|Glaciers act as agents of erosion and deposition to help to create unique landforms which you will study in this unit.|
ice : an agent of
Note: Once snow and ice begin to accumulate in large quantities, they provide positive feedback towards advancing the onset of the ice age. This occurs as a result of snow and ice having a high albedo effect. Albedo is the ability of a surface to reflect solar radiation.
II) How Do Glaciers Move?
eg A Roche Moutonnée, Melville
Peninsula, Nunavut. The ice flowed to the right and plucked rock
from the end of the outcrop.
- because of constant freezing and thawing,
the head of the glacier plucks out the side of
the mountain and a circular amphitheater is cut into the peak.
This huge, armchair-like depression with its vertical sides and
basin-like floor is known as a cirque.
Below are several cirques still partially covered by ice
and snow in Antarctica.
- after the ice in the cirque is gone, the depression may be occupied by a mountain lake called a tarn.
"Lake Ellen Wilson is an example of a tarn. The
back wall of the cirque containing Lake Ellen Wilson is marked
on the topographic map [below] in red. The photo was taken part-way
down the cirque headwall where the camera is located, looking towards
the southwest" (Karen A. Lemke - University of Wisconsin).
- if cirques connect around a peak, only a pinnacle of rock may remain called a horn.
eg Matterhorn peak in the Swiss Alps
- V-shaped river valleys after being occupied by
a glacier become U-shaped due to
- a stream that occupies a hanging valley will enter the main valley as a waterfall
"This hanging valley in Glacier
National Park [below] contains a waterfall called
Bird Woman Falls. A small glacier flowed out of this valley and
joined a larger valley glacier that flowed where Logan Creek is
located today. Since this glacier was small, it was unable to erode
down into the landscape very far, and a hanging valley is what
we see today. We are looking towards the south in this photo. On
the map [below], north is towards the top. The photo was taken
from the camera location on the map. The floor of the hanging valley
is relatively flat, and thus the contour lines on the topographic
map are more widely spaced than those contours representing the
sides of the valley. The close spacing of the contour lines at
the edge of the hanging valley indicates a steep drop-off, which
is where the waterfall is located" (Karen A. Lemke - University
- truncated spurs are
triangular faces on the vertical walls of the U-shaped valley.
They have been formed as a result of the glacier truncating the
interlocking spurs of the former V-shaped river valley
"[The] photo [below] shows two medial moraines
(blue arrows) as seen from the air. The black arrows point to lateral
moraines that have formed along the sides of the valley wall. Where
the two main glaciers shown in the photo flow together, their lateral
moraines join to form a medial moraine. The medial moraine on the
right formed in the same way, however we can't see where the glaciers
flow together to form the moraine" (Karen A. Lemke - University
- terminal moraine marks the farthest extent of glacial advance and thus is the end moraine located at the lowest elevation.
eg Moraine of a piedmont glacier, Bylot Island, Nunavut
- recessional moraines form as glaciers pause during periods of retreat, and thus are located at higher elevations than terminal moraines.
Glaciation - 12 000 years ago
Howe Sound Today
- alps are high altitude pastures eg Swiss Alps
- crevasses are cracks that occur as
a glacier moves into a wider part of the valley or encounters a
change in slope
eg a kettle lake north of Okanagan
Falls, Interior B.C.
eg Glacial spillway, Sachigo River,
glacial ponding: body of water
formed as a result of meltwater not being able to flow away.
Geographical Significance of Glaciation in Canada
- isostatic rebound has been responsible for landforms
such as raised beaches; for instance, the raised beaches at L'Anse
aux Meadows National Historic Site, Newfoundland.
Note: E-mail your work to your instructor for Parts A, C, and D as a word document attachment. This assignment is worth 20 marks.
3) The area of Middle Waterton Lake is approximately
4) Alderson Lake (825350) is an example of
5) The cultural feature at X on the air photograph
6) The main economic activity in the Waterton
7) What type of lake is Upper Waterton lake?
8) What glacial landform feature is Bertha Creek (8535, 8635) flowing in?
9) What glacial landform feature is located at Y on the air photograph?
10) What glacial landform feature is located
at Z on the air photograph?
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