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59 Cards in this Set
- Front
- Back
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What is a firn?
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Granular ice= 1/2 density of water
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What are the 2 portions a glacier can be divided into?
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Zone of accumulation and the zone of ablation
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What is zone of accumulation
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net gain of ice
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what is zone of ablation
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ice loss by melting, evaporating and calving
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what is snowline
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the lowest topographic limits to sustain a year-round snow cover; the boundary between the zone of ablation and the zone of accumulation
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How do snow and ice accumulate in glaciers?
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-snowflakes pressed together by weight of other snowflakes
-More snow adds weight and compresses flakes into small spheres -Increasing depth and pressure cause snow to become crystalline ice |
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What are the two types of glacier movement
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Real movement and apparent movement
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What are the qualities of glacier real movement
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-From zone of accumulation to zone of ablation
-Basal slip: movement as whole along the bottom, slow except surge time -differential movement- central part moves faster and steep slope moves faster, creating crevasses |
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what are the qualities of glacier apparent movement?
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advancement and retreat of its terminus due to the change in snow line
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When was the last ice age?
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The pleistocene glaciation in the late cenozoic era~ 2 mil years ago to 10,000 years ago.
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What percentage of the earth's landmasses were covered in ice during the last ice age?
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30%
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The sea level during the last ice age was _______ ft. lower than it is now
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400
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What evidence supports that there was an ice age 2 mil years ago?
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• Formation of the Great Lakes, the Finger Lakes (11)
• Massive deposits of moraine debris in Midwest, Long Island etc • disruption of drainage system • Numerous pluvial lakes in the western U.S. • Deep grooves and striations in the bedrocks |
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What is glacial deposition commonly referred to as?
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Glacial drift
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What is till?
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Unsorted and unlayered rock directly deposited by glacier ice
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What is a moraine
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a body or ridge of till left behind by a
retreating glacier |
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What is an erratic
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A large boulder that is not from nearby rock. Transported from far away
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What is outwash?
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Deposits from glacial melt water
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Where do alpine valley glaciations occur?
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Form in high altitude regions and move downslope
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How does erosion occur in alpine valley glaciations?
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by plucking and abrasion, dictated by the size of a glacier
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What is a cirque
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spoon-shaped circular depression
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What is a tarn
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small mountain lake by glacier erosion along a glacier trough
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what are paternoster lakes?
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a series of tarns linked by a post-glacier stream
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what is the horn of a glacier
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sharp, pointy peak sculpted by several cirque glacier
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What is an arete
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sharp ridge due to erosion of two adjacent valley glaciers
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What is a U-shaped trough
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glaciated valley with U-shape a cross section
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What is a hanging valley
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tributary glaciated valley hanging way above its
main glacial valley |
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What kind of deposition occurs in alpine valley glaciers
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Erratic, moraines (lateral moraine, medial moraine, end
moraine), outwash plain |
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Where does continental glaciation form?
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Form in polar regions as ice sheets
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Erosion in continental glaciation
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tends to subdue or level off the land surface due to
enormous mass of ice sheet, but do have roche moutonnée |
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Continental glaciation deposition
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Erratic, moraines (terminal moraine, recessional morain,
ground moraine), drumlins, eskers, outwash plain, kettle lakes |
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Global climate change is caused by...
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Tilt of the earth's axis, Wobbling of earth's axis, Orbital change (eccentricity) around the Sun, Anthropogenic activities (fossil fuels, landuse changealbedo, volcanic activities, sun spot activites, and interaction of atmosphere and ocean
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Cause of earthquakes
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faulting, elastic rebound theory,
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What is the focus/hypocenter?
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a subsurface place where earthquake
occurred/started, the initial site of rock failure |
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What is the epicenter?
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the surface location directly above the focus
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What kind of faults cause most earthquakes?
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Strike slip, reverse/thrust faults, and normal faults
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seismic waves radiate _______ from the hypocenter
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outward
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Where is the concentration(distribution) of earthquakes?
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Circum pacific belt- releases 80% energy, alps-himalayans mountinous belt..15-20% energy, and mid-oceanic ridges about 5% energy
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How many km is considered a shallow earthquake
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0-70
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How many km is considered an intermediate earthquake?
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70-300 km deep
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how many km is considered a deep earthquake
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from 300-700
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between shallow, deep, and intermediate quakes, which one is the most common
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shallow
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what are the two types of body waves
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S and P and surface waves
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Properties of P waves
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-Vibration of earth materials are parallel to the direction of the waves
-Travels at the fastest speeds and travels through all media -has the lowest amplitude and the highest frequency |
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Properties of S waves
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S waves:
• shear waves or secondary waves • movements of the earth materials perpendicular to the direction in which the wave is moving • travel only through solid material in a slower speed than P waves • Higher amplitude than that of P waves and lower frequency |
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properties of surface waves
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• Travels along the earth surface
• movements of the earth materials perpendicular to the direction in which the wave is moving • causes a great ground vibration and travels the longest distance in the slowest speed • Highest amplitude |
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how many seismograms are needed to pinpoint an epicenter?
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3 different seismograms
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What does a single seismogram tell you
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-time lapse between s and p waves
-distance to the epicenter -amplitude of ground movement -earthquake magnitude -and the time when the earthquake occured |
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What does the magnitude scale measure?
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It measures the magnitude of ground motions such as the amount of energy released by an earthquake
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In order to find local magnitude measure...
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s-wave amplitude
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What is the intensity scale based on?
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survey of the damage to surface structures
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what is the range of the intensity scale
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1-12
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What do the lower values of the intensity scale represent?
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represent human response to the ground motions
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What do intermediate values of the intensity scale represent
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show the response of infrastructures
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What do the Upper values represent?
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ground failure processes
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What factors govern the intensity of an earthquake
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-Human preparation
-types of rocks and rock structures -the distance from the epicenter -the magnitude and duration of the quake |
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What is liquefaction?
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The process by which water-saturated fine grained sediments liquefy, or behave as a fluid, when shaken by an earthquake
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How are earthquakes predicted
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Monitor the amount of strain built up in rocks
-earth surface changes in tilt and elevation -increase in radon emissions from wells and changes of water levels in wells -abnormal animal behaviors -places of overdue time between quakes |
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What are the earthquake hazards
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loss of life, infrastructure damage, ground shaking, fire, tsunami, liquefaction, and flood
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