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Geology Of London
The geology of London comprises various differing layers of sedimentary rock upon which London, England is built. Oldest rocks The oldest rocks proved through boreholes to exist below London are the old, hard rocks of the Palaeozoic. These consist of Silurian mudstones and sandstones, generally overlain by Devonian strata which are largely of Old Red Sandstone. The Devonian rocks are absent in parts of South London. The Palaeozoic 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. These clays are relatively young, only going back to the early Cretaceous which began around 144 million years ago. 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. In the Lower Chalk and in the lower region of the Middle Chalk there are abundant fossilized shell fragments, especially ''Inoceramus'' clams. In places these form ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geological Map Of London Basin
Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth sciences, including hydrology, and so is treated as one major aspect of integrated Earth system science and planetary science. Geology describes the structure of the Earth on and beneath its surface, and the processes that have shaped that structure. It also provides tools to determine the relative and absolute ages of rocks found in a given location, and also to describe the histories of those rocks. By combining these tools, geologists are able to chronicle the geological history of the Earth as a whole, and also to demonstrate the age of the Earth. Geology provides the primary evidence for plate tectonics, the evolutionary history of life, and the Earth's past climates. Geologists broadly study the properties and processes of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flint
Flint, occasionally flintstone, is a sedimentary cryptocrystalline form of the mineral quartz, categorized as the variety of chert that occurs in chalk or marly limestone. Flint was widely used historically to make stone tools and start fires. It occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones.''The Flints from Portsdown Hill'' Inside the nodule, flint is usually dark grey, black, green, white or brown in colour, and often has a glassy or waxy appearance. A thin layer on the outside of the nodules is usually different in colour, typically white and rough in texture. The nodules can often be found along streams and be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
British Geological Survey
The British Geological Survey (BGS) is a partly publicly funded body which aims to advance geoscientific knowledge of the United Kingdom landmass and its continental shelf by means of systematic surveying, monitoring and research. The BGS headquarters are in Keyworth, Nottinghamshire, England. Its other centres are located in Edinburgh, Wallingford, Cardiff and London. The current motto of the BGS is: ''Gateway to the Earth''. History and previous names The Geological Survey was founded in 1835 by the Board of Ordnance as the Ordnance Geological Survey, under Henry De la Beche. This was the world's first national geological survey. It remained a branch of the Ordnance Survey for many years. In 1965, it was merged with the Geological Museum and Overseas Geological Surveys, under the name of Institute of Geological Sciences. On 1 January 1984, the institute was renamed the British Geological Survey (and often referred to as the BGS), a name still carried today. Competenc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 million years before present during the Ypresian age (lower Eocene). It is found throughout the London Basin with a thickness between 10m and 30m and the Hampshire Basin with a thickness between 50m and less than 25m. Although this sequence only crops out in these basins, the fact that it underlies 25% of London at a depth of less than 30m means the formation is of engineering interest for tunnelling and foundations. History The formation was first known as the Plastic Clay by T. Webster in 1816 after the Argile plastique of Georges Cuvier and A. Brongniart. It was called the Mottled Clay by Joseph Prestwich in 1846, but in 1853 he proposed the name Woolwich-and-Reading Beds to emphasise the differing local aspects of the series. This ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
London Clay
The London Clay Formation is a marine geological formation of Ypresian (early Eocene Epoch, c. 56–49 million years ago) age which crops out in the southeast of England. The London Clay is well known for its fossil content. The fossils from the lower Eocene rocks indicate a moderately warm climate, the tropical or subtropical flora. Though sea levels changed during the deposition of the clay, the habitat was generally a lush forest – perhaps like in Indonesia or East Africa today – bordering a warm, shallow ocean. The London Clay is a stiff bluish clay which becomes brown when weathered and oxidized. Nodular lumps of pyrite are frequently found in the clay layers. Pyrite was produced by microbial activity (sulfate reducing bacteria) during clay sedimentation. Once clay is exposed to atmospheric oxygen, framboidal pyrite with a great specific surface is rapidly oxidized. Pyrite oxidation produces insoluble brown iron oxyhydroxide (FeOOH) and sulfuric acid leading to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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. The Neogene is sub-divided into two epochs, the earlier Miocene and the later Pliocene. Some geologists assert that the Neogene cannot be clearly delineated from the modern geological period, the Quaternary. The term "Neogene" was coined in 1853 by the Austrian palaeontologist Moritz Hörnes (1815–1868). During this period, mammals and birds continued to evolve into modern forms, while other groups of life remained relatively unchanged. The first humans ('' Homo habilis'') appeared in Africa near the end of the period. Some continental movements took place, the most significant event being the connection of North America, North and South America at the Isthmus of Panama, late in the Pliocene. This cut off the warm ocean currents from th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleogene Period
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 of the Neogene Period Mya. It is the beginning of the Cenozoic Era of the present Phanerozoic Eon. The earlier term Tertiary Period was used to define the span of time now covered by the Paleogene Period and subsequent Neogene Period; despite no longer being recognised as a formal stratigraphic term, 'Tertiary' is still widely found in earth science literature and remains in informal use. Paleogene is often abbreviated "Pg" (but the United States Geological Survey uses the abbreviation PE for the Paleogene on the Survey's geologic maps). During the Paleogene, mammals diversified from relatively small, simple forms into a large group of diverse animals in the wake of the Cretaceous–Paleogene extinction event that ended the preceding C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sand
Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of soil or soil type; i.e., a soil containing more than 85 percent sand-sized particles by mass. The composition of sand varies, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non- tropical coastal settings is silica (silicon dioxide, or SiO2), usually in the form of quartz. Calcium carbonate is the second most common type of sand, for example, aragonite, which has mostly been created, over the past 500million years, by various forms of life, like coral and shellfish. For example, it is the primary form of sand apparent in areas where reefs have dominated the ecosystem for millions of years like the Caribbean. Somewhat more rarely, sand may be composed of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clays
Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay particles, but become hard, brittle and non–plastic upon drying or firing. Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impurities, such as a reddish or brownish colour from small amounts of iron oxide. Clay is the oldest known ceramic material. Prehistoric humans discovered the useful properties of clay and used it for making pottery. Some of the earliest pottery shards have been dated to around 14,000 BC, and clay tablets were the first known writing medium. Clay is used in many modern industrial processes, such as paper making, cement production, and chemical filtering. Between one-half and two-thirds of the world's population live or work in buildings made with clay, often ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lambeth Group Gilbert's Pit
Lambeth () is a district in South London, England, in the London Borough of Lambeth, historically in the County of Surrey. It is situated south of Charing Cross. The population of the London Borough of Lambeth was 303,086 in 2011. The area experienced some slight growth in the medieval period as part of the manor of Lambeth Palace. By the Victorian era the area had seen significant development as London expanded, with dense industrial, commercial and residential buildings located adjacent to one another. The changes brought by World War II altered much of the fabric of Lambeth. Subsequent development in the late 20th and early 21st centuries has seen an increase in the number of high-rise buildings. The area is home to the International Maritime Organization. Lambeth is home to one of the largest Portuguese-speaking communities in the UK, and is the second most commonly spoken language in Lambeth after English. History Medieval The origins of the name of Lambeth come f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limestones
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms when these minerals precipitate out of water containing dissolved calcium. This can take place through both biological and nonbiological processes, though biological processes, such as the accumulation of corals and shells in the sea, have likely been more important for the last 540 million years. Limestone often contains fossils which provide scientists with information on ancient environments and on the evolution of life. About 20% to 25% of sedimentary rock is carbonate rock, and most of this is limestone. The remaining carbonate rock is mostly dolomite, a closely related rock, which contains a high percentage of the mineral dolomite, . ''Magnesian limestone'' is an obsolete and poorly-defined term used variously for dolomite, for limestone c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
