rock and rock cycle
TRANSCRIPT
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ROCK
AND
ROCK CYCLE
Ma. Victoria Delis-Naboya
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Rocks
Rocks are any solid massof mineral or mineral-like
matter occurringnaturally as part of our
planet.
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ROCK is a naturally formedsolid material that isusually made of
minerals
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1.MINERAL COMPOSITION
- composed of mineralswith
a. physical propertiesb. chemical properties
ROCKCHARACTERISTICS
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2. TEXTURE
- is the size and shape of themineral crystals or grains in arock
SIZE SHAPE
a. coarse a. angular
b. Fine b. rounded
c. glassy
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3. STRUCTURE
- is the arrangement of themineral crystals or grains in arock
a. crystalline or granular structure= spread throughout the rock
b. Fragmental
= grains are cemented togetherby another material in thespaces between them
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3. STRUCTURE
- is the arrangement of the
mineral crystals or grains in a rock
a. crystalline or granular structure= spread throughout the rock
a. Fragmental= grains are cemented together by
another material in the spaces
between them
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The Rock Cycle
Types ofRocks
1. Igneous rock is formed by the
crystallization of molten magma
or lava
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Rocks
The Rock Cycle
Types of Rocks
2. Sedimentary rock is formed from the
weathered products of preexisting rocks that
have been transported, deposited, compacted,
and cemented.
3. Metamorphic rock is formed by the alterationof pre-existing rock deep within Earth (but still
in the solid state) by heat, pressure, and/or
chemically active fluids.
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The Rock Cycle
The Rock Cycle
Shows the interrelationships among the three
rock types (igneous, sedimentary, andmetamorphic)
Magma is molten material that forms deep
beneath the Earths surface.
Lava is magma that reaches the surface.Weathering is a process in which rocks are
broken down by water, air, and living things.
Sediment is weathered pieces of Earth
elements.
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The Rock Cycle
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Energy That Drives the Rock Cycle
The Rock Cycle
Processes driven by heat from the Earthsinterior are responsible for forming both
igneous rock and metamorphic rock.
External processes produce sedimentary
rocks.
Weathering and the movement of weathered
materials are external processes powered byenergy from the sun.
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Formation ofIgneous Rocks
Igneous Rocks
1.Intrusive igneous rocks are formedwhen magma hardens beneath Earths
surface.
2. Extrusive igneous rocks are formed
when lava hardens.
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Classification ofIgneous Rocks
Igneous Rocks
1. Texture
Igneous rocks can be classified basedon their composition and texture.
Coarse-grained texture is caused by slow
cooling resulting in larger crystals. Fine-grained texture is caused by rapid
cooling resulting in smaller, interconnected
mineral grains.
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Course-Grained Igneous Texture
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Fine-Grained Igneous Texture
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Classification ofIgneous Rocks
Igneous Rocks
1. Texture (continued) Glassy texture is caused by very rapid cooling. Porphyritic texture is caused by different rates
of cooling resulting in varied sized minerals.
2. Composition
Granitic composition rocks are made mostly
of light-colored quartz and feldspar.
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Obsidian Exhibits a Glassy Texture.
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Porphyritic Igneous Texture
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Classification ofIgneous Rocks
Igneous Rocks
2. Composition (continued)
Basaltic composition rocks are made mostly
of dark-colored silicate minerals and
plagioclase feldspar.
Andesitic composition rocks are between
granitic light-color minerals and basalticcomposition dark-colored minerals.
Ultramafic composition rocks are made mostly
from iron and magnesium-rich minerals.
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Basalt
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Classification ofIgneous Rocks
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Igneous rocks are formed from the
solidification of molten rock material.
There are two basic types: 1) intrusive
igneous rocks such as diorite, gabbro,
granite and pegmatite that solidifybelow Earth's surface; and 2) extrusive
igneous rocks such as andesite, basalt,
obsidian, pumice, rhyolite and scoria
that solidify on or above Earth's
surface.
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ANDESITE Andesite is a fine-
grained, extrusiveigneous rock
composed mainly of
plagioclase with
other minerals such
as hornblende,pyroxene and
biotite.
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BASALT Basalt is a fine-
grained, dark-colored extrusive
igneous rockcomposed mainly
of plagioclase andpyroxene.
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DRIORITEDiorite is a coarse-
grained, intrusive
igneous rock that
contains a mixtureof feldspar,
pyroxene,
hornblende and
sometimes quartz.
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GABBRO Gabbro is a
coarse-grained,dark colored,
intrusive igneous
rock that
contains feldspar,
augite andsometimes
olivine.
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GRANITE Granite is a
coarse-grained,light colored,
intrusive igneous
rock that
contains mainly
quartz andfeldspar
minerals.
