The geology of East Sussex is defined by the
Weald–Artois anticline, a wide and long fold within which caused the arching up of the chalk into a broad dome within the middle
Miocene
The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" ...
,
which has subsequently been eroded to reveal a lower
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
to Upper Jurassic stratigraphy. East Sussex is best known geologically for the identification of the
first dinosaur by
Gideon Mantell
Gideon Algernon Mantell MRCS FRS (3 February 1790 – 10 November 1852) was a British obstetrician, geologist and palaeontologist. His attempts to reconstruct the structure and life of '' Iguanodon'' began the scientific study of dinosaurs: in ...
, near
Cuckfield
Cuckfield ( ) is a village and civil parish in the Mid Sussex District of West Sussex, England, on the southern slopes of the Weald. It lies south of London, north of Brighton, and east northeast of the county town of Chichester. Nearby town ...
,
to the famous hoax of the
Piltdown man
The Piltdown Man was a paleoanthropological fraud in which bone fragments were presented as the fossilised remains of a previously unknown early human. Although there were doubts about its authenticity virtually from the beginning, the remains ...
near
Uckfield
Uckfield () is a town in the Wealden District of East Sussex in South East England. The town is on the River Uck, one of the tributaries of the River Ouse, on the southern edge of the Weald.
Etymology
'Uckfield', first recorded in writing ...
.
The county’s chalk has provided a world-class stratigraphic marker giving a great deal of detail in
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
Chalk palaeoecology and palaeontology while in the east of the county on the Kentish border the
Dungeness Foreland is important for the study of geomorphology and
Holocene
The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...
sea level fluctuations.
Geological history
The recorded geological history of East Sussex commenced during
Carboniferous, with the rocks which are today
basement
A basement or cellar is one or more Storey, floors of a building that are completely or partly below the storey, ground floor. It generally is used as a utility space for a building, where such items as the Furnace (house heating), furnace, ...
deposited within a low swamp providing
coal
Coal is a combustible black or brownish-black sedimentary rock, formed as stratum, rock strata called coal seams. Coal is mostly carbon with variable amounts of other Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen ...
s which were exploited to the north and east in
Kent
Kent is a county in South East England and one of the home counties. It borders Greater London to the north-west, Surrey to the west and East Sussex to the south-west, and Essex to the north across the estuary of the River Thames; it faces ...
, but boreholes drilled in the 19th century failed to find this deposit in Sussex. The Carboniferous coals are overlain by Permian and Triassic sediments.
The sediments were uplifted and faulted within the
Variscan Orogeny
The Variscan or Hercynian orogeny was a geologic mountain-building event caused by Late Paleozoic continental collision between Euramerica (Laurussia) and Gondwana to form the supercontinent of Pangaea.
Nomenclature
The name ''Variscan'', comes ...
, with the land now occupied by East Sussex being a low
external fold belt to the main orogeny, which was located within the present day
English Channel
The English Channel, "The Sleeve"; nrf, la Maunche, "The Sleeve" ( Cotentinais) or (Jèrriais), ( Guernésiais), "The Channel"; br, Mor Breizh, "Sea of Brittany"; cy, Môr Udd, "Lord's Sea"; kw, Mor Bretannek, "British Sea"; nl, Het Kan ...
,
the remnants of the mountain belt can be seen today in Devon and Cornwall in what is known as the Cornubian Massif. Although unlike in Devon and Cornwall, there was little or no metamorphism.
[
The mountain belt collapsed soon after the orogeny with the former northward thrusts being reactivated as normal faults and leading to the formation of the Weald Basin which developed as an extension of the considerably larger Wessex Basin.][ The northern margin of the basin was formed by a series of normal faults, against what was then an area of land, known to geologists as the London-Brabant Massif. The Weald Basin gently subsided throughout the Jurassic, Cretaceous and Early Palaeogene leading to a thick succession of sedimentary rocks being deposited.
