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Geology of the Pacific Northwest

Geology-208

Week 4:  METAMORPHIC & SEDIMENTARY ROCKS

Metamorphic Rocks

Igneous, sedimentary, and previously metamorphosed rocks change texture and composition when subjected to differing temperatures and pressures.

  1. TEXTURE:
  2. CHEMICAL COMPOSITION

A rock's metamorphic grade (low, medium, or high grade) is related to the temperature and pressure at the time of contact or regional metamorphism. For instance, a low-grade metamorphic rock is a result of metamorphism at a low temperature and pressure.

See chart.

Sedimentary Rocks

All rocks tell a story. A rock's size tells something of its origin and how fast or slow the water moved that deposited the rock in its present location. A rock's roundness tells how long it traveled to get to its current location. The sorting (whether one size or various sizes) of the its constituent sediments tells whether the rock was transported by landslide or by glacier.

  1. Texture
  2. Composition

See chart.

RESOURCES

Sedimentary and Metamorphic Rocks (McConnell, David, University of Akron, February 11, 1998)

GLOSSARY



Send comments to Rob Viens (e-mail: rviens@bcc.ctc.edu) or call him at his Bellevue Community College office at (425) 564-3158. Office hours are by appointment.


© 2001-2002, Rob Viens, Bellevue Community College. All rights reserved.
Page updated on 5 September 2002  • 
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