The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ± 1.0 Ma to 113.0 ± 1.0 Ma, approximately. The Aptian precedes the Albian, all part of the Lower/Early Cretaceous; the Aptian overlaps the upper part of the regionally used stage Urgonian. The Selli Event known as OAE1a, was one of two oceanic Anoxic events in the Cretaceous period, which occurred around 120 Ma and lasted 1 to 1.3 million years. The Aptian extinction was a minor extinction event hypothesized to have occurred around 116 to 117 Ma; the Aptian was named after the small city of Apt in the Provence region of France, known for its crystallized fruits. The original type locality is in the vicinity of Apt; the Aptian was introduced in scientific literature by French palaeontologist Alcide d'Orbigny in 1840. The base of the Aptian stage is laid at magnetic anomaly M0r. A global reference profile for the base had in 2009 not yet been appointed.
The top of the Aptian is at the first appearance of coccolithophore species Praediscosphaera columnata in the stratigraphic record. In the Tethys domain, the Aptian contains eight ammonite biozones: zone of Hypacanthoplites jacobi zone of Nolaniceras nolani zone of Parahoplites melchioris zone of Epicheloniceras subnodosocostatum zone of Duffrenoyia furcata zone of Deshayesites deshayesi zone of Deshayesites weissi zone of Deshayesites oglanlensisSometimes the Aptian is subdivided in three substages or subages: Bedoulian and Clansayesian. Examples of rock units formed during the Aptian are: Antlers Formation, Cedar Mountain Formation, Cloverly Formation, Elrhaz Formation, Jiufotang Formation, Little Atherfield, Mazong Shan, Potomac Formation, Santana Formation, Twin Mountains Formation, Xinminbao Group and Yixian Formation. Eogaudryceras Georgioceras Lithancylus Pictetia Salfeldiella Zuercherella Lower Ammonitoceras Australiceras Cheloniceras Cicatrites Colombiceras Dufrenoya Eotetragonites Helicancylus Melchiorites Parahoplites Procheloniceras Prodeshayesites Pseudosaynella Roloboceras Shastoceras Upper Acanthohoplites Acanthoplites Ammonoceratites Argonauticeras Beudanticeras Burckhardites Cloioceras Desmoceras Diadochoceras Diodochoceras Eodouvilleiceras Epancyloceras Epicheloniceras Gabbioceras Gargasiceras Gyaloceras Hamites Hulenites Hypacanthoplites Jauberticeras Kazanskyella Knemiceras Mathoceras Mathoceratites Megatyloceras Metahamites Miyakoceras Neosilesites Nodosohoplites Nolaniceras Protacanthoplites Protanisoceras Sinzovia Somalites Tetragonites Theganoceras Trochleiceras Tropaeum Uhligella Conoteuthis Vectibelus Lower Parahibolites Peratobelus Tetrabelus Carinonautilus Heminautilus Upper Zhuralevia Upper Euphylloceras Upper Adygeya Naefia Boluochia zhengi Changchengornis hengdaoziensis Chaoyangia beishanensis Confuciusornis sanctus Cuspirostrisornis houi Jeholornis prima Jixiangornis orientalis Largirostrornis sexdentoris Longchengornis sanyanensis Longipteryx chaoyangensis Sapeornis chaoyangensis Sinornis santensis/Cathayornis yandica Songlingornis linghensis Yanornis martini Yixianornis grabaui Sarcosuchus Hybodus Jinanichthys longicephalus Lycoptera davidi Lycoptera muroii Peipiaosteus pani Protosephurus liui Sinamia zdanskyi Amblydectes Anhanguera Araripedactylus dehmi Araripesaurus castilhoi Arthurdactylus conandoylei Boreopterus cuiae Brasileodactylus araripensis Cearadactylus atrox Chaoyangopterus zhangi Dsungaripterus weii Dsungaripterus brancai Eoazhdarcho liaoxiensis Eopteranodon lii Gegepterus changi Haopterus gracilis Hongshanopterus lacustris Huaxiapterus benxiensis Huaxiapterus corollatus Huaxiapterus jii Istiodactylus latidens Istiodactylus sinensis Jidapterus edentus Liaoningopterus gui Liaoxipterus brachyognathus Lonchodectes Longchengpterus zhaoi Ludodactylus sibbicki Nemicolopterus crypticus Nurhachius ignaciobritoi Ornithocheirus simus Ornithocheirus mesembrinus Pricesaurus megalodon Santanadactylus Sinopterus dongi Sinopterus gui Tapejara navigans Tapejara wellnhoferi Thalassodromeus sethi Tropeognathus mesembrinus Tropeognathus robustus Tupandactylus imperator Aptian extinction Gradstein, F.
