Geo 12 Chapter 14
Transcript of Geo 12 Chapter 14
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Glaciation The effects of large bodies of ice on the landscape and the distinctive landforms created
by erosion, transportation and deposition
Extent of Ice Age Glaciation During the most recent ice age, glaciers (represented on map in white) covered much of
the Earth's northern hemisphere. Ice ages consist of glacial periods and warmerinterglacial periods. Many scientists believe that Earth remains an interglacial state
How do glaciers begin?
Snow accumulates during the winter Some snow does not melt during the summer
This is usually on the mountain tops (north facingslopes)
Next winter's snowfall accumulates on top of lastyearssnow
Some is compressed into ice This process continues until the weight of the ice
becomes too heavy This ice slowly moves downhill
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More snow and ice replaces what has moved and the glacier begins
Corries, cwms, cirques "Near mountain tops where glaciers
formed." Steep back wall and sides, open front
with a lip Formed by new snow collecting in
hollows Compacted and turned into ice due
to new snow on top Moves downhill under its own weight Eroding, abrasion and plucking as it
moves Formation of a corrie: Steepening the corrie
sides and deepening the
corrie floor Lip form due to a
decrease in erosion Today corries often filled
with water forming alake
Process of erosion As a glacier moves
downhill it erodes (wear away) the lands.
Plucking Ice melts, then freezes around a rock and pulls or plucks the rock from the ground as
the ice moves
Abrasion Plucked rocks in the base at the bottom of
the glacier grind and scrape away the landunderneath them when the glacier moves
Freeze thaw (aka. Frost Shattering) Water seeps into cracks in the rock and
then freezes, when water freezes itexpands by 9%, putting the rock underextreme pressure. This is repeated manytimes, causing the rock to shatter. This is atype of Physical Weathering
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Striations Grooves caused by the rocks in the bottom of the glacier scraping against the rock
below (abrasion) These are telltale signs of the Glaciers route
Artes Knife Edged ridge, usually the result
of two corries on different sides ofthe mountain
Formed as the back wall of sides of acorrie are weathered and eroded
Distance between two corries isnarrowed until la "knife edge ridge isformed."
Glacial troughs or U shaped valleys Flat floored, steep sided, U shaped
valley."
Formed as glaciers follow pre glacialriver valleys, easiest way down themountain
The Valley is straightened and thesides of the valley and its floor areeroded
Other glacier also come down fromthe mountain into the main valleybelow resulting in the erosive power ofthe glacier increasing
Hanging valley The creation of hanging valleys and
their waterfalls by tributary valleyglaciers. (a) During glaciation, tributaryglaciers enter a major glacier atdifferent floor levels. (b) afterglaciation ends, the ice melts and theregion is left with hanging valleys. Astream then forms a waterfall as ithurtles over the side of the hanging
valley
Moraines Rock particles carried by the glacier Ground Moraine Lateral Moraine Medial Moraine Terminal Moraine
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Glacial Deposition As a glacier melts and recedes a number of features are left behind Most of these are made from the moraine which the glacier was carrying
Receding Glacier
The farther a glacier moves from its
source of accumulation into
warmer, lower-elevation regions,
the more likely it is to ablate, or
melt. As the ice ablates, it begins to
deposit the material it has eroded in
the mountains, as well as any rock
debris that has fallen into its
crevasses. Just as streams of liquid
water create landforms when theydeposit their load of material,
streams of frozen water glacier
drop their burden and shape the
landscape as they recede.
Erratics These are Alienboulders, scattered over the valley floor after glaciation.
They are most likely pieces of groundmoraine.
Drumlins These are smooth, elongated mounds
of till
Steep on one side, gentle on the other
They are often found in groups
Kettles These form from detached blocks of ice, left behind when the glacier retreats
When the ice melts it leaves behind a depression(hole), which sometimes fills with water(kettle hole lake)
Eskers Very long, narrow ridges of sand and gravel. These mark the course of a sub-glacial
melt-water steam (a stream under the glacier)
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Outwash Plain These are flat areas of meltwater below the snout of the glacier
They are made from till
Eskers, erratic, drumlins are found on this plain
Human Activity in Glaciated Areas (glaciated highland) Tourism
Farming
Forestry
Energy resources
Water Supply
Glacial deposits are mined
Glacial lakes, sport and hydroelectric
Tourism
This marks the end of the glacial, periglacial sections of the notesNot because Im lazy, but
I dont have much time to finish all the notesso
For Coastal Landscape sections of the notes, please refer to these ppt:
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http://www.clydebankhigh.org.uk/New%20CHS%20Website/Files/Geog/Higher%20Geography%20course/Lith
osphere/Lesson%207%20Coasts.ppt
http://dp-geography.wikispaces.com/file/view/Coastal+Processes+and+Landforms.ppt
An important diagram:
Well done! Geo 12s. Good luck in your final test!
http://www.clydebankhigh.org.uk/New%20CHS%20Website/Files/Geog/Higher%20Geography%20course/Lithosphere/Lesson%207%20Coasts.ppthttp://www.clydebankhigh.org.uk/New%20CHS%20Website/Files/Geog/Higher%20Geography%20course/Lithosphere/Lesson%207%20Coasts.ppthttp://www.clydebankhigh.org.uk/New%20CHS%20Website/Files/Geog/Higher%20Geography%20course/Lithosphere/Lesson%207%20Coasts.ppthttp://dp-geography.wikispaces.com/file/view/Coastal+Processes+and+Landforms.ppthttp://dp-geography.wikispaces.com/file/view/Coastal+Processes+and+Landforms.ppthttp://dp-geography.wikispaces.com/file/view/Coastal+Processes+and+Landforms.ppthttp://www.clydebankhigh.org.uk/New%20CHS%20Website/Files/Geog/Higher%20Geography%20course/Lithosphere/Lesson%207%20Coasts.ppthttp://www.clydebankhigh.org.uk/New%20CHS%20Website/Files/Geog/Higher%20Geography%20course/Lithosphere/Lesson%207%20Coasts.ppt