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What is rock?
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• A rock is a naturally occurring
solid mixture of one or more
minerals, or organic matter.
• Rocks are classified by how
they are formed, their
composition, and texture.
• Rocks change over time
through the rock cycle.
What is rock cycle?
Rock cycle is the
continuous changing
of rocks from one
kind to another over
long periods of time.
The process of rock cycle
Weathering
Erosion & Transportation
Deposition of Sediments
Burial & Compaction
Deformation & Metamorphism
Crystallization of magma
Uplift
Weathering
• Weathering is the breakdown of rocks at the
Earth’s surface, by the action of rainwater,
extremes of temperature. And biological
activity.
• There are three types of weathering:
Physical
Chemical
Biological
Erosion and Transport
Erosion is the process by
which soil and rock particles
are worn away and moved
elsewhere by gravity, or by a
moving transport agentwind, water or ice.
Wind
Water
Transport refers to the
processes by which the
sediment is moved along.
Ice
Deposition of Sediments
• Deposition is the laying
down of sediments carried
by wind, water or ice.
Wind
Water
Ice
Burial and Compaction
As layers are piled one upon another,
the sediments beneath are buried,
sometimes by hundreds of meters of
sediment above.
Deformation & Metamorphism
• The huge forces that move
continents stretch and squash
parts of the Earth’s crust.,
generating earthquakes and
building
mountains.
• They cause rocks near the
surface to be fracture and
faulted.
• At greater depth, the heat and
pressure involved can cause
folding and/or metamorphism.
Deformation
Metamorphism
Crystallization of magma
When molten rock tends to work
its way upward. If it reaches the
surface, there will be volcanic
eruption or lava flows. This quickly
cooled magma forms either glassy or
very fine-grained rocks.
Uplift
Uplift happens when the Earth’s
crust is constantly moving, and
mountain ranges are lifted up as
continents collide, squashing, folding
and faulting the rock layers that are
caught up in the process.
Igneous rock
•
•
•
•
Igneous rock begins as magma.
Magma can form:
When rock is heated.
When pressure is released.
When rock changes composition.
Magma freezes between
700 °C and 1,250 °C
Magma is a mixture of many minerals.
Igneous rock
• Felsic: light colored rocks that are rich in
elements such as aluminum, potassium,
silicon, and sodium.
• Mafic: dark colored rocks that are rich in
calcium, iron, and magnesium, poor in silicon
• Coarse-grained: takes longer to cool, giving
mineral crystals more time to grow
• Fine-grained: cools quickly with little to no
crystals
Igneous rock
Coarse-Grained
Felsic
Mafic
Fine-Grained
Igneous rock
• Intrusive Igneous
Rocks: magma
pushes into
surrounding and
the rock solidify
below the Earth’s
surface.
Extrusive Rocks:
forms when magma
erupts onto the
Earth’s surface
(lava), cools quickly
with very small or
no crystals formed
and solidify on or
above Earth's
surface.
Sedimentary rock
Sedimentary rock is formed by
erosion.
Sediments are moved from
one place to another.
Sediments are deposited in
layers, with the older ones on
the bottom.
The layers become compacted
and cemented together.
There are three main types
of sedimentary rocks:
• Clastic: your basic sedimentary
rock. Clastic sedimentary rocks are
accumulations of clasts: little
pieces of broken up rock which
have piled up and been "lithified"
by compaction and cementation.
• Chemical: many of these form when
standing water evaporates, leaving
dissolved minerals behind.
• These are very common in arid lands,
where seasonal "playa lakes" occur in
closed depressions.
• Thick deposits of salt and gypsum can
form due to repeated flooding and
evaporation over long periods of time.
• Organic: any accumulation of
sedimentary debris caused by organic
processes.
• Many animals use calcium for shells,
bones, and teeth.
• These bits of calcium can pile up on
the seafloor and accumulate into a
thick enough layer to form an
"organic" sedimentary rock .
Metamorphic rock
• Meaning to change shape.
•
Changes with temperature and
pressure, but remains solid.
•
Usually takes place deep in the
Earth.
Formation of metamorphic rock
• Contact Metamorphism –
heated by nearby magma.
• Increased temperature
changes the composition
of the rock, minerals are
changed into new
minerals.
• Regional Metamorphism
– pressure builds up in
rocks that is deep within
the Earth.
• Large pieces of the
Earth’s crust collide and
the rock is deformed and
chemically changed by
heat and pressure.
References::
www. google.com
www.geolsoc.org
www.Geology.com
http://jersey.uoregon.edu/~mstrick/AskGe
oMan/geoQuerry14.html
Prepared by:
Irah P. Sanchez