M.. G. & Smith, A. G.. D'Orbigny, A. C. V. M.. GeoWhen Database - Aptian Mid-Cretaceous timescale, at the website of the subcommission for stratigraphic information of the ICS Stratigraphic charts of the Lower Cretaceous: and, at the website of Norges Network of offshore records of geology and stratigraphy
Siltstone is a sedimentary rock which has a grain size in the silt range, finer than sandstone and coarser than claystones. Siltstone is a clastic sedimentary rock; as its name implies, it is composed of silt sized particles, defined as grains 2–62 µm or 4 to 8 on the Krumbein phi scale. Siltstones differ from sandstones due to their smaller pores and higher propensity for containing a significant clay fraction. Although mistaken as a shale, siltstone lacks the fissility and laminations which are typical of shale. Siltstones may contain concretions. Unless the siltstone is shaly, stratification is to be obscure and it tends to weather at oblique angles unrelated to bedding. Mudstone or shale are rocks that contain mud, material that has a range of silt and clay. Siltstone is differentiated by having a majority silt, not clay. Cosmetic palette—made exclusively out of siltstone with a few exceptions Folk, R. L. 1965, Petrology of sedimentary rocks PDF version. Austin: Hemphill’s Bookstore. 2nd ed. 1981, ISBN 0-914696-14-9 Williams, Francis J. Turner and Charles M. Gilbert, 1954, Petrography, W. H. Freeman
West Sussex is a county in the south of England, bordering East Sussex to the east, Hampshire to the west and Surrey to the north, to the south the English Channel. West Sussex is the western part of the historic county of Sussex a medieval kingdom. With an area of 1,991 square kilometres and a population of over 800,000, West Sussex is a ceremonial county, with a Lord Lieutenant and a High Sheriff. Chichester in the south-west is the only city in West Sussex. West Sussex has a range of scenery, including wealden and coastal; the highest point of the county is at 280 metres. It has a number of stately homes including Goodwood, Petworth House and Uppark, castles such as Arundel Castle and Bramber Castle. Over half the county is protected countryside, offering walking and other recreational opportunities. Although the name Sussex, derived from the Old English'Sūþsēaxe', dates from the Saxon period between AD 477 to 1066, the history of human habitation in Sussex goes back to the Old Stone Age; the oldest hominin remains known in Britain were found at Boxgrove.
Sussex has been occupied since those times and has succumbed to various invasions and migrations throughout its long history. Prehistoric monuments include the Devil's Jumps, a group of Bronze Age burial mounds, the Iron Age Cissbury Ring and Chanctonbury Ring hill forts on the South Downs; the Roman period saw the building of Fishbourne Roman Palace and rural villas such as Bignor Roman Villa together with a network of roads including Stane Street, the Chichester to Silchester Way and the Sussex Greensand Way. The Romans used the Weald for iron production on an industrial scale; the foundation of the Kingdom of Sussex is recorded by the Anglo-Saxon Chronicle for the year AD 477. The foundation story is regarded as somewhat of a myth by most historians, although the archaeology suggests that Saxons did start to settle in the area in the late 5th century; the Kingdom of Sussex became the county of Sussex. With its origins in the kingdom of Sussex, the county of Sussex was traditionally divided into six units known as rapes.
By the 16th century, the three western rapes were grouped together informally, having their own separate Quarter Sessions. These were administered by a separate county council from 1888, the county of Sussex being divided for administrative purposes into the administrative counties of East and West Sussex. In 1974, West Sussex was made a single ceremonial county with the coming into force of the Local Government Act 1972. At the same time a large part of the eastern rape of Lewes was transferred into West Sussex; until 1834 provision for the poor and destitute in West Sussex was made at parish level. From 1835 until 1948 eleven Poor Law Unions, each catering for several parishes, took on the job. Most settlements in West Sussex are either along the south coast or in Mid Sussex, near the M23/A23 corridor; the town of Crawley is the largest in the county with an estimated population of 106,600. The coastal settlement of Worthing follows with a population of 104,600; the seaside resort of Bognor Regis and market town Horsham are both large towns.
