Transcript File - Mr. Volpe`s Earth Science Emporium

Glaciers and Glaciation
Page 27
Page 27
GLACIERS- Rivers of Ice
A large mass of moving ice and snow

Types of glaciers
Alpine or Valley
a. ______________
glaciers form in
mountain valleys at high elevations
Continental
b. ___________ glaciers form over vast
areas of land.
Show glacier video from my videos
Extent of the Northern
Hemisphere Ice Sheets
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There is evidence
4
of at least _____
major ice ages
during the last 2
million years.
a. The time period
between ice ages is
called interglacial
periods.
b. The most recent ice
age ended only about
11,000 years ago
How do these large masses of ice move?
• These large ice masses begin to move
down hill by gravity
• It can move several centimeters to
several meters a year depending on its
size
• The steeper the slope or the warmer
the temperatures the faster the rate.
• Glaciers will settle into lower lying
areas as they move.
Because there is friction on the sides of the
glacier, the middle is the fastest, just like a
river.
Example of an Alpine Glacier
Example of an Alpine Glacier
Example of an Alpine Glacier
Example of an Alpine Glacier
Example of an Alpine Glacier
Example of an Alpine Glacier
What happens when glaciers meet water?
Icebergs are large pieces of glacier that break off into
the water.
Icebergs
• When a glaciers reaches the ocean, a large
piece of it may break off and float away.
• Iceberg: large piece of a glacier that enters
the ocean
• Large amounts of sediments may be frozen
into an iceberg. As the iceberg melts, these
sediments sink to the ocean bottom.
• Most of the iceberg is below the
surface of the water. Only a small
portion is visible above the
water’s surface.
• Many ships have crashed. Navy keeps track of iceberg
locations. They travel with the ocean currents and the
path of wind.
– Titanic: April 1912 it struck an iceberg and sank.
2,200 people were on board, only 705 were rescued.
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Some glacial features to look for
1) U-shaped valleys
2) Parallel grooves in bedrock
3) Scratched and polished rocks
4) Erratics
5) Long, deep, glacial lakes
6) Unsorted sediments
7) Drumlins
8) Kettle lakes
Learn these terms. Whenever you see one on a test or
on the regents the answer is always "GLACIERS".
This is a view of a
U-shaped glacial
valley.
And another...........................
A glacier valley
Grand Teton National Park
A hanging valley, Yosemite National Park
(Photo by C. C. Plummer)
As glaciers flow, the rocks embedded in the
bottom of the glacial ice cut deep PARALLEL
GROOVES in the bedrock beneath
The picture to the right shows bedrock
exposed at the Bronx Zoo.
Above more parallel grooves and
scratches in exposed bedrock.
Sometimes the grooves
are
very deep and dramatic
such as these from the
Peruvian Andes
Mtns(left)
Kelley’s Grooves found on
Kelley’s Island, Ohio (right)
These rocks were embedded in
the ice at the bottom of a glacier.
As the glacier moved over
bedrock it was rocks like these
that cut the parallel grooves. In the
process these rocks tumbled and
rolled becoming SCRATCHED and
POLISHED.
SCRATCHED and POLISHED
boulders are evidence of glacial
erosion.
Why is this glacier dirty?
It picks up the dark sediment as it moves over the landscape.
Deposition and landscape features
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3. Erratic
2.
4.
1.
6.
5. Braided stream
8.
9. Esker
7. terminal moraine is a
pile of unsorted glacial
till, dumped where the
glacier stopped
advancing. Long Island
is a terminal moraine
Sierra Nevada, California
(Photo by C. C. Plummer)
• Here’s a view of a glacier showing the Terminal
Moraine
• It forms at the point at which the rate of melting
is equal to the flow of ice. You can also see a
Medial Moraine in the middle of the glacier.
N
S
Drumlin in New York state
• Sometimes glacial till is deposited in mounds or hills
• These are called DRUMLINS
• The drumlins below are found in Scotland but similar
features are found all over the northern hemisphere
• Often drumlins are so large that they cannot be
appreciated for what they are except when photographed
from high altitudes.
The material transported by a glacier is
called TILL. When the glacier melts the
till is deposited in a pile. There is no
sorting as occurs when a stream slows.
UNSORTED SEDIMENTS is good evidence
of glacial deposition.
Above and to the right are
pictures of unsorted glacial
till. Material from fine silt to
large boulders are mixed
together randomly.
You live on unsorted
glacial
till since Long Island is
composed completely of
glacial material.
Esker in northeastern Washington
As glaciers retreat & melt huge blocks of ice may remain
buried in the earth. As these blocks gradually melt they
leave deep depressions which can fill in with water
forming "KETTLE LAKES" such as those seen above.
Kettle lakes represent more evidence that a region has
undergone glaciation
This is a satellite view of the Finger Lakes region of New York State
The finger lakes are very deep, narrow parallel lakes scooped out during
the last ices age
The glaciers movement from north to south accounts for the N-S
orientation of these bodies of water.
Lakes like these are found all over the world wherever the last continental
icesheet scraped and scarred the land
Some erratics come
to rest in strange
places.
Some are deposited closer to home
like this boulder in Eastport.
How was Long Island formed?
Unsorted piles of sediment called moraines were
deposited when the glaciers started to melt or
retreat.
Long Island Glacial Erosional &
Depositional Landscape
Features
Erratics- Random boulders that composition
doesn’t match surrounding bedrock
Long Island Glacial Erosional &
Depositional Landscape
Features
Till- piles of Unsorted Sediments. Big &
smalls, round with angular particles
Kettle Lake- Lake
Ronkonkoma
Long Island Moraines
Long Island Moraines
Long Island Moraines
Moraines- direct glacial deposition
of unsorted sediments
Outwash plain deposition of
layered & sorted particles
such as sand that flow out of
the bottom of a glacier when it
melts
Glaciers and New York’s Economy


Thick, fertile soils developed on till and
outwash – foundation of agriculture in
state
Microclimate associated with Lakes





Water moderates climate
Warmer in winter, cooler in summer
Ideal for growing grapes/producing wine
Aquifers – especially in outwash
Sand and gravel for construction
Lastly, a very quick review of essential terms
that are likely to appear on the next exam & the
regents..............
What kind of sediments do glaciers produce?
UNSORTED
What kind of valleys are associated with glaciers?
U-SHAPED
What term applies to a boulder deposited by a glacier?
ERRATIC
What do glaciers do to the rocks they pass over?
They cut LONG,PARALLEL GROOVES
What evidence indicates that a rock was transported by
a glacier?
It may be SCRATCHED and POLISHED
DJ Glacier is Ice Kold, Yo!!!!
He Scratches out mad grooves
Glacier Exit Card
Page 27
Glacial Erosion Features
Shape of Valley
V or U shaped
Evidence Left on Bedrock
Evidence Left on Particles
Direct Deposition
Sorted or unsorted particle
Deposition from meltwater Sorted or unsorted particle
List 3 other glacial
Landscape features
Glaciers Lab
Corrections:
1.Top of page 2 Question #5- What general
direction did the last ice sheet…
2.Add to bottom of page 3 Question #9- What
is the main difference between sediments
deposited by water and sediments deposited
by glaciers?
3.Top of page 4 Question #16- What evidence
proves that Long Island formed from glacial
deposition?
Answers to Questions on pp 28 & 29
1)
2)
3)
4)
5)
D
B
D
D
A
6)
7)
8)
9)
A
C
A
A