Geology Test 3 (Ch. 15)

What is the slowest form of mass wasting?

Creep

Match the type of motion with the correct definition. Fall

Detached material moves in a free-fall

Which of the following scenarios will be able to maintain the steepest angle of repose?

Dry sand

Mudflows are big enough to move independently of the topography.

False

Slow forms of mass wasting such as creep and solifluction are considered slow because they are restricted to gentle slopes and cannot achieve the same velocity.

False

A piece of gravel is resting on a slope. Which of the following best describes how the gravitational force pulling the gravel downward will vary with the inclination of the slope?

Gravitational force will decrease as the slope angle decreases

________ is the downslope movement of rock, regolith, or soil under the direct influence of gravity.

Mass Wasting

Match the type of motion with the correct definition. Slide

Mass movements in which there is a distinct plane of weakness between the slide material and underlying stable material

Match the type of motion with the correct definition. Flow

Material moves downslope as a viscous fluid

What is the fastest form of mass wasting?

Rockfall

Which of the following locations would be most likely to see large-scale, rapid mass wasting?

Rocky Mountains

What is the crescent-shaped mark found at the top of a slump block?

Scarp

What is the angle of repose?

The steepest angle at which a material remains at rest

A stream is cutting into a valley wall. Which of the following is the most likely trigger for a mass-wasting event?

The stream erodes the toe of the slope, which results in the slope becoming oversteepened

Which of the following scenarios best describes the creation of the lahars associated with the eruption of Mt. St. Helens in 1980?

The volcanic dome exploded, depositing fine ash in the Toutle River

Creep is the most widespread mass-wasting process.`

True

Rockfalls are the primary way in which talus slopes are built and maintained.

True

Solifluction is a slow type of mass wasting that moves at a rate of a few centimeters per year.

True

Solifluction occurs during the warmer months of the melt season.

True

Which factor exerts the greatest control over the velocity of debris flows and the distance they will travel?

Water content