Chichester, the county town, has a cathedral and city status, is situated not far from the border with Hampshire. Other conurbations of a similar size are Burgess Hill, East Grinstead and Haywards Heath in the Mid Sussex district, Littlehampton in the Arun district, Lancing and Shoreham in the Adur district. Much of the coastal town population is part of the Brighton/Worthing/Littlehampton conurbation. Rustington and Southwater are the next largest settlements in the county. There are several more towns in West Sussex; the smaller towns of the county are Arundel, Petworth and Steyning. The larger villages are Billingshurst, Crawley Down, Henfield, Hurstpierpoint, Lindfield and Storrington; the current total population of the county makes up 1.53% of England's population. West Sussex is bordered by Hampshire to Surrey to the north and East Sussex to the east; the English Channel lies to the south. The area has been formed from Upper Jurassic and Lower Cretaceous rock strata, part of the Weald–Artois Anticline.
The eastern part of this ridge, the Weald of Kent and Surrey has been eroded, with the chalk surface removed to expose older Lower Cretaceous rocks of the Wealden Group. In West Sussex the exposed rock becomes older towards the north of the county with Lower Greensand ridges along the border with Surrey including the highest point of the county at Blackdown. Erosion of softer sand and clay strata has hollowed out the basin of the Weald leaving a north facing scarp slope of the chalk which runs east and west across the whole county, broken only by the valleys of the River Arun and River Adur. In addition to these two rivers which drain most of the county a winterbourne, the River Lavant, flows intermittently from springs on the dip slope of the chalk downs north of Chichester; the county makes up 1.52% of the total land of England, making it the 30th largest county in the country. West Sussex is the sunniest county in the United Kingdom, according to Met Office records. Over the last 29 years it has averaged 1902 hours of sunshine per year.
Sunshine totals are highest near the coast wi
Surrey is a subdivision of the English region of South East England in the United Kingdom. A historic and ceremonial county, Surrey is one of the home counties; the county borders Kent to the east, East Sussex and West Sussex to the south, Hampshire to the west, Berkshire to the northwest, Greater London to the northeast. Inhabited by about 1.2 million people, Surrey is the twelfth most populous English county, both the third most populous home county and the third most populous county in the South East. Guildford is considered to be the county town; however despite the town's designation, Surrey County Council has never been based there, being instead seated throughout its history in London. Since the borders of Surrey were altered in 1965 by the London Government Act 1963 which created Greater London, none of these places are now in Surrey, marking an example of a de facto capital, located outside of its administrative area. Surrey is divided into eleven districts: Elmbridge and Ewell, Mole Valley and Banstead, Spelthorne, Surrey Heath, Tandridge and Woking.
Services such as roads, mineral extraction licensing, strategic waste and recycling infrastructure, birth and death registration, social and children's services are administered by Surrey County Council. The London boroughs of Lambeth, Southwark and small parts of Lewisham and Bromley were in Surrey until 1889. Since the 1965 reform the bordering boroughs of the capital have been those taken from it in 1965 plus Bromley and Hounslow; the form of Surrey which remains since 1965 is a wealthy county due to economic, aesthetic and logistical factors. It has the highest GDP per capita of any English county, some of the highest property values outside Inner London and the highest cost of living in the UK outside of the capital. Surrey has the highest proportion of woodland in England, having been rural since it was shorn in 1965 of the urbanised swathes of South London which had hitherto been part of the county, it has large protected green spaces. It has four racecourses in horse racing, the most of any Home County and as at 2013 contained 141 golf courses including international competition venue Wentworth.
Surrey has proximity to London and to Heathrow and Gatwick airports, along with access to major arterial road routes including the M25, M3 and M23 and frequent rail services into Central London. Surrey is divided in two by the chalk ridge of the North Downs; the ridge is pierced by the rivers Wey and Mole, tributaries of the Thames, which formed the northern border of the county before modern redrawing of county boundaries, which has left part of its north bank within the county. To the north of the Downs the land is flat, forming part of the basin of the Thames; the geology of this area is dominated by London Clay in the east, Bagshot Sands in the west and alluvial deposits along the rivers. To the south of the Downs in the western part of the county are the sandstone Surrey Hills, while further east is the plain of the Low Weald, rising in the extreme southeast to the edge of the hills of the High Weald; the Downs and the area to the south form part of a concentric pattern of geological deposits which extends across southern Kent and most of Sussex, predominantly composed of Wealden Clay, Lower Greensand and the chalk of the Downs.
