Geology Chapter 11

51 terms by jbarnaby1206 

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why glaciers are part of water cycle

made of frozen water; melt water is freed

why glaciers are part of rock cycle

erosional agents that accumulate, transport, and deposit sediment

glacier

a thick ice mass that forms over hundred or thousands of years

alpine/valley glacier

a glacier confined to a mountain valley, which in most instances had previously been a stream valley

ice sheet

a very large thick mass of glacial ice flowing outward in all directions from one or more accumulation centers

ice caps

a mass of glacial ice covering a high upland or plateau and spreading out radially

piedmont glaciers

a glacier that forms when one or more valley 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

plastic flow

a type of glacial movement that occurs within the glacier below a depth of approximately 50 meters in which the ice is not fractured

slippage

the entire ice mass slipping along the ground; basal slip

zone of fracture

the upper portion of a glacier consisting of brittle ice

crevasse

a deep crack in the brittle surface of a glacier

surge

a period of rapid glacial advance typically sporadic and short-lived

zone of accumulation

the part of the glacier characterized by snow accumulation and ice formation

zone of wastage

lies below the snowline there is a net loss to the glacier as all of the snow from the previous winter melts so does some of the glacial ice

calving

wastage of a glacier that occurs when large pieces of ice break of into water

ablation

a general term for the loss of ice and snow from a glacier

frost wedging

the mechanical breakup of rock caused by the expansion of freezing water in cracks and crevices

plucking

the process by which pieces of bedrock are lifted out of place by a glacier

abrasion

the grinding and scraping of a rock surface by the friction and impact of rock particles carried by water, wind or ice

striations

scratches or grooves in a bedrock surface caused by the grinding action of a glacier and its load of sediment

polishing

when abrasive actions don't produce striations but polishes the rock

glacial valleys

valley created by a glacier

truncated spurs

Blunt-ended ridge of rock jutting from the side of a glacial trough, or valley.

hanging valleys

a tributary valley that enters a glacial trough at a considerable height above the floor of the trough

pater noster lakes

a chain of small lakes in a glacial trough that occupy basins created by glacial erosion

cirque

an amphitheater-shaped basin at the head of a glaciated valley

glacial trough

a mountain valley that has been widened, deepened, and straightened by a glacier

fiord

a steep-sided inlet of the sea formed when a glacial trough was partially submerged

arete

a narrow knifelike ridge separating two adjacent glaciated valleys

horn

a pyramid-like peak formed by glacial action in three or more cirques surrounding a mountain summit

roche mountonnee

an asymmetrical knob of bedrock formed when glacial abrasion smoothes the gentle slope facing the advancing ice sheet and plucking steepens the opposite side as the ice overrides the knob

inselberg

an isolated mountain remnant characteristic of the late stage of erosion in a mountainous region

glacial drift

an all-embracing term for sediments of glacial origin no matter how, where, or in what shape they were deposited

stratified drift

sediments deposited by glacial meltwater

till

unsorted sediment deposited directly by a glacier

glacial erratic

an ice-transported boulder that was not derived from the bedrock near its present site

lateral moraine

a ridge of till along the sides of a valley glacier composed primarily of debris that fell to the glacier from the valley walls

medial moraine

a ridge of till formed when lateral moraines from two coalescing valley glaciers join

end moraine

a ridge of till marking a former position of the front of a glacier

ground moraine

an undulating layer of till deposited as the ice front retreats

outwash plain

a relatively flat gently sloping plain consisting of materials deposited by melting-water streams in front of the margin of an ice sheet

valley trains

a relatively narrow body of stratified drift deposited on a valley floor by melting-water streams that issue from the terminus of a valley glacier

terminal moraine

the end moraine marking the farthest advance of a glacier

kettle hole

depressions created when blocks of ice become lodged in glacial deposits and subsequently melt

drumlin

a streamlined asymmetrical hill composed of glacial till

esker

sinuous ridge composed largely of sand gravel deposited by a stream flowing in a tunnel beneath a glacier near its terminus

kame

a steep-sided hill composed of sand and gravel originating when sediment collected in openings in stagnant glacial ice

ice age

a time when ice sheets and alpine glaciers were far more extensive than they are today

causes of glaciation

-plate tectonics
-environment/climate changes
-variations in earth's orbit

milankovitch's model for glaciation and the earth's orbit

1. variation in the shape of earth's orbit
2. changes in the angle of the axis
3. wobbling of the axis

consequences of glaciation

-erosional and depositional work
-migration of organisms
-changes in stream courses
-adjustment of the crust
-climate changes
-change in sea level

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