and Kalaugher, 1995; Pitts, 1979, 1981a, 1981b, 1983a, 1983b, 1986), with narrative accounts of some of the largest documented failure events in the British Isles. The Bindon failure of 1839 and 1840 is the most celebrated (Pitts, 1974, 1983b; Pitts and Brunsden, 1987), and is considered to be the biggest coastal landslip along the British coast to have occurred in historical times (Photo 10). There remains, however, considerable controversy over the relative roles of different, but interacting, processes creating both large and small-scale failures (Brunsden, 1996; Pitts and Brunsden, 1987). In only a few cases has it proved possible to isolate and partially quantify 'triggering' mechanisms such as rainfall intensities and groundwater levels in relation to renewed rotational movements. Grainger, Kalaugher and Kirk, (1996) provide an example of this, which occurred at Pinhay in 1993-1995.

In summary, the Axemouth-Lyme Regis coastal slope is a complex set of linked sub-systems, bounded by a well-developed backscar. The Undercliff is characterised by a near-parallel series of inland-tilting ridges and intervening depressions that have a terrace-like morphological appearance. Major landslip events involve either: (i) "first-time" failure of the rear scarp (i.e. "whole slope" events) or (ii) re-activation of the movement along the face of the rearmost displaced block involving sliding of landslide debris within the undercliff. These occur between two and five times per century and therefore require prolonged periods during which failure thresholds are achieved, such as by up-slope loading or toe steepening and unloading by marine erosion. 'Triggering', however, may be induced by climatic conditions such as prolonged and/or intensive rainfall reducing rock strength, promoting groundwater movement and thus initiating a "wave of aggression" affecting landslide stores. More frequent events, perhaps once per decade, involve block disruption, whilst mudsliding takes place almost annually. High magnitude events are normally of the multiple rotational type, associated with internal weathering and erosion, and loss of residual strength. The Bindon event of 1839/40 would appear to have been a planar block slide, with the main conditioning factor being critical water pressures in tension cracks and on the failure surface within low strength bedding partings.

It is now apparent that a key control of landsliding is the precise location of shearing zones in relation to sea-level. Toe erosion is potentially a major factor that will promote instability, but only a limited proportion of this coastline is characterised by basal marine cliffs cut into bedrock. Fallen blocks occupy much of the shoreline and mixed talus derived from several different lithologies moved downslope by previous landslides. Removal of this debris and renewed sea-cliff retreat results in toe unloading and critical profile foreshortening, thus preparing conditions for the downslope movement of the more competent or coherent slipped blocks derived originally from upslope backscar failure. Wave erosion, together with groundwater seepage, is therefore of major significance as a preparatory factor in maintaining slope instability, but not generally in actually triggering movements. Even mudslides must be regarded as the terminal stage of degradation of earlier, upslope rotational slips or translational slides.

Several other specific processes contribute to slope degradation and eventual sediment yield at the shoreline. These include gullying, including gully enlargement of cliff top seepage points (e.g. Culverhole Cliffs); rockfalls, well developed at in sea-cliffs at Haven Cliff and Pinhay Bay where they are induced by weathering along fissures, fractures and other types of parting planes; topples, as along the seaward face of the massive detached block of "Goat Island" created by the Bindon failure; debris slides, usually in association with toe failure, as at Haven Cliffs east of Axemouth; and flows, such as sand runs promoted by liquefaction and earth flows (Gallois and Davis, 2001).

There are several generalised estimates for rates of coastline recession for the sector between Haven Cliffs (Axemouth) and Ware cliffs, Lyme Regis. Posford Duvivier (1994; 1997) calculate a rate of between 0.3 to 0.8ma^-1 (mean of 0.6) operative between Haven Cliffs and Culverhole Point, with a maximum of 1.3m.a^-1 at a few sites. This would yield some 120,000m³a^-1, mostly fines and coarse sand. For the sector between Culverhole Point and Ware Cliffs, Posford Duvivier (1997; 1998a) estimate a mean retreat rate of 0.14ma^-1, producing some 90-100,000m³a^-1. This includes 8,000m³ of gravel, with most of the rest of the material being clay and silt.

Pitts (1981b) and Brunsden (1996) and suggest 0.1 to 0.2m.a^-1 for the entire Axemouth to Lyme Regis landslip shoreline, but notes that rates are highly variable from year to year because of the incidence of episodic slope failure. Pitts (1983a) used serial Ordnance Survey map analysis to calculate the rate of cliff base recession for ten sections between Haven Cliffs and East Pinhay, 1904 to 1958. This was highest in the west, at approximately 0.9m.a^-1, and lowest in the east, adjacent to Monmouth Beach, at 0.1m.a.-1. A toe block slide at Rousden Bay was worn back at a rate of 0.1 to 0.25m.a^-1 during this 50 year period. In places, for example Humble Point and Whitelands Cliff, the coastline has advanced because of seaward displacement of the toes of landslide blocks. This has been in the order of 0.3m.a^-1, 1840-1980 at Bindon (Pitts, 1983). Shoreline advance often occurs episodically, due to rapid but short-lived displacements. Pitts (1974) quotes two examples, viz. 14m at Charton Bay in 1969 and 10m at Rousden in 1911. Grainger and Kalaugher (1995) measured 400mm of forward movement of the Pinhay undercliff between January and April 1994. Advance is also achieved by mudslide surges, but these are usually very short-lived and are rarely recorded. The Dowlands-Bindon failure event of 1839 created an offshore reef some 100-180m seawards. This feature, now interpreted as a pressure ridge (Pitts and Brunsden, 1987) was eroded to below wave base in the succeeding few months. Arber (1940) reports that the same event resulted in 12m of instantaneous uplift of a shore platform cut into clay and shale, which was reduced to sea-level over the next two or three decades.

