geology
Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ea ...
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 ...
. It includes the borough of Medway.''
The geology of Kent in southeast
England
England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...
largely consists of a succession of northward dipping late
Mesozoic
The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretace ...
and Cenozoic sedimentary rocks overlain by a suite of unconsolidated deposits of more recent origin.
Overview
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 ...
is the south-easternmost county in England. It is bounded on the north by the
River Thames
The River Thames ( ), known alternatively in parts as the River Isis, is a river that flows through southern England including London. At , it is the longest river entirely in England and the second-longest in the United Kingdom, after the R ...
and the
North Sea
The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea, epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and 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 Kana ...
. The continent of Europe is a mere 21 miles across the Strait.
The major geographical features of the county are determined by a series of ridges running from west to east across the county. These ridges are the remains 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 the ...
en dome, a denuded anticline across Kent, Surrey and Sussex, which was the result of uplifting caused by the Alpine movements between 10-20 million years ago. The dome was formed of an upper layer of
Chalk
Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. Ch ...
above subsequent layers of
Upper Greensand
Greensand or green sand is a sand or sandstone which has a greenish color. This term is specifically applied to shallow marine sediment that contains noticeable quantities of rounded greenish grains. These grains are called ''glauconies'' and c ...
,
Gault
The Gault Formation is a geological formation of stiff blue clay deposited in a calm, fairly deep-water marine environment during the Lower Cretaceous Period (Upper and Middle Albian). It is well exposed in the coastal cliffs at Copt Point in ...
,
Lower Greensand
The Lower Greensand Group is a geological unit present across large areas of Southern England. It was deposited during the Aptian and Albian stages of the Early Cretaceous. It predominantly consists of sandstone and unconsolidated sand that were ...
,
Weald Clay
Weald Clay or the Weald Clay Formation is a Lower Cretaceous sedimentary rock unit underlying areas of South East England, between the North and South Downs, in an area called the Weald Basin. It is the uppermost unit of the Wealden Group of ro ...
and the
Hastings Beds
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 sedimen ...
. The top of the dome eventually eroded away through
weathering
Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little or no movement) ...
and ridges and valleys resulted across Kent and Sussex due to the exposed clay eroding at a faster rate than the exposed chalk, greensand and red sandstone and normal sandstone. The following ridges and the valleys have formed across Kent, listed from north to south:
* the low lying
London Clay
The London Clay Formation is a marine geological formation of Ypresian (early Eocene Epoch, c. 56–49 million years ago) age which crops out in the southeast of England. The London Clay is well known for its fossil content. The fossils from t ...
marshlands along the Thames/Medway estuaries and along the North Kent coast;
* the chalk
North Downs
The North Downs are a ridge of chalk hills in south east England that stretch from Farnham in Surrey to the White Cliffs of Dover in Kent. Much of the North Downs comprises two Areas of Outstanding Natural Beauty (AONBs): the Surrey Hills a ...
, containing the highest point of the county, Betsom's Hill, at 251m/823 ft.
* the
Vale of Holmesdale
Holmesdale, also known as the Vale of Holmesdale, is a valley in South-East England that falls between the hill ranges of the North Downs and the Greensand Ridge of the Weald, in the counties of Kent and Surrey. It stretches from Folkestone o ...
formed from Gault Clay overlaid in the north with the upper layer greensand;
* the
Greensand Ridge
The Greensand Ridge, also known as the Wealden Greensand is an extensive, prominent, often wooded, mixed greensand/sandstone escarpment in south-east England. Forming part of the Weald, a former dense forest in Sussex, Surrey and Kent, it r ...
, formed from the lower layer of greensand, containing the source of the River Medway and its tributaries;
* the Low
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 the ...
, a
Weald Clay
Weald Clay or the Weald Clay Formation is a Lower Cretaceous sedimentary rock unit underlying areas of South East England, between the North and South Downs, in an area called the Weald Basin. It is the uppermost unit of the Wealden Group of ro ...
valley
* the sandstone High
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 the ...
