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