Class Notes - Geology 101 Rock I
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Class Notes - Geology 101
Rock Identification
Igneos rocks
formed through crystallization from molten rock. Slow cooling
of magma deep below the earth's surface causes coarse
crystalline rocks with crystals easily visible by the naked eye.
Rapid cooling (e.g., in a lavaflow) leads to tiny crystals - need
a microscope (or good hand lens) to see these.
z
z
z
granite
gabbro
basalt
sedimentary rocks
Are formed by weathering and re-deposition of preexisting
rocks. Many have distinct layers (do not confuse with foliation
- that's metamorphic - see below) and you can see the sediment
particles.
Limestone is made up from fossil remains - body parts!
z
z
z
sandstone
shale
limestone
metamorphic rocks
Were buried and subjected to heat and pressure. As a result new,
metamorphic minerals form. These minerals often display
preferred orientation, leading to foliation, which can be confused
with sedimentary layers.
z
z
z
slate
schist
gneiss
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3/7/2006