Download Rocks and the Rock Cycle

Rocks and the Rock
Cycle
LEQ: How have different processes
created the mineral and rocks that
are found in Earth’s crust?
Rocks
 Rocks are
made of
minerals
from Earth’s
crust and
mantle.
Igneous Rocks
 Also known as firestones
because they form from
either magma or lava.
 Intrusive Igneous Rocks
form below Earth’s
surface (magma).
 Cools slowly and form
large mineral crystals
 Ex: Granite, Diorite,
Gabbro
Igneous Rocks
 Extrusive Igneous
Rocks form above
Earth’s surface
(Lava).
 Cools quickly and
forms small crystals
or no crystals (glass).
 Ex: Obsidian, Basalt,
Rhyolite
Igneous Rocks
 Along with crystal size, igneous rocks
are also classified by color or mineral
composition.
 Mafic rocks are dark in color and usually
contain the minerals OLIVINE OR
CALCIUM PLAGIOCLASE.
 Example: Basalt from the black beaches of
Hawaii
Igneous Rocks
 Intermediate rocks are
dark and light in color
(Dalmatian speckled).
 Ex. Diorite
 Felsic rocks are light in
color and usually contain
minerals quartz and
muscovite (high in
silica).
 Ex. Rhyolite
Sedimentary Rocks
 Formed from the processes of erosion,
deposition, compaction, and lithofication.
 Erosion: Breaking up and wearing down rocks.
 Deposition: Rock sediments sinking to the bottom of
lake, river, ocean, glacial deposits.
 Compaction: Pressing sediments together.
 Lithofication: Process where dissolved minerals
crystallize and “glue” sediments together.
Classification of
Sedimentary Rocks
 Chemical Composition
 Clastic: formed from the
cementation (lithofication)
of other rock sediments
 Chemical: formed from
precipitation out of
solution.
 Ex. Rock Salt or some
forms of limestone
(caves)
 Organic: formed from the
remains of once living
creatures.
 Ex. Coal, Coquina
(special limestone from
shells)
Classification of
Sedimentary Rocks
Rock Type
Fragment Size
Breccia
Fragments are > 2mm(gravel) in
size, fragments are jagged.
Conglomerate
Fragments are > 2mm (gravel) in
size, fragments are rounded.
Sandstone
Fragments are 1/16-2mm in size
Siltstone
Fragments are1/16-1/256mm in
size
Shale
Fragments are <1/256 mm in size
(clay)
Mudstone
Composed of 50% shale and
50%silt
Limestone/Coquina
Formed from skeletons of corals
and mollusks
Metamorphic Rocks
 Form from heat and
pressure applied to
igneous, sedimentary or
other metamorphic
rocks.
 Metamorphic Processes
 Contact Metamorphism is
when an igneous intrusion
(magma) causes
surrounding rock to
“bake”.
 Pressure is not a factor.
Metamorphic Rocks
 Regional
Metamorphism is
when heat from
pressure causes
metamorphism.
 Often seen in events
such as continental
collisions.
Types of Metamorphic
Rocks
 Foliated Rocks: Rocks
that have grains
arranged in parallel
layers or bands.
 Gneiss, Slate
 Non-Foliated: Rocks that
have mineral grains
arranged randomly.
 Marble or quartzite
Rock Cycle