Much of Surrey is in the Metropolitan Green Belt. It contains valued reserves of mature woodland. Among its many notable beauty spots are Box Hill, Leith Hill, Frensham Ponds, Newlands Corner and Puttenham & Crooksbury Commons. Surrey is the most wooded county in England, with 22.4% coverage compared to a national average of 11.8% and as such is one of the few counties not to recommend new woodlands in the subordinate planning authorities' plans. Box Hill has the oldest untouched area of natural woodland in one of the oldest in Europe. Surrey contains England's principal concentration of lowland heath, on sandy soils in the west of the county. Agriculture not being intensive, there are many commons and access lands, together with an extensive network of footpaths and bridleways including the North Downs Way, a scenic long-distance path. Accordingly, Surrey provides many rural and semi-rural leisure activities, with a large horse population in modern terms; the highest elevation in Surrey is Leith Hill near Dorking.
It is 294 m above sea level and is the second highest point in southeastern England after Walbury Hill in West Berkshire, 297 m. Surrey has a population of 1.1 million people. Its largest town is Guildford, with a population of 77,057, they are followed by Ewell with 39,994 people and Camberley with 30,155. Towns of between 25,000 and 30,000 inhabitants are Ashford, Farnham and Redhill. Guildford is the historic county town, although the county administration was moved to Newington in 1791 and to Kingston upon Thames in 1893; the county counc
The United Kingdom the United Kingdom of Great Britain and Northern Ireland, sometimes referred to as Britain, is a sovereign country located off the north-western coast of the European mainland. The United Kingdom includes the island of Great Britain, the north-eastern part of the island of Ireland, many smaller islands. Northern Ireland is the only part of the United Kingdom that shares a land border with another sovereign state, the Republic of Ireland. Apart from this land border, the United Kingdom is surrounded by the Atlantic Ocean, with the North Sea to the east, the English Channel to the south and the Celtic Sea to the south-west, giving it the 12th-longest coastline in the world; the Irish Sea lies between Great Ireland. With an area of 242,500 square kilometres, the United Kingdom is the 78th-largest sovereign state in the world, it is the 22nd-most populous country, with an estimated 66.0 million inhabitants in 2017. The UK is constitutional monarchy; the current monarch is Queen Elizabeth II, who has reigned since 1952, making her the longest-serving current head of state.
The United Kingdom's capital and largest city is London, a global city and financial centre with an urban area population of 10.3 million. Other major urban areas in the UK include Greater Manchester, the West Midlands and West Yorkshire conurbations, Greater Glasgow and the Liverpool Built-up Area; the United Kingdom consists of four constituent countries: England, Scotland and Northern Ireland. Their capitals are London, Edinburgh and Belfast, respectively. Apart from England, the countries have their own devolved governments, each with varying powers, but such power is delegated by the Parliament of the United Kingdom, which may enact laws unilaterally altering or abolishing devolution; the nearby Isle of Man, Bailiwick of Guernsey and Bailiwick of Jersey are not part of the UK, being Crown dependencies with the British Government responsible for defence and international representation. The medieval conquest and subsequent annexation of Wales by the Kingdom of England, followed by the union between England and Scotland in 1707 to form the Kingdom of Great Britain, the union in 1801 of Great Britain with the Kingdom of Ireland created the United Kingdom of Great Britain and Ireland.
Five-sixths of Ireland seceded from the UK in 1922, leaving the present formulation of the United Kingdom of Great Britain and Northern Ireland. There are fourteen British Overseas Territories, the remnants of the British Empire which, at its height in the 1920s, encompassed a quarter of the world's land mass and was the largest empire in history. British influence can be observed in the language and political systems of many of its former colonies; the United Kingdom is a developed country and has the world's fifth-largest economy by nominal GDP and ninth-largest economy by purchasing power parity. It has a high-income economy and has a high Human Development Index rating, ranking 14th in the world, it was the world's first industrialised country and the world's foremost power during the 19th and early 20th centuries. The UK remains a great power, with considerable economic, military and political influence internationally, it is sixth in military expenditure in the world. It has been a permanent member of the United Nations Security Council since its first session in 1946.