There are few details of rates of retreat of bounding backscars. Pitts (1983) states that it varies from 73m, at Culverhole, to 25m at East Pinhay over the period 1900-1970. Due to the importance of chert and flint as potential sources of beach gravel Bray (1996) undertook a detailed desk study of the occurrence and potential yield of these materials from these cliffs. The gravels were found only in the upper cliff within the Upper Greensand, Chalk and superficial deposits so the analysis applied backscar retreat rates to calculate the release of gravels into the undercliff. The timescale of transfer of debris through the Undercliff sub-system stores is not known with any precision so it has to be assumed that release at the toe occurs at approximately the same rate as release from the backscar. It could be argued on the basis of the Pitts (1993a) cliff toe erosion data that release at the toe might currently be greater than is calculated for the backscar. Certainly, complexes such as Haven Cliff (Photo 2 and Photo 7) are eroding more rapidly at the toe and in future this could prepare conditions for renewed major failures of the backscar. The analysis is presented as follows:

COMPILATION DETAILS:
Thickness:

Superficial Deposits - based upon field observations of the backscar: Charton Bay - Ware Cliffs.
Upper and Middle Chalk - based upon measured section at Pinhay (Pitts, 1981b).
Upper Greensand Chert Beds - based upon measured section at Binden (Pitts, 1981b).

Superficial Deposits were assumed to be similar in composition to flint gravels capping Black Ven and Stonebarrow.
Middle and Upper Chalk - visual estimation.
Upper Greensand Chert Beds - assumed gravel % similar to West Dorset examples of the same units.

Estimated from geological section (Pitts, 1981b; 1983a).

Based on mean sea-cliff retreat 1904-59 (Pitts, 1983a), because backscar retreat was negligible over the measured time period .

Posford Duvivier and the British Geological Survey (1999), summarised in Posford Duvivier (1999), calculated losses (outputs) arising from the erosion of the intertidal shoreface. This included an unquantified allowance for the abrasion of nearshore rock platforms and submergent boulder aprons created by landslides before and during Holocene sea-level rise. Shoreface down-wearing, over a width varying between 500 and 1,000m was assumed to be in the range 4.0 to 9.0mma^-1 (see value in brackets). On this basis, the following volumetric losses were proposed:

(i) Axemouth to Culver Hole: 12,000m³a^-1 (4mm a^-1)
(ii) Culver Hole to The Cobb, Lyme Regis: 9,100m³a^-1 (9mm a^-1)

3. LITTORAL TRANSPORT (BEACH DRIFT) - LT1 LT2 References Map

Gravel, supplied by (i) cliff erosion and coastal slope mass movement, and (ii) nearshore and/or offshore deposits, tends to be trapped by headlands. This is especially evident within swash-aligned pocket beaches confined by salients composed of either resistant rocks or landslide debris. In these cases, for example the beach at Beer Roads, sediment transport takes place within a discrete pocket or sub cell where cross-shore exchanges are possibly as important as longshore transfers (Posford Duvivier, 1998a). However, it is unlikely that any of these salients are absolute barriers to longshore movements, as they can be by-passed when wave energy is high and there is a substantial store of sediment available for transport.

Fine sediment (clay, silt and fine sand) is provided in substantial quantities by mudsliding, landslips and the breakdown of landslide debris. Some of this material is stored temporarily on local beaches, but most is presumed to move offshore in suspension (Posford Duvivier and British Geological Survey, 1999). Its ultimate fate is unknown, but some must contribute to the dominantly sandy seabed of Seaton Bay and clays could contribute to estuaries throughout the central and western English Channel. However, the coarser sand fraction may be returned to the littoral environment under high energy, storm, wave conditions. This process may, in part, account for some extensive areas of sediment-free bedrock exposure seawards of the shoreline east of Humble Point.

LT1 Beer Head to River Axe (see introduction to littoral transport)

Fringing and small pocket beaches composed of locally derived flint and chert gravel exist between Beer Head and the headland south of Beer village. There may be a small supply via bypassing of Beer Head, but these beaches, separated by areas of shoreline platform, are supplied by small quantities of flints released by erosion of their backing cliffs and a low rate of net northwards drift.

The re-entrant of Beer Roads (Photo 6) contains, in local context, a substantial beach store, with west to east longshore transport confined by a concrete breakwater and protruding shore platform. Posford Duvivier (1998a) suggest that this re-entrant may be a confined transport sub-cell, with only occasional by-passing to beaches further east. The beach in the vicinity of Seaton Hole is a mix of boulder and gravel fractions. Substantial, though fluctuating, loss of sediment was documented for the period 1989-1993 (Posford Duvivier, 1994), with almost total loss of the gravel fraction between July and September 1993. Application of the UNIBEST littoral transport model to beach profile change that occurred at Seaton Hole under exceptional storm surge conditions between the 16th and 17th December 1989 indicated 8,000 to 9,000m³ of eastwards transfer (Posford Duvivier, 1994). This was in the order of some 8-10% of total pre-storm beach volume. Although such exceptionally high rates are only rarely sustained, it is evident that the beach at Seaton Hole is an input source for the gravel beach in front of Seaton Promenade.

