Thursday, February 9, 2012

Sedimentary and Metamorphic Rocks

Let's finish-up talking about rocks.

Sedimentary Rocks:

  • form from the weathering and erosion of previous rocks
  • the process is- weathering, erosion, deposition, compaction, cementation
  • clastic rocks form from fragments of material ex; conglomerate and sandstone
  • chemical rocks form from the precipitation of minerals from water (oceans) ex; rock salt and rock gypsum
  • fossils are found in sedimentary rocks, the other rock processes would destroy the fossils. Interesting fact, even ripple marks from streams or beaches can be fossilized.
Metamorphic Rocks:
  • these rocks form from extreme heat and pressure placed upon pre-existing rocks.
  • heat is the primary agent for contact metamorphism, this heat is supplied by nearby magma.
  • during metamorphism minerals may recrystallize, crystals can grow larger and the rock will become more compact.
  • running water is NOT an agent of metamorphism.
By the way Google Earth has a new version out- download it, pretty cool.

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