Minerals & Rock Unit
Notes
th
7 Grade Science
Rocks
• Are divided into 3 groups
based on how they were
formed
•Sedimentary
•Metamorphic
•Igneous
• Are made of one or more
minerals
• Do not stay the same
• Continually changed by processes
such as Weathering, Erosion
Compaction, Cementation,
Melting, and Cooling.
• Rocks can change to and
from the 3 types
The Rock Cycle
EARTH MATERIALS CHANGE
BACK AND FORTH AMONG
THE DIFFERENT TYPES OF
ROCKS.
Igneous
(Granite #11)
Melting, Solidification
Recrystallization
Melting,
Solidification
Sedimentary
(Sandstone #6)
Recrystallization
Metamorphic
Weathering, Erosion, Deposition,
Compaction, Cementation
(Gneiss #14)
Processes that
form
Sedimentary
Rock
• Weathering: the breaking down of the
Earth’s material by natural processes
(Water, Wind, Ice, Chemicals, etc.) into
smaller pieces or sediments
• Erosion: weathered rock and soil particles
are moved from place to place
• Deposition: weathered sediments are laid
down in a new location creating new
landforms or rocks
• Compaction: heavy sediments press down
on the layers beneath
• Cementation: dissolved minerals flow
between the sediments and cement them
together
Processes that
form Igneous &
Metamorphic
Rock
• Melting: caused by heat and pressure
around the rock to form magma
• Solidification: magma cools and
hardens
• Recrystallization: while cooling, rock
can develop crystals, depending on
conditions
Complete the following:
•Turn in your Rock Cycle Directed Reading &
Earthquake/Volcano Test Corrections
•Get the 2 Directed Readings from the table
•Have something to write with
•Clear off your table
Complete the following:
•Turn in your Rock Cycle Directed Reading,
Comic Strip & Earthquake/Volcano Test
Corrections
•Get the Igneous Rock Directed Reading
from the table
•Get out your Minerals & Rocks Notes
•Have something to write with
•Clear off your table
Igneous
• Igneous is Latin for “born of
fire”
• Formed from cooling magma
or lava
•Forms when magma
cools and solidifies
•Some reaches the
surface of earth
before cooling, other
cools under the surface
Intrusive
(Example: Granite)
Extrusive
• Form below ground from magma
• Usually has coarse crystals
(grains) from cooling slowly
• Some have large and small
crystals
• Form above ground from lava
(Examples: Pumice & • Usually have small or no crystals
Obsidian)
from cooling quickly
Into the
Bedrock
intrusive
(crystals)
On top (Exit)
extrusive
(no crystals)
Bedrock
Magma!
Complete the following:
•Get out your Minerals & Rocks Notes
•Get the Paper from the table
•Have a Textbook
•Have something to write with
But then the
EARTH’S elements
Will not leave
the ROCK alone!
•Ice
•Wind
•Water
ice
wind
water
THEY BREAK UP THE STONE
DEPOSIT & COMPRESS THE SEDIMENTS
One way Sedimentary Rock
can be formed
That ROCK
changed again!
Sedimentary Rock
• Formed from sediments
(rock fragments, mineral
grains, animal and plant
remains) that are pressed
or cemented together or
when sediments
precipitates out of a
solution.
• Sediments are moved by
wind, water, ice, or
gravity.
• Water or wind breaks down
(Weathering), moves
(Erosion), and deposits
sediment (Deposition)
• The heavy sediments press
down on the layers beneath
(Compaction)
• Dissolved minerals flow
between the sediments and
cement them together
(Cementation)
Sedimentary
Rocks & Fossils
•
• Deposited sedimentary
rocks form horizontal layers
called STRATA.
• Process of arranging
sedimentary rocks into
layers is STRATIFICATION
• Scientist know that the
layers and fossils on top are
YOUNGER than the fossils
in lower layers
 LAW OF SUPERPOSITION
Types of
Sedimentary
Rocks
• Clastic: made of broken pieces of
other rocks.
• Organic: remains of once living
plants and animals are deposited in
thick layers called fossils
• Chemical: minerals dissolved in
lakes, seas, or underground water
• Limestone made when calcite
precipitates from sea water
• Rock salt made from evaporation
of sea waters
The Rock Cycle
Igneous
Metamorphic
Sedimentary
?
The Rock Cycle
Igneous
Metamorphic
kinda
melted
Sedimentary
squished
Bands (CAN) Form
Metamorphic
means
“changed”
Metamorphic Rocks
• Rocks changed due to
intense heat and high
pressure
• “Meta-” means “changed”
and “-morphosis” means
“shape” in Greek
• Igneous, Sedimentary and
other Metamorphic rocks
can change to become
Metamorphic rocks
How Metamorphic
m
Rocks Change
• Pressure from overlying rock
layers
• High heat, but not enough to
melt the rock
• Rocks may be flattened or
bent or atoms may be
exchanged to form new
materials.
• Think of metamorphic rocks
as a squished peanut butter
and jelly sandwich in your
lunch.
Types of Metamorphic Rock
• Has visible parallel layers or
Foliated
bands you can see
• Example: Gneiss formed
from rearrangement of
minerals in Granite into
bands
Non-Foliated
• Not layered & no bands are
formed
• Example: Marble formed
from Limestone
The Rock Cycle
Igneous
metamorphic
Sedimentary
The Rock Cycle
always changing…
Youngest
Rocks
Here !
Oldest Rocks
Here !