The geology of London comprises various differing layers of sedimentary rock upon which London, England is built. Sedimentary rock is one of the three main rock types (the others being igneous and Metamorphic rock) London ( ˈlʌndən is the capital and largest urban area in the United Kingdom. England is a Country which is part of the United Kingdom. Its inhabitants account for more than 83% of the total UK population whilst its mainland
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Oldest rocks
The deepest layer below London is that of the old, hard rocks of the Paleozoic. London ( ˈlʌndən is the capital and largest urban area in the United Kingdom. The Paleozoic or Palaeozoic Era (from the Greek palaio (παλαιο "old" and zoe (ζωη "life" meaning "ancient life" These consist of Silurian mudstones and sandstones [1], generally overlain by Devonian strata which are largely of Old Red Sandstone. The Silurian is a geologic period and system that extends from the end of the Ordovician period about 443 The Devonian is a geologic period and system of the Paleozoic era spanning from to million years ago. The Old Red Sandstone is a Rock formation of considerable importance to early Paleontology. The Devonian rocks are absent in parts of South London [2]. The Paleozoic rocks dip southwards and are more than 1,000 metres below the English Channel. Above this is a 60 metre thick layer of impermeable Gault clays. Permeability in the Earth sciences (commonly symbolized as κ, or k) is a measure of the ability of a material (typically a rock or unconsolidated The Gault Clay is a formation of stiff blue Clay deposited in a calm fairly deep water marine environment during the Lower Cretaceous Period (Upper and Middle These clays are relatively young, only going back to the early Cretaceous which began around 144 million years ago. The Cretaceous (kriːˈteɪʃəs, usually abbreviated 'K' for its German translation "Kreide" is a geologic period and system, reaching from the end of
On top of these clays is a non-contiguous layer of Upper Greensand above which lies a rolling bed of white chalk about 200 metres thick. Greensand is an olive-green coloured Sandstone rock which is commonly found in narrow bands particularly associated with bands of Chalk and Chalk (ʧɔːk is a soft white porous Sedimentary rock, a form of Limestone composed of the Mineral Calcite. In the Lower Chalk and in the lower region of the Middle Chalk there are abundant fossilized shell fragments, especially Inoceramus clams. FOSSIL is a standard protocol for allowing serial communication for Telecommunications programs under the DOS Operating system. Inoceramus ("Strong Pot" is an Extinct Genus of fossil marine Pteriomorphian Bivalves that superficially resembled In places these form the greater part of the rock but they decrease in amount upwards in the succession. Flints are abundant in the Upper Chalk. Flint (or flintstone) is a hard sedimentary Cryptocrystalline form of the Mineral Quartz, categorized as a variety of Chert
These bands of chalk form the basis of the London Basin, a v-shaped syncline bounded by chalk outcrops forming hills: the North Downs to the south of London, and the Chilterns to the north. The London Basin is an elongated roughly triangular Syncline approximately long which underlies London and a large area of south east England and south eastern In Structural geology, a syncline is a downward-curving fold, with layers that dip toward the center of the structure The North Downs are a ridge of Chalk hills in south east England that stretch for 120 miles (190 km from Farnham in Surrey to the White The Chiltern Hills are a Chalk Escarpment in Southeast England. The chalk is a soft white limestone that is different in appearance to other limestones because it is porous and earthy whilst others are compact and crystalline. Limestone is a Sedimentary rock composed largely of the Mineral Calcite ( Calcium carbonate: CaCO3
Tertiary period
The chalk basin has been infilled with a sequence of clays and sands of the more recent Tertiary Period (1. Clay is a naturally occurring material composed primarily of fine-grained Minerals which show plasticity through a variable range of Water content, and Sand is a naturally occurring Granular material composed of finely divided rock and Mineral particles The chuprichondira geological time interval covers roughly the time span between the demise of the non- avian Dinosaurs and beginning of the most recent Ice Age, approximately 6 to 66. 4 million years old). Most significant is the stiff, grey-blue London Clay, a marine deposit which is well known for the fossils it contains and can be over 150 metres thick beneath the city. The London Clay is a Marine geological formation of Ypresian (Lower Eocene Epoch c FOSSIL is a standard protocol for allowing serial communication for Telecommunications programs under the DOS Operating system. This supports most of the deep foundations and tunnels that exist under London.
