: ''This article describes the

geology Geology () is a branch of natural science concerned with Earth and other Astronomical object, astronomical objects, the features or rock (geology), rocks of which it is composed, and the processes by which they change over time. Modern geology ...

of the

ceremonial county The counties and areas for the purposes of the lieutenancies, also referred to as the lieutenancy areas of England and informally known as ceremonial counties, are areas of England to which lords-lieutenant are appointed. Legally, the areas i ...

Essex Essex () is a Ceremonial counties of England, county in the East of England. One of the home counties, it borders Suffolk and Cambridgeshire to the north, the North Sea to the east, Hertfordshire to the west, Kent across the estuary of the Riv ...

. It includes the

borough A borough is an administrative division in various English-speaking countries. In principle, the term ''borough'' designates a self-governing walled town, although in practice, official use of the term varies widely. History In the Middle Ag ...

s of

Southend-on-Sea Southend-on-Sea (), commonly referred to as Southend (), is a coastal city and unitary authorities of England, unitary authority area with Borough status in the United Kingdom, borough status in southeastern Essex, England. It lies on the north ...

and

Thurrock Thurrock () is a unitary authority area with borough status and unparished area in the ceremonial county of Essex, England. It is part of the London commuter belt and an area of regeneration within the Thames Gateway redevelopment zone. The ...

.'' The geology of Essex 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 ...

largely consists of

Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configu ...

marine sediments from the

Palaeogene The Paleogene ( ; also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period million years ago ( Mya) to the beginning ...

and

Neogene The Neogene ( ), informally Upper Tertiary or Late Tertiary, is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period Mya. ...

periods overlain by a suite of superficial deposits of

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million year ...

age.

Cretaceous

The oldest rock in Essex is the

White Chalk ''White Chalk'' is the seventh studio album by English singer-songwriter and musician PJ Harvey, released on 24 September 2007 on Island Records. Work on the album started in 2006, with producer Flood and John Parish, who also worked on her '' ...

which occurs in the northwest of the county around

Saffron Walden Saffron Walden is a market town in the Uttlesford district of Essex, England, north of Bishop's Stortford, south of Cambridge and north of London. It retains a rural appearance and some buildings of the medieval period. The population was 15, ...

, as far east as

Sudbury Sudbury may refer to: Places Australia * Sudbury Reef, Queensland Canada * Greater Sudbury, Ontario (official name; the city continues to be known simply as Sudbury for most purposes) ** Sudbury (electoral district), one of the city's federal el ...

and south to

Bishop's Stortford Bishop's Stortford is a historic market town in Hertfordshire, England, just west of the M11 motorway on the county boundary with Essex, north-east of central London, and by rail from Liverpool Street station. Stortford had an estimated popu ...

Palaeogene

With the exception of a small inlier of

Palaeocene The Paleocene, ( ) or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek ''pala ...

sands at

Witham Witham () is a town in the county of Essex in the East of England, with a population ( 2011 census) of 25,353. It is part of the District of Braintree and is twinned with the town of Waldbröl, Germany. Witham stands between the city of Che ...

, the lowest units of the

sequence evident in Essex are the various Palaeocene/Eocene pebbly and shelly sand and clay formations of the Lambeth Group. Their outcrop reaches from Sudbury on the

Norfolk Norfolk () is a ceremonial and non-metropolitan county in East Anglia in England. It borders Lincolnshire to the north-west, Cambridgeshire to the west and south-west, and Suffolk to the south. Its northern and eastern boundaries are the Nor ...

border southwestwards to the

Hertfordshire Hertfordshire ( or ; often abbreviated Herts) is one of the home counties in southern England. It borders Bedfordshire and Cambridgeshire to the north, Essex to the east, Greater London to the south, and Buckinghamshire to the west. For gov ...

border at Bishop's Stortford. However the bedrock of the larger part of the county is formed by the silty clays and sandy clays of the succeeding

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

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 on the Lambeth Group over most of its extent, but may overlie either the Thanet Formati ...

which is ascribed to the

Thames Group The Thames Group is an Eocene lithostratigraphic group (a sequence of rock strata) which is widespread in southeast England, especially in the Hampshire Basin from Dorset through Hampshire to West Sussex and in the Isle of Wight and in the ...

. Isolated patches of later Eocene sand, silt and clay occur in the area between Southend on Sea,

Chelmsford Chelmsford () is a city in the City of Chelmsford district in the county of Essex, England. It is the county town of Essex and one of three cities in the county, along with Southend-on-Sea and Colchester. It is located north-east of Londo ...

and

London London is the capital and List of urban areas in the United Kingdom, largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary dow ...

