Coastal section: Holywell Sections and Foyle Track

Sussex RIGS number: TV69/02

Forms part of the Seaford to Beachy Head SSSI designated for its geological and biodiversity value (Site Code 1000182)
Most of the LGS site is located in Unit 13 of the SSSI but the southern end is in Unit 1.
Forms part of the Beachy Head to Seaford Head Geological Conservation Review (GCR) Site
   Block: Coastal Geomorphology of England (Site Code 1850)

Holywell Sections and Foyle Track LGS is within the South Downs National Park
Grid Reference: TV600965 to TV610978

Owner:
Eastbourne Borough Council

Site access:

The cliffs and foreshore at Holywell are directly accessible on foot from Eastbourne beach at the town end of the cliffs or by the steps at Holywell chalk pinnacle.
An upper track, Foyle Track, starts adjacent to St Bede"s School and follows the cliff top south to Cow Gap steps.
Apart from the risks of cliff falls the site is not particularly hazardous.

Summary Description:

22/09/2011
(from East Sussex RIGS Survey 2011)

Interest Feature(s)

Bedrock:
1 km of chalk cliffs exposing Zig Zag Chalk and Holywell Chalk Formations and including the classic Cenomanian/Turonian boundary. Holywell chalk pinnacle and spring at foot of cliffs (the original holy well). Cliffs are undefended except for a small section of rock armour at the Eastbourne end.
1.8 km of wavecut platform with Upper Greensand reefs.
Chalk exposures along Foyle Track showing New Pit/Lewes Chalk boundary.
New Pit Chalk is apparently exposed in the Eastbourne Water Works Quarry (not mentioned in the RIGGs designation and not investigated)
Stratigraphy:
Upper Greensand Formation, Lower Cretaceous (Albian) in age.
Zig Zag Chalk, Grey Chalk Subgroup, Upper Cretaceous (Cenomanian) in age.
Holywell Nodular Chalk (type locality), New Pit and Lewes Nodular Chalk Formations, White Chalk Subgroup, Upper Cretaceous (Turonian) in age.
Sedimentology:
Upper Greensand: glauconitic, micaceous, fine-grained sandstones. Deposited in shallow marine environment.
Zig Zag Chalk: blocky chalk with marl interbeds and thick Plenus Marl (glauconitic) at top.
Holywell Nodular Chalk: Melbourn Rock member at base, hard nodular chalk, overlain by massive white chalk with nodular beds and thin marl seams.
New Pit and Lewes Chalk: hardgrounds at the base of the Lewes Chalk are nodular chalks with red iron-staining. There are also flint layers, some with tubular and finger flints.
Sedimentary structures: nodular chalks are found in the Holywell and Lewes Chalk Formations. Some thin marl seams in the Holywell Chalk show wispy character.
Structural geology: on the Foyle Track the chalk section is heavily faulted.
Palaeontology: near the C/T Boundary Mytiloides and Belemnitella plenus (in the Plenus marls) are found. Other fossils, including echinoids and occasionally ammonites and brachiopods, may be found.
On the Foyle Track the beds above and below the Glynde Marl are rich in Inoceramus cuvieri.

Geomorphology:
The site displays coastal cliff erosion and an extensive wavecut platform.
At the foot of the cliffs beneath the Holywell pinnacle a perennial spring emerges at the contact between the Melbourn Rock and the underlying Plenus Marl.

Site map - Aerial photography 2005 - Survey visit 22/09/2011

View site images as slideshow

RIGS Designation Criteria:

Scientific Details and Site Description
This coastal section covers the Holywell sections and Foyle Track, Eastbourne.
Stratigraphy: this section of the coast includes the Melbourn Rock at the base of the Turonian and up into the Lewes Nodular Chalk, including the boundary between the Cenomanian and Turonian (CT Boundary). The site consists of three separate exposures:
The classic CT Boundary lies to the west of the steps at the base of the Holywell Nodular Chalk Member (and is seen as far as Gun Gardens). The geochemistry compares with the Pueblo section in South America, and this is the most complete and finest CT boundary section in Europe.
On the Foyle track westwards from the Kiosk, the contact between the New Pit and Lewes Chalk is visible.
On the wavecut platform a reef of Upper Greensand outcrops.
All these rocks are of Cretaceous age.
Sedimentology: the cliff sections are all chalk, the hardgrounds at the base of the Lewes Chalk are nodular chalks with red iron-staining. There are also flint layers, some of these layers are of tubular and finger flints. The marl seams are wispy grey thin layers. The Upper Greensand sediments are glauconitic, micaceous, fine-grained sandstones but are likely to be covered with weed encrustations.
Sedimentary structures: there are nodular hardground layers in the Lewes Chalk.
Palaeontology: on the Foyle track from the Kiosk westward there is a section on the top showing the contact between New Pit and Lewes Chalk; The beds above and below the Glynde Marl are rich in Inoceramus cuvieri. Near the CT Boundary Mytiloides and Belemnitella plenus (in the Plenus marls) are found. Other fossils, including echinoids and occasionally ammonites and brachiopods, may be found.
Structural Geology: On the Foyle Track, the section is heavily faulted. Near the Pinnacle steps between Plenus Marls and Melbourn rock a quantity of water is thrown out.
Educational value: this site is of great importance for research and education purposes because of the CT Boundary present, which is the finest CT section in Europe. The area is easily accessible and suitable for large parties. The cliff and beach are popular areas for walking and recreation and have great tourist appeal.

