Ch. 5 Glaciers & Ice Ages

p. 124-140 guided notes

Glaciers: a part of two basic cycles in the Earth system

Glaciers are a part of both the ________ cycle and _________ cycle

Glacier Definition:

Glaciers: a part of two basic cycles in the Earth system

2 Types of glaciers 1) Valley, or alpine glaciers:

________________________________________________________________2) Ice sheets, or continental glaciers___________________________________________________________________• Other types

• Ice caps and piedmont glaciers

What kind of Glaciers cover

these regions? How

are they different than

the other type?

How Glaciers Move

• 2 Types of glacial movements• Plastic flow: ___________________________• Slipping along the ground: _________________• Average rate of movements very slow up to

______ m a day

• Zone of fracture • Uppermost _____ meters • ____________form in brittle ice

Explain…where is it moving fastest? Why does it fracture on

top?

Glacial Movement

Glacial Budget: _____________________

___________________________________Zones of a Glacier

• Zone of accumulation –• Zone of wastage –

What causes the glacier to advance or retreat?

Figure 6.6

Glacial Erosion

Glaciers erode by • __________ – lifting of rock blocks • Abrasion: ___________________

Evidence of Abrasion:• _______________• ________________

Glacial Erosion: Erosional Landforms

Landforms created by alpine glacial erosion: define and describe how formed• Glacial trough/U-shaped valley:_________• Hanging valley: _________________• Cirque: _____________________• Arête:__________________• Horn:___________________• Fjord:___________________________

Label the Erosional landforms created

by alpine glaciers

Figure 6.9 C

What causes glaciers to deposit material?

Glacial Erosion: Depositional Features

Types of glacial drift (sediment of glacial origin)• ______ – material that is deposited directly by

ice• _______________ - sediment deposited by

meltwater • Glacial erratics: ______________________

What evidence is there that this is glacial till and not river

deposited sediment?

Close up of pebble

Glacial Erosion: Depositional Features

• Moraines :_________________________• How are each of the following formed?• Types of moraines

• Lateral• Medial• End• Ground

Glacial Erosion: Depositional Features

Define and explain the formation of each depositional feature

• Outwash plain• Kettles• Drumlins• Eskers• Kames

Label the depositional features

Figure 6.18

A drumlin in upstate New York… What might you look for on a topographic map of Wellesley to determine if we had any drumlins?

Glaciers of the Ice Age

Alternative explanations given for glacial sediment:_______________________

_________________________

Glacial/interglacial cycles occur every __________

Our “Ice age” contained about _____ cycles • Ice Age

• Began 2 to 3 million years ago • Division of geological time is called the __________epoch • Ice covered ______ of Earth's land area

Maximum extent of ice during the Ice Age: How do we know?

Figure 6.19

Causes of Glaciation

Proposed possible causes

1. Plate Tectonics which could cause a climate shift by ______________________

___________________________________

_____________________________

2. Variations in earth’s orbit which could cause a climate shift by______________________

______________________________________

Variations in earth’s orbit

________________ hypothesis • Shape (____________) of Earth's orbit

varies • Angle of Earth's axis (___________)

changes • Axis wobbles (_____________)

• Changes in climate over the past several hundred thousand years are closely associated with variations in Earth's orbit