earth science ch. 4
glacial and arid landscapes
Terms
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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