Download Rocks, Minerals, and Soil Study Guide Earth`s Crust There are four

Rocks, Minerals, and Soil
Study Guide
Earth’s Crust
There are four main layers of the Earth’s crust.
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crust (outermost layer and the layer on which we live)
mantle (magma is in this layer)
outer core (made of liquid iron and nickel)
inner core (hottest layer)
Rocks
Rocks are classified into three basic groups: igneous, sedimentary, and metamorphic. These
groups are based on how the rock is formed.
Igneous rocks begin as molten rock, a red hot liquid. Igneous means “fire”, so igneous rocks can
also be called “fire rocks.” After a long while, the molten rock cools and hardens to form solid
rock. An example of this type of rock is granite.
Sedimentary rocks are made up of sediments, or bits of rock and sand. Over millions of years,
sediments are buried under ground. There, they are pressed and cemented together to form
sedimentary rocks. Sandstone is an example of a sedimentary rock.
Metamorphic rocks are formed from igneous and sedimentary rocks. Metamorphic rocks are
formed from existing rocks that have been squeezed and heated deep inside Earth’s crust.
Marble is an example of this kind of rock.
Minerals
A mineral is:
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a solid material formed by nature in or on Earth’s crust
has a crystal form
has its own set of properties
not formed by a living thing
Properties of Minerals
Color (can have more than one color)
Luster (shiny, glassy, dull, metallic)
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Hardness (Mohs Hardness Scale from 1-10) Talc (1) Diamond (10)
Streak (color of the mark a mineral makes when it is scraped on a white tile)
Rock Cycle
Forces inside Earth and on its surface change one kind of rock into another kind. The process of
rocks changing into other kinds of rock is called the rock cycle.
Soil
Soil is made of tiny pieces of rock, minerals, and decayed plant and animal matter. The layers
of soil are:
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Undecayed Layer (decaying material in the soil is called humus.)
Topsoil (Rich soil that holds lots of humus and minerals. It soaks up and stores water
well.)
Subsoil (This layer is where you might find clay. Water does not flow easily through
clay.)
Rock (There are large pieces of weathered rock in this layer.)