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White Island, Isles Of Scilly
White Island ( kw, Ar Nor, "facing the mainland" or "white island" ) is one of the larger unpopulated islands of the Isles of Scilly, part of the United Kingdom, and lies off the coast of the northernmost populated island of the group, St Martin's, to which it is joined by a tidal causeway, or isthmus. The island is designated as a Site of Special Scientific Interest (SSSI) and a Geological Conservation Review site and is managed by the Isles of Scilly Wildlife Trust on behalf of the Duchy of Cornwall.White Island (pdf file) ( Natural England, 1989), accessed 1 November 2011 Access to the island can be dangerous when the rocky causeway is covered by the sea, as there are strong currents across it. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isles Of Scilly
The Isles of Scilly (; kw, Syllan, ', or ) is an archipelago off the southwestern tip of Cornwall, England. One of the islands, St Agnes, is the most southerly point in Britain, being over further south than the most southerly point of the British mainland at Lizard Point. The total population of the islands at the 2011 United Kingdom census was 2,203. Scilly forms part of the ceremonial county of Cornwall, and some services are combined with those of Cornwall. However, since 1890, the islands have had a separate local authority. Since the passing of the Isles of Scilly Order 1930, this authority has had the status of a county council and today is known as the Council of the Isles of Scilly. The adjective "Scillonian" is sometimes used for people or things related to the archipelago. The Duchy of Cornwall owns most of the freehold land on the islands. Tourism is a major part of the local economy, along with agriculture—particularly the production of cut flowers. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Entrance Grave
Entrance grave is a type of Neolithic and early Bronze Age chamber tomb found primarily in Great Britain. The burial monument typically consisted of a circular mound bordered by a stone curb, erected over a rectangular burial chamber and accessed by a narrow, stone lined entrance. Entrance graves have been discovered in the Isles of Scilly, west Cornwall, southeast Ireland, southwest Scotland, Brittany and the Channel Islands. They are often referred to as the ''Scillonian Group'', named for the Scillonian Islands where the majority of entrance graves have been discovered. History Entrance graves in Britain are also known as Scillonian entrance graves, because the majority of these ancient burial monuments are found on the Isles of Scilly, a group of islands 25 miles (40 m) west of Cornwall. The islands were originally settled during the Neolithic era, circa 2500 BC. Burials on the islands range in date from the later Neolithic period to the Middle Bronze Age (c.2500-1000 BC). ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loess
Loess (, ; from german: Löss ) is a clastic, predominantly silt-sized sediment that is formed by the accumulation of wind-blown dust. Ten percent of Earth's land area is covered by loess or similar deposits. Loess is a periglacial or aeolian (windborne) sediment, defined as an accumulation of 20% or less of clay and a balance of roughly equal parts sand and silt (with a typical grain size from 20 to 50 micrometers), often loosely cemented by calcium carbonate. It is usually homogeneous and highly porous and is traversed by vertical capillaries that permit the sediment to fracture and form vertical bluffs. Properties Loess is homogeneous, porous, friable, pale yellow or buff, slightly coherent, typically non- stratified and often calcareous. Loess grains are angular, with little polishing or rounding, and composed of crystals of quartz, feldspar, mica and other minerals. Loess can be described as a rich, dust-like soil. Loess deposits may become very thick, more than ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clasts
Clastic rocks are composed of fragments, or clasts, of pre-existing minerals and rock. A clast is a fragment of geological detritus,Essentials of Geology, 3rd Ed, Stephen Marshak, p. G-3 chunks, and smaller grains of rock broken off other rocks by physical weathering.Essentials of Geology, 3rd Ed, Stephen Marshak, p. G-5 Geologists use the term clastic to refer to sedimentary rocks and particles in sediment transport, whether in suspension or as bed load, and in sediment deposits. Sedimentary clastic rocks Clastic sedimentary rocks are rocks composed predominantly of broken pieces or ''clasts'' of older weathered and eroded rocks. Clastic sediments or sedimentary rocks are classified based on grain size, clast and cementing material (matrix) composition, and texture. The classification factors are often useful in determining a sample's environment of deposition. An example of clastic environment would be a river system in which the full range of grains being transported by th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solifluction
Solifluction is a collective name for gradual processes in which a mass moves down a slope ("mass wasting") related to freeze-thaw activity. This is the standard modern meaning of solifluction, which differs from the original meaning given to it by Johan Gunnar Andersson in 1906. Origin and evolution of the concept In the original sense it meant the movement of waste saturated in water found in periglacial regions. However it was later discovered that various slow waste movements in periglacial regions did not require saturation in water, but were rather associated to freeze-thaw processes. The term solifluction was appropriated to refer to these slow processes, and therefore excludes rapid periglacial movements. In slow periglacial solifluction there are not clear gliding planes, and therefore skinflows and active layer detachments are not included in the concept. On the other hand, movement of waste saturated in water can occur in any humid climate, and therefore this kind of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Breccia
