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Earth Science Earth Science A Review of our Earth A Review of our Earth

Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

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Page 1: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Earth ScienceEarth Science

A Review of our EarthA Review of our Earth

Page 2: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

The Composition of the The Composition of the EarthEarth

The Layers BeneathThe Layers Beneath

Page 3: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Structure and CompositionStructure and Composition

• The Earth is comprised of four The Earth is comprised of four distinctive systemsdistinctive systems– AtmosphereAtmosphere– HydrosphereHydrosphere– BiosphereBiosphere– LithosphereLithosphere

Page 4: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath
Page 5: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Structure and CompositionStructure and Composition

Page 6: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Lithosphere (The Crust)Lithosphere (The Crust)

• The The LithosphereLithosphere is the rigid outer is the rigid outer shell of the planet and includes the shell of the planet and includes the crust and the uppermost, hard crust and the uppermost, hard portion of the mantle. portion of the mantle.

• The The Asthenosphere Asthenosphere is the partially is the partially molten layer of the Earth’s crust molten layer of the Earth’s crust which includes the upper and lower which includes the upper and lower mantle as well as the transition zone.mantle as well as the transition zone.

Page 7: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

The CrustThe Crust•The crust is the top layer of the Earth.The crust is the top layer of the Earth.

– Continental crust (0-50 km) is less dense Continental crust (0-50 km) is less dense than oceanic crust and includes volcanic, than oceanic crust and includes volcanic, sedimentary and granitic rocks, with older sedimentary and granitic rocks, with older areas dominated by metamorphic rocks.areas dominated by metamorphic rocks.

– Oceanic crust (0-12 km) contains basalt Oceanic crust (0-12 km) contains basalt which is extrusive igneous rock, and is which is extrusive igneous rock, and is often both fine-grained and dense.often both fine-grained and dense.

Page 8: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

The MantleThe Mantle• The mantle is separated into the upper (outer) The mantle is separated into the upper (outer)

mantle, the transition zone and the lower mantle, the transition zone and the lower (inner) mantle.(inner) mantle.– The outer mantle includes an upper layer made of The outer mantle includes an upper layer made of

silicates of iron and magnesium but is stiffer silicates of iron and magnesium but is stiffer because of its lower temperature; and, a bottom because of its lower temperature; and, a bottom (transition) layer of tough liquid rock made of the (transition) layer of tough liquid rock made of the same material.same material.

– The inner mantle is solid due to pressure and The inner mantle is solid due to pressure and consists of sulphides and oxides of silicon and consists of sulphides and oxides of silicon and magnesium.magnesium.

Page 9: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

The CoreThe Core

• Below the crust and the mantle lies Below the crust and the mantle lies the outer and inner core.the outer and inner core.– The outer core is a molten liquid made The outer core is a molten liquid made

up primarily of Iron and Sulfur. The up primarily of Iron and Sulfur. The outer core account for 30% of the total outer core account for 30% of the total mass of the Earth.mass of the Earth.

– The inner core is a solid Iron-nickel alloy The inner core is a solid Iron-nickel alloy and only accounts for 2% of the total and only accounts for 2% of the total mass of the Earth.mass of the Earth.

Page 10: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Making of The Modern Day Making of The Modern Day EarthEarth

Plate TectonicsPlate Tectonics

Page 11: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Continental BoundariesContinental Boundaries

•Early mapmakers observed that the Early mapmakers observed that the borders of the continents seemed borders of the continents seemed to match, much like a puzzle.to match, much like a puzzle.

• In 1912, a German scientist named In 1912, a German scientist named Wegener proposed a hypothesis of Wegener proposed a hypothesis of continental driftcontinental drift– Pangea (supercontinent)Pangea (supercontinent)

Page 12: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

PangeaPangea• Coastlines Coastlines

matched upmatched up

• Evidence came Evidence came from: from: – rock formationsrock formations– fossilsfossils– ancient climate ancient climate

(glacial deposits)(glacial deposits)

Page 13: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Seafloor SpreadingSeafloor Spreading• The seafloor is a rough terrain with The seafloor is a rough terrain with

ridges, mountains and valleys.ridges, mountains and valleys.

