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3 types of rocks
3 types of rocks
• There are 3 types of
rocks found on Earth:
– Igneous
– Sedimentary
– Metamorphic
• Knowing the differences
between these 3 types
of rocks allows us to
learn about Earth’s past.
Igneous Rocks - Formation
• Igneous Rocks are created
from the cooling and
solidification of magma or
lava the rock's crystal size
depends on how quickly
it cools
• Igneous rocks form as a
result of volcanic activity,
hot spots, and melting
that occurs in the
mantle.
Igneous rocks
• Igneous rocks are common along plate
boundaries or mantle hot spots
Igneous Rocks - Classification
• Igneous rocks are classified
using their texture in the
following ways:
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–
–
–
Glassy
Aphanitic (no visible crystals)
Phaneritic (visible crystals)
Porphyritic (Some visible and
some not visible crystals)
Igneous Rocks - Examples
• The most common
types of igneous rocks
include:
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–
–
–
–
–
–
Andesite
Pumice
Basalt
Granite
Obsidian
Diorite
Gabbro
Sedimentary Rocks - Formation
• Sedimentary rocks are
created from deposition
of sediments and layers
over long periods of
time. It often contains
fossils
• Sedimentary rocks form
in areas where water,
wind, or gravity deposit
sediments.
Sedimentary rocks - formation
• Weathering is the creation
of smaller pieces of rock
through physical or
chemical means
• Erosion is the moving of
settlements from their
original position
• Deposition is the settling of
settlements
• Compaction & Cementation
is a process by which
settlement is squeezed and
glued together into a new
rock
Sedimentary rocks - Examples
• Some of the most
common types of
sedimentary rocks
include:
–
–
–
–
–
–
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Conglomerate
Sandstone
Shale
Limestone
Gypsum
Oolites
Chert (including black
flint and red jasper)
Metamorphic rocks - Formation
• Metamorphic rocks
are existing rocks
are subjected to very
high heat and
pressure. This usually
takes place deep
underground
• Metamorphic rocks
form near lava
intrusions, at plate
subduction zones, and
in deep mountain
roots.
Metamorphic rocks - Formation
• Lava intrusions can
provide heat that
causes metamorphic
rocks to form. These
small areas of
metamorphic rock form
from contact
metamorphosis.
Metamorphic rocks - Formation
• Rocks that
metamorphose
because of increasing
heat and pressure
found at plate
subduction zones and
in deep mountain
roots form large areas
of metamorphic rock
through regional
metamorphosis.
Metamorphic rocks - Formations
• Structures and
formations seen in
metamorphic rocks
include:
–
–
–
–
Folding
Plastic deformation
Stretching
Alternating dark and
light layers (gneissic
foliation)
Metamorphic rocks - Examples
• Some common types of
metamorphic rock
include:
–
–
–
–
–
–
–
Slate
Schist
Gneiss
Amphibolite
Marble
Quartzite
Metaconglomerate
Weathering,
Erosion,
Deposition
Heat and Pressure