Name ___________________________________ Period: _________ Date: _____________Ms. De Pinto

Glacial Erosion &Deposition Lab

Problem: How do glaciers affect the landscape?

Introduction:Glaciers form when snowfall continues to accumulate over time. The weight of the snow

compresses downward creating a dense layer of ice. When it becomes thick enough it begins to ‘flow’ very slowly as a river of ice. When accumulation is great, the glacier advances, or moves, to the south. When accumulation is minimal and the glacier begins to melt, it retreats to the North.

When the glacier is advancing it picks up sediments along the way and carries them over vast distances. The sediments will drag along the bedrock leaving scratches and grooves that show the direction the glacier moved.

When the glacier begins melting and retreating, the sediments begin to be deposited. Some of these features are moraines, drumlins, kettle holes, and outwash plains.

Objectives:At the completion of this lab you should be able to:

Know how glaciers advance and retreat. Know the landscape features associated with glaciers. Know how Long Island was formed.

Materials/Resources: ESRT Colored pencils

Procedure A: Glacial Budget

Accumulation vs. AblationThe glacial budget is the relationship over time between advance (accumulation) and

retreat (ablation). It is basically a mathematical calculation to see if the glacier had more accumulation or more ablation. If it had more net accumulation over time, then the glacier advanced. If it had more net ablation over time, then the glacier retreated.

The topographic map on the following page shows three glaciers found in Alaska. Dashed lines show the Inferred location of the front edge of each glacier in 1948, 1964, and 1980. Solid lines show the location of the front edge of each glacier in 1998. Points A and B show the location of the front edge of the Taku Glacier in 1948 and 1998. Elevations are in feet.

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1. Complete the chart below for the three glaciers in the map of Alaska above. The distance must be measured. If the glacier advanced, the distance should be positive. If the glacier retreated the distance should be negative.

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2. Calculate the rate of advance or retreat for each glacier. Show your work, include the correct units, and round your answer to the nearest hundredth. Box in your final

answer.

3. Which glacier advanced the most distance between 1948 and 1998? ___________________

4. Which glacier retreated between 1948 and 1998? __________________________________

5. Which glacier accumulated at the fastest rate? _____________________________________

Procedure B: NYS GlaciersWhat features does New York exhibit to prove glaciers existed here?

Hole-in-the-wall Glacier (points E to F)

Taku Glacier (points A to B)

Norris Glacier (points C to D)

MAP A

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I. DrumlinsDrumlins are tear dropped shaped piles of unsorted sediments deposited as the glacier retreated. The point of the tear drop is the direction the glacier was advancing.

1. Observe the drumlins shown on map B. Draw an Arrow On Map B showing the direction of glacial advance in the area of Oswego, NY.

2. What was the exact direction of glacial advance?

_____________________________

3. Draw a drumlin in the box below that was formedby a glacier retreating directly NORTH.

II. U-shape valleysAs the glacier advances it gouges out great amounts of sediment and carries it away to be deposited elsewhere. The gouges create U-shaped valleys in sedimentary rock that

appear to be mountains or lakes. Cross section D below is a profile view of the Finger Lakes region in upstate NY. Observe Map A and the profile below to answer the questions that follow.

1. Why do you think these surface features are called the finger lakes?

Profile View D

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2. What general direction do you think, based on Map A, the glacier was advancing near the Finger lakes?

___________________________________

3. What is the general shape of the bottom of each of the lakes? _______________________

4. If these were not filled with water, what would they be called? ______________________

5. How does the shape of the glacial valley compare to the shape of a stream valley?

III. MoraineWhen the glacier ‘stops’ advancing and begins to melt a large amount of unsorted

sediments are deposited along the front leading edge of the glacier. That line of sediments is called moraine. If it represents the farthest point the glacier reached before retreating, it is called terminal moraine. The moraine is always perpendicular to the direction of glacial advance and retreat. Use the diagrams and maps below to answer the questions that follow.

Side View DiagramTerminal Moraine of Ontario Lobe, NYS

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1. In the NYS diagram above trace the terminal moraine of the Ontario Lobe in RED.

2. Draw the sediments that would be deposited by the glacier in the terminal moraine in the box below.

VI. Outwash PlainsOutwash plains are formed by the glacial meltwater. For this reason, the outwash

plains are formed by stream erosion and deposition. This means that the sediments carried are usually pebble sized or smaller and will be sorted in size order with the largest being deposited first.

1. Draw a picture of how the sediments in the outwash plain will be deposited in the box below.

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1. Based on what you have learned, draw a line on the diagram in BLUE where the glacier advanced the farthest.

2. Explain how you knew where to draw the line representing the glaciers furthest point of advance.

3. Explain how the drumlins in the diagram show the direction of advance and retreat.

4. Explain how kettle holes and lakes form.

Procedure C: The Formation of Long Island

The glacier that formed Long Island is called the Wisconsin glacier. This glacier actually covered Long Island at two different times, carrying rock fragments it picked up as it moved across Canada and the New England states. As the climate warmed, the edge of the glacier

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melted back to what is now known as Connecticut. Then, once again, the climate became cold and the glacier advanced once more across Long Island.

As the glacier melted each time, piles of ____________________ sediments were left behind, marking the farthest point that the glacier reached. These large, hilly piles of unsorted rock fragments created the glacial feature perpendicular to the direction of advance called a ______________________. The first advance created the Ronkonkoma moraine and formed the south fork of Long Island. The second advance created the Harbor Hills moraine and formed the north fork of Long Island. The highest elevation on Long Island is part of the Ronkonkoma moraine. It is called Jayne’s Hill and is 399 feet above sea level. It is located in Huntington, NY.

As the glacier melted, streams of water poured down the moraines. These streams of water carried a lot of small sediments as they flowed south toward the ocean. This sediment filled in the uneven ground south of the moraine creating large, smooth land areas called ___________________ plains.

The glaciers also created lakes on Long Island. Round holes, called __________________ holes, were created by large chunks of the glacier. These holes later filled in with groundwater. Lake Ronkonkoma and Lake Success are the two largest kettle lakes on Long Island.

The diagrams below show a map view and a side view between points E and F of Long Island. Use that diagram to answer the questions that follow.

1. The diagrams below represent three sediment samples labeled X, Y, and Z. These samples were collected from three locations marked with empty boxes ( ) on map C

below.

FE

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Write the letter of each sample in the correct box on map C to indicate the location from which each sample was most likely collected.

2. On the next page are two pictures. One is of a North Shore beach, and one is of a South Shore beach. Determine which is the North Shore and which is the South Shore. Provide a

scientific explanation of your determination based on what you have learned in this lab.

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