Download Glaciers

AIM: How do Glaciers change the landscape?
Do Now:
The material seen below was left behind by a retreating
glacier. Describe the sediments seen in the picture.
Tasman Glacial Moraine, New Zealand
I. Types of Glaciers
Formed from the accumulation of ice
and snow over thousands of years.
• Valley Glacier:
- Flow between
mountains (in
valleys)
- Very thick
• Ice Sheets (continental ice):
- thin flat sheet of ice
- expand in all directions covering the land
II. Glacial Movement
- Glacial movement is called
• Glaciers advance when
they accumulate (gain)
more ice or slide very
slowly down hill (gravity)
•Glaciers retreat when
pieces of ice fall off or
melt.
III. Glacier Erosional Features
• U-shaped valleys
are carved in the
landscape as
glaciers move
through the land
The Finger Lakes in
Western NY fill Ushaped valleys carved
out by glaciers 2 MYA
• Glaciers pick up
rocks in process
known as plucking.
• Striations – plucked
rocks trapped in
glacial ice abrade
against rocks on the
surface to form
these scratches.
IV. Glacier Depositional Features
• Leave behind unsorted piles of sediment called till
• moraines are long ridges
of till formed by the
glacier.
• Terminal moraines are
found at the end of the
glacier.
• Outwash plains are created by melt water coming from
the glacier.
- melt water sorts the different sizes of sediments.
(this is why the North shore of Long Island is rocky and the
South shore is sandy).
• kettle lakes are formed from melting ice that was buried.
Lake Ronkonkoma
• Glacial Erratics are large
boulders left behind from
melting glaciers.
Central Park, NY
• Drumlins are teardrop shaped hills
of till.
- The narrow
side of the hill points
in the direction
glacier was moving
(advancing).
Glacier moved this way in the past
Narrow side of hill
V. Glaciers and Long Island
- Glaciers advanced from the North (from Canada) to the
South (30,000 and 20,000 years ago)
- As they moved they plucked and eroded rocks and soil
creating piles of till and moraines.
- When they retreated, this material deposited to form Long
Island.
Drumlins
Closure
• From the bottom do now bin, obtain a
worksheet on Glaciers. With the person
sitting next to you use the notes to answer
the questions on the handout.
How do Glaciers Change the Landscape? Worksheet
1.
Ice Sheets
Glacial Valley
• Thinner, flat expanse of ice
•Creates “U-Shaped” trough
•Covers continents and can
extend out into oceans
•Moves between two
mountains (steep rock)
•Also called continental ice
•Very thick
2. Both cause erosion to occur. Plucking loosens
and picks up rock from the surface of the Earth.
Abrasion is caused when rocks trapped in the
glacier grind against rocks on the surface of Earth.
3.
It was created by
a glacier because
of the “U-shaped”
valley that was
created
4. Over the last 25,000 years glaciers have
shaped the land in New York. Glaciers
advance when they freeze more water than
melts away. At two different times glacial
advances plucked sediment out of the ground
and moved it South. During glacial retreats,
when more water melts than freezes, the
sediment was left behind to form two
moraines. These moraines later became the
North and South shores of Long Island.