Neogene

A small

outlier In statistics, an outlier is a data point that differs significantly from other observations. An outlier may be due to a variability in the measurement, an indication of novel data, or it may be the result of experimental error; the latter are ...

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

'crag' (a shelly sand) is recorded northwest of Braintree and a few isolated pockets are to be found between

Harwich Harwich is a town in Essex, England, and one of the Haven ports on the North Sea coast. It is in the Tendring District, Tendring district. Nearby places include Felixstowe to the north-east, Ipswich to the north-west, Colchester to the south-w ...

and

Walton on the Naze Walton-on-the-Naze is a seaside town on the North Sea coast and (as Walton le Soken) a former civil parish, now in the parish of Frinton and Walton, in the Tendring district in Essex, England. It is north of Clacton and south of the port of H ...

Structure

The concealed northeastern margin of the

Midlands Microcraton The Midlands Microcraton is a triangular block of late Neoproterozoic crust of igneous and volcaniclastic origin which underlies the English Midlands. Its northern tip is at the southern edge of the English Peak District and its other two corners ...

is inferred to run NW-SE beneath Essex - just to the west of Basildon and Bishop's Stortford. Essex lies along the axis of the

Wales-London-Brabant Massif The London-Brabant Massif or London-Brabant Platform is, in the tectonics, tectonic structure of Europe, a high (tectonics), structural high or massif that stretches from the Rhineland in western Germany across northern Belgium (in the province of ...

(also known by other names including the 'Anglo-Brabant Massif' and 'St George's Land'), a zone which was emergent for much of the

Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carboniferou ...

Period.

Quaternary

Glacial till image:Geschiebemergel.JPG, Closeup of glacial till. Note that the larger grains (pebbles and gravel) in the till are completely surrounded by the matrix of finer material (silt and sand), and this characteristic, known as ''matrix support'', is d ...

deriving from the

Anglian glaciation The Anglian Stage is the name used in the British Isles for a middle Pleistocene glaciation. It precedes the Hoxnian Stage and follows the Cromerian Stage in the British Isles. The Anglian Stage is correlated to Marine Isotope Stage 12 (MIS 12), ...

occurs widely across the county northwards of a rough line from Brentwood through Chelmsford to

Colchester Colchester ( ) is a city in Essex, in the East of England. It had a population of 122,000 in 2011. The demonym is Colcestrian. Colchester occupies the site of Camulodunum, the first major city in Roman Britain and its first capital. Colch ...

. The area remained unglaciated during the more recent late- Devensian glaciation (the 'last ice age'). Sheets of glacial sand and gravel occur widely to the south of Colchester and to the east of Chelmsford and are also evident in the valleys of the

Brain A brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as Visual perception, vision. I ...

Ter Ter or TER may refer to: Places * River Ter, in Essex, England * Ter (river), in Catalonia * Ter (department), a region in France * Torre (river), (Slovene: ''Ter''), a river in Italy * Ter, Ljubno, a settlement in the Municipality of Ljubno o ...

Pant Pant may refer to: Clothing * Pants or trousers, an article of outer clothing worn on the lower half of the body * Underpants, an item of underwear Places * Pant, Denbighshire, Wales; a township of Llysfaen *Pant, Merthyr Tydfil, Wales *Pan ...

, Stour and Blackwater. Along the coast are extensive areas of marine and estuarine alluvium, most widespread around the Foulness Island and

Canvey Island Canvey Island is a town, civil parish and reclaimed island in the Thames estuary, near Southend-on-Sea, in the Castle Point district, in the county of Essex, England. It has an area of and a population of 38,170.Office for National Statistics ...

areas.

River terrace Fluvial terraces are elongated terraces that flank the sides of floodplains and fluvial valleys all over the world. They consist of a relatively level strip of land, called a "tread", separated from either an adjacent floodplain, other fluvial te ...

deposits are significant around the Blackwater valley and in the

Burnham on Crouch Burnham-on-Crouch is a town and civil parish in the Maldon District of Essex in the East of England. It lies on the north bank of the River Crouch. It is one of Britain's leading places for yachting. The civil parish extends east of the town ...

, Southend on Sea and Grays areasBritish Geological Survey 1:625,000 scale geological map ''Quaternary Map of the United Kingdom South'' 1st Edn. 1977

References

{{Geology of England Geography of Essex