.Greensand Way in Kent, 1992, Kent Count Council, Britain's Structure and Scenery, L. Dudley Stamp., Pub Sept 1946, Collins
New Naturalist
The New Naturalist Library (also known as ''The New Naturalists'') is a series of books published by Collins in the United Kingdom, on a variety of natural history topics relevant to the British Isles. The aim of the series at the start was: "T ...
Series.
The chalk comes in three layers: the upper layer, about 500 feet thick, is a pure white limestone bedded and jointed with localised masses of flint (ideal for cement); the middle layer, about 170 feet thick, is a compact white chalk occasionally hard enough for building; the lower layer, about 170 feet thick, is a greyish marly chalk.Dartford, Gravesend, The Medway Towns,
Sittingbourne
Sittingbourne is an industrial town in Kent, south-east England, from Canterbury and from London, beside the Roman Watling Street, an ancient British trackway used by the Romans and the Anglo-Saxons and next to the Swale, a strip of sea separa ...
,
Faversham
Faversham is a market town in Kent, England, from London and from Canterbury, next to the Swale, a strip of sea separating mainland Kent from the Isle of Sheppey in the Thames Estuary. It is close to the A2, which follows an ancient Briti ...
,
Canterbury
Canterbury (, ) is a cathedral city and UNESCO World Heritage Site, situated in the heart of the City of Canterbury local government district of Kent, England. It lies on the River Stour.
The Archbishop of Canterbury is the primate of ...
,
Deal
A deal, or deals may refer to:
Places United States
* Deal, New Jersey, a borough
* Deal, Pennsylvania, an unincorporated community
* Deal Lake, New Jersey
Elsewhere
* Deal Island (Tasmania), Australia
* Deal, Kent, a town in England
* Deal, ...
and Dover are built on chalk.
The eastern part of the Wealden dome was eroded away by the sea. The
White cliffs of Dover
The White Cliffs of Dover is the region of English coastline facing the Strait of Dover and France. The cliff face, which reaches a height of , owes its striking appearance to its composition of chalk accented by streaks of black flint, depos ...
occur where the
North Downs
The North Downs are a ridge of chalk hills in south east England that stretch from Farnham in Surrey to the White Cliffs of Dover in Kent. Much of the North Downs comprises two Areas of Outstanding Natural Beauty (AONBs): the Surrey Hills a ...
meets the coast. From there to
Westerham
Westerham is a town and civil parish in the Sevenoaks District of Kent, England. It is located 3.4 miles east of Oxted and 6 miles west of Sevenoaks, adjacent to the Kent border with both Greater London and Surrey.
It is recorded as early ...
is now the Kent Downs Area of Outstanding Natural Beauty. The chalk displays all its characteristic features such as steep sided dry valleys, and sunken roads.
Greensand is a calcareous sandstone containing an uneven distribution of the mineral glauconite, giving the sandstone a greenish tinge. On exposure to the air this oxidises into a yellow stain.
Sevenoaks
Sevenoaks is a town in Kent with a population of 29,506 situated south-east of London, England. Also classified as a civil parish, Sevenoaks is served by a commuter main line railway into London. Sevenoaks is from Charing Cross, the traditio ...
,
Maidstone
Maidstone is the largest town in Kent, England, of which it is the county town. Maidstone is historically important and lies 32 miles (51 km) east-south-east of London. The River Medway runs through the centre of the town, linking it wi ...
, Ashford, and Folkestone are built on the greensand. Greensand comes in four layers: the Folkestone Beds 60–250 ft thick; The Sandgate Beds 5–120 ft thick; the Hythe beds 60–350 ft thick and Atherfield Clays 15–50 ft thick. The soil of the greensand is quite varied, ranging from fertile to fairly sterile. On the fertile soils we see chestnut and stands of hazel and oak, while Scots Pine and Birch colonise the poorer soils.
The
Hastings Beds
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 sedimen ...
, which are resistant to weathering, leading to outcrops, such as
High Rocks
High Rocks is a geological Site of Special Scientific Interest west of Tunbridge Wells in East Sussex and Kent. It is a Geological Conservation Review site.
Prehistory
The location was formed when a melting ice sheet at the end of the last ic ...
