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earth science ch. 4

glacial and arid landscapes

Terms

undefined, object
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lateral moraine
when a glacier wastes away, the large quantites of debris from the valley walls are left as ridges called lateral moraine
slip face
a steep, leeward slope of a sand dune; it maintains an angle of about 34 degrees
horn
sharp, pyramid-like peaks that project above the surroundings
stratified drift
sediments deposited by glacial meltwater
dune
a compilation of commonly deposited sand in mounds or ridges
ephemeral stream
they carry water only in response to specific episodes of rainfall
pleistocene epoch
best known as a time of extensive continental glaciation
piedmont glacier
they occupy broad lowlands at the bases of steep mountains and from when one or more valley glaciers emerge from the confining walls of mountain valleys
outwash plain
a relatively flat, gentle sloping plain consisting of materials deposited by meltwater streams in front of the margin of an ice sheet
glacial trough
what was once a narrow V-shaped valley is transformed into a U-shaped glacial trough
ice cap
covering the top of mountains
deflation
one way the wind erodes; the lifting and removal of loose material by wind
arete
sinuous, sharp-edged ridges
ice sheet
enormous masses that flow out in all directions from one or more centers and obscure all but the hightest areas of underlying terrain; often called continental ice sheets
loess
extensive blankets of fine silt
glacial drift
an all-embracing term for sediments of glacial origin, no matter how, where or in what form they were deposited
desert
dry deserted land
rock flour
ground-up rock produced by the grinding effect of a glacier
zone of wastage
part of a glacier beyond the zone of accumulation, where all of the snow from the previous winter melts, as does some of the glacial ice
blowout
shallow depressions; a depression excavated by the wind in easily eroded deposits
glacier
a thick ice mass; originating from the accumulation, compaction and recrystallization of snow
zone of accumulation
part of a glacier characterized by snow accumulation and ice formation; its outer limit is the snowline
abrasion
as ice and its load of rock fragments slide over the bedrock, they function like sandpaper to smooth the surface belwo
till
unsorted sediment deposited directly by a glacier
kame
steep sided hill composed of sand and gravel originating when sediment collected in openings in stagnant glacial ice
fiord
deep, steep-sided inlets of the sea where mountains are adjacent to the ocean
interior drainage
regions that have a discontinuous pattern of intermittent streams that do not flow out of the desert to the ocean
ground maraine
a large quantity of till that is deposited as the ice melts away, creating a rock-strewn, undulating plain
glacial striations
long scratches and grooves gouged into the bedrock as a result large rock fragments forming at the bottom of a glacier
cross beds
as sand is deposited on the slip face, it forms layers inclined in the direction the wind is blowing.
desert pavement
a surface with a layer of coarse pebbles and cobbles that are too large to be moved by the wind
valley train
a relatively narrow body of stratified drift deposited on a valley floor by meltwater streams that issue from a valley glacier
alpine glacier
a glacier confined to a mountain valley, which in most instances had previously been a stream valley
steppe
1 of the 2 types of dry climate. a marginal and more humid variant of the desert that separates it from bordering humid climates
crevasses
the top 50 meters [ zone of fracture ] results in large cracks
esker
ridges composed of sand and gravel; deposits made by streams flowing in tunnels beneath the ice, near the terminus of a glacier
plucking
process by which pieces of bedrock are lifted out of place by a glacier
playa lake
rare abundant rainfall flows across the alluvial fans to the center of the basin, converting the floor into a shallow lake
cirque
hollowed-out, bowl shaped depressions have precipitous walls on three sides but are open on the down valley side
valley glacier
aka Alpine glacier; a glacier confined to a mountian valley, which in most instances had previously been a stream valley
alluvial fan
a cone of debris at the mouth of the canyon
hanging valley
after the ice as melted, valleys of tributary glaciers are left above the main trough; waterfalls
kettle
basins or depressions that fill with stagnant ice melt, leaving pits in the glacial sediment
end moraine
a ridge of till that forms at the terminus of a glacier; marking a former position on the front of a glacier
glacial erratic
when boulders are found in the till or lying free on the surface
medial moraine
are formed when two advancing valley glaciers come together to form a single ice stream
pluvial lake
a lake formed during a period of increased rainfall
drumlin
streamlined asymmetrical hills composed of till

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