• The theory of seafloor spreading uses The theory of seafloor spreading uses sonar and magnetic mapping to sonar and magnetic mapping to determine the topography.determine the topography.– New ocean crust is formed at ocean ridges New ocean crust is formed at ocean ridges

and destroyed at deep-sea trenches.and destroyed at deep-sea trenches.– This theory was the missing link in This theory was the missing link in

Wegener’s continental drift theory.Wegener’s continental drift theory.

Page 14: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Seafloor Spreading Leads Seafloor Spreading Leads to Continental Driftto Continental Drift•New oceanic New oceanic

crust is formed crust is formed when magma when magma intrudes along a intrudes along a ridge.ridge.

• When this magma cools to form new crust, it spreads the oceanic ridge.

Page 15: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Plate TectonicsPlate Tectonics• Plate tectonicsPlate tectonics is a theory that the is a theory that the

Earth’s crust and upper mantle are Earth’s crust and upper mantle are divided into large portions called divided into large portions called platesplates..

Page 16: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

BoundariesBoundaries

• There are three types of boundaries There are three types of boundaries between these platesbetween these plates– Divergent BoundaryDivergent Boundary– Convergent BoundaryConvergent Boundary– Transform BoundaryTransform Boundary

Page 17: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Divergent BoundaryDivergent Boundary

• A A divergent boundarydivergent boundary is the is the boundary where two tectonic plates boundary where two tectonic plates are moving apart from each other.are moving apart from each other.– Most are found on the seafloor and form Most are found on the seafloor and form

oceanic ridges.oceanic ridges.– Site of the formation of new oceanic Site of the formation of new oceanic

crust.crust.– Underwater earthquakes and volcanos Underwater earthquakes and volcanos

can be found at divergent boundaries.can be found at divergent boundaries.

Page 18: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

ExamplesExamples

The mid-atlantic ridge is an example of a divergent boundary:

• East Pacific Rise

•Red Sea Rift

•Galapagos Rise

Page 19: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Convergent BoundaryConvergent Boundary

• A A convergent boundaryconvergent boundary is where is where two tectonic plates move toward each two tectonic plates move toward each other:other:– oceanic-oceanicoceanic-oceanic– oceanic-continentaloceanic-continental– continental-continentalcontinental-continental

• When one plate moves under another, When one plate moves under another, it is called the it is called the subduction zonesubduction zone

Page 20: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Oceanic-OceanicOceanic-Oceanic

• Deep ocean trenches are formed at Deep ocean trenches are formed at the subduction zonethe subduction zone

• Island Arcs are formed over the Island Arcs are formed over the dominant platedominant plate

Page 21: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Oceanic-ContinentalOceanic-Continental

• Mountain ranges with many volcanos Mountain ranges with many volcanos are formed over the continental crustare formed over the continental crust

• Trenches are formed at the Trenches are formed at the subduction zonesubduction zone

Page 22: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Continental-ContinentalContinental-Continental

• Large mountain ranges are formed Large mountain ranges are formed over the subduction zoneover the subduction zone

Page 23: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Transform BoundaryTransform Boundary

• A A transform boundarytransform boundary is a place is a place where two plates slide horizontally where two plates slide horizontally past each otherpast each other– crust is deformed or fracturedcrust is deformed or fractured– high frequency of earthquakeshigh frequency of earthquakes

Page 24: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

MovementMovement

• Convection is the transfer of energy Convection is the transfer of energy through the movement of heated through the movement of heated mattermatter– Currents move from areas of high heat Currents move from areas of high heat

to areas of low heat.to areas of low heat.– Mantle currents are a result of a transfer Mantle currents are a result of a transfer

of energy from the hot interior and cool of energy from the hot interior and cool exterior.exterior.

