Mass Wasting and Erosion Concepts

A collection of flashcards covering key concepts related to mass wasting, geological processes, and hydrology based on the lecture notes.

What is mass wasting?

Any downhill movement of material caused by gravity.

What causes slope failure in mass wasting?

A slope becomes too steep and unstable for existing materials/conditions.

What materials can be involved in mass wasting?

Soil, rocks, sediments, etc.

What is a landslide?

A general term for sudden material falling or sliding down a slope due to gravity.

What does a scarp indicate?

Steep terrain exposed by land movement.

What is the main scarp?

Marks the uphill edge of the landslide.

What is the slide rupture surface?

Boundary of the moving landslide body.

What is meant by undisturbed ground?

Ground that remains in place below the rupture surface.

What are the flanks of a landslide?

The sides of the landslide.

What is the toe of a landslide?

The end of the landslide, marking the runout limit.

What is a runout point?

The maximum distance a landslide travels.

What characterizes a rotational landslide?

The toe is a large disturbed mound past the rupture surface.

What are extensional cracks?

Cracks that form when the toe moves faster than the rest due to tension.

What are sag ponds?

Small water bodies in drainage-blocked depressions.

What does hummocky terrain refer to?

Bumpy, uneven ground from disturbance.

How are pressure ridges formed?

As material gets shoved upward at the margins.

What event triggered the Gros Ventre landslide?

A translational rock slide that dammed a river.

What was the consequence of the Gros Ventre landslide?

It created Slide Lake, and the dam failure caused flooding that killed 6 people.

What triggered the Madison Canyon landslide?

A 7.5 magnitude earthquake.

What did the Madison Canyon landslide create?

Quake Lake.

What was the effect of the Mount Saint Helens landslide?

Triggered the largest historical landslide followed by a volcanic eruption.

What happened during the La Conchita earthflows in 1995?

Damaged homes after heavy rains.

What characterized the Oso, Washington landslide?

Occurred at 40 mph, buried homes, and killed 43 people.

What caused frequent rock falls in Yosemite National Park?

Tectonic fractures, exfoliation, and frost wedging.

What is notable about the Markagunt Gravity Slide?

One of the largest landslides ever, with 1,700 km³ of material moved fast.

What event did the Thistle Slide cause?

Blocked a canyon, leading to massive flooding and over $200 million in damages.

What was the consequence of the Rockville Rock Fall?

A 2,700 ton boulder destroyed a house and killed 2 people.

What caused the North Salt Lake slide?

Poor drainage and regrading after a wet period.

What is saturated soil?

A solution that has the maximum allowed dissolved components.

What is unsaturated soil?

Soil that has air and water in the pores but is not completely filled with water.

What is the angle of repose?

The steepest angle a pile of loose material can hold before it tumbles down.

What is quick clay?

Stable when calm but can become liquid when disturbed.

What is the driving force in mass wasting?

The part of gravity trying to pull materials downhill.

What does resisting force mean?

The force fighting against sliding, trying to maintain stability.

What is a lahar?

A volcanic mudflow made of water, ash, and debris.

What is infiltration?

When water soaks into the ground through soil and rock.

What factors affect infiltration?

Precipitation type, vegetation cover, land slope, temperature, and soil type.

What does it mean to infiltrate?

The act of water soaking into the ground.

What does oversteepened mean in geology?

When a slope becomes too steep and unstable.

What is exfoliation in geology?

When sheets of rock peel off due to pressure release.

What is regolith?

A layer of dust, soil, and broken rock on top of bedrock.

What does hydrosphere refer to?

All the water on Earth, including oceans, lakes, and rivers.

What is lithification?

The process of turning loose sediment into solid rock.

What is runoff?

Water that flows over land instead of soaking in.

What is talus in geology?

A pile of broken rocks at the bottom of a cliff.

What is creep?

Slow, sneaky downhill movement of soil or rock.

