2. SLOPE
A small strip or patch of the land surface
that is inclined from the horizontal
is mantled with regolith, which grades down
into, unaltered rock called bedrock
Regolith provides the source f sediment,
which consists of rocks and mineral particles
Soil and regolith blanket the bedrock, except
in a few places where bedrock is particularly
hard projects in the form of outcrops
6. Convex slope segments
Form on the upper parts of slopes
Inresponse to soil creep and rain
splash
When slopes are below the
threshold for rapid mass wasting
7.
8. Concave slope segments
Slopesegments that form near the base
of slopes
Inthe absence of removal waste (e.g.
river downcutting)
With increasing run off
downslope, velocity and sediment
transport can be maintained over
increasingly lower slope
16. Climate
Different processes operate in different climate
zones and produce different slope forms and shapes
Humid areas – slopes are frequently rounded due to
chemical weathering
Arid region – slopes are jagged or straight owing to
mechanical weathering and sheetwash
Heavy rain and meltwater both add volume and weight
to the soil increases erosive power make slope
less stable
Heavy snowfall add weight conducive to rapid
movement (Avalanche)
20. Nature of the regolith
Includes soil, scree, weathered bedrock and deposited
material.
Unconsolidated nature prone to downslope movement
Increase weight of deep regolith will increase the
likelihood of instability
Clay rich regoliths – unstable because the ability to retain
water
In a non saturated soil- increases cohesion and reduce
soil movement
In saturated soil – the pore water pressure forces the
particle apart, causing soil movement
21.
22.
23.
24. Vegetation
Can decrease
overland run off
Lack of vegetation
means there are
fewer roots to bind
the soil together
25. How do we get slope failure?
When the
gravitational
force acting on
a slope exceeds
its resisting
forces, slope
failure (mass
wasting occur)
26. What is a shear strength?
The resisting forces that help to
maintain slope stability include the slope
material’s strength and cohesion
The amount of internal friction between
grains and any external support of the
slope known as shear strength
27.
28. How does the force gravity
resulted in slope failure?
Gravity operates vertically
but has a component acting
parallel to the slope causing
instability
The steeper the slope angle
the greater the component of
force acting parallel to the
slope and greater the chances
for mass wasting
29.
30. Define angle of repose
The steepest
angle that a
slope can
maintain
without
collapsing
Angle of
repose for
unweathered
solid rock
steeper than
40 degrees
31. What does it mean by “when a
slope is in a constant state of
dynamic equilibrium”?
Means that they
are constantly
adjusting to new
conditions