A substantial flint gravel beach extends between Seaton Hole at the western limit of Seaton (Photo 11) and the mouth of the River Axe (Photo 5). Littoral transport along this beach has a net eastwards component, demonstrated clearly by a substantial gravel spit that has grown across the former estuary mouth of the Axe, deflecting the river channel some 400m eastwards. It now flows at the base of inner Haven Cliffs, previously exposed to basal marine erosion (Photo 3).

The predominant lithology of clasts on Seaton beach is flint and chert, indicating their local provenance. There are, however, occasional distinctive flattened ovoid pebbles of pink metaquartzite that can only derive from the Budleigh Salterton Pebble Bed, thus implying some long distance, and probably long timescale, supply from the west. This fact also indicates that intervening headlands have been by-passed, but it is uncertain if this is a possibility under the modern transport regime (Posford Duvivier, 1994), or whether the metaquartzites could have been inherited from an earlier more continuous barrier as it migrated landwards in the mid Holocene. The orientation of Seaton Beach is more normal to prevalent waves from the south-south west compared to Sidmouth further west, which has an otherwise comparable morphodynamic setting. Net drift rates are therefore almost certainly lower, possibly in the order of 3,000 to 3,600m³a^-1 (Posford Duvivier, 1994). The refraction effect set up by Beer Head also causes breaking south-south-west waves to be almost parallel to the foreshore. It is thus more probable that the highest drift rates are east to west, caused by waves approaching from the south-east or south. Posford Duvivier (1994) state that 39% of all offshore waves in excess of 0.5m in height at Seaton approached from the east or south-east during the period 1989-1994. Storm waves with a calculated recurrence frequence of 1 in 50 years, which occurred during the winter of 1989/90, and once in 1992, approached from approximately 210º. They caused almost complete removal of beach material, thus suggesting high drift rates (to the east), as well as probable onshore to offshore transport, over short periods of time. Rapid beach drawdown may be partly due to erosion of the substrate of alluvium overlying clay-rich strata, but must also be the outcome of the temporary failure of supply from up-drift sources of sediment. There have been several occasions where Seaton Beach has benefited from losses at Seaton Hole under conditions of strong west to east longshore transport (Posford Duvivier, 1994). The store of sediment at the mouth of the Axe provides potential supply to east to west movements, thus dampening overall beach volume losses. However, the historical tendency of Seaton beach has been one of erosion (Posford Duvivier, 1998a). Further details on the morphodynamic behaviour of Seaton Beach are given in Section 5.

Qualitative studies of littoral transport either side of the mouth of the Axe (Posford Duvivier, 1994; 1998a and b and 2001; Axe Yacht Club, 2001) indicate that gross drift rates are potentially high over short periods and can operate in both east to west and west to east directions. These variations reflect sensitivity of transport to the approach directions of incident waves. Coarse bedload output from the river Axe is considered to be a negligible addition to nearshore and beach littoral transport, although there is strong ebb tide flushing of material entering the Axe inlet from seaward. Sustained strong west to east drift under south-westerly waves has been sufficient to block the mouth of the river with gravel for a few weeks (Parkinson, 1985). The short inlet training breakwater on the eastern side of the Axe channel acts as partial barrier, but it is normally by-passed during storms and other periods of rapid drift. Storage capacity against this structure is limited to approximately 300m³, so that the mouth of the Axe must create only a minor transport discontinuity. Under certain circumstances, determined by prevailing tidal height, wave period and wave height, the mouth of the Axe might locate a divide between fluctuating eastwards and westwards longshore transport.

LT2 River Axe to Lyme Regis (see introduction to littoral transport)

The drift pathway between Axemouth and the Cobb (Lyme Regis) is eastwards, though rates are generally low. Posford Duvivier (1998a) suggest that there may be a drift divide at, or close to, Culverhole Point, with east to west movement along the gravel and boulder beach (Photo 7) towards Axemouth. The evidence for this conclusion is not entirely clear, and it is well documented that pulses of coarse sediment move eastwards from Seaton beach via the banks or bars at the mouth of the Axe (Posford Duvivier, 1998b). Reversals of net drift transport over this sector do occur, but overall movement would appear to be eastwards.

Between Culverhole Point and Seven Rocks, both gravel and boulders, derived from the degradation and downslope movement of debris on the backing coastal slope and basal marine erosion, are retained in a sequence of semi-isolated pocket beaches. These are defined by headlands protected by boulder aprons and shore platforms e.g. Seven Rock Point (Photo 8) and temporary minor salients composed of landslide debris; the latter are especially well developed around Humble Point. Periodic large mudslides also create short-lived lobate-shaped barriers to beach drift, but tend to be removed relatively rapidly by marine erosion. None of these are absolute impediments to longshore transport, and even the larger examples such as Humble Point itself (created by large landslides in 1765 and 1839) are episodically by-passed. This leads to incremental inputs of coarse sediment supply to down-drift beaches. The tendency over the last century has been for all beaches to lose width and volume, suggesting these "pulsed" inputs are infrequent and of relatively small quantities.

The best-studied example of this is Monmouth Beach, immediately updrift of The Cobb breakwater at Lyme Regis - see Photo 4 (High-Point Rendel, 1999; Jezard, 2003). The latter structure, designed to provide shelter for Lyme Regis Harbour, was connected to the mainland in its present configuration in 1754, since when it has functioned as a large terminal groyne and has promoted the up-drift accretion of Monmouth Beach. However, although the position of Mean High Water advanced during the nineteenth century, due in part also to backshore land claim, Mean Low Water has steadily retreated since at least the 1850s (Jezard, 2003). This is an indication that: (i) longshore sediment supply from updrift sources, by-passing Seven Rocks, has steadily diminished and (ii) The Cobb is not an absolute boundary to littoral movement, as evidenced by the accumulation of gravel in Lyme Regis harbour under high energy wave conditions.

