GEOL 8

Avalanche

A rapid flow of snow, ice, and debris down a slope, often triggered by weather or human activity.

Angle of Repose

The steepest angle at which loose material (sand, gravel, soil) can remain stable without collapsing.

Bedding

Layers of sediment or rock deposited over time, forming distinct strata in geological formations.

Clear-cutting

A logging practice where all trees in an area are removed, increasing erosion and landslide risk.

Cornice

An overhanging mass of snow or ice that forms on the leeward side of mountain ridges, prone to breaking and causing avalanches.

Creep

The slow, gradual downhill movement of soil or rock due to gravity.

Daylighting Beds

Rock or soil layers that are exposed on a slope, increasing the likelihood of landslides.

Debris Flow

A fast-moving mass of rock, soil, and water that flows down a slope, often triggered by heavy rain.

Direct Effect

The immediate impacts of a landslide or natural disaster, such as destruction of buildings and loss of life.

Driving Force

The gravitational force that causes materials to move downhill, contributing to landslides.

Flow

A type of mass movement where soil or rock behaves like a fluid, moving downhill due to gravity.

Grading

The process of reshaping land surfaces, often for construction, which can impact slope stability.

Head Scarp

The steep, exposed face at the top of a landslide where material has broken away.

Hummocky

Uneven, irregular terrain often created by landslides or glacial deposits.

Indirect Effect

Secondary consequences of a natural disaster, such as economic loss or displacement following a landslide.

La Conchita

A coastal California town known for deadly landslides, highlighting the risks of unstable slopes in developed areas.

Lahar

A volcanic mudflow consisting of ash, water, and debris, moving rapidly down valleys.

Landslide

A general term for the downslope movement of rock, soil, or debris due to gravity.

Leeward

The side of a mountain or slope that is sheltered from the wind, often drier and less prone to precipitation.

Liquefaction

The process where saturated soil temporarily loses strength and behaves like a liquid during an earthquake.

Mass Movement

The downslope movement of rock, soil, or debris due to gravity, including landslides, creep, and rockfalls.

Mass Wasting

Another term for mass movement, referring to the broad category of gravity-driven landform changes.

Mudflow

A fast-moving, water-rich landslide consisting mainly of mud and fine sediment.

Natural Function

The role a natural process (e.g., erosion, landslides) plays in shaping the environment over time.

Permeability

The ability of soil or rock to transmit water, affecting groundwater flow and landslide potential.

Placer Deposits

Mineral-rich sediments deposited by water movement, often containing valuable materials like gold.

Relief

The difference in elevation between the highest and lowest points in an area, influencing landslide risk.

Resisting Force

The opposing forces (friction, cohesion) that help keep a slope stable and prevent movement.

Rockfall

A type of mass movement where rocks break free from a cliff or steep slope and fall rapidly.

Safety Factor

A ratio used to assess slope stability, comparing resisting forces to driving forces.

Scarification

The removal or disturbance of vegetation and soil, often due to construction or mining, increasing erosion risks.

Slope

The angle or incline of a land surface, determining susceptibility to erosion and landslides.

Slump

A type of landslide where a block of earth moves downward along a curved surface, often creating a step-like feature.

Talus

A pile of rock debris that accumulates at the base of a steep slope due to rockfalls.

Urbanization

The expansion of cities and human settlements, often altering drainage patterns and increasing landslide risks.

Weathering

The breakdown of rocks and minerals at the Earth's surface due to physical, chemical, and biological processes.