CHAPTER 7.1B
GLACIERS
LANDFORMS CREATED BY GLACIAL EROSION
• Glaciers produce things like glacial troughs,
hanging valleys, cirques, aretes, and horns.
GLACIATED VALLEYS
• A glacier will wide, deepen, and straighten a
once narrow valley. It changes it from a Vshaped valley to a U-shaped glacial trough.
• The amount of glacial erosion depends on the
thickness of the ice. This produces an area with
higher valley walls that produce big waterfalls.
CIRQUES
• This is a bowl-shaped depression at the head of
a glacial valley that is surrounded on 3 sides by
steep rock walls. They form where snow and ice
accumulate at the head of a valley glacier.
ARETES AND HORNS
• Aretes are snaking, sharpedged ridges. Horns
are pyramid-like peaks.
• The Matterhorn in Switzerland is an example of
a horn.
GLACIAL DEPOSITS
• When a glacier melts it deposits sediment.
TYPES OF GLACIAL DRIFT
• Glacial drift is all sediments of glacial origin, no
matter how, where, or in what form they were
deposited. There are 2 types:
•
Till is material deposited directly by the glacier.
These are usually unsorted mixtures made of
many different particle sizes.
•
Stratified drift – this is sediment laid down by
glacial melt water. They are sorted according to
size and weight of the debris. It is made of a lot
of sand and gravel.
MORAINES, OUTWASH PLAINS, AND KETTLES
• This are all depositional features. When glaciers
melt they leave layers or ridges called moraines.
LATERAL MORAINES
• Lateral moraines are ridges that form along the
sides of glacier valleys when the glacier melts
and leaves material that it has gathered.
• Medial moraines are when 2 valley glaciers joint
to form a single ice stream.
END MORAINES AND GROUND MORAINES
• When a glacier doesn’t move for a long period
of time the ice is still flowing in the glacier and it
moves rock and material to the end of the
glacier, the deposits are called an end moraine.
• Ground moraines occur when a glacier begins
to recede. The front of the glacier melts and
leaves sediment.
OUTWASH PLAINS
• This is when a glacier is melting and the
sediments accumulate and make an ice sheet
called an outwash plain.
KETTLES
• These are depressions and small lakes.
DRUMLINS AND ESKERS
• Drumlins are hills made of till. It will have a
steep side that faces the direction the ice came
from and a gentler slope that points in the
direction the ice moved.
• Eskers are snake-like ridges made of sand and
gravel.