High-Point Rendel (1999) argue that Monmouth Beach as a whole has experienced loss of sediment volume over the past 250 years due principally to the substantial reduction of drift input from feeder beaches in Pinhay Bay, to the immediate west. This, in turn, is ascribed to the impedence of the drift pathway imposed by post mid-eighteenth century landslides at and close to the Humble Point. This has created large salients that have substantially reduced drift from the beaches of Charton Bay. Thus, the continuing west to east longshore transport along Monmouth Beach has resulted in a progressive increase in the imbalance between input from the west and storage/output adjacent to the Cobb in the east. The actual rate of drift varies according to wave height and period, and approach direction. Posford Duvivier (1998a) calculate an annual average rate of accretion against the Cobb of approximately 1,500m³a^-1, but potential rates of up to 10,000m³a^-1 may be sustained for short periods during winter storms. Under these conditions, bypassing of the Cobb is probable. Net accretion rates are modified by deliberate removal of gravel to re-nourish beaches to the immediate east. This takes place periodically, predicated on a budget-based approach to integrated beach management for the Lyme Regis frontage. For example, 1,500m³ was removed in 1993 to recharge the beach in front of Marine Parade and a further 1,000m³ in 1998.

The growth of eastern Monmouth Beach against the Cobb during much of the twentieth century has been achieved by "cannibalisation" of its sediment-starved western end. This depleted "tail" has thus moved eastwards, so that the current rate of longshore transport is now substantially greater than the rate of fresh input from updrift (Jezard, 2003). High-Point Rendel (1999) also demonstrate that the western sector of Monmouth Beach has experienced re-orientation due to a combination of the progressive migration of the "tail" and continued retreat of Ware Cliff. The latter has altered the focus of cliff toe erosion, much of the product of which is fine debris that is not retained on the beach.

Monmouth Beach is, in effect, currently a virtually closed littoral transport sub-cell, with a negative sediment budget. Unless fresh pulses of gravel re-supply are experienced (unlikely in the short-term), it is no longer an appropriate site for future removal of sediment for down-drift beach nourishment. Re-cycling from within the same sub-cell would be a more appropriate option.

4. OUTPUTS - References Map

4.1 Dredging

The inlet of the Axe is dredged to maintain the Axe Yacht Club access channel to -1.0m. O.D. The spoil is apparently dumped below the beach crest west of the site of the Axe Yacht Club (Axe Yacht Club, 2001; Posford Duvivier, 1998b; 2001).

4.2 Beach Mining

It is known that in the past Seaton beach supported small-scale selective removal of beach cobbles, used locally for a variety of purposes. This probably started at least 200 years ago, but was discontinued in the 1960s or early 1970s. Perkins (1970) implies that "pebble picking" was still being practised on the spit at Axemouth in 1969, at a rate of 10m³a^-1. The backslope of the spit across the mouth of the Axe has been quarried occasionally to provide material for the foundations of enclosure dykes in the lower estuary (Parkinson, 1985). It is possible that losses have been compensated for by the dumping of coarse bed materials dredged from the inlet channel of the Axe to maintain access. This practice continues to the present (Axe Yacht Club, 2001).

Historically, small quantities of gravel and boulders have been removed from Monmouth Beach, for use as local building aggregate. Gravel that accumulates adjacent to the Cobb breakwater is removed specifically as a source of recharge for beaches along the Lyme Regis frontage. Removal is not routine, and averaged 500m³a^-1 during the 1990s with1, 500m³ removed in 1993 and 1000m³ in 1998] (High-Point Rendel, 1999). Studies have shown that overall volume of the beach is diminishing (see Lt2), so unless new inputs arrive from the west, it is no longer an appropriate site for future removal of sediment for down-drift recharge. Re-cycling from within the same sub-cell would be a more appropriate option.

4.3 Attrition

Gravel clasts retained on all beaches along this coastline are subject to abrasion wear, those here are likely to be especially susceptible for gravels supplied from the cliffs are angular and weathered and are not adjusted to marine processes. Losses have not been quantified, but may be similar to the 10% loss within the first year of residence time, for angular particles, on beaches to the east of Lyme Regis (Bray, 1996; 1997). Abrasion loss affecting rounded clasts is considered to be at a much lower rate. Recent experimental work on abrasion wear of flint clasts on East Sussex beaches has indicated that angular and sub-angular particles may loose 25% of their volume every 50 years (BERM project, University of Sussex). It remains uncertain if these rates are applicable to this coastline, as both hydrodynamic conditions and rock mineralogy are different.

5. SEDIMENT STORES AND SINKS - References Map

Detailed studies are currently limited to two sites comprising Seaton and Monmouth Beaches. However, the general consensus is that all beaches within this sector have experienced progressive losses of volume over at least the last 50 to 60 years (Posford Duvivier, 1998a; High-Point Rendel, 1999). This, in part, is a function of increasing spatial compartmentalisation due to a weakening of the continuity of longshore transport following increasing landslide activity between Axmouth and Lyme Regis. As indicated in Section 3, this is not necessarily indicative of longer-term past, or future, behaviour as one or more high magnitude slope failure events would considerably increase gravel inputs pocket beaches. However, it is a possibility that the more substantial beaches between Beer Head and Lyme Regis are relict forms of a formerly more continuous barrier that was driven shoreward and segmented by headlands as sea-level rose during the late Holocene. There is little locally specific evidence to support this hypothesis, apart from a small proportion of erratic, or exotic, clasts that occur and Seaton beach and many others along the East Devon and West Dorset Coast (Bird, 1989; Bray 1996). It is, however, consistent with interpretations of the morphodynamic evolution of beaches between Lyme Regis and West Bay, as well as Chesil Beach to the east and other probable relict barriers to the west (Bray, 1997a and 1997b).