]
Lithologies
The sediments of the Weald
The Weald () is an area of South East England between the parallel chalk escarpments of the North and the South Downs. It crosses the counties of Hampshire, Surrey, Sussex and Kent. It has three separate parts: the sandstone "High Weald" in ...
of East Sussex
East Sussex is a ceremonial and non-metropolitan county in South East England on the English Channel coast. It is bordered by Kent to the north and east, West Sussex to the west, and Surrey to the north-west. The largest settlement in East ...
were deposited during the early stages of the Cretaceous Period, which lasted for approximately 40 million years from 140 to 100 million years ago. These are collectively known as the Wealden Group
The Wealden Group, occasionally also referred to as the Wealden Supergroup, is a group (a sequence of rock strata) in the lithostratigraphy of southern England. The Wealden group consists of paralic to continental (freshwater) facies sedimentary ...
and comprise the Purbeck Group, the Hastings Beds, the Weald Clay, the Lower Greensand, the Gault and the Upper Greensand. The Wealden Group
The Wealden Group, occasionally also referred to as the Wealden Supergroup, is a group (a sequence of rock strata) in the lithostratigraphy of southern England. The Wealden group consists of paralic to continental (freshwater) facies sedimentary ...
is overlain by the Chalk Group
The Chalk Group (often just called the Chalk) is the lithostratigraphic unit (a certain number of rock strata) which contains the Upper Cretaceous limestone succession in southern and eastern England. The same or similar rock sequences occur ac ...
, which is subdivided into the White Chalk Subgroup and the Grey Chalk Subgroup. Each of the subgroups is in turn subdivided to formation level.
Purbeck Group
The oldest exposed rocks in the county are the Purbeck Beds
The Purbeck Group is an Upper Jurassic to Lower Cretaceous lithostratigraphic group (a sequence of rock strata) in south-east England. The name is derived from the district known as the Isle of Purbeck in Dorset where the strata are exposed i ...
or more formally the Purbeck Group, which are of Late Jurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...
to Early Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
age. The Purbeck Beds
The Purbeck Group is an Upper Jurassic to Lower Cretaceous lithostratigraphic group (a sequence of rock strata) in south-east England. The name is derived from the district known as the Isle of Purbeck in Dorset where the strata are exposed i ...
outcrop at three locations north and northwest west of Battle, East Sussex
Battle is a small town and civil parish in the local government district of Rother in East Sussex, England. It lies south-east of London, east of Brighton and east of Lewes. Hastings is to the south-east and Bexhill-on-Sea to the south. ...
and at Netherfield. They also occur at several other locations east of Heathfield, East Sussex and at Beak's Wood near Burwash.[Codd, J.W. (2007) Analysis of the distribution and characteristics of landslips in the Weald of East Sussex. MSc dissertation, University of Brighton]
The Purbeck Group has a typical thickness of 77 to 186m in the Weald
The Weald () is an area of South East England between the parallel chalk escarpments of the North and the South Downs. It crosses the counties of Hampshire, Surrey, Sussex and Kent. It has three separate parts: the sandstone "High Weald" in ...
and is composed of predominantly bluish grey calcareous mudstones. Limited developments of limestone, sandstone, siltstone, ironstone and evaporite
An evaporite () is a water- soluble sedimentary mineral deposit that results from concentration and crystallization by evaporation from an aqueous solution. There are two types of evaporite deposits: marine, which can also be described as oce ...
minerals occur throughout the sequence.
The Purbeck Group was deposited in an environment of braided rivers and muddy lagoons, which periodically dried out, resulting in the now economic deposits of gypsum
Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and dr ...
being deposited in this area,[ The same beds outcrop on the ]Jurassic Coast
The Jurassic Coast is a World Heritage Site on the English Channel coast of southern England. It stretches from Exmouth in East Devon to Studland Bay in Dorset, a distance of about , and was inscribed on the World Heritage List in mid-Decembe ...
in Dorset but there are difficulties in correlating the two exposures, which has led to increased study of these rocks. During their deposition the region lay at a latitude of about 30°N and thus experienced a tropical climate.
In East Sussex
East Sussex is a ceremonial and non-metropolitan county in South East England on the English Channel coast. It is bordered by Kent to the north and east, West Sussex to the west, and Surrey to the north-west. The largest settlement in East ...
the Purbeck Group is formally subdivided into the Blues and Greys Limestones members, which are typically made up of calcilutite and shelly calcarenites. The Greys Limestones Member is of particular significance as it marks the boundary between the Purbeck Beds
The Purbeck Group is an Upper Jurassic to Lower Cretaceous lithostratigraphic group (a sequence of rock strata) in south-east England. The name is derived from the district known as the Isle of Purbeck in Dorset where the strata are exposed i ...
and the overlying Ashdown Formation of the Early Cretaceous. This member is characterised by the disarticulated shells of the brackish water bivalve Neomiodon. The lower boundary of the Purbeck Beds is marked by the base of a widespread evaporite deposit of gypsum and anhydrite
Anhydrite, or anhydrous calcium sulfate, is a mineral with the chemical formula CaSO4. It is in the orthorhombic crystal system, with three directions of perfect cleavage parallel to the three planes of symmetry. It is not isomorphous with t ...
