Glaciers 3 Flashcards

Glacier
Terms Definitions
Lacustrine
lake
till
unsorted glacial sediment
Ground Moraine
unsorted
material left
beneath the
glacier when
the ice melts
• Both glacier
types
Shrinking
Many Alpine Glaciers are
Recessional moraine
Till marking glacial retreat.
Glacial Erratic
large boulders
transported by glaciers
Glacial trough
The movement of glaciers.
Abrasion
wind -carried sand polishes rock
glacier
a moving river of ice
Eskers
(glacial deposit) Long winding ridge of sand and gravel
most glacier deposits are...
scratched and semi-round
Ventifacts
Rocks shaped by wind- blown sediments.
paternoster lake
string of connected glacial lakes
Drumlins
a. asymmetrical hills composed of till. b. Probably molded in the zone of flow.
Two types of glaciers
valley glaiers
continental glaciers
Serac
standing ice tower. Common in icefalls
- also very dangerous.
Accumulation
addition of snowfall, compaction and recrystallization
Alluvial Fans
A sloping deposit of sediment
Drumlins
Tear drop shaped land features; unsorted.
Crevasses
Cracks in surface ice in glaciers going down steeper gradient.
Erratics
A large bolder transported by a Glacier.
drumlin
a long, smooth, canoe-shaped hill that is usually found in groups, shaped by an advancing glacier
esker
result of deposits made by glacial melt waters running through tunnels under the glacier
Col
arete that takes on a saddle shape
Aretes
The ridges between glacial valleys can become very narrow, forming knife-like features
wedging
ice getting into the ground and creating cracks
Mountain glaciers
accumulated snow at colder HIGHER elevations, snow turns to ice and flows to lower elevations where it melts
stratified drift
sediments laid down by glacial meltwater
glacial drift
the material deposited in association with a glacier
A land-form formed when an advancing glacier overruns its old moraines
drumlin
isostasy
balance of the earth's crust which means if one area, the cause is sinking, another area, the crust is rising. isostatic rebound - man cause for earthquakes in ohio.
Striations
Scratch marks gouged into the bedrock by rocks suspended in glacial ice
plastic
lower 60 m, ductile flow heals cracks
kame
a symmetrical hill of sediment formed under crevasses after ice melts
isostatic rebound
removal of ice cause crustal uplift
Snow line
altitude at which snow accumulates on a mountain
mass and size
what two characteristics of glaciers make its distinct and often stunning evidence for their passing
Moulin
a nearly vertical channel in the ice that is formed by flowing water
Erosion by plucking
occurs when rocks disaggregate along pre-existing fractures, which are commonly enhanced by freeze and thaw of meltwateror by pressurized meltwater or ice that is injected into the cracks.
Medial Moraine
A moraine formed when two advancing valley glaciers come together to form a single ice stream, forms in the middle of the glacier
Iceberg
a mass of ice floating in the ocean
Erosion
process in which the glacier or melt water removes pieces rock from the earth's crust
kettle
a small deposition that forms when a chunk of ice is left in glacial till
glacier effect on midwest
erosional and depositional features throughout landscape, reason illinois is so flat, great lakes are the u-shaped glacial valleys
glacial valley
A U-shaped valley formed by glacial erosion
hanging valley
when a small tributary glacier is unable to erode as deeply as the large glaciers they join
Plucking
the process where a glacier flows over land and it picks up rocks
continental features
kame: made of glacier till. kettle: depressents that have water (geauga/punderson). marines: hills of ridges of till. drumlin: teardropped shape hill. esker: made of sand and is like a marine.
Tarn
a small lake (in mountain) occupying a cirque or trough. Usually occupies only a couple of acres
lateral moraines
form on the sides of the glacier
ice ages
times in the past when glaciers covered large parts of the worlds surface
Cirque
basin at the head of a glacial valley
What are the layers of the atmosphere?
Top: ThermosphereMesosphereSratospheretrophosphere(closest to our sky)
Moraines
A deposit of till left behind when a glacier retreats.
ice cap
a glacier that is less than 50,000 square kilometers in area
Medial moraines
The middle of the glacier, when the lateral moraines form they make a medial moraine
Wind Deposits are of Two Distinct Types
loess and dunes
continental glacier
a glacier that covers much of a continent or large island
crevasse
a fracture or crack in the upper 40-50 meters of a glacier
interglacial features
warmer periods of time btwn ice ages currently are living in an interglacial period and the earth should naturally warm for the next 80,000 years.
Self Arrest
a technique that climbers use to stop from falling down a slope by digging an ice ax into the snow
Polar glaciers
ice in a ______ always maintains a temp well below its melting point
What are the parts of a wave?
Top: CrestBottom: Troph
Internal plastic flow-
slow movement of a glacier in which ice crystals slip over each other
Zone of Fracture is Located...
near the surface of a glacier
Glacial erosion: explain proccesses and describe resulting landforms; Abrasion
Abrasion- scraping and grinding (rock flower and striations)
End Moraine
A ridge of till at the leading edge end of a stationary glacier.
How is glacial load transported?
Suspension (material stuck in the ice)
Alpine Glacier
a glacier that moves down from a high valley
Describe the Green House Effect?