5.1 Seaton Beach

Posford Duvivier (1994) conducted an analysis of the behaviour of this beach between 1989 and 1994, particularly its response to a number of high magnitude storm surge events during this period. Anecdotal and incomplete documentary evidence indicated several occasions earlier in the twentieth century when the extant seawall was overtopped and the beach depleted. In December 1989, a storm berm was created, with a maximum crest elevation of +7.0m (higher than the backing seawall), under south south-west approaching waves. During the previous four weeks, south-easterly waves had caused beach drawdown, so that this exceptional surge removed almost all foreshore gravel and caused both shortening and steepening of the cross-shore profile. At the same time, Seaton Hole beach, to the west, was almost totally lost, with bedrock exposed. Similar effects, albeit on a smaller scale, were experienced in August 1992 and September 1993, although some recovery occurred between these events. Over this five-year period beach volumes at Seaton Hole and West Walk, Seaton were less than 30% of those recorded by a borehole survey in 1973. Posford Duvivier (1994) state that 110,000m³ of sediment was removed by storm drawdown over the period 1989-93 from the beaches between Seaton Hole and the mouth of the Axe.

The study concluded that, having experienced a condition of quasi-equilibrium for almost a century, the Seaton Hole and Seaton beaches entered a phase of instability. This could be an expression of their relict nature, being residual segments of a former barrier. The fact that Seaton beach overlies estuarine alluvium is clear evidence that it has experienced landward translation. Its confinement by a backing seawall has, and will, contribute to increased morphodynamic instability, enhanced by on-going sea-level rise and an increasing tendency for wave reflection from the structure. Short-term fluctuations, however, are likely, exemplified by rapid accretion at Seaton Hole since 1995 - though probably partly induced by the placement of rock armouring at the cliff base. It appears difficult to place the 1989, 1992 and 1993 drawdown events into a longer-term context due to lack of long-term beach monitoring. Thus, it is uncertain whether complete natural recovery might be expected, or whether losses are permanent. It is important that that beaches in Seaton Bay are monitored regularly in future to resolve these uncertainties.

5.2 Monmouth Beach

Progressive loss of volume, and profile steepening, over at least the past 100-150 years is described by High-Point Rendel (1999). Accretion is limited to the area immediately updrift of The Cobb breakwater due to its function as a terminal groyne. The causes of morphodynamic change are ascribed to increasing imbalance between updrift inputs and downdrift outputs, the latter including sediment removal to renourish beaches along the town frontage of Lyme Regis (Section 4.2). Shoreline re-orientation is another factor, explaining in part the retreat of the position of Mean Low Water since the late eighteenth century. However, High-Point Rendel (1999) consider that between approximately 1950 and the mid 1990s, there was equilibrium between beach morphology and the forcing function of the local wave climate. Further explanatory background is given in LT2.

In contrast to beaches further west, Monmouth Beach incorporates a large population of clasts derived from the breakdown of limestone bands in the Blue Lias that outcrops along the updrift shoreline. Flint, chert and phosphatised limestone pebbles are delivered to the beach by the breakdown of Chalk and Upper Greensand blocks brought down by landslips along the coast to the west.

5.3 Axe Estuary

The Axe estuary (Photo 12) is a single spit enclosed valley type estuary that is partially infilled (Halcrow2002). The estuary area was previously larger and western part of the lower Axe valley (Photo 3) is an area of historical land claim, where approximately one-third of the original upper and mid saltmarsh had been enclosed by 1660 (Parkinson, 1985). Land claim continued during the mid nineteenth century and, to a smaller extent, in the 1950s. Beach material removed from close to Beer Head was used as the foundation for flood protection banks in earlier centuries. There is some evidence that gravel forming the backslope of the spit confining the mouth of the Axe was quarried for estuary-side bank repair in the late nineteenth century (Parkinson, 1985). The contemporary area of mudflats and saltmarsh (62ha and 34ha respectively) is primarily on the eastern side of the valley. Cliffing of the seaward edges of saltmarsh blocks suggests that erosion is now dominant, with enlargement of mudflats occurring at the expense of saltmarsh. The landward transgression of saltmarshes as sea-level rises is inhibited by the B3172 that flanks the estuary to the east and the embankment of the Seaton and District Electric Tramway that flanks to the west (Photo 12). The fine-grained sediment would appear to be flushed out of the channel and removed removed from the estuary mouth during coincidence of high river flows with ebb spring tides (see Section 2.1) would therefore represent loss from an historical store that has accumulated over several centuries. The spit enclosing the mouth of the Axe may have been a minor feature of the twelfth and thirteenth centuries, but grew to approximately its present dimensions between the early fourteenth and mid-fifteenth centuries (Parkinson, 1985). The estuary inlet is unstable due to: (i) the small estuary tidal prism and (ii) moderately powerful drift and cross shore transport of gravel within Seaton Bay causing deflection and occasional inlet closure. The training walls along both banks of the main channel of the Axe, and the short breakwater on the east side of the river mouth, may serve to increase ebb current velocities, thus accentuating "self-flushing" and maintenance of an otherwise inherently unstable inlet (Posford Duvivier, 2001). Although historical records are not exact, these defences - including those at the back of the spit where it has diverted the river channel eastwards - have been present in various forms for at least some 80 years. In addition, channel dredging contributes to loss of potential sediment input via the flood current, thus adding to the net effect of loss of estuarine storage (Axe Yacht Club, 2001). The estuary tidal regime is ebb dominant and ebb tidal currents concentrated at its narrow inlet are considerably faster than the corresponding longer duration tidal flows (Halcrow, 2002). Sediments drifting into the inlet from the spit are flushed seaward until the ebb tidal current disperses and wave action tends to drive material back landward. Normally, such a regime might be expected to create an ebb tidal delta of accumulated sediment at the lower foreshore and sub-tidal shoreface. There are no records available of such a feature actually being present, although casual observation (Photo 3) suggests the presence of a small delta.

