Weathering, Erosion, and Landform Change

The breaking apart of rock *in place* — no transport involved. A cliff crumbling into grit is weathering.

The pickup and transport of loose sediment by an agent such as running water, waves, glaciers, wind, or gravity.

The dropping of sediment in a new location when the carrying agent loses energy.

Physical weathering where water seeps into a crack, freezes, expands about 9%, and pries the crack wider — producing talus slopes and potholes.

Physical weathering by rocks grinding against each other in streams, surf, or wind-blown air; it rounds river pebbles.

Deeply buried rock expands and peels in curved sheets once overlying weight erodes away — e.g., Half Dome in Yosemite.

Oxidation (iron + oxygen → rust-red iron oxide), hydrolysis (feldspar + acidic water → clay), and carbonation/dissolution (carbonic acid dissolves limestone).

CO₂ + H₂O → H₂CO₃, which dissolves limestone (CaCO₃) to create caves, sinkholes, stalactites — karst landscapes.

Smaller pieces expose more surface, so they weather chemically much faster; physical weathering speeds up chemical weathering.

Chemical weathering dominates in warm, wet climates; physical weathering dominates in cold or dry climates with freeze–thaw cycles.

Running water carves V-shaped valleys; glaciers carve U-shaped valleys, cirques, arêtes, horns, and fjords.