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Chapter 8
Earth Systems and Resources
Are Hybrid Electric Vehicles as
Environmentally Friendly as We Think?
• Hybrid electric vehicles (HEV) and all-electric
vehicles - most exciting innovations of the last
decade?
– Problem- contain neodymium, lithium, and lanthanum
• Environmental trade-offs:
• How we acquire scarce metals: Mining!
– Mining involves ?
– Extraction via surface mining  severe environmental
impacts:
• Why is this important?
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The Earth’s resources were
determined when the planet formed.
• Early Earth was a hot, molten sphere.
– Molten material slowly cooled  elements within
it separated into layers
• What we have is it
• Elements and minerals are distributed
unevenly
– Some minerals are readily available worldwide
– Others are isolated
– Caused many conflicts
The Earth’s Layers
• Core- the innermost
zone of the planet
– Made of nickel and
iron
• Mantle- above the
core containing
magma
• Crust- the outermost
layer of the planet.
The Earth’s Layers
• Asthenosphere- the outer part of the mantle
– Composed of semi-molten rock.
• Lithosphere- the brittle outermost layer of the
planet
– Approximately 100 km thick
– Made of numerous plates
• Soil
• Resources
Convection and Hot Spots
• Earth  very hot at the center
• Causes plumes of hot magma to well upward from the
mantle
• This produces:
– Hotspots- places where molten material from the mantle
reach the lithosphere
– Convection cells in mantle
Theory of Plate Tectonics
• 1912 - German meterologist – Alfred Wegener
– Pangeaea
– Evidence
• In trying to disprove Wegener, scientist found
more evidence to support it
• Wegener’s theory was replaced with:
– Plate tectonics- the theory that states that Earth’s
lithosphere is divided into plates, most of which are in
constant motion
– Tectonic cycle
Tectonic Plates
• We know lithosphere is broken into plates
– Oceanic plates
– Continental plates
• Oceanic and continental plates “float”
– Seafloor spreading
• Subduction – the process of one plate moving
underneath another plate
Geographic Time Scale
• As continents
drifter over
Earth’s surface…
• Scientists use the
fossil record to
determine how
organisms have
adapted over time
Consequences of Plate Movement
• Volcanoes- as a
plate moves over
a hot spot, rising
magma forms a
volcano
• Figure 8.7 –
Hawaiian Islands
formed this way
Types of Plate Contact
• Zones of plate contact:
– Divergent plate boundarieswhen plates move apart from
one another
• Brings important elements (Cu, Pb,
and Ag) to surface of Earth
– Convergent plate boundarieswhen plates move toward one
another and collide
• Oceanic plates + continental plate
• 2 continental plates meet
– Transform fault boundaries- then
plates move sideways past each
other
Faults and Earthquakes
• Faults- a fracture in rock across which there is
movement due to plates moving
– Fault zones
• Earthquakes- occur when the rocks of the
lithosphere rupture unexpectedly along a fault
– Rapid movement
Faults and Earthquakes
• Fault zones also called areas of ___________________
• Epicenter- the exact point on the surface of Earth
directly above the location where the rock ruptures.
• Richter scale- a measure of the largest ground
movement that occurs during an earthquake.
– Scale increases by a factor of 10 (
• Both earthquakes and volcanos are disruptive to
human life
– Ie: Earthquake in Haiti (2010) and Etna Volcano in Italy
(2001)
The Rock Cycle
• Rock cycle- the
constant formation
and destruction of
rock
• Rock – composed of
minerals
– Minerals
• Formed under specific
temperature and
pressure
• Formation of rock
– Weathering
The Rock Cycle
• Igneous rocks- rocks that form directly from magma
– Classified by:
• Chemical composition as basaltic or granite
• Mode of formation: intrusive or extrusive
– Fractures
• Sedimentary rocks- form when sediment such as mud,
sands, or gravels are compressed by overlying
sediments
• Metamorphic rocks- form when sedimentary, igneous
or other metamorphic rocks are subjected to high
temperatures and pressures
Weathering and Erosion
• Weathering- when rocks are exposed to air,
water, certain chemicals or biological agents
that degrade the rock.