Suns short waves heat the ground--warm air raises and heats the greenhouse.--long wave lengths radiated to the atmosphere.
How Did Early Scientists Explain Bubble Rock in Acadia National Park?
came from God (the great flood)
Where is the fastest flow of glaciers?
in the center, at the top
Describe the characteristics of a driftless area
This is an area in southwestern Wisconsin that the glacier went around. The hills are steeper and the land is not flat there.
Any Theory the Attempts to Explain the Causes of Glacial Ages Must Answer...
what causes the on set of glacial conditions? what caused the alternating glacial and interglacial stages that have been documented for the Pleistocene epoch?
ablated
lost ice
Types of deposition
drift
till
outwash
loess
erratics
Alpine
Form in mountainous areas
compress
squeeze or press together
terminus retreats
When wastage > accumulation
land cover
10%, ice age= 30%
end moraines
form at stable toe
Morain
unsorted till. Lateral, Medial, Recessional, Ground, end
Direction
grooves and striations indicate the ___________ a glacier moved
alpine glaciation
glacier in the mountainous regions
ice front
the end of the glacier
horn
a pyramid-like mountain with hollowed out faces in it from glaciers
firn
Partially compacted and refrozen snow which has yet to become a glacier
glacial outwash
meltwater...muds removed, size GRADED and stratified, abraded, rounded...dominated by sand and gravel
outwash
material deposited by melt water streams: some sorting occurs
tidewater glaciers
valley glaciers that flow into sea
Eskers-
long winding ridge of gravel and course sand deposited by a glacier
arete
sharp ridge formed by two glaciers eroding away on opposite sides; separating two cirques
Loess
extensive blankets of silt that is carried by the wind in suspension
Snowline
The lowest elevation in a particular area that remains coverd in snow all year. At the poles, the snowline occurs at sea level.
kinds of glaciers
valley glacier and continental glacier
Terminal Moraine
The farthest advance of a glacier
moraine
rock debris deposited by glaciers form features called
Icefall
broken glacial surface caused by steep inclines. (Very Dangerous)
Drift
any material carried and deposited by a glacier
Kettle Holes
If depressions form underneath a glacier and remain after the glacier is melted then water filling these depressions become small lakes where fine‐grained sediment is deposited.
hanging glaciers
cling to mt sides; wide not long
Moraine-damned lakes
Occurs when a terminal moraine has prevented some meltwater from leaving the valley.
a pile of glacier deposits that looks like an inverted spoon
drumlin
fiord
forms when sea levels rise, filling a valley once cut by a glacier in a coastal region
The Elevation Above Which Snow Remains Year Round
snow line
ice fall
region of crevasses and ice pinnacles (where blocks shear off)
Which movement of glacier occurs upper 150 feet and does not flow like taffy?
Brittle flow
Where are there continental glaciers?
Northern Canada, Greenland, Antarctica
Erratic
Big rock carried and deposited by a glacier.
Internal Flow
results from the deformation of the ice crystal structure, crystals slide over each other like a deck of cards
U
A ______ shaped valley is a valley that has steep sides and a flat bottom
basal slip
Sometimes the weight of the overlying ice
causes the ice at the bottom of a glacier to
melt and refreeze forming either a layer of
meltwater or a slushy layer of water and
sediment. In each case, friction with the
bottom is reduced causing the glacier to
move forward.
ice shelves
ice sheets that extend over the sea and float on water
Chatter Marks or Crescentic Gouges
half-mooned shaped fractures on glaciated rock surfaces caused by the irregular, jerky motion of a glacier
2 types of glacier
1. vallley glacier (alpine) 2. continental (ice sheet/ice cap)
Valley Glacier
A long, narrow glacier that forms when snow and ice build up in a mountain valley
Zone of fracture
Upper ~ 150 feet of the glacier
Glacial Till
What makes up moraines, which are an unsorted mix of rock materials
stratagraphic
most common oil map in NE Ohio also produces the least amount of oil.
Lake and River Ice
Ice forms later and disappears earlier
cryoconite
a depression made in the snow due to rock absorbing heat
Lateral Moraine
Glacial deposit on the side of a valley glacier on valley walls
kettle lakes
form in large numbers in the kettle holes or moraines and outwash plains
Star dune
Dune with a star shape, formed by wind that blows in from many directions
Hanging valleys
occur due to the more rapid erosion in the main glacier channel versus tributary channels, causing a large vertical difference between the channels once the glacier melts. Hanging valleys often contain waterfalls like Bridal Veil Falls in Yosemite
zone of accumulation
The process by which the glacier adds mass
compressant (type of stress)
rock layers are pushed tgthr occurs when large crustal plates collide.
5 acres
amount of cape cod lost every year due to erosion
it's left in place
what happens to a terminal moraine if the glacier retreats
depositional landforms created by alpine glaciation
(what glaciers produce when they melt and deposit their debris cargo at the glacier's terminus) glacial drift: stratified drift, till; moraines: lateral moraine, medial moraine, terminal moraine
glaciers carry lots of sediment
some falls from cliffs, some from erosion of substrate
A ______ is a stream of ice that flows between a steep rock walls from a place near the top of a mountain valley.
Answer: Valley Glacier
What causes a wave to break?
Trips over bottom. When depth to the bottom is 1/2 the wave length.
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