Poole Basin

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The Poole Basin coincides with the area of the "Tertiary Beds" (beige) in this geological map of Dorset Simplified Geology Map of Dorset.jpg
The Poole Basin coincides with the area of the "Tertiary Beds" (beige) in this geological map of Dorset

Poole Basin is a geological formation that forms the western part of the much larger Hampshire Basin from which it is separated by the River Avon.

Hampshire Basin

The Hampshire Basin is a geological basin of Palaeogene age in southern England, underlying parts of Hampshire, the Isle of Wight, Dorset, and Sussex. Like the London Basin to the northeast, it is filled with sands and clays of Paleocene and younger ages and it is surrounded by a broken rim of chalk hills of Cretaceous age.

River Avon, Hampshire River in the south of England

The River Avon is a river in the south of England. The river rises in the county of Wiltshire and flows through the city of Salisbury and the county of Hampshire before reaching the English Channel through Christchurch Harbour in the county of Dorset.

Geology

The rim and bed of the basin are formed by chalk, within which lie the Tertiary sands and clays underlying the Dorset Heaths. The most extensive deposits here are those of the Poole Formation or Bagshot Beds. At one time the whole area was almost all heathland lying on acidic soils. Between the chalk perimeter and the central heaths is a belt where the Reading Beds and London Clays surface, giving rise to richer, albeit still acidic, soils. Deposits of plateau and valley gravels overlie the sands of the Poole Formation, but their soils are likewise poor and acidic. Erosive forces have resulted in an undulating landscape with considerable local variation from narrow, steep-sided valleys and escarpments to areas of flat terrain. The highest point is Creech Barrow Hill (193 m), [1] the highest Tertiary hill in England, capped with Eocene limestone. [2]

Chalk A soft, white, porous sedimentary rock made of calcium carbonate

Chalk is a soft, white, porous, sedimentary carbonate rock, a form of limestone composed of the mineral calcite. Calcite is an ionic salt called calcium carbonate or CaCO3. It forms under reasonably deep marine conditions from the gradual accumulation of minute calcite shells (coccoliths) shed from micro-organisms called coccolithophores. Flint (a type of chert) is very common as bands parallel to the bedding or as nodules embedded in chalk. It is probably derived from sponge spicules or other siliceous organisms as water is expelled upwards during compaction. Flint is often deposited around larger fossils such as Echinoidea which may be silicified (i.e. replaced molecule by molecule by flint).

Tertiary is a widely used, but obsolete term for the geologic period from 66 million to 2.6 million years ago. The period began with the demise of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start of the Cenozoic Era, and extended to the beginning of the Quaternary glaciation at the end of the Pliocene Epoch. The time span covered by the Tertiary has no exact equivalent in the current geologic time system, but it is essentially the merged Paleogene and Neogene periods, which are informally called the Lower Tertiary and the Upper Tertiary, respectively.

Dorset Heaths

The Dorset Heaths form an important area of heathland within the Poole Basin in southern England. Much of the area is protected.

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North Downs ridge of chalk hills in south east England

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Geology of Great Britain

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Geology of Hertfordshire

The geology of Hertfordshire describes the rocks of the English county of Hertfordshire which are a northern part of the great shallow syncline known as the London Basin. The beds dip in a south-easterly direction towards the syncline's lowest point roughly under the River Thames. The most important formations are the Cretaceous chalks, which are exposed as the high ground in the north and west of the county, and the Cenozoic rocks made up of the Paleocene age Reading beds and Eocene age London Clay that occupies the remaining southern part.

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 consist of a mixture of mixed-layer clay minerals, such as smectite and glauconite mica. Greensand is also loosely applied to any glauconitic sediment.

Geology of Dorset

Dorset is a county in South West England on the English Channel coast. Covering an area of 2,653 square kilometres (1,024 sq mi); it borders Devon to the west, Somerset to the north-west, Wiltshire to the north-east, and Hampshire to the east. The great variation in its landscape owes much to the underlying geology which includes an almost unbroken sequence of rocks from 200 Ma to 40 Ma and superficial deposits from 2 Ma to the present. In general the oldest rocks appear in the far west of the county, with the most recent (Eocene) in the far east. Jurassic rocks also underlie the Blackmore Vale and comprise much of the coastal cliff in the west and south of the county; and although younger Cretaceous rocks crown some of the highpoints in the west, they are mainly to be found in the centre and east of the county.

Geography of London

London is the largest urban area and capital city of the United Kingdom. It is located in the southeast of Great Britain. The London region covers an area of 1,579 square kilometres (610 sq mi), and had a population of 7,172,036 in 2001 and a population density of 4,542 people per square kilometre. A larger area, referred to as the London Metropolitan Region or the London Metropolitan Agglomeration covers an area of 8,382 square kilometres (3,236 sq mi), and had a population of 12,653,500 and a population density of 1,510 people per square kilometre.

In geology, the Bagshot Beds are a series of sands and clays of shallow-water origin, some being fresh-water, some marine. They belong to the upper Eocene formation of the London and Hampshire basins, in England and derive their name from Bagshot Heath in Surrey. They are also well developed in Hampshire, Berkshire and the Isle of Wight. The following divisions are generally accepted:

Geology of London

The geology of London comprises various differing layers of sedimentary rock upon which London, England is built.

