Geology Cafe

The Rock Cycle: Recycling Processes Within the Earth System

Processes that shape the earth's surface are ongoing, continuously or intermittently. The landscape is a reflection of many cumulative factors that have occurred over geologic time. Tectonic forces (faulting and folding) and volcanism raise the land's surface, whereas the interactions of gravity, air, water, and ice act to modify (weathering) and move (erosion) earth materials, wearing down the landscape. Long term climate changes also influences weathering and erosion processes, and can cause changes in sea level changes. Asteroid impacts, although infrequent in geologic history, have had dramatic impact on the development on the planet and the life it supports.

The rock cycle illustrates the formation, alteration, destruction, and reformation of earth materials, and typically over long periods of geologic time. The rock cycle portrays the collective system of processes, and the resulting products that form, at or below the earth surface.The illustration below illustrates the rock cycle with the common names of rocks, minerals, and sediments associated with each group of earth materials: sediments, sedimentary rocks, metamorphic rocks, and igneous rocks. On a grand scale, the rock cycle is integral to the processes associated with plate tectonics.

Rock Cycle Illustrated
See a more detailed version of the Rock Cycle Illustrated.
The Rock Cycle
Click on any word to see a link or illustration. See California Rocks illustrated.

To see examples and descriptions of all the rocks and processes listed above, see
Rocks and Geology of the San Francisco Bay Region (USGS Bulletin 2195, 63 p. .pdf file).

See This Dynamic Planet for an overview of how plate tectonic forces shape the globe, and how it influenced the formation of the California landscape over time.
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8/28/2012
Conglomerate Sandstone Mudstone Siltstone Shale Graywacke Limestone Marl Chert Salt Coal Slate Greenschist Greenstone gneiss Marble Metasandstone Quartzite Blueschist Serpentinite Metachert Gypsum Granodiorite Diorite Gabbro Basalt Andesite Rhyolite Peridotite Pyroxenite Dacite Dolostone