glaciated landscapes sg2 - glacial deposition & laurentide ice sheet thing
till sheet: extensive plain unstratified drift. snout = velocity is reduced and bottom melting releases subglacial debris from sediment rich basal layer of ice. lot of erosive power to deposit vast quantities
drumlins: formed by ice (rounded, angular material) movement of ice causes streamlined shape. low energy
erratics: geologic origins are different from surrounding rocks. as ice melts boulders are abandoned and left on surface. geology of the area is different.
rock drumlin: rock core drumlins = formed because of bedrock obstruction beneath moving ice. subglacial debris is plastered around the rock (lodgement till) slower ice flow - lee side results in deposition
lateral moraine:
terminal, rec & push:
recessional moraine:
lis:
areal scouring
great lakes:
material from valley walls are broken up via freeze-thaw
carried along sides, some material is brought up valley from plucking and abrasion
ice melts & retreats - ridge is formed
form at the snout
stand still long enough for deposition to occur (sub, en & supra) builds a ridge
ice acts as a conveyor belt, moves debris to snout
valley floor deposits are thrusted upwards to form a steeper slope
removes any pre-existing superficial deposits (soil)
meaning that bedrock was exposed
erosion produced ellipsodial basins - lake basin, where the ice sheet gouged out deep depressions in the bed rock
occupy former river valleys
advance & retreat action produces many ellipsoidal basins
back and fourth movement of ice loves produce changes in lake levels
ice lobes: tongue shaped glaciers
north america latitude of 37 degrees north
13 million km squared and is 3,000m thick
positive feedback: decreasing temperatures (growth) > more surface is covered in ice which means a high reflection (albedo)
causes the climate to cool rapidly
forms behind the glacier parallel to terminal moraine
glacier = stationary long enough for a ridge of till to develop
push moraine - identified from terminal moraine it will have steeper ice contact slope
deposited material will by originally horizontal and now will show orientation