Glaciers and Glaciation Page 27. GLACIERS- Rivers of Ice A large mass of moving ice and snow Types...

Glaciers and Glaciation Page 27

GLACIERS- Rivers of GLACIERS- Rivers of IceIce

A large mass of moving ice and snowA large mass of moving ice and snow Types of glaciersTypes of glaciers

a. ______________ glaciers form a. ______________ glaciers form in mountain valleys at high in mountain valleys at high elevationselevationsb. ___________ glaciers form over vast areas of land.

Alpine or Valley

Continental

Show glacier video from my videos

Page 27

Extent of the Northern Extent of the Northern Hemisphere Ice SheetsHemisphere Ice Sheets

There is evidence of at least _____ major ice ages

during the last 2 million years.

4

a. The time period between ice ages is called interglacial periods.

b. The most recent ice age ended only about

11,000 years ago

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• 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.

How do these large masses of ice 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 smallportion 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.

Some glacial features to look for

1) U-shaped valleys2) Parallel grooves in bedrock3) Scratched and polished rocks4) Erratics5) Long, deep, glacial lakes6) Unsorted sediments7) Drumlins8) Kettle lakes

Learn these terms. Whenever you see one on a test oron the regents the answer is always "GLACIERS".

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This is a view of aU-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 bedrockexposed at the Bronx Zoo.

Above more parallel grooves andscratches in exposed bedrock.

Sometimes the grooves arevery deep and dramatic such as these from the Peruvian Andes Mtns(left)

Kelley’s Grooves found onKelley’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 andPOLISHED.

SCRATCHED and POLISHEDboulders are evidence of glacialerosion.

Why is this glacier dirty?

It picks up the dark sediment as it moves over the landscape.

Deposition and landscape features

5. Braided stream

7. terminal moraine is a pile of unsorted glacial till, dumped where theglacier stopped advancing. Long Island is a terminal moraine

1.

2.

3. Erratic

4.

6.

8.

9. Esker

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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.

Drumlin in New York state

N

S

• 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 iscalled TILL. When the glacier melts thetill is deposited in a pile. There is nosorting as occurs when a stream slows.UNSORTED SEDIMENTS is good evidenceof glacial deposition.

Above and to the right arepictures of unsorted glacialtill. Material from fine silt to large boulders are mixed together randomly.

You live on unsorted glacialtill 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 StateThe finger lakes are very deep, narrow parallel lakes scooped out duringthe last ices ageThe 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 homelike 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 bya 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 LabGlaciers LabCorrections: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) D

2) B

3) D

4) D

5) A

6) A

7) C

8) A

9) A