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. T ...
, and sterile soil only suited to heathland and forests of Scots Pine. The
Hastings Beds
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 sedimen ...
are divided into three formations:
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 c ...
Ashdown Formation
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 ...
160–700 ft; sandstones. The Fairlight Clays form the upper part of the
Ashdown Formation
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 ...
; grey and varigated shales.
Tonbridge
Tonbridge ( ) is a market town in Kent, England, on the River Medway, north of Royal Tunbridge Wells, south west of Maidstone and south east of London. In the administrative borough of Tonbridge and Malling, it had an estimated populat ...
and
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. T ...
are built on the
Hastings Beds
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 sedimen ...
.
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 the ...
derives its ancient name from the Germanic word ''wald '' meaning simply woodland. Much of the area remains today densely wooded; where there are also heavy clays the tracks through are nearly impassable for much of the year.
The Wealden dome is a
Mesozoic
The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretace ...
structure lying on a Palaeozoic foundation, which usually creates the right conditions for coal formation. This is found in East Kent, roughly between
Deal
A deal, or deals may refer to:
Places United States
* Deal, New Jersey, a borough
* Deal, Pennsylvania, an unincorporated community
* Deal Lake, New Jersey
Elsewhere
* Deal Island (Tasmania), Australia
* Deal, Kent, a town in England
* Deal, ...
,
Canterbury
Canterbury (, ) is a cathedral city and UNESCO World Heritage Site, situated in the heart of the City of Canterbury local government district of Kent, England. It lies on the River Stour.
The Archbishop of Canterbury is the primate of ...
coal measure
In lithostratigraphy, the coal measures are the coal-bearing part of the Upper Carboniferous System. In the United Kingdom, the Coal Measures Group consists of the Upper Coal Measures Formation, the Middle Coal Measures Formation and the Lower Coal ...
s within the Westphalian Sandstone are deep (below 244m - 396m) and subject to flooding. They occur in two major troughs, which extend under the English Channel where similar coalfields are sited.
Seismic activity has occasionally been recorded in Kent, though the
epicentre
The epicenter, epicentre () or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter or focus, the point where an earthquake or an underground explosion originates.
Surface damage
Before the instrumental pe ...
is offshore. In 1382 and 1580 there were two earthquakes exceeding 6.0 on the
Richter Scale
The Richter scale —also called the Richter magnitude scale, Richter's magnitude scale, and the Gutenberg–Richter scale—is a measure of the strength of earthquakes, developed by Charles Francis Richter and presented in his landmark 1935 ...
. In 1776, 1950, and 28 April 2007 there were earthquakes of around 4.3. The 2007 earthquake caused physical damage in Folkestone.
The coastline of Kent is continually changing, due to uplift, sedimentation, and marine erosion. The Isle of Thanet was till recently (AD 960) an island, formed around a deposit of chalk. The channels silted up with alluvium. Similarly Romney Marsh and Dungeness have been formed by accumulation of alluvium.
Kent's principal river, the River Medway, rises near
Edenbridge Edenbridge may mean:
* Edenbridge (band), a symphonic metal band from Austria
*Edenbridge, Kent, a town in England
*Edenbridge, Saskatchewan, a former Jewish settlement in Canada
*Humber Valley Village
Humber Valley Village is a neighbourhood lo ...
and flows some 25 miles (40 km) eastwards to a point near
Maidstone
Maidstone is the largest town in Kent, England, of which it is the county town. Maidstone is historically important and lies 32 miles (51 km) east-south-east of London. The River Medway runs through the centre of the town, linking it wi ...
