88 terms

APES Chapter 8 Review

APES Chapter 8 Review
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4.6 billion years ago
when the earth was formed
-cosmic dust cloud
-heavier metals towards earth's center (iron)
-lighter (silica)
core
the innermost zone
-over 3,000 km (1860 miles) below Earth's surface
-dense mass largely made of nickel and iron
-inner:solid
-outer:liquid
mantle
above the core
-contains molten rock (magma) that slowly circulates in convection cells
magma
the molten rock in the mantle that slowly circulates in convection cells
asthenosphere
-located in the outer part of the mantle
-composed of semi-molten, ductile (flexible) rock
lithosphere
the brittle outermost layer of the planet
-aprox. 100 km (60 miles) thick
-includes upper mantle and crust
-made up of large plates that overlie the convection cells in the asthenosphere
crust
the chemically distinct outermost layer of the lithosphere
tectonic cycle, rock cycle, soil formation
the three major cycles that composes the earth's geologic cycle
hot spots
-places where molten material from the mantle reaches the lithosphere
-produced by the plumes of hot magma welling upward from the mantle caused by heat from radioactive decay of various isotopes (potass.uran.thorium)
pangaea
the single landmass believed to have existed
-alfred wegener (german)
-1912
-same rock formations on both sides of the atlantic
-fossil evidence
theory of plate tectonics
states that the Earth's lithosphere is divided into plates, most of which are in constant motion
tectonic cycle
the sum of the processes that build up and break down the lithosphere
oceanic plates
plates that lie beneath the oceans (lithosphere)
-crusts are dense and rich in iron
continental plates
plates that lie beneath landmasses (lithosphere)
-crusts contain more silicon dioxide (less dense than iron)
-lighter than oceanic, move above them
seafloor spreading
as oceanic plates move apart, rising magma forms new oceanic crust on the seafloor at the boundaries bw those plates
-new rock formed
-creates new lithosphere and brings important elements (copper lead silver) to the earth's surface
-where oceanic meet continental, old oceanic is pulled downward, beneath continental lithosphere
-heavier oceanic plate below light continental plate
subduction
-process of one plate passing under another
-where oceanic meet continental, old oceanic is pulled downward, beneath continental lithosphere
-heavier oceanic plate below light continental plate
geologic time scale
how earth's history is measured
volcano
-a vent in Earth's surface that emits ash, gases, and molten lava
-natural source of carbon dioxide particulates and metals
-formed as a plate moves over a geologic hot spot, heat from rising mantle plume melts the crust
-after plates move past hot spots, leave a trail of extinct volcanic islands
-85% occur along plate boundaries
divergent plate boundaries
beneath the ocean, plates move away from each other
-conveyor belt
-seafloor spreading
convergent plate boundary
form where plates move toward one another and collide
-subduction of the heavier plate (forms long narrow coastal mountain ranges, Andes SA)
transform fault boundary
when plates move sideways past each other
-most move at fingernail rate: 36 mm, 1.4 inches per year
2 plates under the Atlantic have spread and come together twice over 500 mill years
divergent plate, convergent plate, transform fault
the zones of plate contact can be classified into three types of boundaries
fault
a fracture in rock across which there is movement
fault zones
large expanses of rock where movement has occurred
-also called areas of seismic activity
-form in the brittle upper lithosphere where two plates meet
-rock near plate margins becomes deformed/fractured from immense pressures exerted by plate movement
-rocks along it are jagged and resist movement, eventually pressure overcomes it and the plates give way, slipping =earthquake
earthquakes
occur when the rocks of the lithosphere rupture unexpectedly along a fault
-plates can move up to several meters in few secs
common in fault zones
epicenter
of an earthquake, the exact point on the surface of Earth directly above the location where the rock ruptures
richter scale
reports the magnitude of an earthquake
-measure of the largest ground movement that occurs during an earthquake
-logarithmic
8.0 occurs approx. once every 10 years
800000 small quakes of mag 2.0 or less per year
