Mass Wasting - The Changing Earth: Exploring Geology and Evolution - page 280

Slope oversteepening can also be
caused by human activity, such as
the construction of highways and
housing developments. Slumps are
particularly prevalent along high-
way cuts, where they are generally
the most frequent type of slope
failure observed.
Although many slumps are
merely a nuisance, large-scale
slumps in populated areas and
along highways can cause exten-
sive damage. Such is the case in
coastal southern California where
slumping and sliding have been a
constant problem, resulting in the
destruction of many homes and
the closing and relocation of nu-
merous roads and highways (see
Geo-Focus on pages 282 and 283).
A rock or block slide occurs
when rocks move downslope along
a more or less planar surface. Most

Fractures
Scarp

Slump block

Surface of rupture

◗

Figure 11.9 Slumping In a slump, material moves downward along the curved surface of a
rupture, causing the slump block to rotate backward. Most slumps involve unconsolidated or
weakly consolidated material and are typically caused by erosion along the slope's base.

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