Describe the Picture: Use 5 observations (things you see) and 3 inferences (conclusions drawn from knowledge)

Essential Questions What are mass movements? What factors trigger mass movements?

Mass movements  What is it? movements of masses of bodies of soil, bed rock, rock debris, soil, or mud usually occur along steep-sided hills and mountains due to the pull of gravity  Seen as landslides, mud slides, and avalanches

Mass movements

What are the triggers of mass wasting?  Infer two triggers of mass wasting (besides water)  Turn to a neighbor and discuss the triggers you inferred

Mass movement triggers  Triggers Water saturation Oversteepening of slopes Removal of vegetation Earthquakes

Types of Movements  Rockfalls  Slides  Slumps  Flows  Creep

Mass Movements  Rockfalls Occurs when rocks fall freely Common on slopes that are too steep to retain loose materials Frequently caused by frost-wedging British Columbia, Canada. (- Geoscape Vancouver

Mass Movements  Slides Blocks of material move suddenly down flat, inclined surface Exp: rock slides One of the fastest mass movements The rock slide at Frank, Alberta, Canada (1903) moved 33 million m 3 of rock from Turtle Mountain over the town of Frank in less than two minutes killing 70 people, NOAA

Mass Movements  Slumps Downward motion of block of material along curved slope Not a large change in distance or fast Common on oversteepened slopes with thick accumulations of clay Berkeley, CA ndslides/berklandslide1.htm

Mass Movements  Flows mass movements of material containing large amounts of water > move as thick fluids Mudflows-can move up to 80 km/h ○ Common in semiarid mountainous regions Mount St. Helen, WA p06/Landslide1980.htm

Mass Movements  Flows Earthflows ○ move 1 mm/day to several meters/day ○ Occur on hillsides in wet regions ○ Creates tounge- shaped mass cors220_files/lecture11.html

Mass Movements  Creep Slowest type Moves few mm- few cm/ year Freezing and thawing contributes to creep Cause structures to tilt

Writing Assignment:  What is the impact of mass movements on the social and economic status of an area? Yungay, Peru before and after landslide