Comment: 05:41 - 06:42 (01:01)
Source: Annenberg/CPB Resources - Earth Revealed - 15. Weathering and Soils
Keywords: "mechanical weathering", weathering, "chemical weathering", disintegration, "ice wedging", "Earth's surface", "tectonic activity", "rock composition", crystal, quartz, feldspar, "ferromagnesium mineral"
Our transcription: The term, "mechanical weathering," or "disintegration," describes the natural break up or fragmentation of rock at the earth's surface.
A chunk of granite, for example, may be broken up into smaller pieces by ice wedging or tectonic activity.
But this doesn't change the composition of the rock.
It's still granite.
It still consists of its original crystals of quartz, feldspar, and ferromagnesium minerals.
Contrast this with the other main form of weathering.
"Chemical weathering", which has a much more drastic effect on rock, although the two types of weathering are interrelated.
By breaking rocks into smaller pieces, mechanical weathering increases the amount of exposed surface.
This hastens the chemical weathering of the entire rock.
Geology School Keywords