Presentation on theme: "3-1 Mass Movement When slopes fail…. REVIEW Once weathering has occurred, then erosion can take place. What is EROSION?"— Presentation transcript:
3-1 Mass Movement When slopes fail…
REVIEW Once weathering has occurred, then erosion can take place. What is EROSION?
EROSION is the process of carrying away weathered rock. The Grand Canyon is an example of what erosion can do!
Eventually most of the broken bits of rock end up in streams & rivers that flow down from the mountains. These little bits of rock & sand are called SEDIMENTS.
DEPOSITION is the process of laying down weathered rocks in a new location. What is DEPOSITION?
Weathering, sediments, erosion and deposition work together in a cycle! ErosionDeposition WeatheringSediments
What is Mass Movement? Erosion & deposition of large amounts of sediment downhill, sediment is usually loose
How does Mass Movement work? By the force of gravity Can be fast or slow
La Conchita, CA 1995
Close-up La Conchita, CA 1995
Looking down La Conchita, CA 2005
Peru's Main Plaza Landslide's Destruction Before After
Video of a Real Landslide in Japan
Video of a Rockslide in Tennessee
1. LANDSLIDE (very fast) Happens when rock and soil break loose from steep slopes most destructive mass movement falls quickly to the bottom occur in mountainous areas may contain huge masses of rock
Video of a Real Mudslide in California
Video of a Real Mudslide in Italy
2. MUDSLIDE/MUDFLOW (very fast) A thick mixture of sediments and water flow down a slope occur in dry areas where weathering forms thick layers of dry sediment heavy rains mix with sediment to make mud have enough energy to move anything in its path at the bottom of slope, loses its energy of motion deposits all the sediments and debris it has been carrying
Bismarck, North Dakota 1987
Bismarck, North Dakota months later
Video of Real Slump over 8 days
3. SLUMP (not fast) Occurs when loose material or rock layers slip downward as one large mass takes place as one large mass doesn't move materials very fast or very far curved scar (scarp) is left where slumped material was occur because the clay under the slumped material weakens because it gets very wet when it can no longer support overlying material it slips downhill
4. CREEP (very slow) Gets its name from the way sediments slowly creep down a hill especially common in areas where freezing and thawing occur (ice wedging) as the ground freezes, small sediments are pushed up by expanding water in the soil when the soil thaws, the sediments fall downhill trees, utility poles and fence posts lean or slant downhill