(up to 21 m thick). These evaporites have been mined and processed in Mountfield, East Sussex since 1876 and are considered to be strategically important.[
]
Ashdown Formation (Hastings Beds)
The upper Purbeck Group records a transition into more sand being delivered into the Weald
The Weald () is an area of South East England between the parallel chalk escarpments of the North and the South Downs. It crosses the counties of Hampshire, Surrey, Sussex and Kent. It has three separate parts: the sandstone "High Weald" in ...
basin. This has led to the deposition of a mixture of fine sands known as the Ashdown Formation, or Ashdown Beds, which along with the Wadhurst Clay and the Tunbridge Wells Sands
The Tunbridge Wells Sand Formation is a geological unit which forms part of the Wealden Group and the uppermost and youngest part of the unofficial Hastings Beds. These geological units make up the core of the geology of the Weald in the English ...
compose the Hastings Beds. These strata underlie the county from the boundary with West Sussex
West Sussex is a county in South East England on the English Channel coast. The ceremonial county comprises the shire districts of Adur, Arun, Chichester, Horsham, and Mid Sussex, and the boroughs of Crawley and Worthing. Covering an a ...
at East Grinstead
East Grinstead is a town in West Sussex, England, near the East Sussex, Surrey, and Kent borders, south of London, northeast of Brighton, and northeast of the county town of Chichester. Situated in the extreme northeast of the county, the civ ...
, through the Ashdown Forest to Hastings
Hastings () is a large seaside town and borough in East Sussex on the south coast of England,
east to the county town of Lewes and south east of London. The town gives its name to the Battle of Hastings, which took place to the north-west a ...
and Pett
Pett is a village and civil parish in the Rother district of East Sussex, England. The village is located north-east of Hastings on the edge of Pett Level, the one-time marshes stretching along the coast of Rye Bay.
The road through the villag ...
Level on the coast.
The Ashdown Beds
The Ashdown Formation is a geological unit, which forms part of the Wealden Group and the lowermost and oldest part of the now unofficial Hastings Beds. These geological units make up the core of the Weald in the English counties of East Sussex a ...
are the lowermost unit of the Hastings Beds and typically comprise siltstones and silty fine-grained sandstones with small amounts of finely-bedded mudstone and mudstone arranged in rhythmic units ("cyclothems
In geology, cyclothems are alternating stratigraphic sequences of marine and non-marine sediments, sometimes interbedded with coal seams. Historically, the term was defined by the European coal geologists who worked in coal basins formed during ...
") commonly divided by thin pebble beds as described by the British Geological Survey
The British Geological Survey (BGS) is a partly publicly funded body which aims to advance geoscientific knowledge of the United Kingdom landmass and its continental shelf by means of systematic surveying, monitoring and research.
The BGS he ...
.
In the east of the county, the formation tends to be more argillaceous, or clayey, in its lowermost part and fines up to a sandier division in the uppermost 30 to 50m. The clays are identified by their characteristic purple and brick-red mottled nature. In early references, these variations give rise to the division of the formation into the ‘Fairlight Clays’ and the ‘Ashdown Sands
The Ashdown Formation is a geological unit, which forms part of the Wealden Group and the lowermost and oldest part of the now unofficial Hastings Beds. These geological units make up the core of the Weald in the English counties of East Sussex a ...
’. However, it is now considered as one due to the impersistence of the clays across the Weald
The Weald () is an area of South East England between the parallel chalk escarpments of the North and the South Downs. It crosses the counties of Hampshire, Surrey, Sussex and Kent. It has three separate parts: the sandstone "High Weald" in ...
.[ Despite this the variations of clays and sands in the formation are usually marked separately on the maps and records of the ]British Geological Survey
The British Geological Survey (BGS) is a partly publicly funded body which aims to advance geoscientific knowledge of the United Kingdom landmass and its continental shelf by means of systematic surveying, monitoring and research.
The BGS he ...
. In its entirety the formation is usually found to be between 180 and 215m thick
The Ashdown Formation is best exposed in the 8 km cliff section between Hastings
Hastings () is a large seaside town and borough in East Sussex on the south coast of England,
east to the county town of Lewes and south east of London. The town gives its name to the Battle of Hastings, which took place to the north-west a ...
and Pett Level. At this location the formation can be followed from the axis of the Wealden Anticline at Lee Ness Ledge through the well distinguished marker beds and horizons to its juncture with the Wadhurst Clay at Hastings Castle
Hastings Castle is a keep and bailey castle ruin situated in the town of Hastings, East Sussex. It overlooks the English Channel, into which large parts of the castle have fallen over the years.
