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Brackish water, also sometimes termed brack water, is water occurring in a natural environment having more salinity than freshwater, but not as much as seawater. It may result from mixing seawater with fresh water together, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak". Certain human activities can produce brackish water, in particular civil engineering projects such as dikes and the flooding of coastal marshland to produce brackish water pools for freshwater prawn farming. Brackish water is also the primary waste product of the salinity gradient power process. Because brackish water is hostile to the growth of most terrestrial plant species, without appropriate management it is damaging to the environment.
The Pleistocene is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the world's most recent period of repeated glaciations. Before a change finally confirmed in 2009 by the International Union of Geological Sciences, the cutoff of the Pleistocene and the preceding Pliocene was regarded as being at 1.806 million years Before Present (BP). Publications from earlier years may use either definition of the period. The end of the Pleistocene corresponds with the end of the last glacial period and also with the end of the Paleolithic age used in archaeology. The name is a combination of Ancient Greek πλεῖστος and καινός (kainós, "new".
The River Thames, known alternatively in parts as the River Isis, is a river that flows through southern England including London. At 215 miles (346 km), it is the longest river entirely in England and the second-longest in the United Kingdom, after the River Severn.
The geology of Great Britain is renowned for its diversity. As a result of its eventful geological history, Great Britain shows a rich variety of landscapes across the constituent countries of England, Wales and Scotland. Rocks of almost all geological ages are represented at outcrop, from the Archaean onwards.
The Anglian Stage is the name used in the British Isles for a middle Pleistocene glaciation. It precedes the Hoxnian Stage and follows the Cromerian Stage in the British Isles. The Anglian Stage is correlated to Marine Isotope Stage 12, which started about 478,000 years ago and ended about 424,000 years ago.
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.
Horsenden Hill is a hill and open space, located between the Perivale, Sudbury, and Greenford areas of West London. It is in the London Borough of Ealing, close to the boundary with the London Borough of Brent. It is one of the higher eminences in the local area, rising to 85m above sea level, and the summit forms part of the site of an ancient hillfort. It is the site of a trig point, TP4024.
The Ancestral Thames is the geologically ancient precursor to the present day River Thames.
Brickearth is a term originally used to describe superficial windblown deposits found in southern England. The term has been employed in English-speaking regions to describe similar deposits.
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.
The Pre-Illinoian Stage is used by Quaternary geologists for the early and middle Pleistocene glacial and interglacial periods of geologic time in North America from ~2.5–0.2 Ma.
Campden Tunnel Gravel Pit is a 0.2-hectare (0.49-acre) geological Site of Special Scientific Interest in Gloucestershire, notified in 1988. The site is listed in the 'Cotswold District' Local Plan 2001-2011.
The Norwich Crag Formation is a stratigraphic unit of the British Pleistocene Epoch. It is the second youngest unit of the Crag Group, a sequence of four geological formations spanning the Pliocene to Lower Pleistocene transition in East Anglia. It was deposited between approximately 2.4 and 1.8 million years ago, during the Gelasian Stage.
The geology of Norfolk in eastern England largely consists of late Mesozoic and Cenozoic sedimentary rocks of marine origin covered by an extensive spread of unconsolidated recent deposits.
The Crag Group is a geological group outcropping in East Anglia, UK and adjacent areas of the North Sea. Its age ranges from approximately 4.4 to 0.478 million years BP, spanning the late Pliocene and early to middle Pleistocene epochs. It comprises a range of marine and estuarine sands, gravels, silts and clays deposited in a relatively shallow-water, tidally-dominated marine embayment on the western margins of the North Sea basin. The sands are characteristically dark green from glauconite but weather bright orange, with haematite 'iron pans' forming. The lithology of the lower part of the Group is almost entirely flint. The highest formation in the Group, the Wroxham Crag, contains over 10% of far-travelled lithologies, notably quartzite and vein quartz from the Midlands, igneous rocks from Wales, and chert from the Upper Greensand of southeastern England. This exotic rock component was introduced by rivers such as the Bytham River and Proto-Thames.
Downfield Pit is a 3.6 hectare geological Site of Special Scientific Interest near Ware in Hertfordshire. It is in the Geological Conservation Review in the Thames Pleistocene section, and the local planning authority is East Hertfordshire District Council.
The Finchley Gap or Finchley deposits are an array of trace glacial remnants at and at points south of the foot of the Grim's Ditch spanning the breadth of North London. Evidence gathered in the 1980s dispelled the notion of this zone being a wind gap, left by a brief or long flow of the Colne, while confirming its upper course once flowed north-east then east across the Vale of St Albans to reach the Lea Valley at Hertford.
This article describes the geology of the Broads, an area of East Anglia in eastern England characterised by rivers, marshes and shallow lakes (‘broads’). The Broads is designated as a protected landscape with ‘status equivalent to a national park’.
Waldringfield Pit is a 0.8 hectare geological Site of Special Scientific Interest between Martlesham Heath and Waldringfield in Suffolk. It is a Geological Conservation Review site.
The Ludham Borehole was a geological research borehole drilled in 1959 near Ludham, Norfolk, UK. A continuous core sample of late Pliocene and early Pleistocene sediments of the Crag Group was recovered. Analysis allowed biostratigraphic zonal schemes for fossil pollen, foraminifera, mollusca and dinoflagellates to be constructed for horizons of the Red Crag and Norwich Crag Formations, and for these formations to be thus correlated with strata of equivalent age in the North Sea basin and north-west Europe.