Glaciers

In a process called plucking, the rocks dragged by glaciers produce grooves and scratches in bedrock. TRUE OR FALSE

FALSE

Once the depth of snow and ice reaches more than 30 to 40 meters, the force of friction begins to pull a glacier downhill. TRUE OR FALSE

FALSE

Glacial erosion, the picking up and movement of earth beneath a glacier, is also referred to as ____________________.

Plucking

as a glacier flows over the land, it picks up rocks in this process

Plucking

How are kettle lakes formed?

Retreating glaciers often leave behind large chunks of ice in the soil. When these ice chunks melt, depressions in the landscape are left. Kettle lakes are formed when these depressions fill with water.

The mixture of sediments deposited directly by a glacier is called ____________________.

Till

Describe what a moraine is made of and explain how this glacial feature forms.

A moraine is made up of till, the mixture of sediment deposited by a glacier. A moraine forms when a ridge of till is deposited at the edges or at the lower end of a glacier. A terminal moraine forms at the farthest point reached by the glacier as the glacier begins melting back.

The process in which rock fragments freeze to the bottom of a glacier and then are carried away when the glacier moves is called a. plucking. b. surging. c. valley widening. d. abrasion.

A. Plucking

process of erosion in which a glacier drags rocks along the landscape

Abrasion

Present day glaciers are found primarily in _______________. a. Canada and Greenland b. Canada and Iceland c. Antarctica and Greenland d. Antarctica and Iceland

C. Antarctica and Greenland

Which of the following is evidence that an area was once covered by a glacier? a. loess deposits b. V-shaped valley c. U-shaped valley d. alluvial fan

C. U-shaped valley

Compare and contrast the way the two types of glaciers move.

Continental glaciers can cover most of a continent or large island. As they move, they can spread out in all directions. In contrast, valley glaciers move down mountain valleys previously cut by rivers. The sides of mountains prevent valley glaciers from spreading in all directions as continental glaciers do.

Glaciers can only form when a. there is an ice age. b. there is a U-shaped valley in the mountains. c. the amount of snow exceeds the amount of rain. d. more snow falls than melts.

D. More snow falls than melts

How do glaciers cause deposition?

Glacial deposition occurs when glaciers retreat, leaving behind rocks and soil known as till.

The times in the past when continental glaciers covered large parts of Earth's land surface were the ____________________.

Ice Ages

depressions left by melted blocks of ice in glacial deposits

Kettle

fast-moving glaciers that can move up to 6 kilometers per year.

Surging

What processes lead to glacial erosion? Describe them.

The two main processes that lead to glacial erosion are plucking and abrasion. Plucking is the process by which a glacier picks off rocks as it blocks over the land. The rock fragments freeze to the bottom of the glacier, gouging and scratching the bedrock as the glacier advances in the process of abrasion.

A kind of glacier called a(n) ____________________ forms when ice and snow build up in a mountain valley.

Valley Glacier

Describe how a valley glacier forms.

Valley glaciers form high in mountain valleys. Because the temperatures rarely rise above freezing, ice and snow build up year after year. As more snow falls, the ice and snow below become compacted.