Download Glacial Erosion and Deposition

Glacial Erosion and
Deposition
Erosion
• Glaciers have the capacity to carry huge
rocks and piles of debris over large
distances
• They grind out parallel scratches in the
bedrock
– Small scratches are called grooves and larger
ones are called striations
• As valley glaciers erode the land over which they
move, they carve out various U-shaped valleys
and mountain landforms:
Cirques, Aretes and Horns
Deposition
• Glacial deposits are unsorted, unlayered
deposits of various types
• Particles carried by a glacier tend to have
an angular to round shape and a rough
texture
• Much of the debris is left behind in ridges
called moraines
– Terminal moraines mark the farthest advance
of a glacier
Moraines
Glacial Sediment
• Till is the unsorted
rock material directly
deposited by glacial
ice
Glacial Sediment
Erratic – a
large rock
deposited
by a
glacier
Glacial Sediment
• Drumlins – canoe shaped hills of unsorted
sediments that form as a glacier moves over the
land
• They indicate the direction of glacial movement
Outwash Plains
• Beyond the terminal moraine, meltwater
runs and carries sediments of gravel,
sand, silt and clay
• These are deposited in sorted layers as
they are being deposited by running water
as a result of the melting glacier (not by
the ice directly)
Outwash plain in front of Thompson Glacier,
Axel Heiberg Island, Canadian Arctic
When the glacier melts/retreats:
• Gouges out land that becomes filled with
meltwater forming lakes (Finger Lakes)
• Scoops out shallow basins that fill with water
called kettle lakes
Formation of Kettle Lake
Kettle Lakes
Toe of a valley glacier:
• Glacier Review