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- ► Glacial deposits of Norway (4 P)
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1. Geography – Geography is a field of science devoted to the study of the lands, the features, the inhabitants, and the phenomena of Earth. The first person to use the word γεωγραφία was Eratosthenes, Geography is an all-encompassing discipline that seeks an understanding of the Earth and its human and natural complexities—not merely where objects are, but how they have changed and come to be. It is often defined in terms of the two branches of geography and physical geography. Geography has been called the world discipline and the bridge between the human and the physical sciences, Geography is a systematic study of the Earth and its features. Traditionally, geography has been associated with cartography and place names, although many geographers are trained in toponymy and cartology, this is not their main preoccupation. Geographers study the space and the temporal database distribution of phenomena, processes, because space and place affect a variety of topics, such as economics, health, climate, plants and animals, geography is highly interdisciplinary. The interdisciplinary nature of the approach depends on an attentiveness to the relationship between physical and human phenomena and its spatial patterns. Names of places. are not geography. know by heart a whole gazetteer full of them would not, in itself and this is a description of the world—that is Geography. In a word Geography is a Science—a thing not of mere names but of argument and reason, of cause, just as all phenomena exist in time and thus have a history, they also exist in space and have a geography. Geography as a discipline can be split broadly into two main fields, human geography and physical geography. The former largely focuses on the environment and how humans create, view, manage. The latter examines the environment, and how organisms, climate, soil, water. The difference between these led to a third field, environmental geography, which combines physical and human geography. Physical geography focuses on geography as an Earth science and it aims to understand the physical problems and the issues of lithosphere, hydrosphere, atmosphere, pedosphere, and global flora and fauna patterns. Physical geography can be divided into broad categories, including, Human geography is a branch of geography that focuses on the study of patterns. It encompasses the human, political, cultural, social, and it requires an understanding of the traditional aspects of physical and human geography, as well as the ways that human societies conceptualize the environment. Integrated geography has emerged as a bridge between the human and the geography, as a result of the increasing specialisation of the two sub-fields. Examples of areas of research in the environmental geography include, emergency management, environmental management, sustainability, geomatics is concerned with the application of computers to the traditional spatial techniques used in cartography and topographyGeography – Map of the Earth
2. Glacial landform – Glacial landforms are landforms created by the action of glaciers. Most of todays glacial landforms were created by the movement of ice sheets during the Quaternary glaciations. Some areas, like Fennoscandia and the southern Andes, have extensive occurrences of glacial landforms, other areas, such as the Sahara, as the glaciers expanded, due to their accumulating weight of snow and ice, they crush and abrade scoured surface rocks and bedrock. The resulting erosional landforms include striations, cirques, glacial horns, arêtes, trim lines, U-shaped valleys, roches moutonnées, overdeepenings, Cirque, Starting location for mountain glaciers Cirque stairway, a sequence of cirques U-shaped valley, U-shaped valleys are created by mountain glaciers. When filled with water so as to create an inlet. Arête, spiky high land between two glaciers, if the glacial action erodes through, a spillway forms, later, when the glaciers retreated leaving behind their freight of crushed rock and sand, they created characteristic depositional landforms. Examples include glacial moraines, eskers, and kames, drumlins and ribbed moraines are also landforms left behind by retreating glaciers. The stone walls of New England contain many glacial erratics, rocks that were dragged by a glacier many miles from their bedrock origin, esker, Built up bed of a subglacial stream. Moraine, Feature can be terminal, lateral, or medial, outwash fan, Braided stream flowing from the front end of a glacier. Lakes and ponds may also be caused by glacial movement, kettle lakes form when a retreating glacier leaves behind an underground or surface chunk of ice that later melts to form a depression containing water. Moraine-dammed lakes occur when glacial debris dam a stream, Jackson Lake and Jenny Lake in Grand Teton National Park are examples of moraine-dammed lakes, though Jackson Lake is enhanced by a man-made dam. Kettle lake, Depression, formed by a block of ice separated from the main glacier, tarn, A lake formed in a cirque by overdeepening. Paternoster lake, A series of lakes in a glacial valley, glacial Lake, A lake that formed between the front of a glacier and the last recessional moraine. Apart from the left behind by glaciers, glaciers themselves may be striking features of the terrain. Notable examples include valley glaciers where glacial flow is restricted by the walls, crevasses in the upper section of glacial iceGlacial landform – Antique postcard shows rocks scarred by glacial erosion.
3. Drift (geology) – In geology, drift is the name for all material of glacial origin found anywhere on land or at sea, including sediment and large rocks. Glacial origin refers to erosion, transportation and deposition by glaciers, in the UK the term drift is commonly used to describe any deposits of Quaternary age. The Driftless Area refers to a portion of North America devoid of the glacial drift of surrounding regionsDrift (geology) – Rounded erratic boulders of crystalline rock composition that have been drifted next to Ordovician limestone bank along the shoreline in NW Osmussaar, Estonia.
