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77 Cards in this Set
- Front
- Back
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graded vs ungraded: streams adjust their profiles to changes in
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base level
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graded
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correct channel characteristics necesarry to maintain just the velocity required to transport material
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ungraded
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steep slope; far away from base level
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entrenched meanders
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steep sides
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river terraces
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former flood plains
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rictor scale:
measures _________ |
shockwaves by earth movement
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rictor scale:
each # amp increase is ______ each # energy increase is ____ |
10-fold
30-fold |
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lisben, portugal
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1755:
tsunami damage, 70 thou killed |
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new madrid, missouri
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1811:
biggest in us, noone lived there |
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charleston, sc
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1886:
intesity 10 on mercale scale |
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san fran
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1906:
city burned for 3 days |
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alaska
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1964:
8.4-8.6 on rictor scale |
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_____% todays water is glacial
______% of land glacial |
2
10 |
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glacial initiation:
_____ degree drop in reg temperatures to initiate ice age |
4-5
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firn
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granular, used to be snow, turned into glacial ice
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in order for glaciers to form:
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more snow must accumulate than melts
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glacial movement: 2 ways
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-plastic flow
-basal slip |
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internal plastic flow:
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brittle until at 50m of pressure begins to behave as plastic material, flow begins
stress exceeds bonds between layers |
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molecular structure of ice
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layers
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basal slip
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entire ice mass slipping along ground
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in basal slip- melt water acts as...
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lubricant as glacier moves over bedrock
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melt pressure of ice ______ as presure ________
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decreases
increases |
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zone of fracture
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brittle ice on top cracks
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zone of wasteage
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net loss to glacier as all snow from previous years melts
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alpine glaciation =
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valley glaciers
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continental glaciation =
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ice sheets
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glacial erosion: two methods
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plucking
abrasion |
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plucking:
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meltwater penetrates cracks of bedrock, freezes, expands
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abrasion:
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ice and loads of bedrock fragments slide over bedrock- sandpaper
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glacial flour
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fine suspended sediment found in melt water
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best glacial erosion occurs in
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alpine glaciation
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landforms created by glacial erosion (10)
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u shaped troughs
truncated spurs hanging valleys horn cirque arete tarn col pater naster lakes roche montinee |
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u shaped trough
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EROSION
-occupy whole river valleys -combination of abrasion & plucking |
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truncated spurs
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EROSION
-triangular shaped cliffs -eroded sides of u shaped troughs |
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hanging valley
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EROSION
-valley containing main trunk glacier is eroded deeper than smaller valleys -glaciers recede valleys left standing higher -waterfalls |
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horn
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EROSION
-pyramid-like -group of cirques around a single high mountain |
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cirque
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EROSION
-plucking -bowl shaped depression carved in the glacier |
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formation of cirque
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snow accumulates>glacier
starts plucking, glacier gets bigger |
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arete
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EROSION
-knife-like ridge |
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formation of arete (2)
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-cirques on opposite sides
-2 glaciers occupying parallel valleys separating |
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tarn
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EROSION
lake in a cirque |
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col
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EROSION
gap or pass from one valley to another |
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pater noster lakes
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EROSION
-glacial valleys with string of lakes -combo of plucking & abrasion, mostly plucking |
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roche montinee
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EROSION
abrasion- glacier moving, rock grinds away, smearing plucking- side of glacier, frost plucking, not moving |
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drift
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glacial deposition of any origin
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drift consists primarily of __________. depris that underwent little or no _______ weathering prior to deposition.
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-mechanically weathered rock
-chemical |
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till
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material directly deposited by glaciers
unsorted, unstratified |
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stratified drift
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glacial material deposited by melt water
sorted, stratified |
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two types of glacial deposition
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till
stratified drift |
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landforms made of glacial till (3)
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glacial eratics
morraines drumlins |
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glacial erratics
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deposited by glacier- did no originate where it is found- glacier moved it (mainly larger grain)
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end morraines
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ridge of a valley that form at the terminus of a glacier
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lateral morraines
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ice melt, accumulation of depris dropped next to valley walls
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medial morraines
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2 alpine glaciers for single ice stream, forms single strip of debris
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drumlins
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dont occur by themselves
assymetrical made of glacial till directly deposited by glacier |
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formation
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-started as morraines, glacier advances over morraine smearing
-conditions must be perfect |
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example drumlins
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bunker hill,
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landforms made of stratified drift (6)
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valley train
outwash plain kettles kames kame terraces eskers |
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valley train
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STRATIFIED
stratified drift contained to a valley |
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outwash plain
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STRATIFIED
stratified drift deposited in an area in front of where ice was |
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kettles
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STRATIFIED
depressions (can be lakes) |
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example of kettle
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STRATIFIED
waldon pond- concord massachusettes |
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kames
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STRATIFIED
isolated hills of drift begins to melt glaciers get cracks, water moving, accumulating, collects debris |
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kame terraces
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STRATIFIED
narrow masses of stratified drift laid down between the lacier and the side of the valley by a stream |
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eskers
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STRATIFIED
meandering, not linear long, narrow, sinuous ridge |
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other effects of iceage glaciers (2)
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crustal rebound
pluvial lakes |
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example of crustal rebound
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king edward island, canada
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example of pluvial lakes
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salt lake, utah
used to be in utah, nebraska, cali |
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pleistecene pd: swiss geology guy
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louis agassiz
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4 glacial stages in north america
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nebraskan
kansan illinoisan wisconsonan |
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pds of glaciation + interglacials effects of ecosystems
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-arizona cypris
-rivers change their courses- Missouri river |
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2 necessities for glaciation to initiate
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-land in proper latitudes
-slight drop in worldwide temperature |
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guy who used 3 factors to predict next ice age
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molatin molankovitch
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3 factors to predict next ice age
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ecentricity
obliquity precession |
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ecentricity
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changes in orbit around the sun- distance from sun
cycle: 100,000 yrs |
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obliquity
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angle of tilt of earth
cycle:41,000 yrs |
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precession
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wobbling of the earth's axis
cycle: 26,000 yrs |