History
Immediately after landing in England ...
to the west and Cliff End to the east. The Lee Ness Ledge is known for its many well preserved fossilised dinosaur footprints, particularly Iguanodon
''Iguanodon'' ( ; meaning 'iguana-tooth'), named in 1825, is a genus of iguanodontian dinosaur. While many species have been classified in the genus ''Iguanodon'', dating from the late Jurassic Period to the early Cretaceous Period of Asia, ...
.
Wadhurst Clay Formation (Hastings Beds)
The British Geological Survey
The British Geological Survey (BGS) is a partly publicly funded body which aims to advance geoscientific knowledge of the United Kingdom landmass and its continental shelf by means of systematic surveying, monitoring and research.
The BGS he ...
describe the Wadhurst Clay Formation
The Wadhurst Clay Formation is a geological unit which forms part of the Wealden Group and the middle part of the now unofficial Hastings Beds. These geological units make up the core of the geology of the High Weald in the English counties of We ...
as made of soft, dark grey thinly-bedded mudstones ("shales") and mudstones with subordinate beds of pale grey siltstone, fine-grained sandstone, shelly limestone, clay ironstone and rare pebble beds, which shows evidence of unconformable weathering at the top of the bed. The mudstones often degrade in a short period of time when they become exposed at the surface and weather to heavy ochre and greenish grey clays.[
The formation thickness ranges from 55m in the ]Tenterden
Tenterden is a town in the borough of Ashford in Kent, England. It stands on the edge of the remnant forest the Weald, overlooking the valley of the River Rother. It was a member of the Cinque Ports Confederation. Its riverside today is ...
area, to 30m near Lewes
Lewes () is the county town of East Sussex, England. It is the police and judicial centre for all of Sussex and is home to Sussex Police, East Sussex Fire & Rescue Service, Lewes Crown Court and HMP Lewes. The civil parish is the centre ...
and varies in between. Outside of East Sussex
East Sussex is a ceremonial and non-metropolitan county in South East England on the English Channel coast. It is bordered by Kent to the north and east, West Sussex to the west, and Surrey to the north-west. The largest settlement in East ...
, the Wadhurst Clay has been proven to over 70m thick near Tunbridge Wells
Royal Tunbridge Wells is a town in Kent, England, southeast of central London. It lies close to the border with East Sussex on the northern edge of the High Weald, whose sandstone geology is exemplified by the rock formation High Rocks. ...
and up to 80m near Horsham
Horsham is a market town on the upper reaches of the River Arun on the fringe of the Weald in West Sussex, England. The town is south south-west of London, north-west of Brighton and north-east of the county town of Chichester. Nearby ...
.
The base of the Wadhurst Clay is taken at the bottom of the Top Ashdown Pebble Bed. Despite its name this thin and impersistent bed comprises a coarse grained to gravelly sandstone. This horizon is best exposed at Cliff End, but where it is encountered elsewhere in the county it is usually fairly distinctive and easily identified. The Top Ashdown Pebble Bed occurs mainly in the southern half of the county and is often missing in the northern half. Where this is the case, the boundary is taken at a layer of disconnected ripplesl.[Lake, Shepard-Thorn, E.R., Smart, J.G.O., Bisson, G. & Edmonds, E.A. (1966) ''Geology of the country around Tenterden: Memoir for 1:50,000 geological sheet 304''. British Geological Survey, London.]
The Wadhurst Clay hosted small nodules of iron ore which was the very foundation of the Wealden iron industry. The ore was deposited in a tropical environment within which iron brought in from the eroding mountains in the west was altered into small nodules of ilmenite
Ilmenite is a titanium-iron oxide mineral with the idealized formula . It is a weakly magnetic black or steel-gray solid. Ilmenite is the most important ore of titanium and the main source of titanium dioxide, which is used in paints, printing ...
. A succession of clays and sands was deposited into the subsiding basin, with much of the source material also being delivered from the north and east as well as the west.
