Glacial landform

The Glazialmorphologie describes and explains the structure and origin of landforms caused by glaciers and their meltwater.

Etymology

Glazialmorphologie is a hybrid word, it is a combination of words in both Greek and Latin origin. " Glacial " is derived from the Latin word " glacies ", meaning ice, metonymically often brittleness or hardness. " Morphology " in turn, is of Greek origin: " morph " comes from the Greek μορφή, morphé = shape or form, " logos" of λόγος, lógos = word, doctrine, reason.

The word as a whole considered thus means the " science of the forms of ice ", so are the glaciers and other ice deposits, and their geophysical tracks meant.

Structure of glaciers

Glaciers are basically comprised of a accumulation zone ( = accumulation area ) and an ablation zone ( = ablation ), where the former is located at high altitudes, where more snow falls than defrosted and evaporated. The glacier moves below the snow or firn line in the ablation zone, where more ice melts than is formed ( = ablation).

Glacier surfaces are usually torn by many columns, caused by the movement of the glacier, which in turn is made ​​possible by the refreezing. Transverse crevasses are found where the glacier over obstacles such as boulders, which are buried under the ice, flowing or if the ground is steep, the glacial ice flows faster on the surface and crack on. Marginal gaps are found where the glacier flows faster in the center than at the edge, and so the ice ruptures there, like the water turbulence that occur in rivers at the edge. Edge rifts, however, when the glacial ice melts due reinforced by the heating of the surrounding rock at the edge of the glacier. Longitudinal columns are usually located on the front side of the glacier, in the area of the glacier tongue where it is wider and the ice has more space to spread out to the left and right, and fans out thus.

Moraines

The whole of the material transported by a glacier is called moraine. As the solid body can glaciers all grain sizes from clay to sand to large blocks ( boulders ) transported. Furthermore, glacial ice take up a lot of material, so that the transport capacity is also very large. In contrast to the deposits of the water the rock materials are unsorted in moraines and mostly unstratified.

The term moraine is now used in various contexts.

• On the one hand is referred to as the material being transported is an active glacier. Depending on the location in or on the glacier differentiation is high, interior, side, middle, bottom, or terminal moraines. This material is still in motion. While in valley glaciers and glacier related types can all Moränenarten occur, the ice sheet related glaciers have only Untermoränen usually. The other Moränenarten are usually caused by rockfall from towering valley sides. The material then remains on the glacier are or may be incorporated by the flow of the ice in the glacier.
• On the other hand, also be deposited by the glacier, and thus no longer called moving sediments and forms a moraine. Can you see where they were transported as compared to the glacier still, to use for valley glaciers in the same terms as for the active moraines.
• The terms ground moraine and end moraine are today usually only applied to the corresponding forms. The sediment of the ground moraine on the other hand is referred to as boulder clay or till.

Moränenarten

Lateral moraines accompany the glacier already in the upper part of the valley trough. It stores the low collapsing on him rock from the side and pushes it down into the valley. Here, the rubble to waves orders flanking the flowing ice. At the confluence of the glacier tongues ( confluence) that lie at the inner edge of lateral moraines are combined to medial. It separates the originating from the different areas of origin ice streams from each other and remains as debris in the Wall Glacier. While the leading- water mix very quickly in a river, the glacial ice flows in the so-called composite glaciers side by side.

The terminal moraine ( = moraine ) is a rubble wall at the end of the glacier, the glacier tongue surrounding semicircular. However, a prerequisite for the formation of such a moraine that the Glacier is a long time in the same place that it is stationary. The performance by the glacier again and again, the terminal moraine is compressed and pushed together ( moraine ). The glacier facing slope here is steeper than the outside of the Moränenwalls.

Melts from a glacier, several moraines can arise when longer holding periods are switched on. Moraines act like dams (they are often up to 200 m high), many lakes of the Alpine foothills and Alps have emerged along with the ausschürfenden power of the glacier, because the basin have filled with water.

The Untermoräne ( ground moraine ) can be found at the bottom of a glacier stream, particularly where much rock material is transported. The debris is from the surface of the glacier, where he gradually sinking down the bottom of the Eisstromes reached or directly from the material out of the glacier scars from the underground. The rock pieces of the ground moraine are more intense rounded edges than the other moraines, and the proportion of fine grain sizes is higher, but there are also large boulders ( erratics ).

Deposits and shapes of melt water

The forms and deposits of melt water (technical term: glazifluvial ) not be called moraines.

Melting glacier water forms in the systems of channels, gullies and manholes under the ice, it joins the bottom of the glacier and then enters the glacier back to the surface. It is usually mixed with powdered stone, so that it has a white to gray color, it is therefore called glacier milk. Except by melting may lose substance of the glacier also by breaking chunks of ice, this happens when the glacier flows into a lake or the sea. This process is called calving.

• Glaciology
• Geomorphology