- WEATHERING:
Weathering is a general term for the alteration and eventual break-up of solid materials by the effects of weather and other natural processes.
Weathering processes include:
- Wind and wind-blown sand, which can etch our scour surfaces, especially in dry regions.
- WATER, in its many forms, including rainwater, snow, ice (such as scouring by advancing glaciers), stream flow, ocean waves, and groundwater.
A special, but very potent form of weathering by water occurs at temperatures near the freezing point (0o C or 32o F).
By day, liquid water seeps into cracks in rocks. At night, the water expands as it freezes into ice, widening the cracks. The pattern repeats
night after night, with water getting a little deeper into cracks each time.
- Plant roots, which wedge into cracks within and between rocks, then expand forcibly to widen the cracks.
- Burrowing animals, including earthworms.
- Many chemicals secreted by lichens, fungi, bacteria, or other living organisms that release nutrients from the rocks, decomposing the rock material in the process.
- Ground movements, including slumps and slides, which happen both on land and underwater.
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