Tunbridge Wells Sand Formation (Hastings Beds)
The Tunbridge Wells Sand Formation
The Tunbridge Wells Sand Formation is a geological unit which forms part of the Wealden Group and the uppermost and youngest part of the unofficial Hastings Beds. These geological units make up the core of the geology of the Weald in the English co ...
is the uppermost and youngest formation of the Hastings Beds. Its thickness is typically in the region of 110 to 125m. Outside of the county, near Haywards Heath
Haywards Heath is a town in West Sussex, England, south of London, north of Brighton, south of Gatwick Airport and northeast of the county town, Chichester. Nearby towns include Burgess Hill to the southwest, Horsham to the northwest, Crawl ...
, borehole data has proven the formation to be up to 150m thick.[Young, B. & Lake, R.D. (1988) ''Geology of the country around Brighton and Worthing: Memoir for 1:50,000 geological sheets 318 and 333''. British Geological Survey, London.] The formation is lithologically similar to the Ashdown Formation and comprises complex cyclic sequences of siltstones with sandstones and clays, typically fining upwards. In the western parts of the county the Tunbridge Wells Sands
The Tunbridge Wells Sand Formation is a geological unit which forms part of the Wealden Group and the uppermost and youngest part of the unofficial Hastings Beds. These geological units make up the core of the geology of the Weald in the English ...
can be divided into three; the Lower Tunbridge Wells Sand, the Grinstead Clay, and the Upper Tunbridge Wells Sand.
Greensands and Gault
The Greensands and the Gault best define the Wealden Anticline, running in a broad horseshoe from Folkestone in the East, to Petersfield in Hampshire in the West and back to Eastbourne. The Greensands are divided into two units, the Lower Greensand and Upper Greensand, which sandwich the Gault. The three units outcrop in East Sussex
East Sussex is a ceremonial and non-metropolitan county in South East England on the English Channel coast. It is bordered by Kent to the north and east, West Sussex to the west, and Surrey to the north-west. The largest settlement in East ...
along the bottom of the Downs and northward into the Vale of the Weald
The Weald () is an area of South East England between the parallel chalk escarpments of the North and the South Downs. It crosses the counties of Hampshire, Surrey, Sussex and Kent. It has three separate parts: the sandstone "High Weald" in ...
. Although named as such the Lower Greensand is rarely sand and rarely green; the name was applied by mistake by 19th century geologists mistakenly thinking that the mineral glauconite
Glauconite is an iron potassium phyllosilicate (mica group) mineral of characteristic green color which is very friable and has very low weathering resistance.
It crystallizes with a monoclinic geometry. Its name is derived from the Greek () ...
would be found in the seams of sandstone both above and below the Gault clay.[
The Gault is one of the most fossil rich horizons in the UK; yielding plentiful ]bivalves
Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, biv ...
, cephalopod
A cephalopod is any member of the molluscan class Cephalopoda ( Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, ...
(including ammonites) and gastropods. This has allowed for a tight correlation of the age of the Gault with other geological units in Europe, under the science of biostratigraphy
Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them.Hine, Robert. “Biostratigraphy.” ''Oxford Reference: Dictionary of Bio ...
. At its maximum the Gault sea grew to cover the northern landmass which had supplied the sediment for the lower sandstones; by this time Britain was at 35°N and the land and sea teemed with dinosaurs and marine reptiles, the remains of which have been found in the Gault.
Chalk Group
The Chalk Group
The Chalk Group (often just called the Chalk) is the lithostratigraphic unit (a certain number of rock strata) which contains the Upper Cretaceous limestone succession in southern and eastern England. The same or similar rock sequences occur ac ...
is the most well known rock in East Sussex, forming the Downs and where it meets the sea the spectacular Seven Sisters and geologically and biologically rich cliffs from Brighton to Newhaven. The Chalk formed in a warm, clear sea which stretched from Texas to Poland (prior to the opening of the Atlantic) and is subdivided into three units, the Lower, Middle and Upper Chalk.
Cenozoic
After the end of the Cretaceous deposition continued, with the Reading and London Beds (clays and sandstones) being deposited during the Cenozoic, these are no longer exposed in East Sussex, but can be seen in London and North Kent. The older shelly clays of the Woolwich Beds at Newhaven; with gypsum to be found within the beds.