It has been a leading member state of the European Union and its predecessor, the European Economic Community, since 1973. The United Kingdom is a member of the Commonwealth of Nations, the Council of Europe, the G7, the G20, NATO, the Organisation for Economic Co-operation and Development and the World Trade Organization; the 1707 Acts of Union declared that the kingdoms of England and Scotland were "United into One Kingdom by the Name of Great Britain". The term "United Kingdom" has been used as a description for the former kingdom of Great Britain, although its official name from 1707 to 1800 was "Great Britain"; the Acts of Union 1800 united the kingdom of Great Britain and the kingdom of Ireland in 1801, forming the United Kingdom of Great Britain and Ireland. Following the partition of Ireland and the independence of the Irish Free State in 1922, which left Northern Ireland as the only part of the island of Ireland within the United Kingdom, the name was changed to the "United Kingdom of Great Britain and Northern Ireland".
Although the United Kingdom is a sovereign country, Scotland and Northern Ireland are widely referred to as countries. The UK Prime Minister's website has used the phrase "countries within a country" to describe the United Kingdom; some statistical summaries, such as those for the twelve NUTS 1 regions of the United Kingdom refer to Scotland and Northern Ireland as "regions". Northern Ireland is referred to as a "province". With regard to Northern Ireland, the descriptive name used "can be controversial, with the choice revealing one's political preferences"; the term "Great Britain" conventionally refers to the island of Great Britain, or politically to England and Wales in combination. However, it is sometimes used as a loose synonym for the United Kingdom as a whole; the term "Britain" is used both as a synonym for Great Britain, as a synonym for the United Kingdom. Usage is mixed, with the BBC preferring to use Britain as shorthand only for Great Britain and the UK Government, while accepting that both terms refer to the United K
The Precambrian is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the Phanerozoic eon, named after Cambria, the Latinised name for Wales, where rocks from this age were first studied; the Precambrian accounts for 88% of the Earth's geologic time. The Precambrian is an informal unit of geologic time, subdivided into three eons of the geologic time scale, it spans from the formation of Earth about 4.6 billion years ago to the beginning of the Cambrian Period, about 541 million years ago, when hard-shelled creatures first appeared in abundance. Little is known about the Precambrian, despite it making up seven-eighths of the Earth's history, what is known has been discovered from the 1960s onwards; the Precambrian fossil record is poorer than that of the succeeding Phanerozoic, fossils from the Precambrian are of limited biostratigraphic use. This is because many Precambrian rocks have been metamorphosed, obscuring their origins, while others have been destroyed by erosion, or remain buried beneath Phanerozoic strata.
It is thought that the Earth coalesced from material in orbit around the Sun at 4,543 Ma, may have been struck by a large planetesimal shortly after it formed, splitting off material that formed the Moon. A stable crust was in place by 4,433 Ma, since zircon crystals from Western Australia have been dated at 4,404 ± 8 Ma; the term "Precambrian" is recognized by the International Commission on Stratigraphy as the only "supereon" in geologic time. "Precambrian" is still used by geologists and paleontologists for general discussions not requiring the more specific eon names. As of 2010, the United States Geological Survey considers the term informal, lacking a stratigraphic rank. A specific date for the origin of life has not been determined. Carbon found in 3.8 billion-year-old rocks from islands off western Greenland may be of organic origin. Well-preserved microscopic fossils of bacteria older than 3.46 billion years have been found in Western Australia. Probable fossils 100 million years older have been found in the same area.
However, there is evidence. There is a solid record of bacterial life throughout the remainder of the Precambrian. Excluding a few contested reports of much older forms from North America and India, the first complex multicellular life forms seem to have appeared at 1500 Ma, in the Mesoproterozoic era of the Proterozoic eon. Fossil evidence from the Ediacaran period of such complex life comes from the Lantian formation, at least 580 million years ago. A diverse collection of soft-bodied forms is found in a variety of locations worldwide and date to between 635 and 542 Ma; these are referred to as Vendian biota. Hard-shelled creatures appeared toward the end of that time span, marking the beginning of the Phanerozoic eon. By the middle of the following Cambrian period, a diverse fauna is recorded in the Burgess Shale, including some which may represent stem groups of modern taxa; the increase in diversity of lifeforms during the early Cambrian is called the Cambrian explosion of life. While land seems to have been devoid of plants and animals and other microbes formed prokaryotic mats that covered terrestrial areas.
