Glaciers Lab Part 1. The basicsA glacier is long living body of ice that moves under the

Bridalveil Falls

View of Bridalveil Falls, Yosemite National Park. The falls emanate from Bridalveil Creek.

The topographic map and grid for question 6 and 7 can be found at the end of this lab.

Draw the topographic file for the transverse shown on them map labeled Bridalveil Falls.

Question #6: How far does the water in Bridalveil Creek fall in reaching Yosemite Valley (the distance from top to bottom of the fall)?

Question #7: Given that Yosemite Valley is an ancient glacial valley, describe how Bridalveil Falls formed?

Question #8: What name would you apply to the valley that Bridalveil Creek is in?

Snow Creek Glacier

Photo of debris deposited to the side of the glacier that moved down Snow Creek. The road in the foreground is Tioga Road (see illustration below).

Topographic map showing Tioga Road and Snow Creek.

Review the topographic map showing the location of Tioga Road and Snow Creek.

Question #9: After reviewing the above topographic map, which way do you think the glacier was flowing that once filled up Snow Creek?

Question #10: What is a more technical term for the glacial material that was deposited laterally relative to the ancient glacier in Snow Creek?

Olmsted Point lies off of Tioga Road and just before Tenaya Lake. It contains a variety of glacial features a few of which are shown in the next two photographs.

Topographic map showing the location of Olmsted Point and photos A and B.

Photo A. At the base of glaciers a fine powder composed of ground up rock material acts

as a polishing agent. As the overlying ice moves slowly up or down a valley the fine powder under the pressure exerted by the overlying ice polishes the rock beneath the ice. When this polished surface is later exposed after the glacier has melted it is slowly worn away via abrasion and weathering. Can you pick out the polished versus the weathered

surface?  The bedrock in the photo is granite.

Photo B. The ridge above Olmsted Point is in places highly polished and sitting above

this surface are large boulders of rock that appear to be completely out of place. These are believed to be boulders that were carried in the glacial ice, and then when it melted

the boulders came to rest on the polished surface.

Review the map showing the location of Photos A and B, and then study the figures and their captions.

Question # 11: In Photo A what part of the photograph is glacial polish and what part is exposed granite?  Briefly explain your answer.

Question # 12: In Photo B how do we know that the boulders were deposited after the glacier melted and before the modern day topography was developed?

Topographic maps and profile grids: