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Earth MaterialsMineralsA mineral is a naturally occurring
substance with characteristic physical and chemical properties.
Nearly all rocks are composed of minerals.Polymineralic rocks are
composed of more than one mineral, ex. granite.Monomineralic rocks
are composed of only one mineral, ex. limestone.
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Earth MaterialsMineral CompositionMinerals are composed of
elements. Some minerals contain only one element (copper, sulfur
and graphite (carbon)).Most minerals are made up of only a few
elements.Oxygen is the most common element by weight and
volume.Silicon is second most abundant by weight.
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Earth MaterialsProperties of MineralsCharacteristics of minerals
include:colorhardnessluster/cahaya/kilauanstreak/garis/corengcleavage/pecah/potongan
and fracture/patah/retakdensity
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Earth MaterialsProperties of MineralsDifferences in properties
are used to categorize and identify minerals.The acid test is the
use of hydrochloric acid on limestone. The result is that bubbles
of CO2 are liberated/dilepaskan.Minerals have a characteristic
crystalline structure, in many cases the silicon-oxygen
tetrahedron.
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Rock FormationThe Rock Cycle relates the three types of
rocks.
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Earth MaterialsThe Rock CycleAny one rock type can change into
any other rock type.There is no preferred direction of movement of
materials in the rock cycle for any one mass of material.There is
no exact point of separation between the rock types.
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Earth MaterialsThe Rock CycleSedimentary rocks often contain
sediments or fragments which have varied origins.The composition of
some rocks suggests that the materials (sediments or minerals) in
the rock have undergone multiple transformations (changes) within
the rock cycle.
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Weathering and ErosionWeathering is the breakdown of rocks to
form particles called sediment.Physical weathering is the breakdown
of rock without chemical changesFreezing and thawing (frost
action)Thermal expansion and contractionChemical weathering is the
breakdown of rock by chemical actionoxidation, hydration, solution
by acids
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Weathering and ErosionFactors affecting weathering
are:Exposure--more exposure means faster weatheringParticle
size--the smaller the particles, the greater the surface
areaMineral composition--some minerals (quartz) are more resistant
to weathering than others (mica and feldspar)Climate--warmth and
moisture enhance weathering
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Weathering and ErosionSoilSoil is a product of
weathering.Residual soil forms from the weathering of rocks
nearby.Transported soil is brought in by erosion.Soil layers
develop over time. The soil composition generally tends to reflect
the composition of the rocks below.
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Weathering and ErosionSoil ProfilesA soil horizon is a vertical
layer of soil with certain characteristics. For example, the top
layer of soil usually is rich in organic material.Lower horizons
result from weathering. The horizon just above the bedrock will
contain partially weathered rock.There is a subsoil layer just
below the topsoil layer.
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Weathering and ErosionSoil typesResidual soil is formed from the
rocks below the soil layer. These soils usually relate to the
underlying rocks. They can be sandy, clayey or loamy/tanah liat
organik if they have much organic material.Transported soil is one
that has been move into an area from someplace else by erosion.
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Weathering and ErosionErosionErosion is the process by which
sediments are obtained and transported.Transporting agents include
water (streams), glaciers, waves, density currents in water, wind,
and people.Driving forces include gravity and change of potential
to kinetic energy.
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Weathering and ErosionStream/aliran ErosionStream water carries
sediments.Dissolved minerals are carried in solution.Small solid
particles are carried in suspension.Large solid particles are moved
by rolling or bouncing along on the bottom of the stream.
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Weathering and ErosionStream ErosionThe ability to carry
sediment depends on velocity. The velocity depends on the gradient
(slope) and discharge (volume) of the stream.Stream velocity
varies. On a curve, it is fast on the outside and slow on the
inside.
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Weathering and ErosionStream Erosion
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Weathering and ErosionWind ErosionWind causes erosion. When wind
carries sediment, it forms dunes/bukit pasir.
Glacial erosionA glacier can carry large amounts of
dirt/kotoran.When the glacier stops moving, it drops the dirt
forming a moraine/bagian depan sungai es yang bergerak maju.
