Chapter 13=glaciation
-glacier=is solid mass of moving frozen snow
Glaciation
An ice age is a period during which the large parts of several continents are covered by ice sheets the
last ice age has been over a million years ago and ended about 10,000 years ago during this time the
temperatures were so low that snow and ice did not get a chance to melt year after ryea more snow
and ice accumulated until it compacted together to form huge masses of ice called glaciers.glaciers
formed in upland areas.the effect if gravity eventually moved them downslope.some glaciers melted
while other joined together to form ice sheets which covered huge areas of land.
What causes an ice age?
(1)The earth's orbit of the sun changes from an oval or elliptical shape to a circular shape that means
that the temperature on earth does not change much because any point on the earth remains the
same distance from the sun all year round.
(2)the angle of the earth's axis changes that means that those areas of the earth's surface that are
closer to poles are tilted further from the sun and so they are colder.
Glaciers erode the rock, transport the rock and deposit rock.
Processes of glacial erosion
(1)plucking
In order for plucking to occur there needs to be friction friction produces melt water that will flow into
cracks in rock. And refreezes and expands by 9 % that then loses the rock and therefore when he
glacier moves it plucks some of the rock with it effective on rocks such as sedimentary rock like
limestone and sandstone..there is friction between the underside of the glacier and the ground
beneath it.this leads to some melting around the base of the glacier.if the glacier stops moving,the
meltwater refreezes around the rocks on the valley floor.when the glacier moves forward again,it
plucks pieces of rock from the ground and carries them away.
(2)abrasion
As the glacier ,moves along the rocks attached to it scratch and scrape the surface rock
underneath.The scratch marks left behind on rocks over which the ice has moved are called
striations.these marks tell us the direction in which the ice moved.its the force of moving glaciers and
their load(plucked rock-jagged)small stones boulders .plucking and abrasion depend on the size of
glacier and the slope/gradient the steeper the slope the faster the glacier and the resistance of the
rock sedimentary rock is a very weak rock(joints) igneous and metamorphic rock are stronger.
Lubricant=makes something slippy.
Features of glacial erosion
(1)corrie/cirque (2)aretes (3)pyramidal peaks (4) U-shaped valleys (5)ribbon lakes (6)hanging
valleys (7)fjords
Feature of glacial erosion
Feature=corrie/cirque
