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| steep-sided, half bowl-shaped recess carved into a mountain at the head of a valley carved by a glacier |
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| is the sharp peak that remains after cirques have cut back into a mountain on several sides |
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| sharp ridges that seperate adjacent glacially carved valleys |
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| is an ice-transported boudler that has not been derived from underlying bedrock |
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are elongate, low mounds of till that form along the sides of a valley glacier.
Rockfall debris that accumulate along the eges of the ice form lateral moraines |
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| where tributary glaciers join, the adjacent lateral moraines join and are carried downglacier as a single long ridge of till known as... |
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| is an end moraine built while the terminus of a receding glacier remains temporarily stationary |
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| is the end moraine marking the farthest advacne of a glacier |
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| as ice melts, rock debris that have been carried by a glacier are deposited to form...a fairly thin, extensive layer or blanket of till |
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| large bodies of till shaped into streamlined hills |
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| when an ice block melts, a depression or ... forms |
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Large quantities of meltwater usually run over, beneath, and away from ice...the material that is deposited
by this meltwater is...
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an outwash feature of unusual shape associated with former ice sheets and smoe very large valley
glaciers is an... |
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| two layers of sediment representing one year's deposition in a lake |
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after glaciers dissapear, these tributaries remain as ...
high above the main valley |
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| is a characteristic of a glacial erosion |
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| open fissures, that develop along margins of glaciers in places where the path is curved |
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| areas where bedrock is more resistant to erosion stand out after glaciation and are elongated parallel to the direction of glacier flow. |
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| how and why does a glacier form? |
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snowflakes--granular snow--firn--glacier ice
snowflakes settle by compaction of their own weight, sharp points are destroyed as flkes reconsolidate into granules, snowflakes will recrystallize. new snowpack falls and compaction helps "cement" the granules by ice. As more snow accumulates granules are forced toether into tigh interlocking mosaic of glacier ice.
this is all caused by gravity |
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due to gravity move ranging from few millimeters to 15m a day.
thicker +
steeper+
near melting point of ice
+surface of ice
= faster movement
BASAL SLIDING: |
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| how do glaciers transports till and deposits it..? |
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Definition
plucking, b/c they are frozen into the base of the moving glacier. thicker glacier has more pressure=crushing
- bedrock under the glacier is polished, and scratched/striated
- streams drain rock flours and appear milky
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why does it retreat or advance?
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B/c of either accumulation/ablation
advancing=
- glaciers with positive budgets push outward/downward
receding=
- melt back, rate of flow slows
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terrestrial theories that produced the
ICE AGE |
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Definition
- Continential position
- Changes in atomosphere(CO2)
- Ocean circulation
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| closer to the poles, more favorable to glaciation |
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| Changes in Atmosphere(CO2) |
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Definition
| CO2 cause greenhouse effect along with more volcanic eruptions SO2=cold temp for summers |
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| land mass blocks circulation of the warmer Atlantic ocean but with free/open moisture=more snow |
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| Astronomical theories that produced the ICE AGE? |
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MILANKOVITCH:variations in solar, orbital changes cycles of seasons
- axial tilt>obliquity
- orbital eccentricity=elliptical orbit/farther from the sun
- precession="wobble" combined effects of moon to create cooler summers
- low angle
- max distance
- during northern hemis summer
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| evidence for milankovitch~ |
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Definition
cooling/warming of marine variations
shells of marine plankton=silicon,O2,calcite
- oxygen isotopes w/fossil shells measure ration of O18 to O16 or marine plankton fossils(provides a paleo temp)
- O18-COLD
- O16 ice on land
- plankton make shells from O18
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