SSSI Designation Criteria (citation):

Extracts:
Seaford to Beachy Head is an outstanding site of national importance for its biological and geological features. The diverse range of habitats includes herb-rich chalk grassland, chalk heath (a unique, rare habitat on chalk soils), maritime grassland, foreshore and chalk cliffs, river meanders, and Greensand reef. Together, these habitats support a number of nationally rare, nationally scarce and nationally significant plants, invertebrates and birds.
The cliffs and chalk platform beneath, the Greensand reef, and the chalk escarpment at Cow Gap are identified in the Geological Conservation Review as outstanding for their geological and geomorphological interest.
The site lies at the eastern end of the South Downs which terminate in the chalk cliffs of the Seven Sisters. The majority of the site, therefore, lies on chalk but the River Cuckmere breaches the cliffs to form a broad alluvial valley. There is also a distinct coastal zone which includes all of the geological interest.

Geology
The site is important for earth science interests, particularly for its chalk stratigraphy, periglacial geomorphology and the study of chalk landscape evolution.
Seaford -Beachy Head is a key site for coastal geomorphology, comprising a cliff beach- shore platform system developed on chalk. The site includes the classic coastal cliffs of Beachy Head and the Seven Sisters. In contrast with the cliffs at Foreness Point (Kent) and Kingsdown - Dover (Kent) where structural controls prevail, the plan of the Seaford - Beachy Head coastline is controlled primarily by wave energy; with the dominant and prevailing wave energy from the southwest.
The beach is one of six major south west facing beaches in southern England and all of the others differ significantly in geological characteristics. In addition the beach is the most rapidly and consistently fed by flint from cliff falls.

GCR Site Account:

Beachy Head to Seaford Head
Block: Coastal Geomorphology of England (Site Code 1850)
Introduction
The Chalk of the South Downs reaches the sea between Brighton and Eastbourne in a series of cliffs that become generally higher towards the east and culminate in the 150 m-high cliffs of Beachy Head. This site comprises a cliff-beach-platform system developed on the Chalk, includes the classic world-renowned cliffs of Beachy Head and the Seven Sisters, and cuts across the mouth of the Cuckmere Valley. The cliffs reach a maximum height of 156 m at Beachy Head (TV588956) and vary between 14 m and 79 m in height along the Seven Sisters. Retreat of the cliffs has been estimated at 0.42 m a^-1, reaching a maximum of 0.91 m a^-1 at Birling Gap (May, 1971a). A narrow fringing beach of chalk and flint rests upon the cliff-platform junction, except where major falls, especially at Beachy Head, extend below low-tide level. Debris ramparts from cliff-falls are common at Beachy Head. The coastline plan is controlled primarily by dominant and prevailing wave energy from the south-west, with Seaford Head and Beachy Head acting as more resistant points between which a predominantly wave-energy controlled shoreline has developed. Structural variations seem to have had little effect upon the overall coastal plan, the cliff materials being sufficiently rapidly eroded to ensure control by wave action. However, in detail the cliffs are controlled by a rectilinear jointing pattern. The beach is one of six major SW-facing beaches in southern England, all of which differ significantly in their geological characteristics. Most of the site faces south-west and is exposed to Atlantic waves. The fetch from the south-west is similar to that which affects all the major beaches in the English Channel. The cliff and beach of Seven Sisters in particular is unusual in having a very strong similarity in its alignment to such beaches as Chesil Beach and Dungeness. Of the beaches, Seven Sisters beach is the most rapidly and consistently fed by flint from cliff-falls. The most directly comparable cliffs also comprise Upper Chalk along the Normandy coast, but they lack the same aspect and degree of exposure.
Description (extract)
The easternmost part of the site is aligned south-west-north-east and has a cliff height of 24 m. The upper part of the cliff is formed by a staircase of narrow slipped blocks. At the foot of the cliffs, both the Upper Greensand and the Gault Clay crop out, failures in the latter giving rise to the upper cliff features. The platform is distinguished by several repeated outcrops of these rocks, which appear to be related to mass-movements that have penetrated below sea level. At the northern end of the site several springs flow from the top of the Plenus Marl and may affect the erosion of the cliffs. The beach is formed of flint and chalk rubble, and extends northwards towards Eastbourne where it is dominated by flint, the Chalk typically being worn down over a distance of about 1 km.

