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Earth Systems Chapter 8 AP Environmental Science
Terms in this set (60)
The availability of Earth's resources was determined when it formed.
describe the layers of the earth
: dense mass made up of nickel and iron, inner= liquid, outer=solid
: made of molten rock (
), which circulates in convection cells like in the atmosphere
: composed of semi-molten, ductile (flexible) rock
: brittle, includes the two solid upper mantle and the
(chemically distinct), made up of tectonic plates
The Earth is dynamic and constantly changing.
what are the 3 steps of the Earth's geologic cycle?
tectonic cycle, rock cycle, soil formation
why is the core/outer mantle hot? how does this affect the heating of the Earth?
-radioactive decay of isotopes of K, uranium, and thorium
-the heat causes hot plumes of magma to produce
, which are places where molten material hits the lithosphere
who was Alfred Wegener?
he proposed the idea of Pangaea... evidence?
1. identical rock formations on both sides of the atlantic
2. fossil evidence
(after he published, scientists found more evidence)
earth's lithosphere is divided into plates, most of which are in constant motion
sum of the processes that build up and break down the lithosphere
what are the two types of plates?
1. oceanic: crust=dense and rich in iron
2. continental: crust= less dense and rich in silicon dioxide (often rise above the oceanic for this reason)
what moves plates?
convection cells in the mantle
oceanic plates diverge and rising magma makes new oceanic crust between them
when oceanic and continental meet, oceanic goes underneath contintental
how are they formed?
a vent in Earth's surface that emits ash, gas, and molten lava; formed by the rising heat from the mantle which melts Earth's crust as the plate moves over a hot spot
divergent plate boundaries
plates separate/move away
-creates new lithosphere
-brings rarer elements to the surface
convergent plate boundaries
plates move close and collide, generating lots of pressure
what happens when a oceanic and continental plate meet convergent plate boundary?
continental plate will be pushed up over the oceanic (subduction), which forms long, narrow coastal mountain chains
what happens when two continental plates meet at a convergent plate boundary?
both are pushed upwards to form a mid-continental mountain range
transform fault boundary
when plates slide past each other
fracture in rock due to movement along it, areas of high seismic and volcanic activity ("Ring of Fire in pacific ocean)
large expanses of rock where movement occurs, form in upper lithosphere because of tension
occur because of tension at plate boundaries, rocks of the lithosphere rupture unexpectedly along a fault
earthquakes along faults
exact point on the surface above where the rock ruptures (strongest point of the earthquake)
measure of the largest ground movement that occurs during an earthquake, increases by factors of 10 per value
The rock cycle recycles scarce minerals and elements.
the constant formation or destruction of rock, slowest part of the geologic cycle
solid chemical substances with uniform structures that form at certain temperatures or pressures, make up rocks
what is the source of all rock?
forms directly from magma
can be basaltic or granitic
what are the two types of igneous rock?
1. basaltic: dark-colored; contain lots of iron magnesium and calcium; common in ocean plates
2. granitic: lighter-colored; made of feldspar mica and quartz; common in continental plates; with weathering it breaks down to form sand
what are the two methods of forming igneous rock?
1. intrusive: form within Earth as magma rises up and cools in place (underground)
2. extrusive: form when magma cools above the surface (ex: by seafloor spreading or volcanoes)
why is this important?
brings precious elements and metals to the surface
cracks in the Earth
form when sediments are compressed by overlying sediments,
hold the fossil record
form when sedimentary/igneous/metamorphic rocks are in high temperatures and pressures
mechanical breakdown of rocks and minerals by air, water, temperature change, or biological agents
the breakdown of rocks and minerals by chemical reactions OR the dissolving of chemical elements from rocks (OR both)
what might cause chemical weathering?
=rapidly degrades rock and soil
physical removal of rock fragments (sediment, soil, rock, and other particles)
what causes erosion?
-wind, water, and ice
-living organisms (from burrowing)
accumulation or depositing of rock, sediment, or soils
Soil links the rock cycle and the biosphere.
a mix of geologic and organic components, dynamic membrane of Earth's crust
why is soil important?
1. medium for plant growth
2. filters water
3. filters out pollutants
4. habitat for bacteria, fungi, algae, and certain other animals (ex: worms)
5. recycle organic matter (detritus -> nutrients)
how does soil form?
-the physical and chemical weathering of rocks
-the accumulation of detritus from the biosphere
what composes soil?
mineral matter, organic matter, water, air
what determines soil properties?
: (rock underlying it from which its inorganic compounds are derived) determines nutrient content
2. climate: colder=determines weathering and leaching of nutrients
3. topography: (surface slope/landscape) steep slopes cause more erosion
4. organisms: plants take in nutrients and expel chemicals, burrowing animals
5. time: change in properties as they mature
what are the layers of soil horizons?
: organic matter in various stages of decomposition
: (topsoil) zone of mixing overlying organic material and underlying mineral material
: only in acidic soils, zone of leaching)
: (subsoil) zone of accumulation of metals and nutrients, low organic matter
: (subsoil) similar to parent material
what determines soil texture?
percentage composition of sand silt and clay
how fast soil drains
cation exchange capacity
(aka nutrient holding capacity)
the ability of a certain soil to absorb and release cations, highest in clays
the proportion of soil bases to soil acids (%)
the loss of some or all of the ability to support plant growth
how does soil degradation occur?
: topsoil is disturbed
The uneven distribution of mineral resources has social and environmental consequences.
average concentration of an element in the crust
concentrated accumulations of minerals form which economically valuable materials can be extracted
the known quantity of the resource that can be economically recovered
what are the types of surface mining?
: removal of strips of soil and rock to expose ore, take what they want and pour the rest (
) back into the hole they dug
: make a big pit
: explode the top of a mountain off
: looking for precious materials by rivers
mining below 100m in the Earth
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