Tuesday, April 17, 2012


Unconformities-very long times of nondeposition and/or erosion, of which there are three basic types.
  • disconformity- surface(erosion) seperating younger from older rocks. These rock layers are horizontal (parallel) to each other.
  • nonconformity- erosion surface that separates old metamorphic rocks from younger sedimentary rocks.
  • angular unconformity- tilted sedimentary rocks that are overlain by younger flat-lying sedimentary rocks.
Cross-cutting principle- the intrusive rock body is younger than the rocks it cuts. You cannot cross-cut rock layers if they are not already present.

Principle of inclusions- inclusions or fragments in a rock are older than the rock itself.

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