6. COASTAL DEFENCE AND HABITATS ISSUES - References Map

Also of value are some 34 ha. of saltmarsh and 62 ha. of intertidal flats recorded within the Axe estuary. Studies have not been undertaken to formally quantify the detailed distributions and qualities of these estuarine habitats, or determine whether they could be affected adversely by maintenance of existing defences. Due to extensive 17th to 19th century reclamation, embankments confine much of the low-lying estuary perimeter. In particular, the Seaton and District Electric Tramway and B3172 run along the western and eastern shores, respectively, so that their protected embankments could contribute to "squeezing" of fronting intertidal habitats as sea level rises. The Devon Biodiversity Partnership, a grouping of responsible authorities and interest groups has developed to prepare and promote a Biodiversity Action Plan for the County (Devon Biodiversity Partnership, 1998). It sets a series of targets for the maintenance and restoration of key habitats including saltmarsh, which is relatively scarce within the county.

This coastline is of prime international, as well as national, importance for its geological and geomorphological features and was granted UNESCO World Landscape Heritage status in 2001. The World Heritage Site is promoted and managed by the Jurassic Coast Project that maintains an informative website at: http://www.swgfl.org.uk/jurassic/

A consequence of these qualities and international designations is a potential for significant conflicts between habitat, or earth science conservation and shoreline management, wherever the latter could affect the morphology and exposure of the cliffs. As part of its overall management plan for the World Heritage site (Jurassic Coast, 2003) the Jurassic Coast Project is promoting a mechanism for consultations between coastal engineers and the earth science community. It has set up a consultative scientific network so that potential conflicts and issues can be addressed (http://www.swgfl.org.uk/jurassic/consult.htm).

7. OPPORTUNITIES FOR CALCULATION AND TESTING OF LITTORAL DRIFT VOLUMES

The discontinuous nature of the shoreline of this unit with its headlands and pocket beaches means that it is unsuited generally for definitive studies of drift. There are, however, opportunities to study drift occurring along Seaton Beach to obtain a clearer understanding of its overall regime. An initial approach would be to revisit the Posford Duvivier (1994) modelling study to identify data from which to produce updated numerical model of littoral drift potential at a series of points along the full beach length based on an analysis of a long-term (greater than 20 years) hindcast wave climate. Uncertainties encountered in applying numerical model studies would include:

(a) Imprecision in the selection of synthetic wave climates in the absence of field validation of inshore waves. Shelter provided by Beer Head and the tendency for significant wave energy to approach from southwest and southeast direction sectors introduces complexity in the waves actually experienced at the shore. An offshore wave recorder was operated by West Dorset District Council off Lyme Regis (1997-1998) and its data may provide the basis for the improved definition of wave climate;
(b) The problem of selecting a representative sediment gain size on the gravel beach (sediment mobility is highly sensitive to grain size);
(c) Uncertainty relating to the detailed bathymetry of the bay and the presence of nearshore reefs.

The resulting potential littoral drift volumes could then be tested by means of a thorough examination of the budget of beach sediments, especially those that accumulate in the extended spit at the mouth of the Axe. This method would assume that long-term transport can be inferred from changes in beach volume and would offer an independent check on modelling results. For this to be feasible, it is important that beach volumes should be monitored and historical beach volumes are reconstructed (e.g. using map comparison, historical documentary evidence, perhaps supplemented by photogrammetrically derived data from historical air photos dating back to the 1940s).