Holywell Sections LGS site represents part of sub-unit 1 of the GCR:
The Chalk cliffs and Greensand and Gault Clay platforms below Cow Gap and Whitebread Hole (TV 600 968 to TV 595 955).
The full site account is on the JNCC website.

Published in the Geological Conservation Review
Volume 28: Coastal geomorphology of Great Britain (2003)
Chapter 4: Soft-rock cliffs

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East Sussex Local Geological Sites - Coastal Section Holywell and Foyle Track

Cliffs up to 50 m high exposing Holywell Nodular Chalk with Plenus Marl at the base. The Upper Greensand reef is mainly submerged and the visible wavecut platform exposes chalk.
Photograph taken: 22/09/2011
Grid ref TV60929644
Direction NNE

Cliff about 30 m high exposing top Zig Zag Chalk at base overlain successively by Plenus Marls, Melbourn Rock and lower Holywell Nodular Chalk. Thin Pleistocene solifluction deposits (Whitebread Hole) overlie chalk at the cliff top.
Photograph taken: 22/09/2011
Grid ref TV60929648
Direction WNW

Cliffs up to 40 m high at the southern end of the site. The thick greyish Plenus Marls layer dips to the right (north) down to beach level separating the Zig Zag Chalk beneath from the Holywell Nodlular Chalk above. The visible wavecut platform exposes chalk and the Upper Greensand reef is partly submerged.
Photograph taken: 22/09/2011
Grid ref TV60989657
Direction SSW

Cliffs 35 m high exposing massive white blocky Holywell Nodular Chalk. Melbourn Rock is exposed at beach level.
Photograph taken: 22/09/2011
Grid ref TV60989657
Direction WNW

Cliffs towards Holywell exposing Holywell Nodular Chalk including the Pinnacle, above Melbourn Rock. Plenus Marls exposed at base of cliff to left. Wavecut platform exposes chalk. The Upper Greensand reef is further offshore and submerged (at this state of the tide).
Photograph taken: 22/09/2011
Grid ref TV60079670
Direction NNE

Low cliffs exposing thick greyish Plenus Marls layer separating underlying Zig Zag Chalk from overlying Melbourn Rock.
Photograph taken: 22/09/2011
Grid ref TV60109680
Direction NNW

Holywell Pinnacle and cliffs exposing white, blocky Holywell Nodular Chalk with marl seams, overlying Melbourn Rock. The Holywell spring is at the base of the cliffs off to the right.
Photograph taken: 22/09/2011
Grid ref TV60189694
Direction WNW

Holywell spring is located in the recess at the foot of the cliff which exposes basal Holywell nodular chalk with Melbourn Rock at base. The water emerges from the contact between Melbourn Rock and Plenus Marls.
Photograph taken: 22/09/2011
Grid ref TV60189696
Direction WNW

Holywell perennial spring at the base of the cliff where water emerges from the contact between Melbourn Rock and the relatively impermeable Plenus Marls below.
Photograph taken: 22/09/2011
Grid ref TV60189696

Cliffs up to 40 m high north of Holywell steps exposing Holywell Nodular Chalk. Short section of rock armour behind the groyne protects the Holywell spring. Wavecut platform exposes chalk. The Upper Greensand reef is submerged at this state of the tide.
Photograph taken: 22/09/2011
Grid ref TV60199688
Direction NNE

Holywell Nodular Chalk with prominent marl layers exposed in cliffs north of the Holywell spring.
Photograph taken: 22/09/2011
Grid ref TV60249706
Direction NNW

Detail of base of cliff shown in photo 11 exposing Holywell nodular chalk with prominent tabular marl layers and also thin wispy marl seams.
30 cm scale.
Photograph taken: 22/09/2011
Grid ref TV60249707
Direction WNW

Cliffs north of Holywell steps exposing Holywell Nodular Chalk. Nodular layers and prominent marl seams, some with wispy bedding, in lower cliff.
1 m pole for scale.
Photograph taken: 22/09/2011
Grid ref TV60289715
Direction NNW

Holywell Nodular Chalk with Melbourn Rock at base exposed at the north end of the cliffs. About 40 m high. Nodular chalk with prominent marl layers.
Photograph taken: 22/09/2011
Grid ref TV60309717
Direction north

Holywell Pinnacle, chalk cliffs and foreshore to south. The pinnacle exposes Holywell Nodular Chalk. Wavecut platform exposes mostly chalk at this state of the tide. The Upper Greensand reef is largely submerged.
Photograph taken: 22/09/2011
Grid ref TV60179702
Direction SSW

View north from Foyle Track. Wavecut chalk platform is visible as far as Eastbourne beach but not beyond. Rock armour below Holywell Pinnacle is opposite Holywell spring. Part of the submerged Upper Greensand reef can be seen faintly offshore.
Photograph taken: 22/09/2011
Grid ref TV60019679
Direction NE

Lewes Chalk exposed in bank at north side of Foyle Track. Appears to be mostly obscured by vegetation and talus.
Photograph taken: 22/09/2011
Grid ref TV60049697
Direction NNE

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