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Geological
Evidence of
Glacial Activity in
New York State
The ice age in North America began about two
million years ago and ended about 6000 years ago.
During this period four major glacial advances
occurred. Deposits and glacial evidence may be
found in all northern states. But only in New York
can we find the latest glacial evidence. Earlier
glacial evidence has bin swept away. This glacier
that swept away all the evidence is called the
Wisconsin glacier. This took place 20,000 years ago.
Many examples of evidence of this glacier are
visible today. n years ago and ended about 6000
years ago.
GLACIER FACTS
• 20,000 years ago glaciers covered all of Canada and
extended southward over the sites of Seattle, Chicago,
and New York city.
•All of New York ,except for the Allegheny state park
was once buried under ice more than one mile thick.
•The glaciers over road all of the Adirondack
mountains including the highest mountain which is Mt.
Marcy.
•Because of their great thickness and mass, glaciers
completely override all land features even some times
large mountains.
• Today very few places have low enough average
temperatures and sufficient snow fall for glaciers to
form.
•Antarctica is covered by the largest glacier that is one
and a half times as large as the United States.
•New York’s Finger Lakes were carved out by glacial
ice.
•Long Island is a 120 mile long out washed plain. It has
no bedrock.
•Niagara Falls began when the Wisconsin Glacier
melted.
GLACIER TERMINOLOGY
Glacier: is a body of ice showing evidence of movement as reported by
the presence of ice flow line, crevasses and recent geologic features.
Glacial Advances: is the net movement of glacier terminus downvalley.
Advance occurs when the rate of glacier flow downvalley is greater than
its rate of ablation.
Moraine:rock debris deposited by a glacier.
Striations: are the scratches etched in to the rock at the bed of a glacier.
Till:is the unsorted rock debris deposited directly by the glacier without
the extreme reworking by meltwater. Also called Glacial Till.
Erratic:Bolder transported by a glacier that generally differs from the
bedrock beneath the rock.
Kettle: depression in a glacial deposit were outwash was deposited
around a residual block of ice.
Kame: A conical hill of sand and gravel deposited by a melting
glacier.
Continental Glacier: ice sheet of continental proportion.
MeltWater: water from ice and snow, especially from a glacier
This is a glacial erratic that
shows evidence of weathering
and erosion
Two erratics lined up
in approximate
direction of ice flow
May be a small kettle lake or pond,
rounded edges and poor drainage.
A large erratic placed here by a glacier.
Evidence of frost
wedging since
glacial deposition.
One side of this Ushaped glacial valley
shows glacial debris
of all sizes
U-shaped
valley showing
smooth side to
the right.
Unsorted, angular
edged fragments
deposited by
glacial ice.
Young stream eroding
through the glacial debris.
Scratches
on a rock
caused
by
glacial
till
Another large erratic
showing scratching
going in one
direction.
Evidence of weathering of
erratic since the last ice age.
A different
angle of this
large glacial
erratic
Large erratic for this area but in the
mid-west the ‘haystack boulders’
may be as large as a house.
Bibliography
Ramsey, William L. Modern Earth Science. Holt, Rinehart and Winston
Publishers: NewYork, 1979.
USGS. “Glossary of Selected Glacier Terminology”.
http://vulcan.wr.usgs.gov/glossary/Glaciers/glaciers_terminology.html
Van Diver, Bradford B. Roadside Geology. Mountain Press Publishing
Company: Missoula, 1985.