Download Glacier Powerpoint- for May 29, 2008

How do Glaciers Effect the
Land?
By erosion & deposition
 Glacial
erosion forms when glaciers
sculpt, carve and carry away the land
beneath them.
 Glacial
deposition is created by
deposition, or what a glacier leaves as
it retreats or melts away.
Glacial Erosion
A
glacier's weight and movement, can
re-shape the landscape. (this takes
hundreds or thousands of years)
 The
ice erodes the land surface and
carries the broken rocks and soil debris
away.
Types of Glacial Erosion
Glacial Valleys
Horns
Fjords
Cirques
Aretes
Glacial Valleys

trough-shaped, with steep
vertical cliffs where entire
mountainsides were
removed by glacial action.

Ex: Yosemite National
Park. glaciers sheared away
mountainsides, creating
deep valleys with vertical
walls.

Yo
Hanging Valley



Forms when small tributary glaciers join larger glaciers
Since small glaciers are unable to erode down into the
landscape very far a hanging valley formed.
The larger the glacier, the deeper the valley it can
erode.
Look at the hanging valley!
Fjords
 Long, narrow coastal
valleys with steep sides
& rounded bottoms.
 Fjords form when a
glacier erodes the land
below sea level. When
the glacier melts, the
ocean water fills in the
valley floor.
Cirques

Created when glaciers erode backwards into
mountainsides, creating rounded hollows
shaped like shallow bowls.
Tarn Lake

A tarn is a mountain lake or pool, formed in
a cirque after the glacier melts.
Aretes

Jagged, narrow ridges created where the back walls
of two cirque glaciers meet, eroding the ridge on
both sides.
Arete 
Horns
 Created when several cirque
glaciers erode a mountain until
all that is left is a steep, pointed
peak with sharp, ridge-like
aretes leading up to the top.
Matterhorn in Switzerland
Types of Glacial Erosion
Glacial Deposition

Landforms are also created by deposition,
or what a glacier leaves as it retreats or
melts away.
Kettle Lakes
Moraines
Kames
Till
Erratic Boulders
Drumlins
Till


Material that is
deposited as glaciers
retreat, leaving behind
mounds of gravel, small
rocks, sand and mud.
It is made from the
rock and soil ground up
beneath the glacier as it
moves.
Moraines




Material a glacier picks up or pushes as it moves.
They form along the surface and sides of the
glacier.
As a glacier retreats, the ice melts away from
underneath the moraines, leaving long, narrow
ridges that show where the glacier used to be.
Glaciers don't always leave moraines behind,
because sometimes the glacier's own meltwater
carries the material away.
Types of Moraines
Medial Moraine
Kames


Small steep-sided mounds of soil and gravel that
form adjacent to the glacier.
They form from streams flowing out of the
glacier that carry rock and soil.
Kettle lakes


Form when a piece of glacier ice breaks off &
becomes buried by glacial till or moraine deposits.
Over time the ice melts, leaving a small depression
in the land, filled with water. very small, more like
ponds than lakes.
Erratic Boulders


Glaciers pick up rocks as
they slowly move along.
The glaciers carry the
rocks far away from their
source.
When glaciers melt they
leave behind anything they
pick up along the way
(huge rocks, called erratic
boulders)
Drumlins




long, streamlined tear-drop-shaped formations.
They form when a glacier deposits material as it
is flowing and then moves over it.
Because they are deposited and shaped by
glacier movement, all the drumlins left by a
particular glacier will face the same direction.
Often, groups of several thousand drumlins are
found in one place, looking very much like
whalebacks when seen from above.
Drumlins
Glacial Striations

are scratches or gouges cut into the bedrock by
process of glacial abrasion.