This tidewater glacier is a popular stop for tour boats from Seward,
AK. It is one of several
outlet glaciers from the Harding Ice field.
The margin of Bear Glacier discharges into a lake. Because of the low
profile of the glacier, it
breaks apart (calves) along the crevasses and makes icebergs. Debris
carried in the medial
moraine on the left side of the image decorates some of the icebergs.
Color differences in the
water are due to different sediment concentrations.
Hanging Glacier, Jasper National Park, Canada This small hanging
glacier fills the col, or saddle, between
Mount Andromeda and Mount Athabasca. Notice the highly fractured nature
of the ice in the lower part
and compare it to the smoother appearing ice at the upper part. Most
of this glacier is fed by drifting snow.
The ELA of Exit Glacier, Alaska. The ice on the left and in the
center is old and crevassed,
whereas the snow on the right lies above the seasonal melting line
(or equilibrium line
altitude (ELA)). Further to the right lies the snow field of the Harding
Ice Cap.
The debris in the foreground also marks the ELA.
Nunataks and medial moraine, Grewingk Glacier, AK Notice the
dirty icebergs from the small medial
moraine on the right side. Brown colored snow in the upper reaches
of glacier are ash cover.
Crevasses, Exit Glacier, Alaska
Good examples of extensional crevasses. Note that they have the same
shape as normal fault blocks.
Orgives, Juno Ice field, AK. The orgives have a regular spacing
and the relief can trap water and snow.
Notice the location of the medial moraine just below the bedrock peak
the photo was taken from.
Close view, Medial Moraine, Bryn Mawr Glacier, AK, 1997
Here the various bands can be traced from nearly horizontal to vertical
orientations.
Mount McClintock, Antarctica. Several glaciers stream down the
side of the mountain. The rough surfaces of the
ice are due to highs in the bed that the ice must flow up over. As
the it flows over these highs, crevasses open up.
The beginnings of medial moraines (the dark bands) mark the junction
of glaciers.
Molded Wall, New Zealand. Lateral glacial abrasion has smoothed
this metamorphic rock along
the valley side. The flowlines indicate a downward direction.
Striated Graywacke, Yale Glacier, AK 1997. Nice parallel striations.
Bedrock fracture trends across the left
side of the image. Field of view about 1 m. Why the scattered pits?
Which way was the glacier flowing?
Strained lee cavity, Amherst Glacier, AK, 1997. On this sloping
surface a small cavity has been
protected from erosion. Some striations can be seen inside the cavity
indicating that the glacier at times
eroded the bottom of the cavity. What do you make of the staining (from
iron)? Why does it have a
distribution just on the inside of the cavity? What age is it
relative to the other striations
is the cavity? Relative to the striations outside the cavity?
Chatter Marks, Mount Desert Island, Maine. This series of fractures
lies on the crest of a granite
stoss and lee form. The fractures are essentially a series of percussion
marks formed as
an englacial rock was dragged over the ridge. Notice how the width
of the
fractures increases in the down-flow direction until an abrupt termination.
Plucking, New Zealand. This small stoss and lee form shows how
the plucking
process works. The block on the right is scheduled next for erosion.
This is the
beginning of a roche mountonÈe.
Kelley's Island Grooves, Ohio. The grooves on Kelley's Island
have been the source of debate for
over 100 years. Some say they were cut by glacier ice, others
say by jets of subglacial water. Note
the curved forms suggesting fluid flow. The smaller grooves lie inside
a larger one framed by the fence.
You are looking in the direction that the glacier flowed. Note the
texture line about 1/2 way up the
grooves. Above this line the limestone bedrock is more weathered
than below the line
because till was more recently removed, exposing the grooves.
Delta, Lake Pukaki, New Zealand. The extreme limit of the outwash
of the Tasman River. Note the
numerous channels, sediment rich water, and the smaller fan/delta on
the upper right. Roads for scale.
Thin delta, Baker Lake, Quebec. The topset beds do not show distinct
layering, but the contact is sharp.
The grain size variation in the foreset beds is from fine sand to pebble-cobble,
which suggests a
proximal source.
Double Moraines, Exit Glacier, AK. Two moraines, a nice pair.
What would cause such a thing? Note the
rope fence running down the middle of the channel between the two moraines.
People in lower left for scale
Loess in the Wind, Matanuska Valley, Alaska. Winds moving across
the outwash of the
Matanuska River valley entrain the silt fraction to produce loess.
Photo by Warren Huff.
Chatermark Group, Mt. Sirius, Antarctica, 1986. Ice flow from
left. Note the general alignment
of these. Is there any significance to the larger striae that
traces across the top?
Glacial Imprint, Downeast Maine. On this Landsat image the alignment
of lakes reflects glacial erosion cutting the local
bedrock. Note the lakes on Mount Desert Island (cutting through granite)
have a slightly different orientation.
Some of the light colored areas directly up from the word "Mount" are
blueberry fields on gravel glacial marine deposits.
What's that Ridge? Part 1. Glacier deposits are funny things.
Is the ridge shown in this image of the
same or different origin as the ridge in the next image?
What's that Ridge? Part 2. They look the same, but are
they? One is an esker and contains gravel,
the other is a moraine and contains till.
Flutes, Bear Glacier, Alaska. These linear ridges formed below
the Bear Glacier as it moved
from upper right to lower left. Notice that they trace over sinuous
ridges. Can you spot
the start of any single flute? Bonus: What are the sinuous ridges?
Back to the Class Schedule
Please direct comments about this page to John
Stimac
URL http://www.ux1.eiu.edu/~cfjps/1300/glacier_photos.html
Revised 9/6/99
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