Weathering and Mass Wasting (Geology Final)

What are the two main types of weathering?

mechanical (physical) weathering and chemical weathering (alteration)

What is mechanical weathering?

The physical breakdown of rock without changing its composition

What is chemical weathering

the breakdown of rock through chemical reactions that change mineral composition

which rock type weathers fastest chemically

limestone due to dissolution

how does climate affect weathering?

Warm, wet climates increase chemical weathering; cold or dry climates favor mechanical weathering

What is differential weathering

when softer rocks erode faster than harder rocks, creating an uneven surface

What is ice wedging

water freezes in cracks, expands, and breaks rock apart

What is regolith?

layer of loose, weathered material covering bedrock

what is talus?

piles of broken rock fragments at the base of slopes or cliffs

what is the primary driving force of mass movement

gravity

what factors influence mass movement

slope steepness, water content, vegetation, rock type, and human activity

what does a free body diagram of a slope show?

forces acting on an object (gravity vs. resistance)

What happens when driving forces exceed resisting forces?

mass movement occurs

name the six types of mass movement

rockfall, landslide, debris flow, mudflow, slump, creep

what is creep

very slow downhill movement of soil

what is slump

downward movement along a curved surface

what is topography

the shape and features of Earth’s surface

what is topographic profile

a side view of elevation changes across land

what is dissolution

minerals dissolve in water (acdic)

what is hydrolysis?

reaction with water that forms new minerals (feldspar to clay)

what is oxidation?

reaction with oxygen (iron rusting)

how does surface area affect weathering

more surface area - faster weather

how do plants and organisms contribute to weathering

roots break rock, organism produce acids

how does water increase mass movement risk?

adds weight and reduces friction between particles

what is shear stress

downslope force (gravity)

when does mass movement occur

when shear stress is greater than shear strength

what is the angle of repose

the steepest angle at which material remains stable

what commonly triggers mass movements?

heavy rain, earthquakes, volcanic activity, human activity

how does vegetation affect slope stability?

roots stabilze soil, removing vegetation increases risk