mass wasting
the movement in which bedrock, rock debris, or soil moves downslope in bulk, or as a mass, because of the pull of gravity
landslides
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soil
(also called engineering _________) any unconsolidated material at the Earth's surface, regardless of particle size or composition
debris
soil that is coarse-grained fragments
earth
soil that is predominantly fine-grained
mud
soil that has a high content of water, clay or silt
flow
the descending mass is moving downslope as a viscous fluid
slide
the descending mass remains relatively intact, moving along one or more well-defined surfaces
fall
the descending mass free-falls or bounces down a cliff
translational slide
the descending mass moves along a plane approximately parallel to the slope of the surface
rotational slide
the descending mass moves along a curves surface, the upper part moving downward while the lower part moves outward.
relief
the vertical distance between valley floor and mountain summit
trigger
the immediate cause of failure of already unstable ground
normal force
force that is perpendicular to the slope and is the component of gravity that tends to hold the block in place
shear force
force that is parallel to the slope and indicates the mass's ability to move. Friction is its opposite force.
shear resistance
force that would be needed to move the mass
shear strength
resistance to movement or deformation of that soil
pore pressure
when water forces sand grains apart
surface tension
characteristic of water in which a surface film is created that attracts water molecules to one another
soil creep
very slow, downslope movement of soil
earthflow
earth moves downslope as a viscous fluid (can be slow or rapid) - remember "earth" refers to soil that is predominantly fine-grained
scarp
a steep cut
slump-earthflow
can refer to a rotational slide or earthflow
hummocky
land characterized by mounds and depressions; usually forming at the toe or front of an earthflow where soil has accumulated
solifluction
the flow of water-saturated soil over impermeable material such as over permafrost
permafrost
a layer of ground that remains frozen for many years, as hard as concrete
debris flow
flow involving soil in which coarse material (gravel, boulders) is predominant
mudflow
a flowing mixture of soil and water, usually moving down a channel; remember _______ refers to soil that has a high content of water, clay or silt
debris avalance
fastest variety of debris flow; very rapidly moving, turbulent mass of debris, air, and water
rock fall
when blocks of bedrock break off and falls freely or bounces down a cliff
talus
accumulation of rocks from a rockfall at the base of a cliff
rockslide
a rapid sliding of a mass of bedrock along an inclined surface of weakness, such as a bedding plan, a major fracture in the rock, or a foliation plane
rock avalanche
a very rapid moving, turbulent mass of broken-up bedrock
Landslides" is an ineffective term because . . .
. . . it tells nothing of the process involved
The classification system in the book is based on . . .
. . . rate of movement, type of materials and nature of movement
Difference between rock avalanche and debris avalanche is . . .
. . . rock avalanche begins as bedrock
the relationship between _______ and ________ determine if a mass will move down a slope
shear resistance and shear force
shear resistance > shear force =
#NAME?
shear resistance < shear force =
#NAME?
positive correlation between normal force and _______
shear force
shear strength > shear force =
#NAME?
shear strength < shear force =
#NAME?
Ways construction creates potential of mass wasting
base of slope is undercut; vegetation is removed; structures on upper part of slope add weight; extra water adds weight and weakens shear strength