Ch4 Review – Rocks
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Most metamorphic rock forms deep underground
A rock called a porphyry has large crystals surrounded by smaller crystals
Granite is not a sedimentary rock
The minerals that make up most of Earth’s crust are called rock-forming minerals
A rock’s texture is the look and feel of the rock
Erosion and deposition play roles in the formation of a sedimentary rock
Slate is basically a denser, more compact version of shale
Basalt is an igneous rock
The names of the three major groups of rocks refer to how the rocks formed
Chemical rocks form when minerals that are dissolved in a solution crystallize on Earth’s
surface
Metamorphic rocks that have their grains arranged in parallel bands are said to be
foliated
The process in which dissolved materials crystallize and glue particles of sediment
together is called cementation
The series of processes that change rock from one type to another is called the rock
cycle
Igneous rocks may be similar in mineral composition and yet have different textures
A sedimentary rock that forms when rock fragments are squeezed together is called a(n)
clastic rock
The process that presses sediments together is called deposition; F – compaction
Basalt is the most common intrusive rock; F – extrusive rock
Sandstone that began as coral can be found on continents; F – limestone
Forces inside Earth help to drive the rock cycle; T
Coal is a type of organic rock; T
Study the rock cycle on p.115
How are the forces inside Earth are related to the rock cycle
o Plate movements start the rock cycle by helping to form magma, the source of
igneous rocks
What characteristics do geologists use to identify rocks
o Geologists observe rock’s color and texture and determine its mineral
composition
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Which would have larger crystals, an igneous rock formed from magma that cooled
deep below the surface or an igneous rock that cooled from lava on the surface?
Explain why
o An igneous rock formed from magma that cooled below the surface would have
larger crystals because it had cooled slowly
A sedimentary rock containing fossils is pushed deep beneath Earth’s surface, where it
changes to metamorphic rock. Would the fossil still be recognizable in the rock?
Explain.
o Probably not. The heat and pressure that forms metamorphic rock changes the
shape of a rock’s grains and also changes its mineral composition. This process
would destroy the fossil
Magma from a volcano pushes its way through a thick layer of shale, a fine-grained
sedimentary rock. What effect would this have on the shale? Explain
o Heat from the magma would cause the shale near the magma to change to the
metamorphic rock slate
Describe granite using the three characteristics geologists use to classify igneous rocks
o Granite is a coarse-grained igneous rock that is generally light-colored. Its
mineral composition includes quartz and feldspar
One the walls of the Grand Canyon, you can see many layers of sandstone, one on top
of another. Describe how one of those layers might have formed
o Processes that form sedimentary rock, including erosion and deposition,
compaction, and cementation
What would happen to a coral reef if a disease suddenly killed most of the algae in the
reef? Explain your answer
o The coral animals would die, because they are dependent on the algae for the
food produced by photosynthesis, and the reef would stop growing