Download Rocks: Records of Geologic Processes Chapter 4

Rocks: Records of
Geologic Processes
Chapter 4
Does not contain complete lecture
notes. To be used to help organize
lecture notes and home/test studies.
Igneous Rocks
Rocks are formed by the solidification of
magma
Classified by mineralogy: chemical
composition; or
Classified by texture: Fine-grained(volcanic or
aphanitic) or Coarse-grained (plutonic or
phaneritic).
Where the magma cools determine the rock
appearance and where and how it was formed.
Most of the minerals in igneous rocks are
silicates.
Sedimentary Rocks
Sedimentary rocks are formed by
weathering, transportation by erosion,
and lithification.
Weathering and erosion produce clastic
and non-clastic sediments.
Lithification converts sediments into solid
rocks by compaction and cementation.
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Sedimentary Rocks
Clastic sedimentary rocks are characterized by
bedding. Common minerals include silicates,
quartz, feldspar, and clay.
Non-clastic sedimentary rocks (chemical and
biochemical) are formed by precipitation,
dissolved, and carried into the river’s water
into the sea.
Two other non-clastic sedimentary rocks are
gypsum and halite from evaporation.
Metamorphic Rocks
Metamorphism changes any class of
rocks (igneous rocks, sedimentary rocks,
or even other metamorphic rocks) into
different metamorphic rocks.
Changes occur by contact or regional
metamorphism, which is determined by
the type and amount of heat and
pressure.
Rock Outcrops
Rock outcrops are places where bedrock
is laid bare. Arranged by the geologic
history of the region.
The rock cycle is the interaction between
plate tectonics and climatic systems.
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