The Thanet Formation is a

geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

found in the

London Basin The London Basin is an elongated, roughly triangular sedimentary basin approximately long which underlies London and a large area of south east England, south eastern East Anglia and the adjacent North Sea. The basin formed as a result of compre ...

of southeastern

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 ...

.Thanet Formation
at Fossilworks.org It is of early to mid-

Thanetian The Thanetian is, in the ICS Geologic timescale, the latest age or uppermost stratigraphic stage of the Paleocene Epoch or Series. It spans the time between . The Thanetian is preceded by the Selandian Age and followed by the Ypresian Age ( ...

(late

Paleocene 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 ''pal ...

) age and gave its name to that stratigraphic interval. It was previously known as the Thanet Beds, the Thanet Sands and the Thanet Sand Formation. It was named after 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 ...

. The

type section A stratotype or type section in geology is the physical location or outcrop of a particular reference exposure of a stratigraphic sequence or stratigraphic boundary. If the stratigraphic unit is layered, it is called a stratotype, whereas the stan ...

s are

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 ...

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 ...

for the upper part of the formation and

Pegwell Bay Pegwell Bay is a shallow inlet in the English Channel coast astride the estuary of the River Stour north of Sandwich Bay, between Ramsgate and Sandwich in Kent. Part of the bay is a nature reserve, with seashore habitats including mudflats and ...

for the lower part. It lies

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 the Late Cretaceous Chalk Group. It unconformably underlies the Lambeth Group, generally the Upnor Formation but in Essex it is the

Reading Formation The Reading Formation is a geologic formation in southern England. It dates to the Paleocene period, and is part of the Lambeth Group. It overlies the London Basin and is below the Harwich Formation. The formation is composed of "a series of len ...

Distribution

The Thanet Formation is known at outcrop and in the subsurface over central and eastern parts of the London Basin. To the west it is missing, with 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 ...

lying directly on the Chalk, and to the north it is replaced by the Ormesby Clay Member. It thins to the west and north of London. It reaches a maximum thickness of over 30 m in North Kent.

Lithology

The predominant lithology is very pale grey or buff fine-grained

glauconitic 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 () me ...

sand. Particularly towards the base of the formation, the sand is interbedded with silts and clays. At the base of the formation a bed of flint pebbles is often developed with clasts up to cobble size in a matrix of glauconitic clayey sand. At Herne Bay the beds are divided as follows (top to bottom): * A layer of concretionary blocks (‘doggers') of calcareous indurated sandstone of 0.3 metre thickness * A pale grey sandstone with abundant shells 2.6 metre thickness * A layer of calcareous sandstone doggers, 0.3 metre thickness * A bedded, clayey buff sand with many shells, seen to 0.9 metre thickness

Depositional environment

The Thanet Formation was deposited in open marine conditions. The water depth was relatively shallow, above normal wave-base, in an inner or outer shelf setting.

Fossil content

The sequence is known for its rich fossil content, particularly molluscs and fish. The fauna give somewhat contradictory evidence of the climate, with molluscs of both cold and warm water type being found and tropical to sub-tropical fish recognised. Overall, a sub-tropical climate is indicated. The formation also has provided fossils of flora of '' Pinus macrocephalus'', '' Pinus prestwichi'',

Palmae The Arecaceae is a family of perennial flowering plants in the monocot order Arecales. Their growth form can be climbers, shrubs, tree-like and stemless plants, all commonly known as palms. Those having a tree-like form are called palm tree ...

and '' Osmunda dowkeri''.

Distribution

Lithology

Depositional environment

Fossil content

See also