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Drumlin Field
A drumlin, from the Irish word ("little ridge"), first recorded in 1833, in the classical sense is an elongated hill in the shape of an inverted spoon or half-buried egg formed by glacial ice acting on underlying unconsolidated till or ground moraine. Assemblages of drumlins are referred to as fields or swarms; they can create a landscape which is often described as having a 'basket of eggs topography'. Morphology Drumlins occur in various shapes and sizes, including symmetrical (about the long axis), spindle, parabolic forms, and transverse asymmetrical forms. Generally, they are elongated, oval-shaped hills, with a long axis parallel to the orientation of ice flow and with an up-ice (stoss) face that is generally steeper than the down-ice (lee) face. Drumlins are typically between long and between wide. Drumlins generally have a length to width ratio of between 1.7 and 4.1 and it has been suggested that this ratio can indicate the velocity of the glacier. That is, since ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drumlins Around Horicon Marsh In Wisconsin
A drumlin, from the Irish Gaelic, Irish word ("little ridge"), first recorded in 1833, in the classical sense is an elongated hill in the shape of an inverted spoon or half-buried egg formed by glacier, glacial ice acting on underlying unconsolidated till or ground moraine. Assemblages of drumlins are referred to as fields or swarms; they can create a landscape which is often described as having a 'basket of eggs topography'. Morphology Drumlins occur in various shapes and sizes, including symmetrical (about the long axis), spindle, parabolic forms, and transverse asymmetrical forms. Generally, they are elongated, oval-shaped hills, with a long axis parallel to the orientation of ice flow and with an up-ice (stoss) face that is generally steeper than the down-ice (lee) face. Drumlins are typically between long and between wide. Drumlins generally have a length to width ratio of between 1.7 and 4.1 and it has been suggested that this ratio can indicate the velocity of the gla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gravel
Gravel () is a loose aggregation of rock fragments. Gravel occurs naturally on Earth as a result of sedimentation, sedimentary and erosion, erosive geological processes; it is also produced in large quantities commercially as crushed stone. Gravel is classified by grain size, particle size range and includes size classes from granule (geology), granule- to boulder-sized fragments. In the grain size, Udden-Wentworth scale gravel is categorized into granular gravel () and pebble gravel (). ISO 14688 grades gravels as fine, medium, and coarse, with ranges for fine and for coarse. One cubic metre of gravel typically weighs about , or one cubic yard weighs about . Gravel is an important commercial product, with a number of applications. Almost half of all gravel production is used as construction aggregate, aggregate for concrete. Much of the rest is used for road construction, either in the road base or as the road surface (with or without bitumen, asphalt or other binders.) Natu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ireland
Ireland (, ; ; Ulster Scots dialect, Ulster-Scots: ) is an island in the North Atlantic Ocean, in Northwestern Europe. Geopolitically, the island is divided between the Republic of Ireland (officially Names of the Irish state, named Irelanda sovereign state covering five-sixths of the island) and Northern Ireland (part of the United Kingdomcovering the remaining sixth). It is separated from Great Britain to its east by the North Channel (Great Britain and Ireland), North Channel, the Irish Sea, and St George's Channel. Ireland is the List of islands of the British Isles, second-largest island of the British Isles, the List of European islands by area, third-largest in Europe, and the List of islands by area, twentieth-largest in the world. As of 2022, the Irish population analysis, population of the entire island is just over 7 million, with 5.1 million in the Republic of Ireland and 1.9 million in Northern Ireland, ranking it the List of European islands by population, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clew Bay
Clew Bay (; ) is a large ocean bay on the Atlantic coast of County Mayo, Ireland. It is roughly rectangular and has more than a hundred small islands on its landward side; Ireland's best example of sunken drumlins. The larger Clare Island guards the entrance of the bay. The bay is overlooked by Croagh Patrick to the south and the Nephin Beg Mountains to the north. From the southwest part of the bay eastwards are the settlements Louisburgh, Lecanvey, Murrisk, and Westport; north of Westport is Newport, and westwards from there lies Mulranny, gateway to Achill. History The bay was historically known in Irish as ''Cuan Mod'' ("harbour of Mod") or ''Modlind'' ("pool of Mod"), and was associated with the Fir Bolg. This later became ''Cuan Modha''. Some writers claim that this name derives from Modh, one of the Tuatha Dé Danann. Another possibility is the Old Irish ''mod'', ''moth'', which meant "penis" or "man". Another old name is ''Cuan Umhaill'' ("harbour of Umhai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clew Bay, Ireland (ASTER)
