UNIVERSITY OF SOUTH ALABAMA
Last Time
Glacial Geomorphology (alpine variety)
•
GY 301: Geomorphology
•
Erosive features
Depositional features
Lecture 23:
Glacial Geomorphology
2: Continental Glaciers
http://www.indiana.edu/~librcsd/etext/hoosier/image/rm-01.jpg
Alpine Glaciers and Erosion
When alpine glaciers form and advance, significant changes to
the terrain will occur
Before Glaciation
Alpine Glaciers and Erosion
When alpine glaciers form and advance, significant changes to
the terrain will occur
During Glaciation
http://www.uwsp.edu/geo/projects/virtdept/ipvft/arete.html
http://www.uwsp.edu/geo/projects/virtdept/ipvft/arete.html
Alpine Glaciers and Erosion
Head area features
•Cirques
•Arêtes
•Horns
•Tarns
•Pater Noster lakes
Alpine Glaciers and Erosion
Toe area features
•U-shaped valleys
•Truncated spurs
•Hanging valleys
http://virtual.yosemite.cc.ca.us/ghayes/Tuolumne_Meadows_Field_Trip_files/image024.jpg
http://virtual.yosemite.cc.ca.us/ghayes/Tuolumne_Meadows_Field_Trip_files/image024.jpg
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Alpine Glaciers and Deposition
In alpine settings, most
till is deposited in linear
deposits called moraines
•Lateral moraine
•Medial moraines
•Terminal moraines
•Recessional moraines
Types of Glaciers
• Alpine: rivers of ice that flow through valleys to
lower elevations
• Continental: large ice masses that cover significant
portions of continents and are a mile or more thick
Today’s Lecture
Glacial Geomorphology (Continental variety)
•
Continental glaciers today and in the past
•
Erosive features
•
Depositional features
Continental Glaciers
• Thick ice masses actually
depress the lithosphere
below sea level
• Currently only 2 large continental glaciers exist: the
Greenland and Antarctic ice sheets (but there are a
few smaller ice caps; e.g., Baffin Island)
http://opa.yale.edu/images/articles/6449-E-Oice.jpg
Ice Shelves
• Large portions of
continental glaciers that
are floating in the
oceans
The Ice Age
•
18,000 years ago, the
last glacial maximum
covered all of Canada
and a good chunk of
Europe in a continental
glacier.
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Continental Glaciation and Erosion
• Polished and striated
bedrock
• Roche moutonee
http://upload.wikimedia.org/wikipedia/commons
Continental Glaciation and Erosion
• Polished and striated
bedrock
• Roche moutonee
http://education.usgs.gov/schoolyard
http://libwiki.mcmaster.ca/clip/uploads/Main/rocheformation.jpg
http://www.swisseduc.ch/glaciers/glossary/icons/roche-moutonnee.jpg
Continental Glaciation and Deposition
• Landforms are produced
by the motion of a thick
ice sheet
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Continental Glaciation and Deposition
• Moraines produced
by continental
glaciers are the same
as those produced by
alpine glaciers….only
larger.
Moraines
Drumlins
Eskers
Erratics
Outwash
Kettle Lakes/Kames
Varves
Loess
Oak Ridges Moraine
Continental Glaciation and Deposition
• Drumlins are deposits
of till produced
underneath
continental glaciers
Continental Glaciation and Deposition
• Eskers are also deposits of till
produced underneath
continental glaciers, but
associated with melt water
Jenkins esker
http://www.geography-site.co.uk/pages/physical/glacier
Bedshiel esker
http://geopanorama.rncan.gc.ca/calgary/geotour/6_e.php
http://www.drumlinarealandtrust.org/images/drumlins.jpg
http://z.about.com/d/geology/1/0/E/L/esker.jpg
http://www.paddling.net/sameboat/Images/esker.gif
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Continental Glaciation and Deposition
• Erratics are large boulders deposited randomly on the
Earth’s surface by the conveyor belt action of
continental glaciers.
Continental Glaciation and Deposition
• Outwash plains are large areas of deposition produced
during by meltwater.
http://geoimages.berkeley.edu
http://www.soils.umn.edu
http://gsc.nrcan.gc.ca/landscapes/photos/slave_natmap/img0036.jpg
Continental Glaciation and Deposition
• Kames are Kettle Lakes frequently occur together.
Continental Glaciation and Deposition
• Kettle Lakes are water-filled depressions caused by a
“block” of glacial ice trapped in outwash.
Kettle Lake
http://nevis.k12.mn.us/
http://www.climatechange.umaine.edu
Continental Glaciation and Deposition
• Kames are piles of sediment originally deposited in
depression on the ice that falls as a pile when the ice
melts.
Continental Glaciation and Deposition
• Varves are laminated silt layers
deposited in glacial lakes.
Kame
http://www.backyardnature.net/loess/vertbluf.jpg
http://www.geologyrocks.co.uk/system/files/u2/varves.jpg
http://brianmillerphoto.com
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Continental Glaciation and Deposition
• Loess is wind blown silt
deposited on alluvial
plains a long way from
the glacier.
Upcoming Stuff
Homework
Alpine Glaciation Lab (due Friday)
Next Lecture:
More Continental Glaciations
Friday’s Lab:
Map interpretation (continental glaciers)
http://www.backyardnature.net/loess/vertbluf.jpg
http://landcovertrends.usgs.gov
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