A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited summit area, and is usually higher than a hill, typically rising at least 300 metres (1,000 feet) above the surrounding land. A few mountains are isolated summits, but most occur in mountain ranges.
High elevations on mountains produce colder climates than at sea level at similar latitude. These colder climates strongly affect the ecosystems of mountains: different elevations have different plants and animals. Because of the less hospitable terrain and climate, mountains tend to be used less for agriculture and more for resource extraction, such as mining and logging, along with recreation, such as mountain climbing and skiing.
A tunnel valley is a U-shaped valley originally cut under the glacial ice near the margin of continental ice sheets such as that now covering Antarctica and formerly covering portions of all continents during past glacial ages. They can be as long as 100 km (62 mi), 4 km (2.5 mi) wide, and 400 m (1,300 ft) deep.
Tunnel valleys were formed by subglacial erosion by water and served as subglacial drainage pathways carrying large volumes of meltwater. Their cross-sections often exhibit steep-sided flanks similar to fjord walls. They presently appear as dry valleys, lakes, seabed depressions, and as areas filled with sediment. If they are filled with sediment, their lower layers are filled primarily with glacial, glaciofluvial or glaciolacustrine sediment, supplemented by upper layers of temperate infill. They can be found in areas formerly covered by glacial ice sheets including Africa, Asia, North America, Europe, Australia and offshore in the North Sea, the Atlantic and in waters near Antarctica. (Full article...)
A traverse is a lateral move or route when climbing or descending (including skiing); going mainly sideways rather than up or down. The general sense of 'a Traverse' is to cross, or cut across and in general mountaineering, a road or path traveled traverses the steep gradient of the face. In civil engineering, road bed cuttings (or 'traverses') dug by construction operations creating an navigable incline into a hillside traverse the slope, also cut across the gradient as does the skier, climber, or builder. (Full article...)
Image 25The Andes, the world's longest mountain range on the surface of the Earth, have a dramatic impact on the climate of South America (from Mountain range)
Image 26The northern Urals at high latitude and elevation have an alpine climate and barren ground. (from Mountain)
Image 27This 1848 "Sketch showing the actual elevation of the Snow Line in different Latitudes" by Alexander Keith Johnston shows the snow lines of mountains in America, Europe and Asia (from Snow line)
Speed skiing is the sport of skiing downhill in a straight line at as high a speed as possible, as timed over a fixed stretch of ski slope. There are two types of contest: breaking an existing speed record or having the fastest run at a given competition. Speed skiers regularly exceed 200 kilometres per hour (124 mph) (Full article...)