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Rocks
Table of Contents: Rocks
Writing Prompt:
Rocks, what are they?
Rocks are….
• A solid or liquid
mixture of one or
more minerals and
sometimes organic
matter (dead stuff).
• The very solid matter
that makes up Earth.
There is no such
thing as a plain old
rock. Every rock
tells a story.
There are three major groups of rocks: These
terms refer to how the rocks in each group formed.
• igneous
• sedimentary
• metamorphic
Observing Rocks
• For each group of rocks that your table
receives you will make a list of
observations in your notebook.
• Observations will include…?
• Physical properties
• Similarities or differences between the rocks
• Connections or inferences you make as to how
the rocks formed or where they can be found
You Rock!
• Have a pencil ready
• You DO NOT need your notebooks
Sedimentary Rock
• forms when sediments (tiny pieces) of
other rocks or the remains of plants and
animals are compacted and cemented
together.
Metamorphic Rock
• forms when an existing rock is changed
by heat & pressure. Most metamorphic
rock forms deep underground.
Igneous Rock
• forms from the cooling of molten rock—
either magma below the surface or lava at
the surface
Brain Pop!
How do sedimentary rocks form?
•
Destructive forces are constantly breaking
up and wearing away all the rocks on Earth's surface.
These forces include heat and cold, rain, waves, and
grinding ice.
•
Erosion occurs when running water or wind loosen and
carry away the fragments of rock.
• Deposition Eventually, the moving water or wind slows
and deposits the sediment. If water is carrying the
sediment, rock fragments and other materials sink to the
bottom of a lake or ocean. Deposition is the process by
which sediment settles out of the water or wind carrying
it
THEN….
•
Compaction is the process that presses
sediments together. Year after year more
sediment falls on top, creating new layers.
The weight of the layers further compacts
the sediments, squeezing them tightly
together. The layers often remain visible in
the sedimentary rock. .
•
Cementation While compaction is taking
place, the minerals in the rock slowly
dissolve in the water. The dissolved
minerals seep into the spaces between
particles of sediment. Cementation is the
process in which dissolved minerals
crystallize and glue particles of sediment
together. It often takes millions of years for
compaction and cementation to transform
loose sediments into solid sedimentary rock.
How metamorphic rocks form ?
• Every metamorphic rock is a rock that has
changed its form. In fact, the word
metamorphic comes from the Greek words
meta, meaning “change,” and morphosis,
meaning “form.” But what causes a rock to
change into metamorphic rock? The
answer lies inside Earth.
Metamorphic Changes!
• When rock changes into metamorphic
rock, its appearance, texture, crystal
structure, and mineral content change.
Metamorphic rock can form out of igneous,
sedimentary, or other metamorphic rock.
Heat and pressure deep beneath
Earth's surface can change any
rock into metamorphic rock.
The Rock Cycle:
A cycle of many pathways
• The enormous granite dome that forms Stone Mountain
in Georgia looks as if it will be there forever. The granite
formed hundreds of millions of years ago as a
batholith—a mass of igneous rock beneath Earth's
surface. But this rock has stood exposed to the weather
for millions of years. Bit by bit, the granite is flaking off.
Washed away in streams, the bits of granite will
eventually be ground down into sand. But that's not the
end of the story. What will become of those sand
particles from Stone Mountain? They are part of a series
of changes that happen to all the rocks of Earth's crust.
Stone Mountain, near Atlanta, GA
Earth's rocks are not as
unchanging as they seem.
• Forces inside Earth and at the surface
produce a rock cycle that builds,
destroys, and changes the rocks in the
crust .
• The rock cycle is a series of processes
on Earth's surface and inside the planet
that slowly change rocks from one kind to
another
What drives the rock cycle?
• Earth's constructive
and destructive
forces—including
plate tectonics—move
rocks through the
rock cycle.
The Rock Cycle