, when it turns north. Here it breaks through the
North Downs
The North Downs are a ridge of chalk hills in south east England that stretch from Farnham in Surrey to the White Cliffs of Dover in Kent. Much of the North Downs comprises two Areas of Outstanding Natural Beauty (AONBs): the Surrey Hills a ...
at
Rochester
Rochester may refer to:
Places Australia
* Rochester, Victoria
Canada
* Rochester, Alberta
United Kingdom
*Rochester, Kent
** City of Rochester-upon-Medway (1982–1998), district council area
** History of Rochester, Kent
** HM Prison ...
before joining the
River Thames
The River Thames ( ), known alternatively in parts as the River Isis, is a river that flows through southern England including London. At , it is the longest river entirely in England and the second-longest in the United Kingdom, after the R ...
as its final
tributary
A tributary, or affluent, is a stream or river that flows into a larger stream or main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributaries and the main stem river drain the surrounding drai ...
near Sheerness. The river is tidal as far as Allington lock, but in earlier times cargo-carrying vessels reached as far upstream as
Tonbridge
Tonbridge ( ) is a market town in Kent, England, on the River Medway, north of Royal Tunbridge Wells, south west of Maidstone and south east of London. In the administrative borough of Tonbridge and Malling, it had an estimated populat ...
. The Medway has captured the head waters of other rivers such as the
River Darent
The Darent is a Kentish tributary of the River Thames and takes the waters of the River Cray as a tributary in the tidal portion of the Darent near Crayford, as illustrated by the adjacent photograph, snapped at high tide. 'Darenth' is frequen ...
Rocks of this age are encountered at great depth in boreholes but are not exposed at the surface.
Carboniferous
The Kent Coalfield is a concealed coalfield working the Coal Measures at depth. These rocks are nowhere exposed at the surface but considerable detail is known from
borehole
A borehole is a narrow shaft bored in the ground, either vertically or horizontally. A borehole may be constructed for many different purposes, including the extraction of water ( drilled water well and tube well), other liquids (such as petrol ...
s and underground workings for
coal
Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen.
Coal is formed when ...
. A number of
coal seam
Coal mining is the process of extracting coal from the ground. Coal is valued for its energy content and since the 1880s has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron fro ...
s were worked in the past from the upper, middle and lower Coal Measures. Fourteen seams are named sequentially downwards as Kent No 1, Kent no 2 etc. The Lower Coal Measures lie
unconformably
An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval ...
on
Carboniferous Limestone
Carboniferous Limestone is a collective term for the succession of limestones occurring widely throughout Great Britain and Ireland that were deposited during the Dinantian epoch (geology), Epoch of the Carboniferous period (geology), Period. T ...
.
Triassic and Jurassic
Rocks of this age are encountered in boreholes but are not exposed at the surface. The
Jurassic
The Jurassic ( ) is a geologic period and 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 Jurassic constitutes the middle period of ...
succession detected reflects that exposed at the surface further west in southern England.
Cretaceous
The oldest rocks to appear at the surface in Kent are the mudstones,
limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...
sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicates ...
s of the Wealden Group which underpin the wooded landscape 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 the ...
. These are in turn overlain by the sandstones of the Lower Greensand Group, the Upper Greenstone Formation and the mudstone of the Gault. The Grey Chalk Subgroup and finally the White Chalk Subgroup overlie these and form the
North Downs
The North Downs are a ridge of chalk hills in south east England that stretch from Farnham in Surrey to the White Cliffs of Dover in Kent. Much of the North Downs comprises two Areas of Outstanding Natural Beauty (AONBs): the Surrey Hills a ...
Maidstone
Maidstone is the largest town in Kent, England, of which it is the county town. Maidstone is historically important and lies 32 miles (51 km) east-south-east of London. The River Medway runs through the centre of the town, linking it wi ...
before turning slightly south of west at the Medway gap towards
Sevenoaks
Sevenoaks is a town in Kent with a population of 29,506 situated south-east of London, England. Also classified as a civil parish, Sevenoaks is served by a commuter main line railway into London. Sevenoaks is from Charing Cross, the traditio ...
. The succession can be listed with modern stratigraphic terminology thus:
*Chalk Group
**White Chalk Subgroup
**Grey Chalk Subgroup
*
Upper Greensand Formation
The Upper Greensand Formation is a Cretaceous formation of Albian to Cenomanian in age, found within the Wessex Basin and parts of the Weald Basin in southern England. It overlies the Gault Clay and underlies the Chalk Group. It varies in thick ...