Page 25: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Push and PullPush and Pull• Ridge push is where the weight of the Ridge push is where the weight of the

uplifted plate is pushed toward the uplifted plate is pushed toward the trench formed at the subduction zone.trench formed at the subduction zone.

• Slab pull is where the weight of the Slab pull is where the weight of the subducted plate pulls it further into the subducted plate pulls it further into the subduction zone.subduction zone.

Page 26: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Earth’s Natural DisastersEarth’s Natural Disasters

• EarthquakesEarthquakes

• VolcanoesVolcanoes

• Tsunamis or Tidal WavesTsunamis or Tidal Waves

• Heavy Rains or Severe Weather Heavy Rains or Severe Weather

Page 27: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

How is our Environment How is our Environment Affected?Affected?

PoliticsPolitics EconomyEconomy

EnvironmentEnvironment

PopulationPopulation

Page 28: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

History of the EarthHistory of the Earth

The Geologic Time ScaleThe Geologic Time Scale

Page 29: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

How old is the Earth?How old is the Earth?

• Geologists use fossil records to Geologists use fossil records to separate the history of the Earthseparate the history of the Earth

• The divisions are from largest to The divisions are from largest to smallest length of time smallest length of time

eon eon era era period period epoch epoch

Page 30: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

4.6 Billion Years Old4.6 Billion Years Old

• Eon: measured in billions of years Eon: measured in billions of years

• Era: measured in hundreds of millions of Era: measured in hundreds of millions of years and marked by differences in life-years and marked by differences in life-forms that are preserved in rocks.forms that are preserved in rocks.

• Period: measured in tens of millions of Period: measured in tens of millions of years and marked by life-forms that were years and marked by life-forms that were abundant and then extinctabundant and then extinct

• Epoch: measured in millions of years and Epoch: measured in millions of years and marked by different groups of organismsmarked by different groups of organisms

Page 31: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

The Four EonsThe Four Eons

• Hadean (4.6-3.9 bya)Hadean (4.6-3.9 bya)

• Archeozoic (3.9-2.5 bya)Archeozoic (3.9-2.5 bya)

• Proterozoic (2.5-0.54 bya)Proterozoic (2.5-0.54 bya)

• Phanerozoic (540 mya - present)Phanerozoic (540 mya - present)

Precambrian

Time

Page 32: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath
Page 33: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

What era do we come in?What era do we come in?

• Precambrian times: bacteriaPrecambrian times: bacteria

• Paleozoic Era (540-248 mya): fish, Paleozoic Era (540-248 mya): fish, reptiles, marine invertebrates, land reptiles, marine invertebrates, land plants and amphibians plants and amphibians

• Mesozoic Era (248-65 mya): age of Mesozoic Era (248-65 mya): age of dinosaurs (triassic, jurassic & cretaceous)dinosaurs (triassic, jurassic & cretaceous)

• Cenozoic Era (65 mya - present): age of Cenozoic Era (65 mya - present): age of mammelsmammels

Page 34: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

What period do I have What period do I have human?human?• Cenozoic EraCenozoic Era

– Tertiary PeriodTertiary Period•Paleocene EopchPaleocene Eopch

•Eocene EpochEocene Epoch

•Oligocene EpochOligocene Epoch

•Miocene EpochMiocene Epoch

•Pliocene EpochPliocene Epoch

– Quaternary PeriodQuaternary Period•Pleistocene EpochPleistocene Epoch

•Holocene EpochHolocene Epoch

You are here

Page 35: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Relative Age of RocksRelative Age of Rocks

• The relative age of rocks can be The relative age of rocks can be determined by examining the determined by examining the different horizontal layersdifferent horizontal layers– rocks rocks – fossilsfossils– unconformitiesunconformities

Page 36: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Absolute Age DatingAbsolute Age Dating