Tracks from an animal with leg like appendages have been found in what was mud 551 million years ago. Evidence of the details of plate motions and other tectonic activity in the Precambrian has been poorly preserved, it is believed that small proto-continents existed prior to 4280 Ma, that most of the Earth's landmasses collected into a single supercontinent around 1130 Ma. The supercontinent, known as Rodinia, broke up around 750 Ma. A number of glacial periods have been identified going as far back as the Huronian epoch 2400–2100 Ma. One of the best studied is the Sturtian-Varangian glaciation, around 850–635 Ma, which may have brought glacial conditions all the way to the equator, resulting in a "Snowball Earth"; the atmosphere of the early Earth is not well understood. Most geologists believe it was composed of nitrogen, carbon dioxide, other inert gases, was lacking in free oxygen. There is, evidence that an oxygen-rich atmosphere existed since the early Archean. At present, it is still believed that molecular oxygen was not a significant fraction of Earth's atmosphere until after photosynthetic life forms evolved and began to produce it in large quantities as a byproduct of their metabolism.
This radical shift from a chemically inert to an oxidizing atmosphere caused an ecological crisis, sometimes called the oxygen catastrophe. At first, oxygen would have combined with other elements in Earth's crust iron, removing it from the atmosphere. After the supply of oxidizable surfaces ran out, oxygen would have begun to accumulate in the atmosphere, the modern high-oxygen atmosphere would have developed. Evidence for this lies in older rocks that contain massive banded iron formations that were laid down as iron oxides. A terminology has evolved covering the early years of the Earth's existence, as radiometric dating has allowed real dates to be assigned to specific formations and features; the Precambrian is divided into
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 and Kent; the other component formations of the Hastings Beds are the overlying Wadhurst Clay Formation and the Tunbridge Wells Sand Formation. The Hastings Beds in turn forms part of the Wealden Supergroup which underlies much of southeast England; the sediments of the Weald of East Sussex, including the Ashdown Formation, were deposited during the Early Cretaceous Period, which lasted for 40 million years from 140 to 100 million years ago. The Ashdown Formation is of Late Berriasian to Early Valanginian to age; the Formation takes its name from the Ashdown Forest in the High Weald of Sussex. The Ashdown Formation comprises sandstones and mudstones. In the east of the county, the formation tends to be more argillaceous in its lowermost part and fines up to a sandier division in the uppermost 30 to 50m.
The clays are identified by 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’. However, it is now considered as one due to the impersistence of the clays across the Weald. Despite this the variations of clays and sands in the formation are marked separately on the maps and records of the British Geological Survey. In its entirety the formation is found to be between 180 and 215m thick The base of the Hastings Beds and the Ashdown Formation is taken at the top of the Greys Limestones Member of the Purbeck Beds, although this boundary is not exposed anywhere in the Weald; the top of the Ashdown Formation is marked as the top of a massive sandstone bed known as the Top Ashdown Sandstone. This is overlain by an identified coarse grained sandstone known as the Top Ashdown Pebble Bed, considered to be part of the overlying Wadhurst Clay Formation; the Top Ashdown Sandstone is the most persistent marker horizon in Early Cretaceous strata throughout the region.
It comprises a fine to medium grained sandstone ranging in thickness from 1.2m to 8m. Other marker beds can be found throughout the formation including the Cliff End Sandstone and the Lee Ness Sandstone; the Ashdown Beds are best exposed in the 8 km cliff section between Pett Level. Part of this section has been designated a Site of Special Scientific Interest, cited by Natural England because of its geological importance; the cliffs between Hastings and Pett Level are difficult to get to safely because of the tidal range of the English Channel and the unstable cliffs. 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 to the west and Cliff End to the east; the mottled degraded silty clays of the former ‘Fairlight Clays’ can be distinguished against the well bedded sandstones and interbedded siltstones of the ‘Ashdown Sands’. The Lee Ness Ledge is known for the prominent Lee Ness Sandstone and its many well preserved fossilised dinosaur footprints Iguanodon.
The Hastings to Pett Level section of the coast has suffered a number of significant recent and historic landslips, dating back to the 18th Century. These can be seen in and around Covehurst Wood and the Fairlight and Warren Glens; this has been attributed to lithological variations of the Ashdown Beds and to the effects of wave action at the base of the cliffs. At high tide, waves cut into the lowermost, argillaceous part of the cliffs and undercut the overlying sandstones and siltstones resulting in toppling and rock falls. Where sandstones are interbedded with silts and clays, this may result in single and multiple rotational type landslides as well as block slides and mud flows. In theory, the remains of previous landslips should protect the toe of the cliff from further weathering. However, these blocks and sediments are transported west with shingle and other beach deposits by long-shore drift, leaving the cliffs vulnerable to wave action and susceptible to further landslides. Geology of East Sussex Hastings Beds Tunbridge Wells Sand Formation Wadhurst Clay Formation British Geological Survey lexicon