*
Gault Formation
The Gault Formation is a geological formation of stiff blue clay deposited in a calm, fairly deep-water marine environment during the Lower Cretaceous Period (Upper and Middle Albian). It is well exposed in the coastal cliffs at Copt Point in Fol ...
*
Lower Greensand Group
The Lower Greensand Group is a geological unit present across large areas of Southern England. It was deposited during the Aptian and Albian stages of the Early Cretaceous. It predominantly consists of sandstone and unconsolidated sand that were ...
Hauterivian
The Hauterivian is, in the geologic timescale, an age in the Early Cretaceous Epoch or a stage in the Lower Cretaceous Series. It spans the time between 132.9 ± 2 Ma and 129.4 ± 1.5 Ma (million years ago). The Hauterivian is preceded by the ...
to
Barremian
The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 129.4 ± 1.5 Ma (million years ago) and 121.4 ± 1.0 Ma). It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is precede ...
age)
**Tunbridge Wells Sand Formation (
Valanginian
In the geologic timescale, the Valanginian is an age or stage of the Early or Lower Cretaceous. It spans between 139.8 ± 3.0 Ma and 132.9 ± 2.0 Ma (million years ago). The Valanginian Stage succeeds the Berriasian Stage of the Lower Cretace ...
Ashdown Formation
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 ...
Note that the lowermost three units were formerly known by the names 'Ashdown Beds', 'Wadhurst Clay' and 'Tunbridge Wells Sand' and together constituted the 'Hastings Beds', a name no longer formally recognised by geologists but nevertheless common in the literature. The old name 'Wealden Series' includes the 'Hastings Beds' and overlying 'Weald Clay Formation'.
Palaeogene
Unconformably
An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval ...
overlying the Chalk are a succession of sands and clays of Palaeocene and
Eocene
The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...
age. The
Thanet Formation
The Thanet Formation is a geological formation found in the London Basin of southeastern England.Sandwich
A sandwich is a food typically consisting of vegetables, sliced cheese or meat, placed on or between slices of bread, or more generally any dish wherein bread serves as a container or wrapper for another food type. The sandwich began as a po ...
east through
Canterbury
Canterbury (, ) is a cathedral city and UNESCO World Heritage Site, situated in the heart of the City of Canterbury local government district of Kent, England. It lies on the River Stour.
The Archbishop of Canterbury is the primate of ...
to
Sittingbourne
Sittingbourne is an industrial town in Kent, south-east England, from Canterbury and from London, beside the Roman Watling Street, an ancient British trackway used by the Romans and the Anglo-Saxons and next to the Swale, a strip of sea separa ...
,
Rochester
Rochester may refer to:
Places Australia
* Rochester, Victoria
Canada
* Rochester, Alberta
United Kingdom
*Rochester, Kent
** City of Rochester-upon-Medway (1982–1998), district council area
** History of Rochester, Kent
** HM Prison ...
and, intermittently, to Dartford. North of this outcrop, and stratigraphically above it, is a thinner band of pebbly, shelly sands and clays ascribed to the
Lambeth Group
The Lambeth Group is a stratigraphic group, a set of geological rock strata in the London and Hampshire Basins of southern England. It comprises a complex of vertically and laterally varying gravels, sands, silts and clays deposited between 56-55 ...
. North again and following the
Thames Estuary
The Thames Estuary is where the River Thames meets the waters of the North Sea, in the south-east of Great Britain.
Limits
An estuary can be defined according to different criteria (e.g. tidal, geographical, navigational or in terms of salini ...
coast is the Eocene age silty and sandy clay of the London Clay Formation. It underlies
Herne Bay
Herne Bay is a seaside town on the north coast of Kent in South East England. It is north of Canterbury and east of Whitstable. It neighbours the ancient villages of Herne and Reculver and is part of the City of Canterbury local governmen ...
,
Whitstable
Whitstable () is a town on the north coast of Kent adjoining the convergence of the Swale Estuary and the Greater Thames Estuary in southeastern England, north of Canterbury and west of Herne Bay. The 2011 Census reported a population of ...
and the
Isle of Sheppey
The Isle of Sheppey is an island off the northern coast of Kent, England, neighbouring the Thames Estuary, centred from central London. It has an area of . The island forms part of the local government district of Swale. ''Sheppey'' is derive ...
