Glaciers Section 9.4
Glaciers are any large mass of ice that moves over land Continental Glaciers - cover much of a continent or large island (10% of Earth’s land today - Antarctica, Greenland)
Continental Glaciers - spread out in all directions -during the last ice age, glaciers covered 1/3 of Earth and retreated 10,000 years ago
Continental Glaciers
Valley Glaciers Long narrow glacier that forms when snow and ice build up in mountains move down valleys that were cut by rivers
Valley Glaciers can be many kilometers long form in areas where more snow falls than melts
Valley Glaciers moves down hill when snow reaches 30-40m can move a few centimeters to a few meters per day. A surging glacier can move up to 6km per year
Valley Glaciers
Glacial Erosion Plucking- weight of a glacier breaks underlying rock and pieces stick to bottom
Abrasion- pieces of rock on the bottom of a glacier gouge and scratch the bedrock
Plucking and Abrasion
Glacial Deposit Till – jumble of different sized rock deposited when a glacier melts Moraine – ridge of till deposited at the end of a glacier
Terminal Moraine – ridge formed at the furthest point reached by a glacier (Long Island)
Kettle – a depression in till that is left when a chunk of ice is left by a retreating glacier. Often filled with water.
Other land forms Fiord Horn Cirque Arete Drumlin