The structural reversal of the basin
For much of its history the Weald had been slowly subsiding basin, but the growth of the Alpine Chain to the south during the Cenozoic caused a reactivation of the Variscan basement
A basement or cellar is one or more Storey, floors of a building that are completely or partly below the storey, ground floor. It generally is used as a utility space for a building, where such items as the Furnace (house heating), furnace, ...
basin-bounding faults, the rocks were arched into a broad anticline
In structural geology, an anticline is a type of fold that is an arch-like shape and has its oldest beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex up in which the hinge or crest is the ...
which stretched across the English Channel
The English Channel, "The Sleeve"; nrf, la Maunche, "The Sleeve" ( Cotentinais) or (Jèrriais), ( Guernésiais), "The Channel"; br, Mor Breizh, "Sea of Brittany"; cy, Môr Udd, "Lord's Sea"; kw, Mor Bretannek, "British Sea"; nl, Het Kan ...
to Northern France Northern France may refer to:
*the north of France, especially:
**the region of Hauts-de-France
**the former region of Nord-Pas-de-Calais
**Nord (French department)
Nord (; officially french: département du Nord; pcd, départémint dech Nord ...
, the Weald–Artois anticline. Inversion
Inversion or inversions may refer to:
Arts
* , a French gay magazine (1924/1925)
* ''Inversion'' (artwork), a 2005 temporary sculpture in Houston, Texas
* Inversion (music), a term with various meanings in music theory and musical set theory
* ...
of the basin is closely correlated to compressional events within the Alps and occurred alongside deformation in Hampshire, Dorset and northern France. The basin was compressed between two 'blocks' of basement rocks, with the northward movement of the block against the London Platform;[ the areas of land that earlier in the Weald's history supplied the sediments. The Anticline has since been eroded down to reveal the pattern of stratigraphy with the oldest rocks in the centre of the anticline forming a low ridge which runs roughly from ]Crowborough
Crowborough is a town and civil parish in East Sussex, England, in the Weald at the edge of Ashdown Forest in the High Weald Area of Outstanding Natural Beauty, 7 miles (11 km) south-west of Royal Tunbridge Wells and 33 mile ...
to Battle
A battle is an occurrence of combat in warfare between opposing military units of any number or size. A war usually consists of multiple battles. In general, a battle is a military engagement that is well defined in duration, area, and force ...
and onto Boulogne
Boulogne-sur-Mer (; pcd, Boulonne-su-Mér; nl, Bonen; la, Gesoriacum or ''Bononia''), often called just Boulogne (, ), is a coastal city in Northern France. It is a sub-prefecture of the department of Pas-de-Calais. Boulogne lies on the C ...
.
Economic Resources
The geology of East Sussex includes a number of natural resources, at Mountfield, Robertsbridge there is a gypsum
Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and dr ...
mine which produces significant quantities of gypsum extracted from the Purbeck Beds. As previously mentioned the Wadhurst Clay holds ferrous ore which was extracted up to the 17th century. Although source rocks for oil underlie East Sussex and the major geologic structure in the area is an anticline, petroleum is not considered to be hosted below East Sussex. However while drilling for water at Heathfield railway station, natural gas
Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbon ...
was discovered, which was utilised to provide the first gas lighting in the UK, however it was recognised that economic oil reserves were not accessible. Ongoing exploration for petroleum is active in West Sussex
West Sussex is a county in South East England on the English Channel coast. The ceremonial county comprises the shire districts of Adur, Arun, Chichester, Horsham, and Mid Sussex, and the boroughs of Crawley and Worthing. Covering an a ...
however.
The largest amount of clay extraction occurs within the low Weald, with brickworks
A brickworks, also known as a brick factory, is a factory for the manufacturing of bricks, from clay
Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 S ...
extracting the Weald and Wadhurst clay. Chalk is also extracted in the south of the county, with commercial extraction ongoing near Lewes
Lewes () is the county town of East Sussex, England. It is the police and judicial centre for all of Sussex and is home to Sussex Police, East Sussex Fire & Rescue Service, Lewes Crown Court and HMP Lewes. The civil parish is the centre ...
where a number of chalk extraction pits also lie disused.
References
External links
Geological map of Surrey and Sussex
Fossil collecting in Hastings
Illustrations of the Geology of Sussex, Gideon Mantell, 1827. From Google Books
West Sussex Geology
{{DEFAULTSORT:Geology Of East Sussex
Geography of East Sussex
East Sussex
East Sussex is a ceremonial and non-metropolitan county in South East England on the English Channel coast. It is bordered by Kent to the north and east, West Sussex to the west, and Surrey to the north-west. The largest settlement in East ...
East Sussex
East Sussex is a ceremonial and non-metropolitan county in South East England on the English Channel coast. It is bordered by Kent to the north and east, West Sussex to the west, and Surrey to the north-west. The largest settlement in East ...