Ch.5 - Gravity Landforms Flashcards
Mass Wasting
all processes by which masses of rock and soil move downslope
Mass wasting occurs when _______ exceeds the ________ of the material as it moves downslope
gravity; strength
Types of Mass Movements
- Fall
- Slide
- Flow
Fall
movement where singular/multiple blocks of rocks plunge from a height
Slide
a mass movement that occurs as one unit
Flow
Internally chaotic and turbulent; sediment riding on a cushion of air
Avalanche
a type of flow made up in large part of snow and ice
Lahar
A mudflow/debris flow consisting mainly of volcanic material
What dictates the nature/behavior of mass movement?
- Nature of Slope Materials
- Amount of Water
- Steepness and stability
What factors change the nature of the slope materials
- consolidation of materials
- angle of repose
Lubrication
addition of water that lowers the force of friction
Liquefaction
Temporary transformation of solid material into a fluid state caused by the pressure of water in the pores of the material
Triggers of mass movement
- Earthquake vibrations
- Rainfall and Water infiltration
- Vegetation Loss
Types of Unconsolidated Mass Movement:
- creep
- earthflow
- debrisflow
- mudflow
- debris avalanche
- slump
- debris slide
A _____ occurs very slowly, driven only by the tendency of matter to move downhill
creep
Creeps occur __________
Seasonally
(earth/debris) flows have larger particles than (earth/debris) flows
debris; earth
______ flows can leave a “scar” on the landscape
Debris
Slumps occur when ____ _____ _____ is raised to a high enough level to support the weight of soil and rock
pore water pressure
Solifluction
Gradual movement of soil down a slope due to freeze thaw cycles
Debris Avalanche
a type of flow where unconsolidated ash and rock move downhill at high speeds on a cushion of air
Angle of Repose
The slope at which sediment is completely stable
