Glaciers and Glaciation Page 27 Glaciers and Glaciation

GLACIERS- Rivers of Ice A large mass of moving ice and snow Page 27 GLACIERS- Rivers of Ice A large mass of moving ice and snow Types of glaciers a. ______________ glaciers form in mountain valleys at high elevations Alpine or Valley Continental b. ___________ glaciers form over vast areas of land. Show glacier video from my videos

Extent of the Northern Hemisphere Ice Sheets Page 27 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

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.

Some glacial features to look for Page 27 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...........................

Grand Teton National Park A glacier valley Grand Teton National Park A hanging valley, Yosemite National Park (Photo by C. C. Plummer)

The picture to the right shows bedrock exposed at the Bronx Zoo. 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.

Kelley’s Grooves found on Kelley’s Island, Ohio (right) 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)

SCRATCHED and POLISHED boulders are evidence of glacial erosion. 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 Page 27 3. Erratic 2. 4. 1. 6. 5. Braided stream 7. terminal moraine is a pile of unsorted glacial till, dumped where the 8. glacier stopped advancing. Long Island is a terminal moraine 9. Esker

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

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

He Scratches out mad grooves 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 List 3 other glacial Landscape features

Glaciers Lab Corrections: Top of page 2 Question #5- What general direction did the last ice sheet… Add to bottom of page 3 Question #9- What is the main difference between sediments deposited by water and sediments deposited by glaciers? Top of page 4 Question #16- What evidence proves that Long Island formed from glacial deposition?

Answers to Questions on pp 28 & 29 D B A A C