What characterizes a fall in geological terms?

Material free-falls through the air down a slope.

What defines a slide in geology?

A chunk of material moves downhill along a set surface.

What is rock fall debris?

Broken rock pieces resulting from a rock fall.

What is lahar infiltration?

Not common, refers to water soaking in from a lahar.

What is a flow in geological terms?

Material moving like a thick liquid down a slope.

What is stream gradient?

How steep a stream is, measured by vertical drop per distance.

What is the atmosphere?

The layer of gases surrounding Earth.

What is groundwater?

Water stored underground in soil, rock pores, and cracks.

What is recharge in hydrology?

When water refills an aquifer or groundwater supply.

What is a drainage basin?

Area where all rainwater drains into one river system.

What is a tributary?

A smaller stream or river that flows into a bigger one.

What are headwaters?

The start or source of a river.

What is an aquifer?

A body of rock or sediment that holds and transmits groundwater.

What is climate?

The average weather patterns over an extended period.

What is a glacier?

A massive, slow-moving mass of ice.

What is evaporation?

When liquid water turns into vapor and rises into the air.

What defines a spring in hydrology?

Where groundwater naturally flows out to the surface.

What is an alluvial fan?

A fan-shaped deposit of sediment where a stream slows down.

What is load in a stream?

The sediment, rocks, and minerals carried by the stream.

What does saltation refer to in geology?

When sediment bounces along the ground due to wind or water.

What is the vadose zone?

The area underground above the water table where pores have both air and water.

What are backswamps?

Low-lying areas behind levees that may be poorly drained.

What is a delta?

A landform where a river deposits sediment into a standing body of water.

What is a meandering stream?

A stream with looping bends and curves.

What is a braided stream?

A stream that splits into crisscrossing channels due to high sediment load.

What characterizes a floodplain?

Flat land next to a river that floods when it overflows.

What is evapotranspiration?

Water leaving the ground through both evaporation and transpiration.

What is a distributary?

A smaller river branch that leaves the main river.

What is base level in relation to rivers?

The lowest point a river can erode down to.

What is sublimation?

When solid water turns directly into vapor without melting first.

What is a stream?

A flowing, channeled body of water smaller than a river.

What is discharge in hydrology?

The amount of water flowing past a point in the stream.

What does fluvial refer to?

Anything related to rivers and streams.

What is condensation in the water cycle?

When water vapor cools and turns back into liquid.

What is a drainage divide?

High land that separates two drainage basins.

What is bedload in a stream?

The big, heavy materials a river rolls along its bottom.

What is lithification?

The process of sediment being glued together into solid rock.

What is an outwash plain?

Flat area where meltwater from a glacier spreads and drops sediment.

What is a graded stream?

A stream balanced between erosion and deposition.

What is an oxbow lake?

A U-shaped lake cut off from a meandering river.

What does cutoff mean in rivers?

When a river forms a shortcut slicing off a meander.

What does nonpoint source pollution mean?

Pollution that doesn’t come from one identifiable source.

What is an arête?

A sharp ridge between two glaciers or cirques.

What is a cirque?

A bowl-shaped valley made by glacier erosion.

What is a hanging valley?

A small glacial valley left hanging above a bigger one.

What is till in geology?

Random junk dumped directly by glaciers.

What is an ice age?

Long periods when glaciers covered significant parts of the Earth.

What is an unconfined aquifer?

An aquifer open to the surface, allowing water to easily move in and out.

What is a confined aquifer?

An aquifer trapped between impermeable rock layers.

What is a tsunami?

A giant wave usually caused by earthquakes.

What is a lagoon?

Shallow water separated from the sea by sandbars or reefs.

What are tides?

The daily rise and fall of sea level caused by the moon's gravity.

What are trade winds?

Steady winds blowing from east to west in the tropics.

What characterizes a desert?

An area receiving less than 25 cm (10 in) of rain per year.