Glacial Modification of Terrain
(Chapter 19)
Glacial Modification of Terrain
Glaciations Past and Present
Types of Glaciers
How Glaciers Form
Continental Ice Sheets
Mountain Glaciers
The Periglacial Environment
Pleistocene Glaciations
1
Pleistocene Glaciations
Extent of Glacial Ice Today
Figure 19-2
Types of Glaciers
Continental Ice Sheets
Mountain Glaciers
Highland Icefields
Alpine Glaciers
2
Continental Ice Sheet - Antarctica
Figure 19-A
Outlet Glacier
Figure 19-4
Mountain Glaciers - Highland Icefields
Figure 19-5
3
Alpine Glaciers
Figures 19-6
and 19-7
How Glaciers Form
Changing Snow to Ice
Glacial Movement
Erosion by Glaciers
Transportation by Glaciers
Deposition
Glaciers
Meltwater
Snow to Ice
Figure 19-8
4
Accumulation and Ablation
Figure 19-9
Glacial Movement
feet per day
surges – 100 ft/day
Figure 19-10
Continental Ice Sheets
Development and Flow
Erosion by Ice Sheets
Deposition by Ice Sheets
Moraines
Kettles
Drumlins
Glaciofluvial features
Outwash Plains, Eskers, and Kames
5
Glacial Erosion
Glacial striations,
Glacier Bay, Alaska
Figure 19-10
Glacial erosion - Roche Moutonee
Glacial deposition - Till
Figure 19-13
6
Glacial deposits - Erratic
Figure 19-14
Glacial deposits -drumlins
Figure 19-14
Growth of a Terminal Moraine
Figure 19-18
7
Terminal Moraines in US
Figure 19-19
Glaciofluvial features
Figure 19-14
Kames and Kettles
Kettle Formation
Kame
Figures 19-21 and 19-22
8
Kettle
Walden Pond - al glacial kettle
Ice Sheet Deposition - summary
Figure 19-17
Mountain Glaciers
Development and Flow
Erosion by Mountain Glaciers
Mountain Landforms
Cirques, Arretes, Horns
Tarns
Valley Landforms
Glacial Trough
Paternoster Lakes
Hanging Valleys
Deposition by Mountain Glaciers
9
Mountain glaciers - Mt. Rainier, WA
Figure 19-23
Mountain Landform Development
Figure 19-27
Mountain glaciers effect of erosion
Grand Tetons, Wyoming
Figure 19-23
10
Cirques
Figures 19-25 and 19-26
Glacial “Horn”
Horn
Cirque
Cirque
Cirque
Cirque
Cirque
Arete
U-shaped glacial valley
Figure 19-32
11
Glaciated Valleys
Figures 19-31 and 19-33
Moraines in Mountains
Figure 19-35
Medial Moraines
Figure 19-37
12
Sea level changes
In an ice age (or cooler periods) more of
Earth’s oceans as solid H2O in icecaps,
therefore, sea level lowers
- reverse when climate is warmer in
interglacials – sea level rises
Sea level changes
Lots of water in glaciers: during last ice age sea level
lowered by ~130 m
shoreline 100 km from NYC –
Bering Strait, English Channel were land bridges
karstification of Miami Oolite
Today: if all ice in glaciers melts, sea level would rise 65m:
Florida, Egypt, Hong Kong, London, Houston would all be
underwater !!!!
Climate fluctuations and Global
warming controversy - 1
Climate is not a constant.
Global warming is a fact !!
Sea level rising.
Tropical glaciers retreating
13
Climate fluctuations and Global
warming controversy - 2
How fast – controversial; UN uses figure that
sea level will be 25cm higher in 2050?
Cause? Anthropogenic CO2? possibly, but
could be part of some natural cycle
(anthropogenic CO2 does not help, of course)
End
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