Sail components include the features that define a sail's shape and function, plus its constituent parts from which it is manufactured. A sail may be classified in a variety of ways, including by its orientation to the vessel (e.g. ''fore-and-aft'') and its shape, (e.g. ''(a)symmetrical'', ''triangular'', ''quadrilateral'', etc.). Sails are typically constructed out of flexible material that is shaped by various means, while in use, to offer an appropriate airfoil, according to the strength and apparent direction of the wind. A variety of features and fittings allow the sail to be attached to lines and spars. Whereas conventional sails form an airfoil with one layer of fabric, wingsails comprise a structure that has material on both sides to form an airfoil—much like a wing placed vertically on the vessel—and are beyond the scope of this article. Classifications Sails may be classified as either ''triangular'', which describes sails that either come to one point of suspen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glaciofluvial Deposits
Fluvioglacial landforms or glaciofluvial landforms are those that result from the associated erosion and deposition of sediments caused by glacial meltwater. Glaciers contain suspended sediment loads, much of which is initially picked up from the underlying landmass. Landforms are shaped by glacial erosion through processes such as glacial quarrying, abrasion, and meltwater. Glacial meltwater contributes to the erosion of bedrock through both mechanical and chemical processes.Glasser, N. F. & Bennett, M. R. Glacial erosional landforms: Origins and significance for palaeoglaciology. ''Prog. Phys. Geogr.'' 28, 43–75 (2004). Fluvio-glacial processes can occur on the surface and within the glacier. The deposits that happen within the glacier are revealed after the entire glacier melts or partially retreats. Fluvio-glacial landforms and erosional surfaces include: outwash plains, kames, kame terraces, kettle holes, eskers, varves, and proglacial lakes. Meltwater streams and fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shear Stress
Shear stress (often denoted by , Greek alphabet, Greek: tau) is the component of stress (physics), stress coplanar with a material cross section. It arises from the shear force, the component of force vector parallel to the material cross section. ''Normal stress'', on the other hand, arises from the force vector component perpendicular to the material cross section on which it acts. General shear stress The formula to calculate average shear stress or force per unit area is: \tau = ,where is the force applied and is the cross-sectional area. The area involved corresponds to the material face (geometry), face parallel to the applied force vector, i.e., with surface normal vector perpendicular to the force. Other forms Wall shear stress Wall shear stress expresses the retarding force (per unit area) from a wall in the layers of a fluid flowing next to the wall. It is defined as:\tau_w := \mu\left.\frac\_,where is the dynamic viscosity, is the flow velocity, and is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clastic Rock
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 b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limestone
Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science), crystal forms of calcium carbonate . Limestone forms when these minerals Precipitation (chemistry), 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 (rock), dolomite, a closely related rock, which contains a high percentage of the mineral Dolomite (mine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Granite
Granite ( ) is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies underground. It is common in the continental crust of Earth, where it is found in igneous intrusions. These range in size from dike (geology), dikes only a few centimeters across to batholiths exposed over hundreds of square kilometers. Granite is typical of a larger family of ''granitic rocks'', or ''granitoids'', that are composed mostly of coarse-grained quartz and feldspars in varying proportions. These rocks are classified by the relative percentages of quartz, alkali feldspar, and plagioclase (the QAPF diagram, QAPF classification), with true granite representing granitic rocks rich in quartz and alkali feldspar. Most granitic rocks also contain mica or amphibole minerals, though a few (known as leucogranites) conta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dilatancy (granular Material)
In soil mechanics, dilatancy or shear dilatancy is the volume change observed in granular materials when they are subjected to shearing (physics), shear deformations. This effect was first described scientifically by Osborne Reynolds in 1885/1886 and is also known as Reynolds dilatancy. It was brought into the field of geotechnical engineering by . Unlike most other solid materials, the tendency of a compacted dense granular material is to dilate (expand in volume) as it is sheared. This occurs because the grains in a compacted state are interlocking and therefore do not have the freedom to move around one another. When stressed, a lever motion occurs between neighboring grains, which produces a bulk expansion of the material. On the other hand, when a granular material starts in a very loose state it may continuously soil compaction, compact instead of dilating under shear. A sample of a material is called dilative if its volume increases with increasing shear and contracti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