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Weathering and ErosionGlacial ErosionAn example is the Hubbard
Glacier in Alaska
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Weathering and ErosionGlacial ErosionThere is a moraine in New
Jersey left over from the last ice age. The glacier also formed
Long Island.
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DepositionDeposition is also known as sedimentation.Deposition
occurs when the velocity of water, wind or other erosional system
decreases. Deposition depends on:Particle size--heavier particles
sediment fasterShape--spherical particles sediment
fasterDensity--denser particles sediment faster
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DepositionRock layers are formed by sediments. The size of the
particles determines the rock type.Boulders, gravel, pebbles/batu
kerikil--conglomerateSand--sandstoneSilt--siltstoneColloids,
clayshale/serpihColloids, chemical sediments--limestone
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DepositionDeposition by moving water
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DepositionDeposition by moving waterWhen a river enters the
ocean, the velocity decreases.Sediments are deposited and form a
delta.An example is the Mississippi River Delta.
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Rock FormationRocks are the solid material that make up the
Earth. There are three types:Sedimentary Rocks--formed by solid
sediments weathered from pre-existing rocksIgneous Rocks--formed by
cooling of liquid rockMetamorphic Rocks--formed by transformation
of igneous or sedimentary rocks by reheating
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Rock FormationFormation of sedimentary rocksCementation--larger
particles are cemented by minerals precipitated out of the
waterCompression--very small particles are compressed by immense
weight of water and sediment layers about themChemical
action--ionic materials precipitate out of the waterBiological
processes--precipitation of minerals by biological organisms
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Rock FormationProperties of sedimentary rocksParticles of
sedimentary rocks resemble the sediments they came fromSome contain
a mixture of sediments, others a single type of sedimentSome
sedimentary rocks are of organic origin (example: coal)Sedimentary
rocks form layers called strata Sedimentary rocks frequently
contain fossils
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Sedimentary RocksIdentifying sedimentary rocksThere are three
major groups of sedimentary rocks.Detrital rocks form from
sediments washed in by water, such as gravel, sand and mud.Chemical
sedimentary rocks have crystalline texture: limestone, dolostone,
gypsum, saltBiochemical sedimentary rocks: clastic (limestone from
shells), chert, coal
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Igneous RocksProperties of igneous rocksIgneous rocks are
nonsedimentary in originThey form by solidification or
crystallization of liquid rock under the Earth called magma Longer
cooling time causes big crystals in the rock. Shorter cooling time
causes small crystals in the rock.Texture of igneous rock depends
on the size of the crystals.
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Igneous RocksTypes of igneous rocksIgneous rocks form a
gradation between two extremes.Felsic rocks are high in Al and
Si.Mafic rocks are high in Mg and Fe.Generally, igneous rocks are
identified on the basis of crystal size (texture) and mineral
composition
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Igneous RocksSequence of cooling of silicate minerals--Bowens
Reaction SeriesBowens reaction series accounts for the
crystallization of intermediate and felsic magmas from an original
basaltic (mafic) magma. It has two branches, continuous and
discontinuous.In the continuous branch, calcium-rich plagioclase
feldspar crystallizes first followed by sodium-rich plagioclase
feldspar.
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Igneous RocksSequence of cooling of silicate minerals--Bowens
Reaction SeriesIn the discontinuous branch there is a series of one
mineral changing to another over time as the melt cools. The
sequence is: olivine --> pyroxene --> amphibole -->
biotite mica.At this point the two sequences finish with: potassium
feldspar (orthoclase) --> muscovite mica --> quartz.
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Igneous RocksImportance of texture and compositionThe texture of
igneous rocks depends on the size of the crystals as well as their
arrangement. Rocks with large crystals cooled slowly. Those with
small crystals cooled faster.Mafic rocks are denser and darker than
felsic rocks (ex: pyroxene, olivine). Felsic rocks are lighter in
color and denser (ex: quartz, felspar, mica)
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Metamorphic RocksProperties of metamorphic rocksMetamorphic
rocks are also nonsedimentary in origin.Metamorphism is a response
to heat and pressure within the Earths crust.Such conditions result
from plate collisions, mountain building and sometimes localized
heating such as with volcanic eruptions.