. The youngest Palaeogene strata is a patch of late Eocene sand, silt and clay around
Eastchurch
Eastchurch is a village and civil parish on the Isle of Sheppey, in the English county of Kent, two miles east of Minster. The village website claims the area has "a history steeped in stories of piracy and smugglers".
Aviation history
Eastch ...
and Minster on the Isle of Sheppey. The succession in Sheppey can be listed with modern stratigraphic terminology thus:
* London Clay Formation
*
Harwich Formation
The Harwich Formation is a geological formation found in the London Basin of southeastern England. It is Ypresian (early Eocene) in age. It lies unconformably
An unconformity is a buried erosional or non-depositional surface separating two roc ...
*
Lambeth Group
The Lambeth Group is a stratigraphic group, a set of geological rock strata in the London and Hampshire Basins of southern England. It comprises a complex of vertically and laterally varying gravels, sands, silts and clays deposited between 56-55 ...
**
Upnor Formation
The Upnor Formation is a geological formation found in the London Basin of southeastern England.Lenham Formation occurs in a few small pockets around the village of
Lenham
Lenham is a market village and civil parish in Kent situated on the southern edge of the North Downs, east of Maidstone. The picturesque square in the village has two public houses (one of which is a hotel), a couple of restaurants, and a tea ...
Hampshire
Hampshire (, ; abbreviated to Hants) is a ceremonial and non-metropolitan county in western South East England on the coast of the English Channel. Home to two major English cities on its south coast, Southampton and Portsmouth, Hampshire ...
and east 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 Kana ...
into northern
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan area ...
. The fold arises from the continuing Alpine orogeny and results in the general northward dip of the rock strata in most of Kent.
Quaternary
There are extensive spreads of coastal and estuarine
alluvium
Alluvium (from Latin ''alluvius'', from ''alluere'' 'to wash against') is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. ...
on the Thames Estuary coast, in the low ground surrounding the
Isle of Thanet
The Isle of Thanet () is a peninsula forming the easternmost part of Kent, England. While in the past it was separated from the mainland by the Wantsum Channel, it is no longer an island.
Archaeological remains testify to its settlement in an ...
and across
Romney Marsh
Romney Marsh is a sparsely populated wetland area in the counties of Kent and East Sussex in the south-east of England. It covers about . The Marsh has been in use for centuries, though its inhabitants commonly suffered from malaria until th ...
. Alluvium also floors the valleys of the River Medway and Stour. 'Clay-with-flints' is a commonly occurring deposit across the North Downs which is a product of periglacial conditions during the last ice age. Loessic deposits, of Aeolian origin, i.e., windblown, are common in east Kent, especially on the northern slopes of the Downs where they are known as brickearths.
Landslip
Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, deep-seated slope failures, mudflows, and debris flows. Landslides occur in a variety of environments, ...
s are known along the north coast of the Isle of Sheppey, the coast near
Reculver
Reculver is a village and coastal resort about east of Herne Bay on the north coast of Kent in south-east England.
It is in the ward of the same name, in the City of Canterbury district of Kent.
Reculver once occupied a strategic location ...
and either side of Folkestone and indeed the former coastline west of Folkestone overlooking Romney Marsh.British Geological Survey 1:625,000 scale geological map ''Quaternary Map of the United Kingdom South'' 1st Edn. 1977
See also
*
Geology of the United Kingdom
The geology of Great Britain is renowned for its diversity. As a result of its eventful geological history, Great Britain shows a rich variety of landscapes across the constituent countries of England, Wales and Scotland. Rocks of almost all geolo ...
*
Geology of England
The geology of England is mainly sedimentary. The youngest rocks are in the south east around London, progressing in age in a north westerly direction.
Further reading
* British Geological Survey 1:50,000 scale geological map series sheets (England and Wales) 270-274, 287-290, 303-306 & 320/21 and accompanying memoirs.