Lab 9: Glaciers and Deserts

What is glacial till?

As glaciers retreat, the ice deposits, or dumps out, sediments ; Clay, sand, cobbles, boulders.

What are dunes?

Consist of sand-sized particles that are carried along the desert floor by the wind.

Why is ice a poor sorting agent?

It transports virtually all particle sizes

Would bajadas and alluvial fans make good places for houses?

No, bc they will shift and move

Dunes: What do particles do?

Particles roll up the windward slopes and down the leeward slope.

What is stratified drift?

Sediments deposited by meltwater streams at the lower edge or terminus of a glacier. ; Sand and gravel.

What does till contain?

a large amount of clay mixed with larger particles such as sand, cobbles, and boulders

What are the different types of water erosion in deserts?

alluvial fans and bajadas

What are the types of glaciers?

alpine (valley) glaciers and continental glaciers

How are hanging valleys formed?

by a smaller glacier meeting a larger glacier

What are continental glaciers

covers continents

What are alpine glaciers?

covers mountain valleys

Glaciers contain rock fragments, which recreate what?

deep scratches called striations in the bedrock. You can determine the direction of glacial movement (parallel to the striations)

What is Plastic flow?

deform rather than break like putty and flows rather than fractures

What are glaciers?

flows of ice;Thick masses of ice that originate on land from the accumulation and compaction of snowfall.

What are bajadas?

form when alluvial fans join together

what are the different types of glacier sediment?

glacial till and stratified drift

spectacular waterfalls often form where the smaller, _______ ______ meet the main valley.

hanging valleys

When do glaciers remain stationary?

ice accumulation equal losses

When do glaciers retreat?

ice losses exceed accumulation

What are alluvial fans?

large amounts of sediments that accumulate where mountain streams reach the desert floor.

Is there any evidence that the alluvial fan is dynamic (growing or shifting position over time?)

lighter areas is new and darker areas is old

How do glaciers move?

plastic flow and basal slip

When do glaciers advance?

rate of ice accumulation exceeds rate of losses through melting and sublimation

What does stratified drift contain?

sand and gravel

At the lower edge or terminus of a glacier ________ _______ sort and deposit stratified drift consisting mainly sand and gravel.

stratified drift

What is Basal slip?

the entire ice mass slides over the land surface.

How can you experiment how ice is moving faster in the center or along the sides of the glacier?

the ice is moving faster in the center. Along the sides, friction is happening. You can experiment by putting tracking devices in the ice.

Dunes migrate in the direction of :

the prevailing winds.

What are the sinuous features radiating down alluvial fans and describe the surface:

there are channels where the water flowed after alluvial fan..; sloped, a lot of stream beds, relatively sorted

As glaciers retreat, the ice deposits (dumps out) sediment called ____.

till

Which will make a more productive aquifer? glacial till or stratified drift?

till; because it has a mix of particles. There will be more and larger pore spaces so water can go through

Glaciers often develop crevasses, which can reach up to 50 m. How do crevasses form?

when the top of a glacier bulges outward as the ice rides over a high spot in the underlying terrain

____ shapes deserts. A lack of ________ and vast open expanses allow desert wind to accumulate a lot of _______. They become powerful sediment ________ ______.

wind; vegetation; energy; transporting agents

Larsen B Ice Shelf, Antarctica: About 3,250 square kilometers of shelf area disintegrated in __ days.

35