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

Rocks:Records of Geologic

Processes

Rocks: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.

Major Rock GroupsMajor Rock Groups

Fig. 3.1

IGNEOUS SEDIMENTARY METAMORPHIC

Igneous RocksIgneous Rocks

Rocks formed from the cooling

and consolidation of magma.

Fig. 3.2

Fig. 3.2

IntrusiveGranite

Fig. 3.2

ExtrusiveBasalt

Fig. 3.2

Intrusive GraniteIntrusive Granite

Fig. 3.2

Extrusive BasaltExtrusive Basalt

Rocks formed by the consolidation of

fragments of previously existing rock

or chemically precipitated from

solution.

Sedimentary RocksSedimentary Rocks

Fig. 3.3

From Weathering to Sedimentary RockFrom Weathering to Sedimentary Rock

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

Fig. 3.4

How common are sedimentary How common are sedimentary rocks? rocks?

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

Fig. 3.5

Where does Metamorphism occur?Where does Metamorphism occur?

Regional Metamorphism Contact Metamorphism

• Outcrops

• Drilling

Where we see rocksWhere we see rocks

Fig. 3.6

Outcrop

Fred Hirschmann Fig. 3.7

Russ Kinne/ Comstock Fig. 3.8

Carr Clifton Fig. 3.9

TheTheRockRockCycleCycle

Fig. 3.10

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

Convergence of Convergence of plates causes plates causes deformation, deformation,

uplift, and uplift, and regional regional

metamorphism.metamorphism.

Fig. 3.11e