Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
29 Cards in this Set
- Front
- Back
|
what are the 5 main types of glaciers? |
cirque glacier valley glacier piedmont glacier outlet glacier Ice sheet |
|
|
what are the temperature temperate glaciers? |
the base of the glacier is at melting point (warm ice) >0 degrees which leads to a water path. |
|
|
what is the temperature of cold glaciers? |
the base of the glacier is bellow the melting point (cold ice) <0 degreese |
|
|
what is the temperature of polythermal glaciers? |
warm and cold based ice have basal and no basal water |
|
|
how do glaciers form? |
balance between temperature and precipitation which leads to a glacier mass balance. if accumulation is > ablation (mass loss) a glacier |
|
|
what does a steep glacier valley look like and ice cap/ sheet? |
|
|
|
when do you get a positive mass balance? what does this cause? |
when accumulation is greater than ablation net gain of mass: glacier thickens and advances. |
|
|
when do you get a negative mass balance and what happens? |
accumulation is less than ablation so there is a net loss of mass so the glacier retreats. |
|
|
draw the annual mass balance changes through the year: |
|
|
|
how do glaciers flow? |
according to its gravitational mass stress. this is linked to the ice thickness and how steep the surface of the slope is |
|
|
how do you potentially get a fast flow ? |
thin ice and steep slopes and thick ice and shallow slopes. |
|
|
what are the three different mechanisms that ice can move by? |
internal deformation of ice basal sliding due to the presence of melt water subglacial deformation of sediments. |
|
|
what is ice flow determined by? |
the thermal regime of the glacier: ice temp presence of melt water at the bed availability of deformable sediment. |
|
|
what are the three processes of subglacial erosion? |
crushing abrasion quarrying |
|
|
what happens during crushing? |
its when the weight of the ice/ ice pushing the rock into one another |
|
|
what happens during abrasion? |
debris at the base of the glacier at like sand paper |
|
|
what happens during quarrying? |
glacier flow phyically ripping out chunks of rocks from the bedrock. |
|
|
what are the 6 processes of glacial deposition? |
frictional drag, shear, injection, slump, basal melt and flow |
|
|
describe the glacial hydrological cycle: |
melt water is the main product of ablation and can control the rate of ice flow. it removes and transports high quantities of sediment. |
|
|
how does flow vary on a range of temporal scales in response to melt? |
diurnal (daily temps) short term (weather) annual and random |
|
|
how does the hydrological system evolve in response to melt? |
annually |
|
|
what is glacier velocity linked to? |
subglacial water pressure |
|
|
what can proglacial streams do? |
can erode and re work moraine ridges and other landforms so that evidence of post glacier behaviour can be destroyed. |
|
|
what can landforms from subglaciers tell us? |
wide range of landforms emerge. and once the ice sheets have disapeared they can tell us about the past behaviou |
|
|
how does ice sheet reconstruction take place ? |
combined geomorphological evidence available to generate ice sheet reconstructions. these can use moraines (ice marginal landforms). reconstruct ice sheet extent. can use subglacial landforms to reconstruct the ice sheet flow dynamics |
|
|
how do we know these landforms reflect these glacier dynamics? |
theres a lot of interesting things under the ice so have to look at recently deglaciated areas of fast flowing ice use a radar to look under the ice but takes a lot of effort to get a full 3D picture |
|
|
what is going to happen in the futre? |
surface melt of glacial valley glaciers and greenland ice sheet will be a significant source of sea level change there is major uncertainty in the behaviour of calving glaciers |
|
|
how much ice loss is from greenland and antarctica and what will this lead to ? |
50% greenland 90% antarctica and will contribute to the sea level. 66m approx sea level rise |
|
|
how big of a problem is this. |
everywhere below sea level west antarctica has approximately 5 m of sea level rise east antarctica has 53 m w is more likely to collapse. |
