Glaciers erosion

Hallet, B., Hunter, L., and Bogen, J. (1996). Rates of erosion and sediment yield by glaciers A review of... 

Glaciers are powerful agents of physical erosion. In a detailed geomorphological study of the glaciated Canadian Shield, Sugden (1978) concluded that erosional style was related primarily to the basal thermal regime of the ice. From the center of divergence on an ice cap. 

The estimation of depth of erosion by continental ice sheets has been a controversial endeavor. In mountainous regions such as the North American Rockies, alpine glaciers have... 

The clastic sedimentary rocks are the most common forms. They arise when an original rock wears down due to mechanical erosion and the weathering products are transported by gravity, mudflows, running water, glaciers and wind and eventually sorted by size deposited in various settings. 

Mechanical erosion is influenced by temperature differences, plant roots, wind, water and glaciers. A well-known example is frost which not only affects nature but can also have annoying consequences inside, just think of frozen water pipes. In both cases the fact that water increases in volume when it freezes is the cause of all problems. 

Loess is especially common in parts of China and US Midwestern states. Chinese loess primarily forms from the wind erosion of the uplifting Himalaya Mountains under arid and semiarid conditions. In the US Midwest, loess accumulated as winds scoured deposits left by retreating glaciers about 10000 years ago (Press and Siever, 2001), 318-319. 

Erosion from wind, water, or glaciers picks up materials from weathering rocks and deposits them as sediments or soil. A process called lithification describes the conversion of sediments to sedimentary rocks. In contrast to the parent igneous rocks, sediments and sedimentary rocks are porous, soft, and chemically reactive. Metamorphic rock is formed by the action of heat and pressure on sedimentary, igneous, or other kinds of metamorphic rock that are not in a molten state. 

Figure 6 Glacial chemical-erosion rates, as measured by the cationic fluxes, for a range of glaciers worldwide as a function of specific annual runoff. Higher cationic fluxes for a given specific runoff are associated with carbonate/carbonate-rich (C-rich) and basaltic bedrock lithologies. Lower fluxes are associated with other sedimentary (sed) and plutonic/metamorphic bedrocks (Pl/m) (after Hodson et aL, 2000) (reproduced by permission of John Wiley Sons from Earth Surf.

In the valley at the bottom of this mountain, there may be a river or a glacier removing material from the base of the talus slope and transporting it away. Removal and transport by a flowing medium (rivers, glaciers, wind) is termed erosion. 

The dominant processes controlling metal distribution in the Southern Ocean, in particular the effects of local phenomena on the water composition, such as formation and melting of pack ice and bed rock erosion due to glacier flow, should be clarified. Here an overview is given of the distribution of some trace metals of particular interest. 

Iron may be supplied to the euphotic zone from advective and diffusive processes within the ocean as well as by atmospheric deposition of particulate matter to the ocean surface. In coastal areas the water composition can be affected by the contribution of rivers and in polar regions the glacier effect, in terms of ice melt and erosion during the ice flow, can be important. 

Equator for a time.3 This would have meant that all the land masses on Earth were free of ice. To understand why this should matter, we must look at what happens when rock is exposed to the air, or to warm oceans with plentiful carbon dioxide. Rock can be eroded by dissolved carbon dioxide, which is weakly acidic. As a result of this reaction, carbon dioxide is lost from the air and becomes petrified in carbonates. But when glaciers form over land, the underlying rock becomes insulated from the air by the thick layer of ice. This means that the rate of rock erosion by carbon dioxide is cut to a fraction and the carbon dioxide stays in the air. In fact, in such a situation, carbon dioxide actually builds up in the air, because it is also emitted more or less continuously from active volcanoes. 

---