- Glaciers are large persistent bodies of ice that form where snow accumulation exceeds melting over many years. Their sheer weight and plasticity causes them to slowly flow under gravity.
- The approximate areas covered by glaciers worldwide are provided, totaling nearly 15 million square kilometers, with over half of that in Antarctica and Greenland.
- Glaciers are classified by their location and behavior, such as ice sheets, ice caps, valley glaciers, and tidewater glaciers.
3. Glaciers are large persistent
body of ice that forms where
the accumulation of snow
exceeds its ablation (melting
and sublimation) over many
years.
4.
5.
6.
7. The sheer weight of a thick layer of ice
and the fact that it deforms as a
"plastic" material, combined with
gravity's influence, causes glaciers to
flow very slowly. Movement along the
underside of a glacier is slower than
movement at the top due to the
friction created as it slides along the
ground's surface.
8.
9. Approximate Worldwide Area Covered by Glaciers square kilometers)
Antarctica 11,965,000 Total glacier
without iceshelves and ice rises) coverage is nearly
15,000,000 square
Greenland 1,784,000
kilometers, or a
Canada 200,000 little less than the
Central Asia 109,000 total area of the
Russia 82,000 South American
continent. The
United States 75,000 including Alaska) numbers listed do
China and Tibet 33,000 not include smaller
South America 25,000 glaciated polar
islands or other
Iceland 11,260
small glaciated
Scandinavia 2,909 areas, which is
Alps 2,900 why they do not
New Zealand 1,159 add up to
15,000,000.)
Mexico 11
Indonesia 7.5
Africa 10
10.
11. Ice Sheets Ice Shelves
-enormous continental - occur when ice sheets
masses of glacial ice extend over the sea,
and snow expanding and float on the water.
over 50,000 square In thickness they range
kilometers from a few hundred
meters to over 1000
meters
12. Ice Caps Ice Streams & Outlet
Glaciers
-miniature ice sheets, -channelized glaciers
covering less than that flow more
50,000 square rapidly than the
kilometers. They surrounding body of
form primarily in
polar and sub-polar ice
regions that are
relatively flat and
high in elevation.
13. Ice fields Mountain Glaciers
- similar to ice caps, - develop in high
except that their mountainous
flow is influenced regions, often
by the underlying flowing out of ice
topography, and
they are typically fields that span
smaller than ice several peaks or
caps. even a mountain
range.
14. Valley Glaciers Piedmont Glaciers
-commonly originating -occur when steep
from mountain glaciers
or ice fields, these
valley glaciers spill
glaciers spill down into relatively flat
valleys, looking much plains, where they
like giant tongues. spread out into
-may be very long, bulb-like lobes.
often flowing down
beyond the snow line,
sometimes reaching
sea level.
15. Cirque Glaciers Hanging Glaciers
-found high on -also called ice
mountainsides and aprons, these
tend to be wide glaciers cling to
rather than long.
steep
-named for the mountainsides.
bowl-like hollows
they occupy.
16. Tidewater Glaciers
-valley glaciers that flow
far enough to reach out
into the sea.
-responsible
for calving numerous
small icebergs.
25. Muir Glacier, located in Glacier Bay, Alaska, photographed by W. Field in Aug. 1941 (left)
and B. Molnia in Sep. 1976 (middle) and Aug. 2004 (right). Note how the glacier has
retreated and exposed rock in 1976 that has since become lush vegetation in 2004.
26. The Larsen Ice Shelf in Antarctica, March 21, 1998. Taken at the beginning of the
Antarctic winter, the ice shelf is clearly visible. Notice that sea ice is forming over the
ocean to the right the ice shelf.
27. The massive lobe of Malaspina Glacier is clearly visible in this photograph taken from a
Space Shuttle flight in 1989. Agassiz Glacier is to the left of Malaspina Glacier, and
towards the top of the photograph Seward Ice Field is just visible.
28. Retreating mountain glaciers in Bhutan. This satellite image shows the termini of several
glaciers in the Himalayan mountains of Bhutan. The glaciers have been receding over the
past few decades, and lakes have formed on the surfaces and near the termini of many
of the glaciers.
29. Glacier at the head of Canon Fiord, Ellesmere Island, Canada