8. KNOWLEDGE LIMITATIONS AND MONITORING REQUIREMENTS - References Map

1. Quantitative assessment of the wave climate at least two inshore points along Seaton Beach. An initial examination of data collected by Posford Duvivier (1994; 1998a) should attempt to identify the extent to which suitable data already exists, together with the additional studies needed to fill gaps. It ideally requires a representative long-term hindcast offshore wave climate based on some 20-30 years of wind data, together with shoaling and refraction analysis to derive inshore climates for the points selected. Temporary inshore field measurements of waves would be beneficial to validate model studies of the effects of refraction and diffraction on waves approaching from different directions. A magnitude-frequency analysis should also be linked to a quantitative study of the recurrence probabilities of extreme water levels. This is considered important for it is storm waves and storm tidal surges in combination that appear to cause erosion events and beach drawdown at Seaton Hole and along Seaton esplanade. To some extent, data obtained from an offshore wave recorder operated by West Dorset District Council off Lyme Regis (1997-1998) may provide the basis for the improved definition of wave climate. (This data was not available at the time of writing.)
2. Regular beach profile measurement with specific analyses of beach volume changes and derivation of longshore transport rates within Seaton Bay. It is currently uncertain if beach: nearshore exchange involves a net gain or loss of sediment, or if the beach budget as a whole is in balance. To gain more insight into this critical issue changes in morphology occurring over the full active profile "envelope" are required. Ideally, a "one-off" bathymetric survey is needed of Seaton Bay together with periodic terrestrial and being extended to cover the bathymetry several hundred metres seawards of each intertidal profile line to water depths where there is limited gravel and coarse sand mobility. As the monitoring record builds in the future, it should enable more definitive studies to be undertaken of cross-shore transport. If some sediment sampling surveys could also be factored into this programme they might reveal the fate of beach gravels lost during drawdown and possibly indicate the presence of sediment stores capable of shorewards transport. Studies should especially cover the area immediately seaward of the mouth of the Axe to determine the extent to which an ebb tidal delta is maintained. The type of comprehensive monitoring approach initiated in south and southeast England (Bradbury 2001) co-ordinated by the Channel Coast Observatory - see website at: http://www.channelcoast.org provides an excellent model.
3. To understand beach profile changes it is important to have knowledge of the beach sedimentology (gain size and sorting). Sediment size and sorting can alter significantly along this frontage due to cross shore and longshore transport, cliff sediment inputs and could also be affected by beach management. Ideally, a one-off field-sampling programme is required to provide baseline quantitative information together with a provision for a more limited periodic re-sampling to determine longer-term variability. Such data would also be of great value for future modelling of sediment transport, because uncertainty relating to grain size is often a key constraint in undertaking modelling. It would also provide insights into potential transport paths (via grain size and sorting analyses) and likely sediment provenance. This work could be prioritised for the Seaton bay beaches, but would also yield valuable knowledge of the Axmouth to Lyme Regis frontage.
4. Historical analysis of rates and patterns of coastline recession throughout the unit based on updating and extending the original work by Pitts (1981b). This could involve using Tithe Map and Ordnance Survey large scale map comparisons, perhaps supplemented by photogrammetrically derived data from historical air photos dating back to the 1940s. Mapping should involve plotting the positions of the cliff top, cliff toe, MHW and MLW. Work should also involve an assessment of: (i) the degree of present cliff activity and (ii) the potential for reactivation of relic landslides, an important consideration in anticipation of future climate change as recommended by (Halcrow et al., 2001). A useful element would be to produce cliff behaviour models for each main section of cliff line based on methods outlined by Rendel Geotechnics, (1998).
5. A geomorphological assessment of is needed of the shoreline between Axmouth and Lyme Regis to identify beach volumes, the degree of connectivity between the beaches and the behaviour of intervening headlands and landslide toes. This could indicate the pathways clear for drift enabling a better understanding of the extent to which a theoretically significant source of cliff gravel could actually contribute to beaches to the east e.g. Monmouth Beach.
6. Baseline surveys of the extents and qualities of the estuarine habitats are needed covering the Axe estuary. For forthcoming SMP revisions, it is likely that intertidal habitat changes and the possible influences of defences will need to be assessed. It is acknowledged that it is unlikely to be feasible to complete all tasks immediately, indeed, some will require the accumulation of quality monitoring data. Thus, it is recommended that the profile monitoring relating to Seaton Bay should be prioritised. Remaining tasks should be factored into the preparatory work for the forthcoming SMP revision, or progressed soon thereafter as part of the implementation of that Plan.

9. REFERENCES - Map

ARBER, M.A. (1940) The Coastal Landslips of South-East Devon, Proc. Geologists' Association, 51(3), 257-271.

ARBER, M.A. (1973) Landslips near Lyme Regis, Proc. Geologists' Association, 84, 121-133.

AXE YACHT CLUB (2001) Beach Erosion Report, 4pp..

BIRD, E.C.F., (1989). The Beaches of Lyme Bay, Proceedings Dorset Natural History and Archaeological Society, 111, 91-97.

BRAY, M.J. (1996) Beach Budgets and Shingle Transport Dynamics on the West Dorset Coast. PhD thesis, University of London. 2 volumes. 641p.

BRAY, M.J. (1997a) Episodic shingle supply and the modified development of Chesil Beach, England. Journal of Coastal Research, 13 (4), 1035-1049.

BRAY, M.J. (1997b). West Dorset Coast Research Meeting: Minutes of the meeting of April 3rd - 4th 1997 at the Fern Hill Hotel, Charmouth. 16p.

BRUNSDEN, D. (1996) Landslides of the Dorset Coast: Some Unresolved Questions, Proc. Ussher Soc., 9, 1-11.

DEVON BIODIVERSITY PARTNERSHIP (1998) Devon Biodiversity Action Plan. Devon Biodiversity Partnership. Ess website at: http://www.devon.gov.uk/biodiversity/actionplan.shtml

GALLOIS, R.W. and DAVIS, G.M. (2001) Saving Lyme Regis From the Sea: Geological Investigations at Lyme Regis, Dorset, Geoscience in South-West England, 10, 183-189.

GRAINGER, P. and KALAUGHER, P.G. (1995) Renewed Landslide Activity at Pinhay, Lyme Regis, Proc. Ussher Soc., 8, 421-425.

GRAINGER, P., KALAUGHER, P.G. and KIRK, S. (1996) The Relation Between Coastal Landslide Activity at Pinhay, East Devon, and Rainfall and Groundwater Levels, Proc. Ussher Soc., 9, 12-16.

HALCROW, (2002) Futurecoast: research project to improve the understanding of coastal evolution over the next century for the open coastline of England and Wales. Report and CD-ROM produced by Halcrow-led consortium for DEFRA.

HIGH-POINT RENDEL (1999) Coastal Processes and Geomorphology: Monmouth Beach (Lyme Regis). Report to West Dorset District Council.

