Warm-up What 3 particles are used to determine soil texture? Number them 1-3, where 1 is the largest particle size and 3 is the smallest particle size.

Erosion

Weathering and Erosion Order Weathering Erosion Deposition Weathering breaks down the rocks, erosion moves the particles, and deposition drops the sediments in another location. Badlands National Park, South Dakota

Erosion Erosion – the process where sediments are transported by: Wind Gravity Glaciers Running water Living Things

Mass Movement: Creep Slow, steady, downhill flow of loose materials – 3 cm/year Oops!

Mass Movement: Slides Rapid, downslope movement of layer of loose material – landslide – NOT just due to water! http://scientistmalikasblog.wordpress.com/2011/01/24/compare-contrast-mudflows-landslides/

Mass Movement: mudflow Swiftly moving mixtures of mud and water Triggered by earthquakes, heat from volcanoes, melting snow, and rainstorms http://earthscienceinmaine.wikispaces.com/10.5+Erosion+and+Deposition+by+Gravity

Mass Movement: Slump Landslide along a curved surface Common after rains along steep slopes http://www.geology.sdsu.edu/visualgeology/naturaldisasters/Chapters/Chapter8Landslides.pdf

Mass Movement: Avalanche Landslides of snow On steep slopes Can be very high speeds – 300 km/h!

Glacial Erosion Glacier: large, moving mass of ice Cover 10% of Earth’s surface Great size, weight and density slowly moving grind out bedrock

Glacier Formation Form near poles and high elevations Accumulation of snow – increases each year Weight of top layers exerts downward pressure forcing snow below to recrystallize into ice

If Formed in Valley: Snow accumulation causes glacier to become heavy and to flow downhill, due to gravity Speed affected by slope, temperature, thickness of ice and valley shape – 1mm/day

Valley Glaciers Carve out U-shaped valleys from bedrock Change valleys from a V shape to a U shape More rounded – U Shape V Shaped

Valley Glaciers The deep depressions where carved out from valley called a cirques.

Moraine The rock piles deposited from melted glaciers