Earth's Surface Processes and Landforms
Domain III tests the processes that sculpt the surface - weathering, erosion, mass wasting, running water, groundwater, glaciers, wind, and waves - and the landforms each produces. Items ask you to predict which process dominates in a given climate or setting and to read landforms as evidence of past conditions.
Weathering versus erosion
- Weathering breaks rock in place; erosion transports the debris; deposition builds landforms.
- Physical: frost wedging, salt-crystal growth, exfoliation, abrasion, root wedging. Chemical: dissolution (limestone with carbonic acid), oxidation, hydrolysis. Warm-wet climates favor chemical weathering; cold or arid climates favor physical weathering.
- Soils are weathering products; horizons reflect parent material, climate, biota, topography, and time.
Mass wasting and slopes
Creep, slump, debris flow, and rockfall. Water raises pore pressure and reduces friction, so heavy rain triggers failure; steep slopes approach the angle of repose.
Streams, groundwater, ice, wind, coast
- Streams: V-shaped valleys and rapids near the head; meanders with point bars (inside, slow) and cut banks (outside, fast); oxbow lakes, floodplains, deltas. Competence is the largest clast carried; capacity is the total load. Base level limits downcutting.
- Groundwater: porosity stores, permeability transmits; water table, aquifer, cone of depression, karst caves and sinkholes.
- Glaciers: U-shaped valleys, striations, till, moraines, drumlins, eskers, kettles, erratics.
- Wind: dunes, loess, deflation hollows. Waves: longshore drift, spits, sea stacks, barrier islands.
Worked example
A meander bend erodes its outer bank and builds a bar on the inner bank. Flow is fastest on the outside of the curve, so shear stress and erosion peak there; velocity drops on the inside, so the coarsest bedload settles first and builds the point bar. Over time the neck narrows until a flood cuts through, abandoning the loop as an oxbow lake.
Traps
Using weathering as a synonym for erosion; assuming U-shaped valleys are river-cut; believing groundwater flows in underground rivers rather than through pore spaces; and mixing up porosity with permeability.