• Radiometric DatingRadiometric Dating– Half-life Half-life – Thorium-232 (14.0 billion yrs) to Lead-208Thorium-232 (14.0 billion yrs) to Lead-208– Uranium-238 (4.5 billion yrs) to Lead-206Uranium-238 (4.5 billion yrs) to Lead-206– Uranium-235 (0.7 billion yrs) to Lead-207Uranium-235 (0.7 billion yrs) to Lead-207– Carbon-14 (only 5,730 yrs) to Nitrogen-14Carbon-14 (only 5,730 yrs) to Nitrogen-14

Page 37: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Rocks & MineralsRocks & Minerals

The Building Blocks of EarthThe Building Blocks of Earth

Page 38: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Rocks vs. MineralsRocks vs. Minerals

• Rock is an indefinite mixture of Rock is an indefinite mixture of naturally occurring substances, naturally occurring substances, mainly minerals. mainly minerals. – Its composition may vary in containment Its composition may vary in containment

of minerals and organic substances, of minerals and organic substances, and are never exact. and are never exact.

Page 39: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Rocks vs. MineralsRocks vs. Minerals•A mineral is any naturally A mineral is any naturally

occurring, inorganic substance, occurring, inorganic substance, often characterized by an exact often characterized by an exact crystal structure. crystal structure. – Its chemical structure can be exact, or Its chemical structure can be exact, or

can vary within limits. can vary within limits. – Elements that occur naturally Elements that occur naturally

are also considered minerals.are also considered minerals.

Rough diamond

Page 40: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Mineral GroupsMineral Groups

• Elements, Elements,

• Sulfides, Sulfides,

• Oxides, Oxides,

• Halides, Halides,

• Carbonates, Carbonates,

• Nitrates, Nitrates,

• Borates,Borates,

• Chromates, Chromates,

• Sulfates Sulfates

• Phosphates, Phosphates,

• Arsenates, Arsenates,

• Vanadates, Vanadates,

• Tungstates, Tungstates,

• Molybdates, and Molybdates, and

• Silicates. Silicates.

All minerals belong to a chemical group:

Carbonate crystals

Barite with cerussite are sulfide minederals

Page 41: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Three Types of RocksThree Types of Rocks

• Sedimentary RocksSedimentary Rocks

• Igneous RocksIgneous Rocks

• Metamorphic RockMetamorphic Rock

Page 42: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Sedimentary RockSedimentary Rock

• For thousands of years, little pieces of our For thousands of years, little pieces of our earth have been eroded--broken down and earth have been eroded--broken down and worn away by wind and water. worn away by wind and water.

• These little bits of our earth are washed These little bits of our earth are washed downstream where they settle to the bottom downstream where they settle to the bottom of the rivers, lakes, and oceans and deposited of the rivers, lakes, and oceans and deposited in layers on top of each. in layers on top of each.

• These layers are pressed down more and more These layers are pressed down more and more through time, until the bottom layers slowly through time, until the bottom layers slowly turn into rock.turn into rock.

Page 43: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Clastic RocksClastic Rocks

• Sediments may also include pieces of Sediments may also include pieces of stones and shells and other objects, stones and shells and other objects, not just grains of pure minerals. not just grains of pure minerals.

• Geologists use the word clasts to Geologists use the word clasts to denote particles of all these kinds, denote particles of all these kinds, and rocks made of clasts are called and rocks made of clasts are called clastic rocks. clastic rocks.

Page 44: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Marine Organic RocksMarine Organic Rocks

• Microscopic plankton build shells out Microscopic plankton build shells out of dissolved calcium carbonate or of dissolved calcium carbonate or silica.silica.

• When these plankton die, their When these plankton die, their bodies accumulate in thick layers on bodies accumulate in thick layers on the seafloor. the seafloor. – Limestone (carbonate) and chert (silica). Limestone (carbonate) and chert (silica).

Page 45: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Botanic Organic RockBotanic Organic Rock

• Dead plant material builds up into Dead plant material builds up into thick layers. With a small degree of thick layers. With a small degree of compaction, this becomes compaction, this becomes peatpeat and and after much longer and deeper burial, after much longer and deeper burial, it becomes it becomes coal.coal.