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OBSIDIANObsidian is a dark-
colored volcanic
glass that forms
from the very
rapid cooling ofmolten rock
material. It cools so
rapidly that
crystals do not
form.
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PEGMATITE Pegmatite is a light-
colored, extremely coarse-grained intrusive igneous
rock. It forms near the
margins of a magma
chamber during the final
phases of magma chamber
crystallization. It often
contains rare mineralsthat are not found in other
parts of the magma
chamber.
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PERIDOTITEPeridotite is a coarse-
grained intrusiveigneous rock that is
composed almost
entirely of olivine. It
may contain small
amounts ofamphibole, feldspar,
quartz or pyroxene.
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PUMICE Pumice is a light-
colored vesicularigneous rock. It
forms through very
rapid solidification ofa melt. The vesicular
texture is a result of
gas trapped in themelt at the time of
solidification.
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RHYOLITE Rhyolite is a light-
colored, fine-grained, extrusive
igneous rock thattypically contains
quartz and
feldspar minerals.
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SCORIA Scoria is a dark-colored,vesicular, extrusive igneous
rock. The vesicles are aresult of trapped gas within
the melt at the time of
solidification. It often formsas a frothy crust on the top
of a lava flow or as material
ejected from a volcanic vent
and solidifying while
airborne.
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TUFF Welded Tuff is a rockthat is composed of
materials that were
ejected from a volcano,
fell to Earth, and then
lithified into a rock. It is
usually composed mainly
of volcanic ash and
sometimes contains
larger size particles such
as cinders.
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Formation ofSedimentary Rocks
Sedimentary Rocks
Erosion involves the weathering and the
removal of rock.
Deposition occurs when an agent of
erosionwater, wind, ice, or gravityloses
energy and drops sediments.
Weathering, Erosion, and Deposition
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Formation ofSedimentary Rocks
Sedimentary Rocks
Compaction is a process that squeezes, or
compacts, sediments.
Cementation takes place when dissolved
minerals are deposited in the tiny spaces
among the sediments.
Compaction and Cementation
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Classification ofSedimentary Rocks
Sedimentary Rocks
1. Clastic sedimentary rocks are composed
of weathered bits of rocks and minerals.
Classified by particle size
Two Main Groups
- Shale (most abundant)
Common rocks include
- Conglomerate
- Sandstone
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Shale with Plant Fossils
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Conglomerate
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Classification ofSedimentary Rocks
Sedimentary Rocks
Two Main Groups
2. Chemical sedimentary rocks form whendissolved substances precipitate, or
separate, from water.
Common rocks include
- limestonemost abundant chemical rock- microcrystalline quartz known as chert, flint,jasper, or agate
- evaporites such as rock salt or gypsum
- coal
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Fossiliferous Limestone
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Classification of
Sedimentary Rocks
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Features ofSome Sedimentary Rocks
Sedimentary Rocks
Features of sedimentary rocks are cluesto how and where the rocks are formed
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Sedimentary Rocks
Sedimentary rocks form at or near the
Earth's surface.
R
ocks made from particles of erodedsediment are called clastic sedimentary
rocks, rocks made from the remains or
living things are called biogenicsedimentary rocks, and those that form
by minerals precipitating out of solution
are called eva orites.
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LIMESTONE Limestone is
usually made of thetiny calcite
skeletons ofmicroscopic
organisms that once
lived in shallow
seas like today's
Bahamas.
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SANDSTONE Sandstone forms
where sand is laiddown and
buriedbeaches,dunes and
seafloors. Usuallysandstone is
mostly quartz.
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ROCKSALT
Rock salt is anevaporite
composed mostlyof the mineral
halite, source oftable salt, as well
as sylvite.
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SHALE Shale is a
claystone that isfissile, splitting in
layers. Shale isusually soft and
does not crop outunless harder
rock protects it.
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SILTSTONE Siltstone is made
of sediment that is
between sand and
clay in the
Wentworth grade
scale; it's finer
grained thansandstone but
coarser than shale.
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TRAVERTINE Travertine is a
kind of limestonedeposited by
springs. It is anodd geological
resource that can
be harvested and
renewed.
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ROCK GYPSUMRock gypsum is an
evaporite rock that
forms as shallow sea
basins or salt lakesdry up enough for
the mineral gypsum
to come out of
solution.
.
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PEAT Peat is soft, made
of plant remains,but it's hard
enough to beconsidered a
rock. With heat
and long burial,
peat becomes
coal.
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BRECCIA Breccia is a clasticsedimentary rock that
is composed of large
(over two millimeter
diameter) angular
fragments. The spaces
between the large
fragments can be filled
with a matrix of
smaller particles or a
mineral cement which
binds the rock to ether.
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CHERTChert is a microcrystalline or
cryptocrystalline sedimentary
rock material composed ofsilicon dioxide (SiO
2). It
occurs as nodules and
concretionary masses and less
frequently as a layereddeposit. It breaks with a
conchoidal fracture, often
producing very sharp edges.
