A
LTHOUGH MOST SLOPES,
MAY APPEAR TO BE STABLE
AND UNCHANGING THE
force of gravity causes material to
move. At one extreme, the movement
may be gradual and practically
imperceptible. At the other extreme,
it may consist of a roaring debris flow
or a thundering rock avalanche.
Landslides are a worldwide natural
hazard. When these hazardous
processes lead to loss of life and
property, they become natural
disasters.
F O C U S O N C O N C E P T S
To assist you in learning
the important concepts in this
chapter, focus on the following
questions:
What is the process of mass
wasting?
What role does mass wasting
play in the development of
valleys?
What are the controls and
triggers of mass wasting?
What criteria are used to divide
and describe the various types
of mass wasting?
What are the general
characteristics of slump,
rockslide, debris flow, earthflow,
and creep?
Landslide debris atop Buckskin Glacier in Alaska’s Denali
National Park. In the evolution of many landforms, gravitydriven mass-wasting processes transfer the products of
weathering downslope where an erosional agent, in this case a
valley glacier, carries the debris away. (Photo by Michael Collier)