Term
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Definition
bodies of ice that are sufficiently thick that the ice flows
not to be confused with permanent snow fields and thin bodies of ice that also flow or with ice floating on water (though some glaciers that terminate in the ocean will have a floating tongue) |
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Term
| how are glaciers related to fresh water? |
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Definition
| they hare the largest reservoir of fresh water on earth, though not always accessible |
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Term
| how does loss of glacier ice contribute to sea level? |
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Definition
| loss of glacier ice causes sea level rise. glaciers are the second largest contributor to current sea level rise, they have the potential to cause around a meter of sea level rise in the next century |
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Term
| how do glaciers affect the landscape? |
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Definition
| they create asthetically appealing landscapes (dotted with cirques, aretes, horns, patenoster lakes) and they produce fine-grained rock flour that is a good basis for fertile soil formation |
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Term
| how do glaciers respond to climate change? |
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Definition
they advance and retreat, acting as a good indicator of climate, helping us interpret past climate change and better predict future climate change
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Term
| where are the best terrestrial archives of climate history found? |
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Definition
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Term
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Definition
| snow falls, if it does not melt over the summer, it begins the slow metamorphosis into ice. eventually, enough ice accumulates to begin deforming under its own weight, and there you are, a flowing body of ice that we call a glacier |
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Term
| what is the composition of new snow? |
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Definition
| the snow crystals come in a variety of shapes, but in general they produce a low density (fluffy) pile of small ice crystals. the density is 50-70kg/m3 with porosity of up to 90% |
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Term
| how does snow undergo metamorphism? what happens to the ice crystals? how does this happen? |
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Definition
first it compacts, making it denser
metamorphism is a change in form or structure; in the case of snow metamorphosis, the snow recrystallizes
the snow crystals grow larger (small ones lost, bigger ones grow) and lose their sharp edges becoming more rounded
this occurs by vapor transport - water sublimates from one ice surface, and recrystallizes on another. ice is more likely to sublimate from a highly curved surface - a smaller crystal or a needle point of a crystal |
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Term
| what is firn and how is it composed? |
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Definition
the snow that survives at least one summer
compaction is mostly accomplished with round grains than with pointy ones, so this is much more dense than snow (due to the compaction)
density ranges frm 400-830kg/m3 |
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Term
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Definition
a process increasing density
growth of ice at points of contact, essentially gluing the ice grains together |
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Term
| how does recrystallization increase density? |
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Definition
| by internal diffusion of molecules |
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Term
| what is glacier ice? how is the air arranged in glacial ice? |
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Definition
when pore spaces are no longer interconnected
occurs at a density of 830kg/m3
pure ice has a density of 910kg/m3 so glacial ice can have densities from 830-910kg/m3
the pores in glacier ice are bubbles. the air in the bubbles does not interact with the atmosphere b/c they are sealed off
at densities greater than 830kg/m3 the air in these bubbles compresses rather than being expelled
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Term
| what are two schemes for classifying glaciers? |
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Definition
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Term
| what are two types of temperature classified glaciers? |
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Definition
| temperate glaciers and polar glaciers |
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Term
| what are temperate glaciers? |
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Definition
the glacier is at the same temperature almost everywhere in the ice - namely at the pressure melting point
the surface layer of the glacier (up to about 10m) will get colder than the melting point in the winter - will freeze
glaciologists call temperate glaciers "warm" ice
produce a lot of meltwater discharge, most erosive type of glacier (do lots of work on the landscape)
water can be present anywhere within or under the glacier |
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Term
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Definition
glaciologists "cold" ice
the ice is everywhere below the melting point, is water-free
little capability to erode their beds; glacier is frozen to the bed |
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Term
| how does the presence of water affect temperate ice? |
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Definition
| it allows the ice to slide on its bed |
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Term
| how does the low temperature of polar ice affect its flow? |
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Definition
| it makes the ice mch stiffer, hence it flows much more slowly |
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Term
| does it take longer to form glacier ice in a polar or thermal glacier? |
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Definition
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Term
| what are some reasons for the slow formation of glacial ice in polar glaciers compared to temperate glaciers? |
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Definition
the low temp of environments where polar ice is found reduce the rates of snow metamorphism
the diff in deposition rate: temperate glaciers tend to occur in high deposition rate areas. ex: the upper seward glacier is a very wet area, and the transformation from snow to ice occurs in 3-5 years at 13m depth (that's lots of snow each year) |
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Term
| what are the two categories of shape classified glaciers? |
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Definition
| ice sheet/ice caps and glaciers |
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Term
| ice sheet/ice caps, what are they? |
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Definition
large glaciers unconstrained by topography
cover most obstacles with only a few mountain peaks called nunataks sticking up through the ice (these are usually found only near the margins of the ice sheet or ice cap where it is thin)
ice sheets are the largest - the greenland ice sheet, and the antarctic ice sheets (west antarctic ice sheet and east antarctic ice sheet)
ice caps are smaller in scale, may be steered by topography on their edges. ex: Vatnajokull Ice cap in Iceland and Barnes Ice cap on Baffin Island in arctic Canada |
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Term
| what are glaciers (as far as the shape classification definition)? |
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Definition
bodies of ice that are constrained or controlled by topography
accumulate on the sides of mountains and within valleys
many types: vally, cirque, hanging, piedmont |
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