Transcript Ch. 5 Glaciers & Ice Ages

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