Also in this area are the Reading/Woolwich sand beds and Thanet sands. Most of these sand and clays were deposited 60-50 million years ago during the Eocene. Sand is a naturally occurring Granular material composed of finely divided rock and Mineral particles Clay is a naturally occurring material composed primarily of fine-grained Minerals which show plasticity through a variable range of Water content, and The Eocene epoch (558 ± 02 - 339 ± 01 Ma) is a major division of the Geologic timescale and the second epoch of the Palaeogene period in Southern England at this time was covered by a warm tropical sea: this is shown by the fossil evidence. England is a Country which is part of the United Kingdom. Its inhabitants account for more than 83% of the total UK population whilst its mainland The sands contain animals that lived in both estuaries and freshwater. Some species burrowed into the underlying chalk. [3]
Above this is the subsoil which consists of deposits of gravel up to 10 metres deep. Gravel is rock that is of a specific Particle size range In Geology, gravel is any loose rock that is larger than two millimeters (2mm This was deposited during the last ice-age ½ million years ago when the River Thames was diverted to its present position. An ice age is a period of long-term reduction in the Temperature of the Earth 's surface and atmosphere resulting in an expansion of continental Ice sheets The Thames ( is a major River flowing through southern England. While establishing its new path, the river eroded its valley, creating a series of sand and gravel terraces. These terraces are named after the area they are best known in, for example: Dartford Heath Gravel, Swanscombe, Orsett Heath, Corbets Tay, Mucking, West Thurrock, Kempton Park, Shepperton, Staines and Tilbury Gravels. Dartford is the principal town in the borough of Dartford. It is situated in the northwest corner of Kent, England, 16 miles (25 km east south-east Swanscombe is a small town part of the Borough of Dartford on the north Kent coast in England. Orsett is a village in the South East of Essex within the borough of Thurrock in England United Kingdom. Mucking is a hamlet and former parish adjoining the Thames estuary in southern Essex, England. West Thurrock is an area of Thurrock, Essex, England, located 17 Kempton Park is a locality in the Spelthorne district of Surrey, which is the location of Kempton Park Racecourse. Shepperton is a Town in Surrey in the borough of Spelthorne, in England. Staines is a Thames -side town in the Spelthorne borough of Surrey and part of the London Commuter Belt of South East England, Tilbury is a town in the borough of Thurrock, Essex, England. [4]
The sand and gravel terraces are made up of pebbles with flint, quartz and quartzite. Quartz (from German) is the most abundant Mineral in the Earth 's Continental crust (although Feldspar is more common in Quartzite (from German Quarzit) not to be confused with the Mineral Quartz, is a hard Metamorphic rock which was originally In places, there are deposits of brick-earth, which is a mixture of clay and sand that has supported London's long-standing brick-making industry. A brick is a block of Ceramic material used in Masonry construction laid using mortar. Atop these natural layers are the deposits of hundreds of years of human occupation. In the oldest parts the City of London and the City of Westminster this layer can be up to 6 metres deep. For London as a whole see the main article London. The City of London is a geographically The City of Westminster ( is a borough of London with city status. [5]
References
- ^ Chilterns 1:250,000 map sheet, British Geological Survey (1991)
- ^ Sumbler, M. G. , London and the Thames Valley, British Geological Survey (1996)
- ^ Story of London retrieved 14/1/07
- ^ BBC retrieved 14/1/07
- ^ Shoreham by Sea Geology retrieved 14/1/07
See also
External links
The Geology of Great Britain is hugely varied and complex and gives rise to the wide variety of landscapes found across the islands The Geology of England is mainly sedimentary. The youngest rocks are in the south east around London, progressing in age in a north westerly In central and southern Britain during the Early and Middle Pleistocene, two rivers drained Britain the Bytham River and the Thames.Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic