Classroom presentations Classroom presentations to accompany to accompany
Understanding EarthUnderstanding Earth, 3rd edition, 3rd edition
prepared by
Peter Copeland and William Dupré
University of Houston
Chapter 3Chapter 3Rocks: Records of Geologic Processes
Three types of rocksThree types of rocks
Igneous
Sedimentary
Metamorphic
Igneous rocks make up most of the earth
sedimentary rocks make up most of the
surface.
Rocks formed by the consolidation of
fragments of previously existing rock
or chemically precipitated from
solution.
Sedimentary RocksSedimentary Rocks
Genesis of Sedimentary RocksGenesis of Sedimentary Rocks
• Physical weathering: reduction in size• Chemical weathering: change in
composition• Transportation:
–Solid particles ... clastics by water, wind, ice
–Ions in solution ... chemical
Rocks whose original form has
changed in the solid state due to
increased temperature and/or
pressure.
Metamorphic rocksMetamorphic rocks
Fig. 3.5
Where does Metamorphism occur?Where does Metamorphism occur?
Regional Metamorphism Contact Metamorphism
The production and destruction of
rocks is ultimately related to plate
tectonics.
Plate tectonics Plate tectonics and the rock cycleand the rock cycle
Fig. 3.11a
Subduction at Subduction at convergent plate convergent plate
boundaries boundaries causes partial causes partial
melting to form melting to form magma and magma and
resulting igneous resulting igneous rocks.rocks.
Fig. 3.11b
Magma Magma rises from rises from the mantle the mantle
at divergent at divergent plate plate
boundaries.boundaries.
Fig. 3.11c
Subsidence at Subsidence at rifted plate rifted plate
margin allows margin allows for the for the
deposition, deposition, burial, and burial, and
lithification lithification of sediments.of sediments.
Plate interiors Plate interiors are dominated by are dominated by
sedimentary sedimentary processes, with processes, with some volcanism some volcanism due to mantle due to mantle “hot spots.”“hot spots.”
Fig. 3.11d
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