High elevations on mountains produce colder climates than at sea level. 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 and recreation, such as mountain climbing.
Drumlins around Horicon Marsh, Wisconsin. Note the curve (click to enlarge) in the direction of flow of the old Wisconsin Ice Sheet. This area has one of the highest concentration of drumlins in the world.
A drumlin, from the Irish word droimnín ("littlest ridge"), first recorded in 1833, and 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. Read more...
The Richat Structure in the Sahara Desert of Mauritania. Briefly considered to be an impact structure, it is now believed by most to be a structural dome.
A dome is a feature in structural geology consisting of symmetrical anticlines that intersect each other at their respective apices. Intact, domes are distinct, rounded, spherical-to-ellipsoidal-shaped protrusions on the Earth's surface. However, a transect parallel to Earth's surface of a dome features concentric rings of strata. Consequently, if the top of a dome has been eroded flat, the resulting structure in plan view appears as a bullseye, with the youngest rock layers at the outside, and each ring growing progressively older moving inwards. These strata would have been horizontal at the time of deposition, then later deformed by the uplift associated with dome formation. Read more...
Selected glacier-related article
Sognefjord in Norway, the second longest fjord in the world, shows characteristic overdeepening.
Overdeepening is a characteristic of basins and valleys eroded by glaciers. An overdeepened valley profile is often eroded to depths which are hundreds of metres below the deepest continuous line (the thalweg) along a valley or watercourse. This phenomenon is observed under modern day glaciers, in salt-water fjords and fresh-water lakes remaining after glaciers melt, as well as in tunnel valleys which are partially or totally filled with sediment. When the channel produced by a glacier is filled with debris, the subsurface geomorphic structure is found to be erosionally cut into bedrock and subsequently filled by sediments. These overdeepened cuts into bedrock structures can reach a depth of several hundred metres below the valley floor.
Overdeepened fjords and lakes have significant economic value as harbours and fisheries. Overdeepened basins and valleys filled with sediment (termed tunnel valleys) are of particular interest to engineers, petroleum geologists, and hydrologists; engineers apply the information for developing foundations and tunnel construction, petroleum geologists use tunnel valley locations to identify potential oil fields, while hydrologists apply this knowledge for groundwater resource management. Read more...
Selected climbing article
A figure-eight loop (also figure-eight on a bight, figure-eight follow-through, Flemish loop, or Flemish eight) is a type of knot created by a loop on the bight. It is used in climbing and caving where rope strains are light to moderate and for decorative purposes. The knot is commonly followed by tying a strangle knot (a.k.a. half a double fisherman's knot) or an overhand knot around the standing end.
The double figure eight is used to put a loop in the end of a rope, or around an object. It is relatively easy to tie and is secure, but can become difficult to untie after heavy loading, and can jam badly in any rope type. Read more...
A climber taking the final few steps onto the 6,160 m (20,210 ft) summit of Imja Tse (Island Peak) in Nepal, 2004
A packrafter passes a wall of freshly exposed blue ice on Spencer Glacier, in Alaska. Glacial ice acts like a filter on light, and the more time light can spend traveling through ice, the bluer it becomes.
Glacier as seen by HiRISE under the HiWish program. Area in rectangle is enlarged in the next photo. Zone of accumulation of snow at the top. Glacier is moving down valley, then spreading out on plain. Evidence for flow comes from the many lines on surface. Location is in Protonilus Mensae in Ismenius Lacus quadrangle.
Enlargement of area in rectangle of the previous image. On Earth the ridge would be called the terminal moraine of an alpine glacier. Picture taken with HiRISE under the HiWish program. Image from Ismenius Lacus quadrangle.
Shear or herring-bone crevasses on Emmons Glacier (Mount Rainier); such crevasses often form near the edge of a glacier where interactions with underlying or marginal rock impede flow. In this case, the impediment appears to be some distance from the near margin of the glacier.
Mountaineers descending mixed rock, snow and ice slope in winter High Tatras, Slovakia
Mountain rescue team members and other services attend to a casualty in Freiburg Germany.
Aerial view of a glacier in Chugach State Park, Alaska, United States.