Cornell Notes pgs. 61-65
Rocks
What is a rock?
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Classifying Rocks
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Igneous Rocks
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--Formation of Igneous Rocks
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--Texture and Composition
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Sedimentary Rocks
--Formation of Sedimentary Rocks
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--Texture and Composition
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Metamorphic Rocks
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A rock is a naturally occurring solid
mixture composed of minerals, smaller
rock fragments, organic matter, or glass.
The individual particles in rocks are called
grains.
Rocks are classified by the way they form.
The three major types of rocks are
igneous, metamorphic, and sedimentary.
Igneous rocks are the most abundant rocks
on earth.
Molten rock is called magma when it is
inside Earth.
Molten rock that erupts onto Earth’s
surface is called lava.
Geologists classify igneous rocks according
to texture and mineral composition.
For rocks, texture refers to grain size and
how the grains are arranged.
When rocks have small crystals in them
geologists describe the texture as finegrained.
When rocks have larger crystals in them
geologists describe the texture as coarsegrained.
Rock and mineral fragments that are loose
or suspended in water are called
sediment.
Lithification is the process through which
sediment turns into rock.
Sediment is formed through weathering by
water, ice, or wind; which can also
remove, or erode, the sediment.
Sediment is deposited in low areas called
basins.
Layers of sediment build up, and the
weight of the upper layers compacts the
lower layers.
Sedimentary rocks can be described as
fine-grained or coarse-grained.
The composition of sedimentary rock
depends on the minerals in the sediment
from which it formed.
Rocks can change in different rocks by
means of high temperatures and pressure.
The original rocks are called parent rocks,
Cornell Notes pgs. 61-65
--Formation of Metamorphic Rocks
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--Texture and Composition
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--Foliated Metamorphic Rocks
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--Nonfoliated Metamorphic Rocks
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Rocks in Everyday Life
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and the new rocks are called metamorphic
rocks.
Metamorphic rocks form when parent
rocks are squeezed, heated, or exposed to
hot fluids.
They remain solid, but the texture, and
sometimes the mineral, composition of
the parent rock change and this process is
called metamorphism.
The textures of most metamorphic rocks
result from increases in temperature and
pressure.
The mineral composition of metamorphic
rocks might be the result of minerals that
are present in the parent rock, or they
might grow in the new metamorphic rock.
Foliation results when uneven pressures
cause flat minerals to line up, giving the
rock a layered appearance.
These types of rocks do not exhibit
foliation.
Rocks are abundant natural resources that
are used in many ways based on their
physical characteristics.