Early people took advantageof how chert breaks and used
it to fashion cutting tools and
weapons.
C l i i
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COALCoal is an organic
sedimentary rock
that forms mainlyfrom plant debris.
The plant debris
usually accumulates
in a swamp
environment.C
oal iscombustible and is
often mined for use
as a fuel.
C l t i
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CONGLOMERATEConglomerate is a
clastic sedimentary rock
that contains large(greater then two
millimeters in diameter)
rounded particles. Thespace between the
pebbles is generally
filled with smallerparticles and/or a
chemical cement that
binds the rock together.
IRON ORE
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IRON ORE Iron Ore is a chemicalsedimentary rock that
forms when iron and
oxygen (and sometimes
other substances)
combine in solution and
deposit as a sediment.
Hematite (shown
above) is the mostcommon sedimentary
iron ore mineral.
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Formation of Metamorphic Rocks
Metamorphic Rocks
Metamorphism means to change
form.
Conditions for formation are found a fewkilometers below the Earths surface and
extend into the upper mantle.
Most metamorphic changes occur at
elevated temperatures and pressures.
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Formation of Metamorphic Rocks
Metamorphic Rocks
Contact metamorphism occurs when
magma moves into rock.
Changes are driven by a rise in temperature.
Occurs near a body of magma
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Formation of Metamorphic Rocks
Metamorphic Rocks
Regional metamorphism results in
large-scale deformation and high-grade
metamorphism.
Directed pressures and high temperatures
occur during mountain building.
Produces the greatest volume of metamorphic
rock
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Agents of Metamorphism
Metamorphic Rocks
Heat
Pressure
Provides the energy needed to drive chemical
reactions
Causes a more compact rock with greaterdensity
Origin of Pressure in
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Origin ofPressure in
Metamorphism
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Agents of Metamorphism
Metamorphic Rocks
Hot water-based solutions escaping from the
mass of magma
Promote recrystallization by dissolving original
minerals and then depositing new ones
Hydrothermal Solutions
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Classification of Metamorphic Rocks
Metamorphic Rocks
1. Foliated Metamorphic Rock
2. Nonfoliated Metamorphic Rock
Two main categories
Has a banded or layered appearance
Does not have a banded texture
Classification of
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Classification of
Metamorphic Rocks
Gneiss Typically Displays a
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Gneiss Typically Displays a
Banded Appearance
Marble A Nonfoliated
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MarbleA Nonfoliated
Metamorphic Rock
AMPHIBOLITE
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AMPHIBOLITEAmphibolite is a non-
foliated metamorphicrock that forms through
recrystallization under
conditions of highviscosity and directed
pressure. It is composed
primarily of amphiboleand plagioclase, usually
with very little quartz.
GNEISS
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GNEISSGneiss is foliated
metamorphic rock thathas a banded
appearance and is
made up of granularmineral grains. It
typically contains
abundant quartz orfeldspar minerals.
HORNFELS Hornfels is a fine-
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HORNFELS Hornfels is a fine-grained nonfoliated
metamorphic rock withno specific composition.
It is produced by
contact metamorphism.Hornfels is a rock that
was "baked" while
near a heat source suchas a magma chamber,
sill or dike.
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PHYLLITE Phyllite is a foliate
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PHYLLITE Phyllite is a foliatemetamorphic rock that
is made up mainly ofvery fine-grained mica.
The surface of phyllite
is typically lustrous andsometimes wrinkled. It
is intermediate in grade
between slate andschist.
QUARTZITE
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QUARTZITEQuartzite is a non-
foliatedmetamorphic rock
that is produced bythe metamorphism
of sandstone. It is
composed primarilyof quartz.
CHLORITE SCHIST
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CHLORITE SCHIST
Schist is metamorphic
rock with well developedfoliation. It often
contains significant
amounts of mica whichallow the rock to split
into thin pieces. It is a
rock of intermediatemetamorphic grade
between phyllite and
gneiss.
MUSCOVITE SCHIST
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MUSCOVITE SCHIST
Schist is metamorphic
rock with well developedfoliation. It often
contains significant
amounts of mica whichallow the rock to split
into thin pieces. It is a
rock of intermediatemetamorphic grade
between phyllite and
gneiss.
G SC S S hi t i t hi k
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GARNETSCHIST Schist is metamorphic rock
with well developed foliation.
It often contains significantamounts of mica which allow
the rock to split into thin
pieces. It is a rock of
intermediate metamorphic
grade between phyllite and
gneiss. The specimen shown
above is a "garnet schist"because it contains a
significant amount of garnet.
SLATE
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SLATESlate is a foliated
metamorphic rockthat is formed
through themetamorphism of
shale. It is a low
grade metamorphicrock that splits into