Greensand Ridge sandstone escarpment and range of hills in south-east England

The Greensand Ridge is an extensive, prominent, often wooded, mixed greensand/sandstone escarpment in south-east England. It runs to and from the East Sussex coast, around the Weald, a former dense forest in Sussex, Surrey and Kent. It reaches its highest elevation, 294 metres (965 ft), at Leith Hill in Surrey—the second highest point in south-east England, while another hill in its range, Blackdown, is the highest point in Sussex at 280 metres (919 ft). The eastern end of the ridge forms the northern boundary of Romney Marsh.

Geography of Kent

Kent is the south-easternmost county in England. It is bounded on the north by the River Thames and the North Sea, and on the south by the Straits of Dover and the English Channel. The continent of Europe is a mere 21 miles across the Strait.

Bardenas Reales protected area

The Bardenas Reales (sometimes referred as Bárdenas Reales; is a semi-desert natural region, or badlands, of some 42,000 hectares in southeast Navarre. The soils are made up of clay, chalk and sandstone and have been eroded by water and wind creating surprising shapes, canyons, plateaus, tabular structures and isolated hills, called cabezos. Bardenas Reales lacks urban areas, vegetation is scarce and the many streams that cross the territory have a markedly seasonal flow, staying dry most of the year.

London Basin The basin of river Thames in London

The London Basin is an elongated, roughly triangular sedimentary basin approximately 250 kilometres (160 mi) 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 compressional tectonics related to the Alpine orogeny during the Palaeogene period and was mainly active between 40 and 60 million years ago.

Geology of Yorkshire

The Geology of Yorkshire in northern England shows a very close relationship between the major topographical areas and the geological period in which their rocks were formed. The rocks of the Pennine chain of hills in the west are of Carboniferous origin whilst those of the central vale are Permo-Triassic. The North York Moors in the north-east of the county are Jurassic in age while the Yorkshire Wolds to the south east are Cretaceous chalk uplands. The plain of Holderness and the Humberhead levels both owe their present form to the Quaternary ice ages. The strata become gradually younger from west to east.

Geology of East Sussex

The geology of East Sussex is defined by the Weald–Artois anticline, a 60 kilometres (37 mi) wide and 100 kilometres (62 mi) long fold within which caused the arching up of the chalk into a broad dome within the middle Miocene, which has subsequently been eroded to reveal a lower Cretaceous to Upper Jurassic stratigraphy. East Sussex is best known geologically for the identification of the first dinosaur by Gideon Mantell, near Cuckfield, to the famous hoax of the Piltdown man near Uckfield.

Geography of Dorset

Dorset is a county located in the middle of the south coast of England. It lies between the latitudes 50.512°N and 51.081°N and the longitudes 1.682°W and 2.958°W, and occupies an area of 2,653 km². It spans 90 kilometres (56 mi) from east to west and 63 kilometres (39 mi) from north to south.

The geology of Kent in southeast England largely consists of a succession of northward dipping late Mesozoic and Cenozoic sedimentary rocks overlain by a suite of unconsolidated deposits of more recent origin.

The geology of West Sussex in southeast England comprises a succession of sedimentary rocks of Cretaceous age overlain in the south by sediments of Palaeogene age. The sequence of strata from both periods consists of a variety of sandstones, mudstones, siltstones and limestones. These sediments were deposited within the Hampshire and Weald basins. Erosion subsequent to large scale but gentle folding associated with the Alpine Orogeny has resulted in the present outcrop pattern across the county, dominated by the north facing chalk scarp of the South Downs. The bedrock is overlain by a suite of Quaternary deposits of varied origin. Parts of both the bedrock and these superficial deposits have been worked for a variety of minerals for use in construction, industry and agriculture.

Geology of Surrey. Towards the beginning of the Cretaceous age Surrey alternated between a fresh-to-brackish water embayment depositing Hastings Beds and Weald Clay, comprising shales and mudstones that are often finely banded. Offshore muds of the Atherfield Clay were deposited followed by shallow marine sands of the Hythe, Sandgate and Folkestone Beds. Where not eroded to lower heights, there is then a marine layer of the sands of the Hythe Beds topped by chert seen on today's remaining Greensand Hills. Instead of the mudstone and sandstone-producing three beds mentioned before Hythe Beds, west of Dorking the marine Bargate Beds made of calcareous sandstone were deposited. The Folkestone Beds contain phosphatic and iron-rich nodules, which locally yield a rich fossil fauna of marine shells.

This article describes the geology of the New Forest, a national park in Hampshire, in southern England.

References

  1. Ordnance Survey 1:50,000 Landranger series, no. 195.
  2. The nature conservation interest of the Natural Area at www.naturalareas.naturalengland.org.uk. Accessed on 4 Sep 2013

Coordinates: 50°42′N1°54′W / 50.7°N 1.9°W / 50.7; -1.9

Geographic coordinate system Coordinate system

A geographic coordinate system is a coordinate system that enables every location on Earth to be specified by a set of numbers, letters or symbols. The coordinates are often chosen such that one of the numbers represents a vertical position and two or three of the numbers represent a horizontal position; alternatively, a geographic position may be expressed in a combined three-dimensional Cartesian vector. A common choice of coordinates is latitude, longitude and elevation. To specify a location on a plane requires a map projection.