Breccia () is a rock composed of large angular broken fragments of minerals or rocks cemented together by a fine-grained matrix. The word has its origins in the Italian language, in which it means "rubble". A breccia may have a variety of different origins, as indicated by the named types including sedimentary breccia, tectonic breccia, igneous breccia, impact breccia, and hydrothermal breccia. A megabreccia is a breccia composed of very large rock fragments, sometimes kilometers across, which can be formed by landslides, impact events, or caldera collapse. Types Breccia is composed of coarse rock fragments held together by cement or a fine-grained matrix. Like conglomerate, breccia contains at least 30 percent of gravel-sized particles (particles over 2mm in size), but it is distinguished from conglomerate because the rock fragments have sharp edges that have not been worn down. These indicate that the gravel was deposited very close to its source area, since otherwise th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Head
A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may not have a head, but many bilaterally symmetric forms do, regardless of size. Heads develop in animals by an evolutionary trend known as cephalization. In bilaterally symmetrical animals, nervous tissue concentrate at the anterior region, forming structures responsible for information processing. Through biological evolution, sense organs and feeding structures also concentrate into the anterior region; these collectively form the head. Human head The human head is an anatomical unit that consists of the Human skull, skull, hyoid bone and cervical vertebrae. The term "skull" collectively denotes the mandible (lower jaw bone) and the cranium (upper portion of the skull that houses the brain). Sculptures of human heads are general ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Raised Beach
A raised beach, coastal terrace,Pinter, N (2010): 'Coastal Terraces, Sealevel, and Active Tectonics' (educational exercise), from 2/04/2011/ref> or perched coastline is a relatively flat, horizontal or gently inclined surface of marine origin,Pirazzoli, PA (2005a): 'Marine Terraces', in Schwartz, ML (ed) ''Encyclopedia of Coastal Science.'' Springer, Dordrecht, pp. 632–633 mostly an old abrasion platform which has been lifted out of the sphere of wave activity (sometimes called "tread"). Thus, it lies above or under the current sea level, depending on the time of its formation.Strahler AH; Strahler AN (2005): ''Physische Geographie.'' Ulmer, Stuttgart, 686 p.Leser, H (ed)(2005): ‚''Wörterbuch Allgemeine Geographie.'' Westermann&Deutscher Taschenbuch Verlag, Braunschweig, 1119 p. It is bounded by a steeper ascending slope on the landward side and a steeper descending slope on the seaward side (sometimes called "riser"). Due to its generally flat shape, it is often used for a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quaternary
The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ago to the present. The Quaternary Period is divided into two epochs: the Pleistocene (2.58 million years ago to 11.7 thousand years ago) and the Holocene (11.7 thousand years ago to today, although a third epoch, the Anthropocene, has been proposed but is not yet officially recognised by the ICS). The Quaternary Period is typically defined by the cyclic growth and decay of continental ice sheets related to the Milankovitch cycles and the associated climate and environmental changes that they caused. Research history In 1759 Giovanni Arduino proposed that the geological strata of northern Italy could be divided into four successive formations or "orders" ( it, quattro ordini). The term "quaternary" was introduced by Jules Desnoye ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Pleistocene
The Late Pleistocene is an unofficial Age (geology), age in the international geologic timescale in chronostratigraphy, also known as Upper Pleistocene from a Stratigraphy, stratigraphic perspective. It is intended to be the fourth division of the Pleistocene Epoch within the ongoing Quaternary Period. It is currently defined as the time between c. 129,000 and c. 11,700 years ago. The Late Pleistocene equates to the proposed Tarantian Age of the geologic time scale, preceded by the officially ratified Chibanian (formerly known as Middle Pleistocene) and succeeded by the officially ratified Greenlandian. The estimated beginning of the Tarantian is the start of the Eemian interglacial period (Marine Isotope Stage 5). It is held to end with the termination of the Younger Dryas, some 10th millennium BC, 11,700 years ago when the Holocene Epoch began. The term Upper Pleistocene is currently in use as a provisional or "quasi-formal" designation by the International Union of Geological ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hut Circle
In archaeology, a hut circle is a circular or oval depression in the ground which may or may not have a low stone wall around it that used to be the foundation of a round house. The superstructure of such a house would have been made of timber and thatch. They are numerous in parts of upland Britain and most date to around the 2nd century BC. Hut circles are usually around in internal diameter, the rocks themselves being wide and around high. Hut circles were also almost certainly covered by conical rounded roofs and supported by posts that were internal and sometimes external. Wales There are more than 100 registered hut circles and enclosures in Wales. They are to be found in areas which have not been ploughed and the stones have not been disturbed. They are quite common in the north. Remains of a hut circle on Tre'r Ceiri - geograph.org.uk - 1571421.jpg, Tre'r Ceiri Celtic Iron Age hut circle Cytiau Celtaidd - Celtic Iron Age Huts at Mynydd Twr, Caergybi (Holyhead), Wale ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Field System
The study of field systems (collections of fields) in landscape history is concerned with the size, shape and orientation of a number of fields. These are often adjacent, but may be separated by a later feature. Field systems by region Czech Republic In the Czech Republic (ancient Bohemia, Moravia and Czech Silesia), Ervín Černý undertook a study of medieval field systems. England Although agriculture was practised earlier, the earliest recognisable field systems in England are neolithic. Cairnfields, which are pre-historic in date, are found in upland areas. They contain scattered stones and boulders and originated in surface clearance for agriculture.''Field Systems'', English Heritage, May, 2011 So called Celtic fields can date from the Bronze Age through to the early Middle Ages. These fields are typically small and rectangular. They are frequently coaxial - that is they form a system in which the boundaries of adjacent fields make a series of long, roughly parallel lines ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
