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Glaciers
N/A
33
Geology
Undergraduate 3
12/07/2010

Additional Geology Flashcards

 


 

Cards

Term
cirque
Definition
steep-sided, half bowl-shaped recess carved into a mountain at the head of a valley carved by a glacier
Term
horn
Definition
is the sharp peak that remains after cirques have cut back into a mountain on several sides
Term
aretes
Definition
sharp ridges that seperate adjacent glacially carved valleys
Term
erractic
Definition
is an ice-transported boudler that has not been derived from underlying bedrock
Term
lateral moraine
Definition

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

Term
medial moraine
Definition
where tributary glaciers join, the adjacent lateral moraines join and are carried downglacier as a single long ridge of till known as...
Term
recessional moraine
Definition
is an end moraine built while the terminus of a receding glacier remains temporarily stationary
Term
terminal moraine
Definition
is the end moraine marking the farthest advacne of a glacier
Term
ground moraine
Definition
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
Term
drumlin
Definition
large bodies of till shaped into streamlined hills
Term
kettle
Definition
when an ice block melts, a depression or ... forms
Term
outwash
Definition

Large quantities of meltwater usually run over, beneath, and away from ice...the material that is deposited

by this meltwater is...

 

Term
esker
Definition

an outwash feature of unusual shape associated with former ice sheets and smoe very large valley

glaciers is an...

Term
varve
Definition
two layers of sediment representing one year's deposition in a lake
Term
hanging valley
Definition

after glaciers dissapear, these tributaries remain as ...

high above the main valley

Term
U-shaped valley
Definition
is a characteristic of a glacial erosion
Term
crevasses
Definition
open fissures, that develop along margins of glaciers in places where the path is curved
Term
roche mountonnee's
Definition
areas where bedrock is more resistant to erosion stand out after glaciation and are elongated parallel to the direction of glacier flow.
Term
how and why does a glacier form?
Definition

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

Term
glacier movement
Definition

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:

Term
how do glaciers transports till and deposits it..?
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

 

Term

why does it retreat or advance?

 

Definition

B/c of either accumulation/ablation 

 

advancing=

  1. glaciers with positive budgets push outward/downward
receding=
  1. melt back, rate of flow slows

Term

terrestrial theories that produced the 

ICE AGE

Definition

 

  1. Continential position
  2. Changes in atomosphere(CO2)
  3. Ocean circulation 

 

Term
Continential Positions
Definition
closer to the poles, more favorable to glaciation
Term
Changes in Atmosphere(CO2)
Definition
CO2 cause greenhouse effect along with more volcanic eruptions SO2=cold temp for summers
Term
Ocean circulation
Definition
land mass blocks circulation of the warmer Atlantic ocean but with free/open moisture=more snow
Term
Astronomical theories that produced the ICE AGE?
Definition

MILANKOVITCH:variations in solar, orbital changes cycles of seasons
  1. axial tilt>obliquity
  2. orbital eccentricity=elliptical orbit/farther from the sun
  3. precession="wobble" combined effects of moon to create cooler summers
  • low angle
  • max distance
  • during northern hemis summer

Term
evidence for milankovitch~
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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