UNIVERSITY OF SOUTH ALABAMA
Last Time
Glaciers and Glacial Mechanics
GY 301: Geomorphology
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Types of glaciers (alpine)
Formation of glacial ice
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Movement of ice
Lecture 22:
Glacial Geomorphology
1: Alpine Glaciers
http://www.roberts-1.com/t/s07
Glaciers
Glaciers
Glaciers are thick masses of ice that originate on land through
the accumulation of snow.
Glaciers are thick masses of ice that originate on land through
the accumulation of snow.
Glaciers form through a 3
step process
All that is required is
for more snow to fall
in the cold winter
months than melts in
the warm summer
months.
Snow
Firn
Glacial Ice
http://media-cdn.tripadvisor.com/media/photo-s/01/25/4a/ee/in-the-mountains-above.jpg
http://www.ig.utexas.edu
Alpine Glaciers
Alpine or Valley Glaciers
(Zone of Accumulation; Zone of Wasting/Ablation, Calving,)
http://www.scienceclarified.com/images/uesc_05_img0282.jpg
Ice Movement
Ice moves down slope
from the zone of
accumulation to the
zone of ablation due to a
combination of plastic
flow and basal slip.
http://stloe.most.go.th/html/lo_index/LOcanada3/305/images/5_2.jpg
http://nevis.k12.mn.us/academics/science/glacier_hor_profile1.jpg
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Ice Movement
Ice moves down slope
from the zone of
accumulation to the
zone of ablation due to a
combination of plastic
flow and basal slip.
Geological Effects of Glaciers
Firn
Flow
50 m
Slip
Ice exerts
tremendous erosive
force on bedrock
forming unique
geomorphologic
features and
transporting great
quantities of
sediment ….
… to be continued
http://www.kschapterc.org/album-mead/23.jpg
Today’s Lecture
Glacial Geomorphology (alpine variety)
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Erosive features
Depositional features
Alpine Glaciers and Erosion
When alpine glaciers form and advance, significant changes to
the terrain will occur
Before Glaciation
http://www.uwsp.edu/geo/projects/virtdept/ipvft/arete.html
Alpine Glaciers and Erosion
When alpine glaciers form and advance, significant changes to
the terrain will occur
During 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
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Alpine Glaciers and Erosion
Alpine Glaciers and Erosion
Arêtes on topographic maps… look for sharp ridges
Head area features
•Cirques
•Arêtes
•Horns
•Tarns
•Pater Noster lakes
http://virtual.yosemite.cc.ca.us/ghayes/Tuolumne_Meadows_Field_Trip_files/image024.jpg
http://www.gdargaud.net/
Chalk Board
http://www.csus.edu/indiv/s/slaymaker/archives/Geol10L/landforms.htm
Alpine Glaciers and Erosion
Alpine Glaciers and Erosion
Cirques on topographic maps… look for flat bottomed, steep sided embayments
Horns on topographic maps… look for sharp sided peaks
http://www.homepage.montana.edu
http://www.csus.edu
http://www.sonata-photographica.com
Alpine Glaciers and Erosion
Tarns/Pater Noster Lakes on topographic maps… look for blue splotches!
http://www.csus.edu/indiv/s/slaymaker/archives/Geol10L/landforms.htm
Alpine Glaciers and Erosion
Toe area features
•U-shaped valleys
•Truncated spurs
•Hanging valleys
http://www.csus.edu/indiv/s/slaymaker/archives/Geol10L/landforms.htm
http://virtual.yosemite.cc.ca.us/ghayes/Tuolumne_Meadows_Field_Trip_files/image024.jpg
http://images.absoluteastronomy.com/images/
Chalk Board
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Alpine Glaciers and Erosion
Alpine Glaciers and Erosion
U-shaped valleys/truncated spurs on topographic maps
Hanging valleys on topographic maps: look for water falls
http://www.geology.wisc.edu
http://www.uwsp.edu/geo/
http://www.csus.edu/indiv/s/slaymaker/archives/Geol10L/landforms.htm
Alpine Glaciers and Deposition
When alpine glaciers advance they push with incredible force,
enough to scrape down to bedrock and push all manner of
sediment as they go.
Alpine Glaciers and Deposition
In alpine settings, most till is deposited in linear deposits called
moraines
•Lateral moraine
•Medial moraines
•Terminal moraines
•Recessional moraines
Till: unsorted sediment
(grain size from clay to
huge boulders)
http://images.encarta.msn.com/xrefmedia/aencmed/targets/illus/ilt/T790634A.gif
Alpine Glaciers and Deposition
Alpine Glaciers and Deposition
In alpine settings, most till is deposited in linear deposits called
moraines
•Lateral moraine
•Medial moraines
•Terminal moraines
•Recessional moraines
http://www.swisseduc.ch/glaciers
http://www.swisseduc.ch/glaciers
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Alpine Glaciers and Deposition
In alpine settings, most till is deposited in linear deposits called
moraines
Alpine Glaciers and Deposition
Moraines on topographic maps (modern glaciers): look for sediment on ice
•Lateral moraine
•Medial moraines
•Terminal moraines
•Recessional moraines
http://nsidc.org/glaciers/gallery/images/bylot_island_valley_large.jpg
http://www.csus.edu/indiv/s/slaymaker/archives/Geol10L/landforms.htm
Alpine Glaciers and Deposition
Moraines on topographic maps (post glaciation): tricky; look for ridges
Upcoming Stuff
Homework
Groundwater and Karst Geomorphology (due tomorrow)
Next Lecture:
Continental Glaciations
Friday’s Lab:
Map interpretation (alpine glaciers)
Soup Day Tomorrow
Chicken veggi (w rice)
4 breads
http://www.csus.edu/indiv/s/slaymaker/archives/Geol10L/landforms.htm
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