Mass Wasting-Planet Earth-Chapter 8

Causes of slope instability

(1) The amount of water contained within the slope materials and, (2) the presence or absence of vegetation.

Mass wasting processes are classified according to what 3 factors?

(1) The kinds of materials they involves, (2) the rate of movement, and (3) the amount of water.

Go Force

A force directed parallel to the surface and downslope which attempts to move the object downslope.

Stay Force

A force directed perpendicular to the surface that is proportional to cohesion and friction, both of which attempt to keep the object in place.

Retaining wall

A method of slope stabilization, in hopes that it will increase the resistance of the slope materials to movement.

Objects resting on horizontal surfaces will not move unless:

An outside force is applied

The angle at which loose regolith will begin to move downslope

Angle of Repose

The angle of slope where the effects of the Go and Stay forces are balances is called the __

Angle of Repose

The maximum slope, measured in degrees from the horizontal, at which loose solid material will remain in place without sliding.

Angle of Repose

Frost heaving is a major agent involved in

Creep

Mass wasting that is constantly occurring

Creep

Most common type of mass wasting

Creep

Process of mass wasting that you can see bent walls and trees

Creep

The mass wasting process that is particularly effective in permafrost regions is:

Creep

The slow downhill movement of regolith

Creep

What process of mass wasting is responsible for the movement of the greatest mass of material?

Creep

Within the regolith, cohesion and friction ___ as the angle of slope increase.

Decrease

Earthflow

During the spring and summer, the upper layers of the regolith frequently become saturated with water, which reduces cohesion and friction and accelerates the slow downslope movement. Only involves a limited area of the slope surface.

"Hummocky surface"

Earthflow

Loosely embedded w/ sediment, and falls off

Fall

Type of mass wasting process that involves low amounts of water to no water at all

Fall

What type of mass wasting is an avalanche?

Fall

Slump

Fast mass wasting process. May affect the regolith, the bedrock, or both. Regolith becomes saturated w/ water and coherence and friction diminish. Regolith may begin to move as an earthflow. Forms as continued movement causes a volume of the material to break away from the adjacent regolith and slide along curved slip surfaces as a coherent mass. The mass rotates downward and out, forming curved scarps at the upper margin and bulging and flowage at the base. After moving short distance, the material regains coherence and comes to rest.

Acts like plastic liquid

Flow

Type of mass wasting process that involves a moderate to large volume of water

Flow

What type of mass wasting is creep?

Flow

Mass wasting can be classified as: (3 types)

Flows, slides, or falls

Cohesion can be effectively reduced by the growth of ice crystals, a process called ___.

Frost Heaving

The energy for all processes of mass wasting comes from

Gravity

The force of _____ or the weight of an object is always directed toward Earth's center.

Gravity

What is needed for mass wasting?

Gravity, and various amounts of water

Deadmen

Help making retaining walls stronger by taking advantage of the weight of the sloper materials to anchor the wall.

With the exception of ___ mass wasting process do not go very far. The process usally looses momentum once it reaches downhill.

Lahar

Large Size of Debris

Larger than a desk.

Weight

Mass of an object times the effect of gravity

Solifluction

Mass wasting process responsible for movement of materials in permafrost regions on slopes of only a few degrees, high amount of water, small-large particle sizes, and slow flow rate of movement.

Flows like a highly viscous stream

Mudflow

Lahar

Mudflows associated w/ volcanoes. Very wet, moves things far distances.

Rock Falls

Rapid mass wasting process is the free-fall or tumbling of rock dislodged from the face of a cliff.

Mudflow

Rapid mass wasting process that involves a lot of water. Consist mainly of particles smaller than sand.

Landslide

Refers to any variety of downhill movements of rock, regolith, and soil with no restrictions on the kind or amount of material involved or the rate or movement.

Creep

Refers to the slow downslope movement of the upper layers of regolith

The most rapid form of mass wasting

Rock Fall

No water is involved in this process of mass wasting:

Rock Falls

Talus

Rock fragments that collect as an accumulation of rubble, as a result of mass wasting, when falling downward.

Gabion

Rock-filled wire basket used to stabilize steep slopes

Small Size of Debris

Size of baseball to basketball, or smaller. Example: Cobble

Medium Size of Debris

Size of basketball to size of a desk at home.

Keep contact w/ ground, but shifts down

Slide

Type of mass wasting process that involves a low to moderate amount of water

Slide

What type of mass wasting is a slump?

Slide

Landslides include what processes of mass wasting:

Slump, Rock falls, Rock slides, Debris slides, Debris flows, and mudflows

Moves slowly downhill, only happens in tundra's with permafrost.

Solifluction

Mass

The amount of "stuff" the object contains and is the same everywhere throughout the universe.

The relative magnitudes of the Go and Stay forces depend on:

The angle of slope

Mass Wasting

The downslope movement of rock materials by gravitational forces without being carried within, on, or under any other medium.

The force of gravity will depend on

The mass of the object

Benching

The process commonly employed to provide slope stability to large road cuts

The major factor that results in the reduction of cohesion and friction is_____

Water

The mass wasting process that transports material for the greatest distance is _____

mudflow

Mass wasting movement of material

usually limited to the distance from hill top to valley floor

Angle of Repose

~40 degrees, any rock structure becomes unstable past 40 degrees.