4. Dropstone – Dropstones are isolated fragments of rock found within finer-grained water-deposited sedimentary rocks. They range in size from pebbles to boulders. The critical distinguishing feature is there is evidence that they were not transported by normal water currents. When deposited into fine layered mud, such evidence includes an impact depression beneath the dropstone, subsequent deposits of mud drape over the dropstone and its crater. Dropstones differ from erratics found in glacial till in that they are deposited in a lake or marine environments, Dropstones may also be deposited by a variety of non-glacial means. There are five mechanisms that produce dropstones, As glaciers move across a surface, they pluck rocks from it. At the coast, fragments of glacier detach and float away as icebergs, which are often transported many miles into the ocean, when entrained rocks sink to the ocean floor, they can be incorporated into the oceanic sediments, which are typically fine grained. Whilst dropstones were once thought to be diagnostic of glaciers, it has since realised that they can also be formed via volcanic eruptions. Volcanic bombs are large fragments of rock, projected many miles by the force of an eruption, if these land in fine sediments, they can form dropstones. Dropstones originating in this fashion are rare in the geological record as most will land on high ground. However, a large blast may spread bombs far enough for them to end up in a setting of fine enough sediment for them to be recognised. Dropstones can also be deposited through the action of strong ocean-floor turbidity currents, whilst turbidity currents are cited as the origin of the boulders, they are not found in association with deposits formed by them. Stones can also be transported large distances by becoming bound in a raft of floating plant material or in the roots of floating trees, when such a raft disintegrates due to waterlogging and sinking of its constituents, the transported rocks would also sink. Dropstones formed in this manner are typically associated with organic matter, vertebrates may also act as rafts by ingesting gastroliths and depositing them in standing bodies of water by regurgitation or when the organism dies. Meteorites landing in marine environments are a fifth category of dropstone. A number of meteorites have been found in Swedens Thorsberg quarry, glacial erratic Ice rafting Media related to Dropstones at Wikimedia CommonsDropstone – A dropstone of quartzite in layered rhythmite at Itu, Brazil.
5. Till – Till or glacial till is unsorted glacial sediment. Till is derived from the erosion and entrainment of material by the ice of a glacier. It is deposited some distance down-ice to form terminal, lateral, medial, till is classified into primary deposits, laid down directly by glaciers, and secondary deposits, reworked by fluvial transport and other processes. Glacial drift is the graded and extremely heterogeneous sediment of a glacier. Its content may vary from clays to mixtures of clay, sand, gravel and this material is mostly derived from the subglacial erosion and entrainment by the moving ice of the glaciers of previously available unconsolidated sediments. Bedrock can also be eroded through the action of glacial plucking and abrasion, eventually, the sedimentary assemblage forming this bed will be abandoned some distance down-ice from its various sources. This is the process of glacial till deposition, when this deposition occurs at the base of the moving ice of a glacier, the sediment is called lodgement till. Rarely, eroded unconsolidated sediments can be preserved in the till along with their original sedimentary structures, till is deposited at the terminal moraine, along the lateral and medial moraines and in the ground moraine of a glacier. Prospectors use trace minerals in tills as clues to follow the glacier upstream to find kimberlite diamond deposits, in cases where till has been indurated or lithified by subsequent burial into solid rock, it is known as the sedimentary rock tillite. Matching beds of ancient tillites on opposite sides of the south Atlantic Ocean provided early evidence for continental drift, the same tillites also provide some support to the Precambrian Snowball Earth glaciation event hypothesis. There are various types of classifying tills, primary deposits – laid down directly by glacier action secondary deposits – reworked by fluvial transport, erosion, traditionally a further set of divisions has been made to primary deposits, based upon the method of deposition. Lodgement tills – sediment which has been deposited by plastering of glacial debris from a sliding glacier bed, deformation tills – Sediment which has been disaggregated and homogenised by shearing in the sub glacial deformed layer. Melt out tills – Released by melting of stagnant or slowly moving debris-rich glacier ice, split up into sub glacial melt out till and supraglacial melt-out till. Sublimation till – similar to melt out till, except the ice is lost through sublimation rather than melt, often occurs only in extremely cold and arid conditions, mainly in Antarctica. Van der Meer et al.2003 have suggested that these classifications are outdated and should instead be replaced with only one classificationTill – Closeup of glacial till. Note that the larger grains (pebbles and gravel) in the till are completely surrounded by the matrix of finer material (silt and sand), and this characteristic, known as matrix support, is diagnostic of till.