3. Geomorphology
The science of landforms
Origin
Processes of change
Distribution on the planet
Landforms are the product of
Forces that build up the landforms
Forces that wear it down or modify it
Denudation
weathering
mass movement
erosion, transportation and deposition
Gravity and moving air, water, waves, and ice
4. Dynamic Equilibrium Model
Energy constantly flowing through landscapes
Potential energy: energy of position (gravity): uplift
Kinetic energy: energy of motion: hydrologic cycle
Heat energy: solar energy: sun
Chemical energy: from atmosphere and within the crust
Landforms are a balance between stabilizing forces
(friction, inertia, cohesion) and destabilizing forces
that can set things in motion
Cycle
Equilibrium stability
A destabilizing event
Adjustment
New equilibrium stability
8. Mass Movements
Also called: Mass Wasting
Weathering prepares material for movement
Gravity sets material in motion
Steepness of slope
Friction and cohesive nature of the material
Angle of repose
Amount of moisture available
Characteristics of a particular mass movement
depend on speed of movement and amount of
water mixed with the material
Fall, slide, flow, creep
9. Angle of Repose
The maximum angle at which slope material
can be inclined without moving downslope
It is a critical value for stability for a
particular slope
If the actual slope angle is less than the angle of
repose, the slope is stable
If the actual slope angle is greater than the angle
of repose, mass movement can occur
The angle of repose changes as slope conditions
(such as soil moisture) changes
The angle of repose can never be exceeded
Angle of repose can decrease under severe
motion (earthquakes) or saturation
10. Types of Mass Movements
Rockfall
Loose rocks fall through the air, accumulate in a talus cone
High angle of repose
Debris avalanche
Rocks, debris and soil
Extremely high velocity
Water and ice often fluidize debris
Landslide
Unsaturated mass of bedrock and regolith that moves suddenly and
rapidly
Rotational slumping
Translational slides
Flows
earthflow
mudflow
Creep: a persistent movement of soil down slope