Page 46: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

CoalCoal

• Although peat is forming in parts of Although peat is forming in parts of the world today, the great beds of the world today, the great beds of coal we mine formed during past coal we mine formed during past ages in enormous swamps. ages in enormous swamps. – There are no coal swamps around today, There are no coal swamps around today,

because conditions do not favor them. because conditions do not favor them.

Page 47: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Chemical RocksChemical Rocks• As ancient shallow seas began to dry As ancient shallow seas began to dry

and become more concentrated, and become more concentrated, minerals begin to precipitate.minerals begin to precipitate.– Calcite (CaCOCalcite (CaCO33), gypsum (CaSO), gypsum (CaSO44

. . 2H2H22O)O),, and and halite (NaCl). halite (NaCl).

• The resulting rocks are certain The resulting rocks are certain limestones or dolomites, gypsum rock, limestones or dolomites, gypsum rock, and rock salt respectively. and rock salt respectively. – Part of the Part of the evaporiteevaporite sequence. sequence.

Page 48: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Sedimentary RockSedimentary Rock

• SandstoneSandstone

• LimestoneLimestone

• GypsumGypsum

• ConglomerateConglomerate

• ShaleShale

Page 49: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

SandstoneSandstone

• Sandstone rocks are sedimentary Sandstone rocks are sedimentary rocks made from small grains of rocks made from small grains of the minerals quartz and feldspar. the minerals quartz and feldspar. They often form in layers as seen They often form in layers as seen in this picture. They are often used in this picture. They are often used as building stones. as building stones.

Page 50: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

LimestoneLimestone• Limestone rocks are sedimentary Limestone rocks are sedimentary

rocks that are made from the rocks that are made from the mineral calcite which came from mineral calcite which came from the beds of evaporated seas and the beds of evaporated seas and lakes and from sea animal shells. lakes and from sea animal shells. This rock is used in concrete and is This rock is used in concrete and is an excellent building stone for an excellent building stone for humid regions.humid regions.

Page 51: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

ShaleShale

• Shale rock is a type of sedimentary Shale rock is a type of sedimentary rock formed from clay that is rock formed from clay that is compacted together by pressure. compacted together by pressure. They are used to make bricks and They are used to make bricks and other material that is fired in a kiln.other material that is fired in a kiln.

Page 52: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

ConglomerateConglomerate

• Conglomerate rocks made up of Conglomerate rocks made up of large sediments like sand and large sediments like sand and pebbles. The sediment is so large pebbles. The sediment is so large that pressure alone cannot hold the that pressure alone cannot hold the rock together; it is also cemented rock together; it is also cemented together with dissolved minerals.together with dissolved minerals.

Page 53: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

GypsumGypsum

• Gypsum rocks are sedimentary rocks Gypsum rocks are sedimentary rocks made up of sulfate mineral and made up of sulfate mineral and formed as the result of evaporating formed as the result of evaporating sea water in massive prehistoric sea water in massive prehistoric basins. basins.

• It is very soft and is used to make It is very soft and is used to make Plaster of Paris, casts, molds, and Plaster of Paris, casts, molds, and wallboardswallboards

Page 54: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Metamorphic RocksMetamorphic Rocks

• Metamorphic rocks are igneous or Metamorphic rocks are igneous or sedimentary rocks that have sedimentary rocks that have "morphed" into another kind of rock. "morphed" into another kind of rock.

• How do sedimentary and igneous How do sedimentary and igneous rocks change? rocks change? – The rocks are under tons and tons of The rocks are under tons and tons of

pressure, which fosters heat build up, pressure, which fosters heat build up, and this causes them to change. and this causes them to change.