– Include: physical processes, chemical processes,
and erosion
Weathering and Erosion
• Physical weathering- the mechanical
breakdown of rocks and minerals
– Caused by…
• Chemical weathering- the breakdown of rocks
and minerals by chemical reactions
– Releases essential nutrients from rocks – now
available for use by plants and other organisms
– Some is the result of human activities
Erosion
• Erosion- the physical removal of rock
fragments from a landscape or ecosystem
– Wind, water, ice transport and living organisms
can erode materials
– Natural process
– Human caused
• Deposition- the accumulation or depositing of
eroded material such as sediment, rock
fragments or soil
Soil
• Soil – mix of geologic
and organic
compounds
• Important because it
– Is a medium for plant
growth
– Serves as a filter for
water
– A habitat for living
organisms
– Serves as a filter for
pollutants
The Formation of Soil
• Takes hundreds to thousands of years
• Soil results from physical and chemical weathering
processes
• Factors that determine the formation of soil:
– Parent material- what the soil is made from influences soil
formation
– Climate- what type of climate influences soil formation
– Topography- the surface and slope can influence soil formation
– Organisms- plants and animals can have an effect on soil
formation
– Time- the amount of time a soil has spent developing can
determine soil properties.
The Formation of Soil
Soil Horizons
• As soils form, they develop characteristics
layers (horizons)
Physical Properties of Soil
• Texture- the percentage of sand, silt and clay
the soil contains.
Physical Properties of Soil
• Permeability - how quickly the soil drains (which
depends on its texture)
• Best agricultural soil is a mix of all three soil
particles
• Soil and pollution
Chemical Properties of Soil
• Cation exchange capacity- the ability of a soil to
adsorb and release cations, positively charged mineral
ions
– Clay particles attract positively charged mineral ions
– Soil with high CECs
• Soil bases- calcium, magnesium, potassium and sodium
– Promotes plant growth
• Soil Acids- aluminum and hydrogen
– Detrimental to plant nutrition
• Base saturation- the proportion of soil bases to soil
acids
Biological Properties of Soil
• Many organisms are found in
the soil
– 3 main groups of organisms =
80-90% of biological activity in
soil
• Detritivores
• Soil fixing bacteria
– Others:
• Rodents and earthworms
• Snails and slugs
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Soil Degradation
• Soil degradation – loss of some or all of the
ability of soils to support plant growth
• Occurs from overuse of land for agriculture,
forestry and other human activities
– Soil erosion
– Compaction of soil by machines, humans and
livestock
– Extensive agriculture use and irrigation
Elemental Composition of the Earth’s
Crust
• Finite quantities of rocks, minerals and fossil
fuels
• Crustal abundance – average concentration of
an element in the crust
• Obtaining mineral resources:
– Ores
– Metals
Reserves
• Reserves- the known quantity of a resource
that can be economically recovered
– Some reserves in US have already been depleted
Types of Mining
• Surface Mining
– Mineral and energy resources are extracted near
Earth’s surface by removing soil, subsoil and over-lying
rock strata
– More common because less expensive
– Two kinds: open pit and strip mining
• Subsurface Mining
– Mineral and energy resources are extracted from deep
underground deposits
– Two kinds: shaft mine and slope mine
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Types of Mining
Types of Mining
• Some more terms:
– Mountain top removal- removing the entire top of
a mountain with explosives
• Problem – damage to streams and nearby groundwater
cannot be rectified by the reclamation process
– Placer mining- looking for metals and stones in
river sediments
Types of Mining
Mining Laws
• Effectiveness has varied
• Mining Law of 1872 – goal to regulate the
mining of silver, copper, and gold ore as well
as fuels, including natural gas and oil, on
federal lands
• The Surface Mining Control and Reclamation
Act of 1977 - regulates surface mining of coal
and the surface effects of subsurface coal
mining