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Metamorphic RocksProperties of metamorphic rocksMetamorphic
rocks form from recrystallization of pre-existing rocks.Metamorphic
rocks often show banding where like crystals are arranged in
layers.They have a distorted structure caused by curving and
folding of the bands.
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Metamorphic RocksFoliated vs nonfoliated metamorphic
rocksFoliated rocks have crystals arranged in parallel planes.
Examples are slate, schist, gneiss.Nonfoliated rocks do not have a
preferred orientation among their minerals. Examples are marble,
quartzite, greenstone.
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Metamorphic RocksSteps leading to the formation of gneissMost
gneiss begins with recrystallization of clay-rich sedimentary rocks
during regional metamorphism.Gneisses are composed mainly of quartz
and/or feldspar, which cause the light bands.The dark bands come
from biotite and hornblende.
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Metamorphic RocksOrigin and composition of marbleMarble is a
metamorphic rock that was originally limestone or dolomite.
Limestone marble is made of CaCO3. Dolomite marble is made of
CaMg(CO3)2. Limestone marble reacts with the acid test. Dolomitic
marble also reacts with the acid test but it must be powered
first.
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Metamorphic RocksRegional metamorphismRegional metamorphism
occurs over a wide area and results from tremendous temperatures,
pressures and deformation conditions deep under the surface.It
results in a gradation from from low to high metamorphism depending
on the levels of temperature and pressure involved.
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Civilization and Earth MaterialsHumans use fossil fuels for the
major part of their energy needs. These include coal, oil and
natural gas.Minerals are used in a variety of human
activities.Rocks are quarried and used as building stones and
pavement.Earth resources are not renewable. They cannot be restored
easily in your lifetime.
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Landscape developmentLandscapes are the features of the surface
of the Earth.Features include:slope of the landshape of surface
featuresstream drainage patternsstream slopesoil
characteristics
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Landscape developmentMeasuring Landscape
CharacteristicsMeasurements can be made using actual observations,
maps, aerial photographs or satellite images.Gradients, slopes and
profiles are given on topological maps.Major types are mountains,
plateaus and plains
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Landscape developmentForces that produce landscapesUplift is a
raising up of a region of land caused by forces in the crust or by
tectonic interaction.Leveling forces break down rocks and transport
material on the Earths surface. These include weathering, erosion,
deposition, subsidence.
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Landscape developmentForces that produce landscapesErosion is
the removal of weathered rock materials from their source area.Mass
wasting is the downslope movement of rocks, sediments, or soil
under the influence of gravity.
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Landscape developmentFactors that influence landscape
developmentClimate affects the rate of change of a
landscape.Glaciers produce U-shaped valleys and deposit soil with a
wide range of particle sizes.Streams may not flow all the time in
arid climates. Some arid regions have internal drainage where
streams deposit water into a basin rather than leading to the
ocean. The Great Salt Lake is an example.
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Landscape developmentU-shaped valley caused by a glacier
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Landscape developmentFactors that influence landscape
developmentBedrock greatly influences the landscape above
it.Different types of rock have different degrees of resistance to
weathering and erosion.Stream drainage patterns indicate
information regarding the contour of the bedrock below.
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Landscape developmentHuman influence on landscape
developmentRemoval of forests for development leads to accelerated
erosion of soil when it rains.Acid rain causes increased chemical
weathering of rocks. Example: accelerated erosion of
limestone.Environmental conservation can help conserve limited
natural resources.
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Landscape developmentGeologic features can be represented by
photographs, as well as topographic and geological maps.Maps are
interpreted using scales and colors to represent
features.Topographic maps indicate locations of equal altitude
using contour lines.Geologic maps use colors and symbols to
represent rock ages and structures.
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Landscape developmentOn a topographic map, the steepness of a
slope is indicated by the nearness of the contour lines.A very
steep slope has contour lines very close together.A long, gradual
slope has contour lines far apart.Direction on a contour map is
indicated by an arrow pointing north. Distances are given by a
distance scale.
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Natural HazardsPeople live in risky places.A flood plain can
fill up with water and carry away the work of generations.Seismic
hazards are issues near faults, such as the San Andreas Fault.It is
not a good idea to live on the slopes of a volcano, lest it erupt.
People live near Mt. Etna, anyhow.