Corrie, cirque, cwm hollow where a glacier formed

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Corrie, cirque, cwm hollow where a glacier
formed Armchair shaped hollow usually northerly
aspect in UK and N. Hemisphere. Steep back
wall e.g. Llyn Cau on Cader Idris
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Llyn Cau -Corrie lake - Or tarn Back wall of
corrie plucking Overdeepening of hollow
abrasion Rotational slip at base of
glacier Corrie lip at front edge
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Looking down into a tarn From high up on the
backwall Backwall subject to freeze thaw
weathering in post-glacial periglacial times
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An arete A knife edge ridge formed where two
cories developed back to back This example is
Striding Edge on Helvellyn in the Lake District.
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A pyramidal peak or horn e.g. Matterhorn Where 3
or more corries form back to back
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A glacial trough or U shaped valley. Steep sides
are truncated spurs prexisting river valley
profile altered by glacial erosion Ice more
effective at eroding by Plucking and abrasion
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A hanging valley and waterfall called Bird Woman
Falls near Mt. Oberlin, Canadian Rockies.
A smaller tributary glacier could not erode the
base of its valley as deep as the main valley
glacier. Thus after the ice melts the smaller
valley is left hanging above the main valley
floor and enters it at up to 90.
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A fjord is a drowned glaciated valley. The ice
did not use present day sea level as its base
level The ice could erode much deeper than
todays sea level. So after the Ice Age the sea
enter and drowned glaciated valleys. Many
examples in Norway
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Wastwater
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In some areas the glaciated valley can be
overdeepened by glacial erosion. Perhaps the
rocks locally were less resistant. Alluvial fans
may be formed where a post glacial stream flows
into the lake. The lake may be split into two.
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Keswick lies between Derwentwater and
Bassenthwaite. Interlaken is another
example. Lakes are temporary features they fill
up with sediment or the post glacial reiver cuts
down through the dam blocking the lake so that
all the water drains away.
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These striations are on rocks in the Indian Peaks
Wilderness, Utah. They were formed as individual
particles carried at the base of a glacier moved
across the bedrock and scratched the rock. The
striations provide important clues to the
orientation of ice flow, particularly important
if we were not around to observe the glacier when
it existed.
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Definition rock hills shaped by the passage of
ice to give  a smooth up-ice side and a rough,
plucked and cliffed surface on the down-ice side.
The upstream surface is often marked with
striations.