ISAAC, K.P., (1981) Tertiary weathering profiles in the plateau deposits of east Devon. Proceedings of the Geologists' Association, 92, 159-168.

ISAAC, K.P., (1983) Tertiary lateritic weathering in Devon, England and the Palaeogene continental environment of south west England. Proceedings of the Geologists' Association, 94, 105-115.

JEZARD, J (in preparation, 2003) The Effects of Artificial Barriers on Updrift and Downdrift Shorelines within Littoral Transport Cells in Southern England, Ph.D. thesis, Department of Geography, University of Portsmouth.

JURASSIC COAST (2003) Dorset and East Devon Coast World Heritage Site Management Plan, First Revision 2003. produced by Jurassic Coast Dorset and East Devon Coast World Heritage Site. 42p. plus 11 Appendicies. See website at: http://www.swgfl.org.uk/jurassic/

LEWIS AND DUVIVIER (1975a) Report on Stabilisation of Beer Cliffs. Report to East Devon District Council, 8pp.

LEWIS AND DUVIVIER (1975b) Coast Erosion at Beer Cliffs. Report on Site Investigation. Report to East Devon District Council, 10pp.

LEWIS AND DUVIVIER (1975c) Report on Sea Defences at Seaton Hole. Report to East Devon District Council. Unpaginated.

PARKINSON, M. (1985) The Axe Estuary and Its Marshes, Reports and Trans. Devonshire Assoc. Advancement of Science, 117, 19-62.

PERKINS, J. (1971) Geology Explained in South and East Devon. Newton Abbot: David and Charles, Ltd.

PITTS, J. (1974) The Bindon Landslip of 1839, Proc. Dorset Natural History and Archaeological Soc., 95, 18-29.

PITTS, J. (1979) Morphological Mapping in the Axemouth-Lyme Regis Undercliffs, Devon, Quarterly Journal of Engineering Geology, 12, 205-217.

PITTS, J. (1981a) An Historical Survey of the Landslips of the Axemouth-Lyme Regis Undercliffs, Devon, Proc. Dorset Natural History and Archaeological Soc., 103, 101-106.

PITTS, J., (1981b). The landslides of the Axmouth-Lyme Regis Undercliff NNR, Devon. Unpublished PhD thesis, University of London.

PITTS, J. (1983a) The Recent Evolution of Landsliding the Axemouth-Lyme Regis National Nature Reserve, Proc. Dorset Natural History and Archaeological Soc., 105, 119-125.

PITTS, J. (1983b) The Temporal and Spatial Development of Landslides in the Axemouth-Lyme Regis Undercliffs, Earth Surface Processes and Landforms, 8, 589-603.

PITTS, J. (1986) The Form and Stability of a Double Undercliff: An Example from South-West England, Engineering Geology, 22, 209-216.

PITTS, J. and BRUNSDEN, D. (1987) A Reconsideration of the Bindon Landslide of 1839, Proc. Geologists' Association, 98(1), 1-18.

POSFORD DUVIVIER, (1990). Lyme Regis Environmental Improvements: a coast protection and harbour management scheme. Consulting Engineer's Appraisal, Report to West Dorset District Council, 24p.

POSFORD DUVIVIER, (1991) Lyme Regis Environmental Improvements: report on further investigations into the alternative scheme. Report to West Dorset District Council, 7p.

POSFORD DUVIVIER (1994) Seaton-Coastal Study. Report to East Devon District Council, 38pp.

POSFORD DUVIVIER (1997) SCOPAC Research Project: Sediment Inputs to the Coastal System. Phase 2: Cliff Erosion. Report to SCOPAC.

POSFORD DUVIVIER (1998a) Lyme Bay and South Devon Shoreline Management Plan. 3 Volumes. Report to Lyme Bay and South Devon Coastal Group.

POSFORD DUVIVIER (1998b) Axemouth Harbour Arm Extension. Report to Axe Yacht Club and East Devon District Council.

POSFORD DUVIVIER (2001) Axemouth Harbour Extension: Monitoring. Report to Axe Yacht Club and East Devon District Council.

POSFORD DUVIVIER AND BRITISH GEOLOGICAL SURVEY (1999) SCOPAC Research Project: Sediment Inputs to the Coastal System. Phase 3: Inputs from the Erosion of Coastal Platforms and Long-Term Sedimentary Deposits. Report to SCOPAC, 48pp.

POSFORD DUVIVIER (1999) SCOPAC Research Project: Sediment Inputs to the Coastal System. Summary Document. Report to SCOPAC, 54pp and 11 Appendices.

RENDEL GEOTECHNICS AND THE UNIVERSITY OF PORTSMOUTH (1996) Sediment Inputs into the Coastal System: Fluvial Flows. Report to SCOPAC, 52pp.

RENDEL GEOTECHNICS (1998). The Investigation and Management of Soft Rock Cliffs in England and Wales. Report to Ministry of Agriculture Fisheries and Food. 236p.

TRESISE, G.R., (1960) Lithology of the Wessex Upper Greensand. Proceedings of the Geologists' Association, 71, 316-339.

TRESISE, G.R., (1961) Chert in the Upper Greensand of Wessex. Proceedings of the Geologists' Association, 72, 333-356.

DAVID ROCHE GEOCONSULTANCY (2001) Beer Beach Cliffs. Report to East Devon District Council.

WOODWARD, H.B. and USSHER, W.A.E. (1911, 2nd Edition) The Geology of the Country near Sidmouth and Lyme Regis, London: HMSO (Geological Survey of Great Britain).