Page 55: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Four Agents of Four Agents of MetamorphosisMetamorphosis

• HeatHeat

• PressurePressure

• Fluid ContentFluid Content

• StrainStrain

Page 56: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Metamorphic RockMetamorphic Rock

• SchistSchist

• GneissGneiss

Page 57: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

SchistSchist

• Schist rocks are metamorphic Schist rocks are metamorphic formed from basalt, shale, or slate, formed from basalt, shale, or slate, a metamorphic rock. Through a metamorphic rock. Through tremendous heat and pressure, tremendous heat and pressure, these rocks were transformed into these rocks were transformed into this new kind of rock. this new kind of rock.

Page 58: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

GneissGneiss• Gneiss rocks are metamorphic that Gneiss rocks are metamorphic that

may have been granite, but heat may have been granite, but heat and pressure changed it. The and pressure changed it. The mineral grains in the rock were mineral grains in the rock were flattened through tremendous heat flattened through tremendous heat and pressure and are arranged in and pressure and are arranged in alternating patterns.alternating patterns.

Page 59: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

IgneousIgneous

• Igneous rocks are formed either Igneous rocks are formed either underground or above ground from underground or above ground from the cooling and crystallization of the cooling and crystallization of magma.magma.– Extrusive (aboveground)Extrusive (aboveground)

– Intrusive (below ground)Intrusive (below ground)

– Plutonic (deep magma)Plutonic (deep magma)

Page 60: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Igneous MineralsIgneous Minerals

• The main minerals in igneous rocks The main minerals in igneous rocks are:are:– feldspar (silicates)feldspar (silicates)

– quartz (SiOquartz (SiO22))

– olivine (Mg and Fe silicates)olivine (Mg and Fe silicates)

– mica (sheet silicates)mica (sheet silicates)

Page 61: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Intrusive Igneous RockIntrusive Igneous Rock

• Intrusive igneous rocks are formed Intrusive igneous rocks are formed when magma, becomes trapped in when magma, becomes trapped in small pockets. As these pockets of small pockets. As these pockets of magma cool slowly underground, the magma cool slowly underground, the magma forms igneous rocks. magma forms igneous rocks. – Intrusive rocks cool more slowly (over Intrusive rocks cool more slowly (over

thousands of years) and have small to thousands of years) and have small to medium grains. medium grains.

Page 62: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Deep Intrusive Igneous Rock Deep Intrusive Igneous Rock

• Igneous rock formed from deep Igneous rock formed from deep magma is called magma is called plutonicplutonic..– Plutonic rocks cool over millions of Plutonic rocks cool over millions of

years, deep underground, and can have years, deep underground, and can have grains as large as pebbles and even a grains as large as pebbles and even a meter across.meter across.

Page 63: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Extrusive Igneous RockExtrusive Igneous Rock

• Igneous rocks are also formed when Igneous rocks are also formed when volcanoes erupt, causing the magma to volcanoes erupt, causing the magma to rise above the earth's surface. rise above the earth's surface.

• When magma appears above the earth, it When magma appears above the earth, it is called lava. Igneous rocks are formed is called lava. Igneous rocks are formed as the lava cools above ground.as the lava cools above ground.– Extrusive rocks cool quickly (over periods of Extrusive rocks cool quickly (over periods of

seconds to months) and have invisible or seconds to months) and have invisible or very small grains.very small grains.

Page 64: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Igneous RockIgneous Rock

• GraniteGranite

• ScoriaScoria

• PumicePumice

• ObsidianObsidian

Page 65: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Famous Rock StarsFamous Rock Stars

• The two best-known igneous rock types The two best-known igneous rock types are are basaltbasalt and and granitegranite..– Basalt is the dark, fine-grained rock from lava Basalt is the dark, fine-grained rock from lava

flows and magma intrusions. Its dark flows and magma intrusions. Its dark minerals are rich in magnesium (Mg) and iron minerals are rich in magnesium (Mg) and iron (Fe). (Fe).

