   #copyright

Geology of Dorset

2007 Schools Wikipedia Selection. Related subjects: Geography of Great
Britain

   Stylised simple Geology map of Dorset
   Stylised simple Geology map of Dorset

   Dorset, England, rests on a variety of different rock types which give
   the county its interesting landscapes and habitats. Dorset is
   particularly noted for its coastline, the Jurassic Coast, which in 2001
   was designated a World Heritage Site because of the variety of
   landforms and fossils exhibited along the coast. 44% of the county is
   within the Dorset AONB, which includes most of the Downs, Blackmore
   Vale, Purbecks, the Chesil Beach and Fleet SSSI and Poole Harbour.

Downland

   The top of the downs from above Cerne Abbas looking south east towards
   the River Piddle valley
   Enlarge
   The top of the downs from above Cerne Abbas looking south east towards
   the River Piddle valley

   Throughout Dorset there are a number of limestone ridges. These ridges
   support arable agriculture and calcareous grassland habitats, as well
   as aquifers. The largest and most notable of the limestone bands is the
   band of Cretaceous chalk which runs from the south west to the north
   east of the county and forms part of the Southern England Chalk
   Formation which underlies much of south of England, including Salisbury
   Plain, the Isle of Wight and the South Downs. The central Dorset
   section of the chalk formation is known as the Dorset Downs, and the
   north eastern section, which runs into Wiltshire, as Cranborne Chase.
   The two are separated by the Stour Valley which cuts through the hills
   at Blandford Forum. In the Isle of Purbeck is another, smaller, ridge
   of the chalk formation, known as the Purbeck Hills.

   The high chalk hills were important in the pre-Roman history of Dorset,
   the location of settlements in the neolithic, bronze age and iron age,
   and are noted for the hill forts at Maiden Castle, Hambledon Hill and
   Badbury Rings and for the Cerne Abbas giant chalk hill figure. Running
   through the chalk hills are a number of winterbourne valleys.

Valleys

   Sturminster Newton water mill in the Blackmore Vale
   Enlarge
   Sturminster Newton water mill in the Blackmore Vale

   Between the bands of limestone and chalk are wide Tertiary clay vales
   with large flood plains, which sustain many small settlements and dairy
   farms. The most notable of the valleys are those of the Stour and
   Frome. The Stour flows into the north of the county at Gillingham, into
   a wide basin, the Blackmore Vale, where it collects from many small
   tributaries. The river then flows south, through a gap in the chalk and
   across the healthand of south east Dorset. The Frome collects water
   from the aquifer of the Dorset Downs, forming in the hills in west
   Dorset, and flowing through Dorchester into a wide estuary, Poole
   Harbour, where it reaches the weak sands in the south east of the
   county.

Heathland

   South-east Dorset, around Poole and Bournemouth, and the New Forest,
   lie on very unresistant Tertiary beds: Eocene clays (mainly London Clay
   and Gault Clay), sands and gravels. These thin soils support a
   heathland habitat which supports all seven native British reptile
   species. Dorset Heath, a species of the genus Erica, grows in this
   area, and in 2002 was chosen as a symbol of the county by Plantlife's "
   county flower" competition.

   The River Frome estuary runs through this weak rock, and its many
   tributaries have carved out a very wide estuary. At the mouth of the
   estuary sand spits have been deposited turning the estuary into Poole
   Harbour, the second largest natural harbour in the world (after Sydney
   Harbour, though since artificial expansion Sydney's claim is disputed).
   The harbour is very shallow in places and contains a number of islands,
   notably Brownsea Island, famous for its Red Squirrel sanctuary and as
   the birthplace of the Scouting movement.

   The harbour, and the chalk and limestone hills of the Purbecks to the
   south, lie atop Britain's largest onshore oil field. The field,
   operated by BP from Wytch Farm, produces a high-quality oil and boasts
   the world's oldest contiuously pumping well ( Kimmeridge, since the
   early 1960s) and longest horizontal drill (5  miles, ending underneath
   Bournemouth pier). The clay pottery produced by Poole pottery from the
   local clays is famous for its quality.

Coastline

   Lulworth Cove
   Enlarge
   Lulworth Cove

   Dorset's coastline is one of the most visited and studied coastlines in
   the world because it shows, along the course of 95 miles (including
   some of east Devon) rocks from the beginning of Triassic, through the
   Jurassic and up to the end of the Cretaceous, documenting the entire
   Mesozoic era with well preserved fossils. Particularly famous are the
   Triassic and Jurassic cliffs around Lyme Regis which have yielded many
   notable fossil finds, including Mary Anning's Ichthyosaur. The variety
   of geology leads to a variety of habitats, from the heathland of the
   Tertiary beds at Poole harbour and Studland, to the Chalk downland
   where the Cretaceous beds reach the sea. There are also small areas of
   karst landscape on the Jurassic limestones.

   What makes Dorset's coast particularly important to geologists though
   are the series of landforms which occur so close together, on the
   concordant and discordant coastlines. The most famous include Lulworth
   Cove, Durdle Door natural arch, Old Harry Rocks and Chesil Beach, a
   tombolo. The Portland limestone of the Isle of Portland and the Purbeck
   Limestone of Purbeck have been quarried for use in building much of
   London, hundreds of thousands of British war grave stones and
   memorials, and the United Nations head quarters.

   Retrieved from " http://en.wikipedia.org/wiki/Geology_of_Dorset"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
