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53 Cards in this Set
- Front
- Back
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What are the two basic cycles of glaciers? |
Hydrologic cycle and Rock cycle |
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What is a glacier? |
A thick mass of ice that originates on land from the accumulation, compaction, and re-crystallization of snow. |
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What are the two main types of glaciers? |
Alpine or valley glaciers and Ice sheets |
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What are the other types of glaciers? |
Icecaps Outlet glacier Piedmont glacier |
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What is an Alpine or valley glacier? |
Exist in mountain areas Flow down a valley from an accumulation center at its head |
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What is and ice sheet? |
Exist on a larger scale that valley glaciers Two major ice sheets on Earth are Greenland and Antarctica Often called continental ice sheets Ice flows out in all directions from one or more snow accumulation centers |
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What are icecaps? |
Completely covers uplands and underlying landscape |
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What are outlet glaciers? |
A stream or ribbon of ice from an ice cap to the sea |
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What are Piedmont glaciers? |
When one or more alpine glaciers merge |
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What are the two types of movement of glaciers? |
Plastic flow and Basal Slip |
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What is plastic flow in glaciers? |
Occurs within the ice Has zones of fracture - occurs in the uppermost 50 meters Has crevasses --forms in brittle ice |
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What is Basal Slip? |
Entire ice mass slipping along the ground most glaciers move by basal slip |
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What are the rates of glacial movement? |
Average velocities vary considerably from one glacier to another Rates or up to several meters per day |
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What is glacial budget? |
The balance between accumulation at the upper end of the glacier and loss at the lower end |
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What happens if accumulation is greater than the loss? (called ablation) |
The glacial front advances |
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What will happens if ablation increase? (accumulation decreases) |
The ice front will retreat |
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What is the Zone of Accumulation? |
area where a glacier forms Elevation of the snowline varies greatly |
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What is the Zone of Wastage? |
Area where ther is a net loss to the glacier due to melting and calving. |
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What is calving? |
Calcing is the breaking off of large pieces of ice (icebergs where the glacier has reached the sea) |
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What is glacial erosion? |
Capable of great erosion and sediment transport Erode the land primarily by plucking and abrasion |
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What is plucking? |
Lifting of rock |
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What is abrasion? |
rocks within the ice acts like sand paper to smooth and polish surface below |
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What does abrasion produce? |
Rock flour (pulverized rock) and glacial striation (grooves in the bedrock) |
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What are the 7 landforms created by glacial erosion? |
Hanging trough Hanging valley Cirques Tarn Aretes Horns Fjords |
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What is a Hanging Trough? |
erosion changes a narrow V-shaped valley into a U-shaped trough |
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What is a Hanging Valley? |
After ice has receded, valleys are left hanging above the main trough with rivers flowing through producing spectacular waterfalls (yosemite) |
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What is a cirque? |
an amphitheater-shaped basin (walls on three sides but open on the downvalley side) at the head of a glaciated valley produced by frost wedging and plucking |
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What is Tarn? |
after the glacier has melted away, the cirque basin is often occupied by a small lake called a tarn |
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What are Aretes? |
a narrow sinuous sharp-edged ridge separating two adjacent glaciated valleys |
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What are Horns? |
a pyramid-like peak formed by glacial action in three or more cirques surrounding a mountain summit (Matterhorn, Switzerland) |
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What are Fjords? |
steep-sided inlets of the sea formed when glacial troughs were partially submerged |
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What are type of glacial drift? |
Till Stratified drift Erratic |
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What is Till? |
type of glacial drift material that is deposited directly by the ice and is typically unstratified and unsorted |
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What is Stratified Drift? |
sediments laid down by glacial meltwater |
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What is erratic? |
an ice-transported boulder that was not derived from bedrock near its present site |
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What are depositional landforms made of till? |
moraines |
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what are moraines? |
layers of ridges of till |
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What moraines are produced by alpine glaciers? |
Lateral moraine and medial moraine |
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What is a lateral moraine? |
till deposits that form ridges along the side of a valley glacier that accumulate large quantities of debris from the valley walls |
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What is a medial moraine? |
formed when two advancing valley glaciers come together to form a single ice stream that leaves a single dark stripe of debris within the newly enlarged glacier |
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What are other types of moraines? |
End moraine and Ground moraine |
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What is an End Moraine? (terminal or recessional) |
a ridge of till that accumulates at the terminus of a glacier where a state of equilibrium is attained between wastage and ice accumulation (when the ice starts melting near the end of the glacier at a rate equal to the forward advance of the glacier) |
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What is a Ground Moraine? |
When wastage exceeds nourishment, a large quantity of till is deposited as the ice melts away, creating a rock-strewn undulating plain. (a gently rolling layer of till deposited as the ice front recedes) |
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What are Drumlins? |
smooth, elongated, parallel hills, with steep sided faces that face the direction from which the ice advanced. Occur in clusters called drumlin fields. |
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What are Outwash plains? |
as the water leaves the glacier upon melting, it rapidly losses velocity and much of its bed load is dropped. The result is a brroad, ramp- like accumulation of stratified drift built adjacent to the downstream edge of most end moraines with an ice sheet. |
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What is a Valley Train? |
formed in the same manner as outwash plains but in association with a valley and not an ice sheet |
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What are kettles? |
often end moraines, outwash plains, and valley trains are pckmared with basins or depressions. Form when blocks of stagnant ice become buried in drift and eventually melt, leaving pits in the glacial sediment. Most do not exceed 1.25 miled with a depth of 10 meters. |
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What are Kames? |
ice-contact stratified deposits that form steeped-sided hills from meltwater flowing over, within, and at the vase of motionless ice. |
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What are eskers? |
Ice-contact stratified deposits that are sinuous ridges composed largely of sand and gravel. They are made by streams flowing in tunnels beneath the ice, near the terminus of a glacier. They may be several meters high and extend for many kilometers. |
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During the ice age, what percent of Earth's land was covered by ice? |
30% |
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How long ago did the ice age begin? |
2-3 million years ago |
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what geological time did the ice age occur? |
pleistocene |
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What are 5 indirect effect of ice age glaciers? |
Forces of migration of animals and plants changes in stream courses rebounding upward of the crust in former centers of ice accumulation worldwide change in sea level climate change |