– Granite is the light, coarse-grained rock Granite is the light, coarse-grained rock formed at depth and exposed after deep formed at depth and exposed after deep erosion. It is rich in feldspar and quartz erosion. It is rich in feldspar and quartz (silica). (silica).

Page 66: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

BasaltBasalt• Basalt is a common extrusive Basalt is a common extrusive

volcanic rock. It is usually gray to volcanic rock. It is usually gray to black and fine-grained due to rapid black and fine-grained due to rapid cooling of lava at the surface of a cooling of lava at the surface of a planet. planet.

• It may be porphyritic containing It may be porphyritic containing larger crystals in a fine matrix, or larger crystals in a fine matrix, or vesicular, or frothy scoria. vesicular, or frothy scoria.

Page 67: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

GraniteGranite• Granite rocks are igneous rocks which were Granite rocks are igneous rocks which were

formed by slowly cooling pockets of magma that formed by slowly cooling pockets of magma that were trapped beneath the earth's surface. were trapped beneath the earth's surface.

• Granite is used for long Granite is used for long

lasting monuments and for lasting monuments and for

trim and decoration on trim and decoration on

buildings.buildings.

Page 68: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

ScoriaScoria

• Scoria rocks are igneous rocks which Scoria rocks are igneous rocks which were formed when lava cooled were formed when lava cooled quickly above ground. You can see quickly above ground. You can see where little pockets of air had been. where little pockets of air had been. Scoria is actually a kind of glass and Scoria is actually a kind of glass and not a mixture of minerals.not a mixture of minerals.

Page 69: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

PumicePumice• Pumice rocks are igneous rocks Pumice rocks are igneous rocks

which were formed when lava which were formed when lava cooled quickly above ground. You cooled quickly above ground. You can see where little pockets of air can see where little pockets of air had been. had been.

Page 70: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

PumicePumice

• Pumice rock is so light, that many Pumice rock is so light, that many will actually float in water. Because will actually float in water. Because this rock is so light, it is used quite this rock is so light, it is used quite often as a decorative landscape often as a decorative landscape stone. Ground to a powder, it is used stone. Ground to a powder, it is used as an abrasive in polish compounds as an abrasive in polish compounds and in Lava© soap.and in Lava© soap.

Page 71: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

ObsidianObsidian• Obsidian rocks are igneous rocks Obsidian rocks are igneous rocks

that form when lava cools quickly that form when lava cools quickly above ground. Obsidian is actually above ground. Obsidian is actually glass and not a mixture of glass and not a mixture of minerals. The edges of this rock minerals. The edges of this rock are very sharp.are very sharp.

Page 72: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

GEOLOGIC PROCESSESGEOLOGIC PROCESSES

• The San The San Andreas Andreas Fault is an Fault is an example of a example of a transform transform fault.fault.

Figure 15-5Figure 15-5

Page 73: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Wearing Down and Building Wearing Down and Building Up the Earth’s SurfaceUp the Earth’s Surface

• Weathering Weathering is an is an external external process process that wears that wears the earth’s the earth’s surface surface down.down.

Figure 15-6Figure 15-6

Page 74: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

Fig. 15-6, p. 340

Parent material (rock)

Biological weathering (tree roots and lichens)

Chemical weathering (water, acids, and gases)

Physical weathering (wind, rain, thermal expansion and contraction, water freezing)

Particles of parent material

Page 75: Earth Science A Review of our Earth. The Composition of the Earth The Layers Beneath

MINERALS, ROCKS, AND THE MINERALS, ROCKS, AND THE ROCK CYCLEROCK CYCLE

• The earth’s crust consists of solid The earth’s crust consists of solid inorganic elements and compounds inorganic elements and compounds called minerals that can sometimes be called minerals that can sometimes be used as resources.used as resources.– Mineral resourceMineral resource: is a concentration of : is a concentration of

naturally occurring material in or on the naturally occurring material in or on the earth’s crust that can be extracted and earth’s crust that can be extracted and processed into useful materials at an processed into useful materials at an affordable cost.affordable cost.