geology ch. 10
Which of these landslides dammed a lake and caused flooding? SELECT THREE
Madison Canyon; Gros Ventre; Thistle
If you are considering a home site, what is one pretty sure evidence of possible landslides affecting the property?
a history of previous mass wasting events in the area
Which of the following are common triggers of landslides? SELECT FOUR
adding weight; oversteepening of slope; adding water; earthquake
The number one factor responsible for triggering landslides is the ______.
additional water
The steepest angle at which sediments will be stable and NOT move down hill is called _____.
angle of repose
What factors contribute to over-steepening of slopes? SELECT THREE
bulldozing of road cuts; wave cutting on sea cliffs; excessive stream erosion
A slump (rotational landslide) is often preceded by ________________?
cracks, possibly with some vertical displacement, occur upslope
Which mass wasting type is very slow movement that can cause fences, retaining walls, and telephone poles to tilt downhill?
creep
The 1959 Madison Canyon landslide killed 28 people near Hebgen Lake. What was the trigger for this landslide?
earthquake
What forces are involved in a mass sliding down an inclined plane? SELECT THREE
friction; shear; normal
What weather conditions can cause mass waisting?
greater than average precipitation
What happened in the 1925 Gros Ventre slide in Wyoming?
heavy rains saturated a shale layer causing the already oversteepened slope of rock to slide down and dam up a river
Which of the following combination of features would best indicate a slow moving rotational landslide is occurring? SELECT TWO
landslide toe; scarp
What was the largest known terrestrial landslide?
markagunt gravity slide
What is solifluction?
movement of soil lobes on slopes
The 2005 La Conchita slide in California and the 2014 Oso landslide in Washington were both deadly landslides in residential areas. They were principally triggered by ______.
precipitation
What is the greatest mass wasting hazard to guests in Yosemite National Park?
rock falls
Which type of mass wasting moves rapidly and can be deadly? SELECT TWO
rockfalls; flows
Adding water to materials on a slope can reduce _______ and cause mass wasting to occur.
shear strength of slope material
Materials on a slope tend to move downslope when the ________ force exceeds the ________ force.
shear; normal
What are some clues that a proposed home site may be susceptible to landslide activity? SELECT THREE
talus blocks; fissures and cracks; nearby cliff (with crescent shapes indicating scarp)
When a landslide dams a river, what is the ultimate hazard?
the dam forms a rising lake that may overtop the dam, washing it out, and causing deadly flooding downstream
Which of these is NOT a type of mass movement?
transform
