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66 Cards in this Set

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  • Back
What percent of the Earth's land surface is covered by glaciers?
10%
What two Earth cycles are glaciers part of?
The water cycle and the rock cycle
What is a glacier?
A think ice mass that forms over hundreds or thousands of years.
What are valley or alpine glaciers?
Small glaciers that exist in lofty mountain areas, where they usually follow a valley originally occupied by streams.
What are ice sheets?
A very large, thick mass of glacial ice flowing outward in all directions from one or more accumulation centers.
What are ice caps?
Masses of glacial ice covering a high upland or plateau and spreading out radially.
What is a piedmont glacier?
A glacier that forms when one or more alpine glaciers emerge from the confining walls of mountain valleys and spread out to create a broad sheet in the lowlands at the base of the mountains.
What is the movement of glacial ice called?
flow
Ice flows in two basic ways. What are those ways?
1) one mechanism involves plastic movement w/in the ice.
2) consists of the entire ice mass slipping along the ground
what is the zone of fracture?
the uppermost 50 meters of a glacier that consists of brittle ice.
What are cracks in glaciers called?
crevasses
What is the zone of accumulation?
Where snow accumulates and ice forms on a glacier.
What is the zone of wastage?
Where the net loss of the glacier takes place.
What is calving?
When large pieces of ice break off the front of glaciers.
What are icebergs?
When glaciers reach the sea.
What is the budget of the glacier?
The balance between accumulation and wastage.
What two ways do glaciers erode land?
1) plucking
2) abrasion
What is plucking?
The process by which pieces of bedrock are lifted out of place by a glacier.
What is abrasion?
The grinding and scraping of a rock surface by particles carried by a glacier.
What is rock flour?
The pulverized rock produced by the glacial abrasion.
What are glacial striations?
Long scratches and grooves gouged into bedrock.
What four factors control erosion by ice?
1)rate of glacial movement
2) thickness of the ice
3) shape, abundance, and hardness of the rock fragments contained in the ice at the base of the glacier
4) erodibility of the surface beneath the glacier.
What is a glacial trough?
when a glacier moves down a valley and widens, deepens, and straightens the valley. It changes it's shape from a V to a U.
What are hanging valleys?
A tributary valley that enters a glacial trough at a considerable height above its floor.
What is cirque?
An amphitheater-shaped basin at the head of a glaciated valley produced by frost wedging and plucking.
What are aretes?
A narrow knife like ridge separating tow adjacent glaciated valleys.
What are horns?
A pyramid like peak formed by glacial action in three or more cirques surrounding a mountain summit.
What are fiords?
A steep-sided inlet of the sea formed when a glacial trough was partially submerged.
What is glacial drift?
An all-embraced term for sediments of glacial origin, no matter how, where, or what form they were deposited
Most glacial drift is divided into 2 groups. WHat are they?
1) materials deposited directly by the glacier, known as till
2) sediments laid down by glacial melt water, called stratified drift.
What is till?
deposited as glacial ice melts and drops its load of rock fragments.
What is stratified drift?
Sorted according to the size and weight of the fragments.
What are glacial erratics?
When boulders are found in the till or lying free on the surface that is different from the bedrock
What are moraines?
Layers or ridges of till.
What are lateral moraines?
when the glacier wastes aways it leaves ridges along the sides of the valley.
What are medial moraines?
When two advancing valley glaciers come together to form a single ice stream.
What is an end moraine?
a ridge of till that forms at the terminus of a glacier.
What is ground moraine?
Gently rolling layers of till deposited as the ice front recedes.
What are outwash plains?
A relatively flat, gentle sloping plani consisting of materials deposited by meltwater streams in front of the margin of an ice sheet.
What is a valley train?
A relatively narrow body of stratified drift deposited on a valley floor by meltwater streams that issue from a valley glacier.
What is are kettles?
Depressions created when blocks of ice became lodged in glacial deposits and subsequently melted.
what are drumlins?
Stream like asymmetrical hills composed of till.
What are eskers?
Ridges composed largely of sand and gravel that were made by streams flowing in tunnels beneath the ice near the terminus of a glacier.
What are kames?
Steep-sided hill that, like eskers, are composed largely of stratified drift.
What is the Pleistocene epoch?
A time of extensive continental glaciation.
What are pluvial lakes?
Lakes that formed in the cooler, wetter climate. Pluvia =rain in Latin
What percent of Earth's land surface is dry regions?
30%
What does desert mean?
Deserted or unoccupied
What are the 2 water-deficient areas?
1)desert or arid
2) steepe or semiarid
What are ephemeral streams?
Streams that carry water only in response to specific episodes of rainfall.
What is most responsible for erosion in the desert?
Running water NOT wind.
What is interior drainage?
It means that the streams have a discontinuous pattern of intermittent streams that do not flow out of the desert to the ocean.
What is an alluvial fan?
A fan-shaped deposit of sediment formed when a stream's slope is abruptly reduced.
What is a playa lake?
A temporary lake in a playa.
What is a playa?
A dry, flat lake bed.
What are 2 ways that the transport of sediment by wind differs from running water?
1)wind has a low density so it can't pick up and transport coarse materials.
2)wind is not confined to channels and can spread over large areas and even the atmosphere.
What is deflation?
the lifting and removal of loose material by the wind.
What is saltation?
When larger grains of sand are rolled or skipped along the surface and comprise the bed load.
What are blowouts?
A depression excavated by the wind in easily eroded deposits.
What is desert pavement?
a layer of coarse pebbles and gravel created when wind removed the finer material.
What 2 ways does wind deposit?
1) extensive blankets of silt called loess
2)mounds and ridges of sand from the wind's bed load called dunes.
What are loess?
Deposits of windblown silt, lacking visible layers, generally buffcolored, and capable of maintaining a nearly vertical cliff.
What are dunes?
Hills or ridges of wind-deposited sand.
Where do most of the sediment that makes loess come from?
deserts and glacial deposits of stratified drift
What is the slip face?
The steep, leeward slope of a sand dune; it maintains angle of about 34 degrees.
What are cross beds?
Structures in which relatively thin layers are inclined at an angle to main bedding. Formed by currents of wind or water.