use the map to answer the question. louisiana has lost and gained land on its coast over the years....
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Use the map to answer the question.
Louisiana has lost and gained land on its coast over the years. The red color on the map shows the land gained in Atchafalaya Bay between the years 1932 and 2000. What caused the new land to form?1.A.sediments moved by waves2.B.tectonic uplift3.C.sediments carried by rivers4.D.dropping sea levels
The downslope movement of loose sediments and weathered rock resulting from gravity
Weathering erosion mass movements Climate controlled All occur on slopes
Mass movements
Material’s weight Resistance to sliding or flowing A trigger event (ex. Earthquake) Erosion at the foot of a slope water
Influencing variables
Too little prevents sediments from holding together, increasing potential for movement
Too much water increases the weight of the soils; can also act as a lubricant
Not involved as transport agent
Water and mass movements
Slow, steady downhill flow of soils Noticeable over long periods Observe structures to identify creeps Solifluction occurs when layer above
permafrost slides downhill
Creeps
Flow as if the mass was a thick liquid Can move fast or slow Mudflows-swiftly moving mixtures of mud
and water Common in volcanic regions Also common in semi-arid regions that
experience intense short rainstorms (So Cal)
Flows
Rapid, downslope movement of earth’s materials
Happens when a thin block of loose soil, rock, and debris separate from the bedrock (landslide)
Can cause flooding Common on slopes that are water saturated Rock slides are triggered by earthquakes
Slides
When material in a landslide rotates and slides along a curved surface
Occur in areas with thick soils and steep to moderate slopes
Common after rains Leave crescent shaped scars
Slumps
Landslides that occur in mountainous areas with snow
Usually occur on slopes of at least 35 degrees
10000 avalanches occur every year in west US alone
Sun melts surface snow refreezes over night loose snow accumulates becomes heavy and slips off
Snow refreezes into crystals vibrations send the layer down slope
Avalanches
Occur at high elevations, in steep road cuts, and rocky shorelines
Rock breaks and falls downward Produces a cone shaped pile of debris called
talus Less likely to occur in humid regions
Rock Falls
Constructing heavy buildings and roads and poor maintenance of sewer systems can result in mass movements
Venezuela 1999 experienced heavy rains which resulted in severe mudflows killing tens of thousands of people
Can be avoided by not building structures on steep slopes
Trenches can be dug to divert water
Mass movements and people
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