mag 5.0-5.9
moderate earthquakes
rock cycle
the constant formation and destruction of rock
-second part of geologic cycle
1)rock forms when magma from Earth's interior reaches the surface, cools, and hardens
2)weathering and erosion breaks rock masses up, moves them and deposits them to new locations *new rocks may be formed
3)rock is subducted into the mantle, melting and becoming magma again
rock
substance of the lithosphere
-composed of one or more minerals
minerals
solid chemical substances with uniform (often crystalline) structures that form under specific temps and pressures
-usually composed, some single (gold+silver)
igneous, sedimentary, metamorphic
3 modes of formation for rocks form 3 rock types
igneous rocks
rocks that form directly from magma
chemical comp: basaltic, granitic
mode of formation: intrusive or extrusive
basaltic rocks
(igneous): dark-colored rock that contains minerals with high concentrations of iron, magnesium, and calcium
granitic rocks
(igneous): lighter-colored rock made up of the minerals feldspar, mica, quartz (contain elements silicon, alum. potass. and calcium)
-dominant rock type in continental plates
-when broken down (weathering): sand
-soils formed from it are generally more permeable
intrusive igneous rocks
igneous rocks that form within Earth as magma rises up and cools in place underground
extrusive igneous rocks
igneous rocks that form when magma cools above Earth's surface, ejected by volcano or released by seafloor spreading
-cool rapidly, minerals have little time to expand into large indiv. crystals
-fine grained rock types: obsidian
fractures
the cracks that occur when rock cools and is subject to stresses that cause it to break
veins
the concentrated deposits formed by the precipitated metals from the fractures when water from the E's surface runs through fractures and dissolves valuable metals
sedimentary rocks
rocks that form when sediments (muds, sands, gravels) are compressed by overlying sediments
-occurs over long periods
-hold fossil record
metamorphic rock
rocks that form when sedimentary rocks, igneous rocks, or other metamorphic rocks are subjected to high temps and pressures
-slate, marble, anthracite (coal)
-good for building (strong, attractive)
weathering
physical or chemical
-occurs when rock is exposed to air, water, certain chems compounds, or biological agents (plant roots, lichens and burrowing animals )
physical weathering
the mechanical breakdown of rocks and minerals
-caused by wind, water, variations in temps, plant roots, burrowing animals
-coarse grained (slow cooling) weather more than fine grained (rapid cooling)
-exposes more surface area, making it more vulnerable to further degradation -inc. rate of chem
chemical weathering
the breakdown of rocks and minerals by chem. reactions, the dissolving of chem elements from rocks, or both
-releases essential nutrients from rocks for plants and orgs
-most important on newly exposed minerals (primary minerals)
-alters primary to form secondary minerals + ionic forms of constituent chem elements
-rocks that contain compounds that dissolve easily (calcium carb.) weather quickly
acid precipitation (acid rain)
-sulfur dioxide from sulfur in the atm (human ff combustion). combined with oxygen
-resp. for rapid degradation of old statues, gravestones, limestone, and marble
-can create chemical weathering
erosion
the physical removal of rock fragments (sediment, soil, rock, and other particles) from a landscape or ecosystem
-wind, water, ice transport soil + other earth materials through downward slope
-living orgs burrowing
-natural process, but can be done by humans
deposition
the accumulation or depositing of eroded material (sediment, rock frags, soil)
soil
a mix of geologic and organic components
-result of phys and chem weathering + gradual accumulation of detritus from the biosphere
-forms dynamic membrane over earth's surface
-medium for plant growth
-water filter
-habitat, biodiversity contributor

-* best agric: mixture of sand, silt, and clay
soil formation
3rd part of the geologic cycle, on earth's surface
parent material, climate, topography, organisms, time
5 factors that determine the properties of soil
soil's parent material
the rock material underlying the soil from which its inorganic compounds are derived
quart sand: nutrient poor soil, Atl. coast of US
calcium carbonate: high pH and abundant supply of calcium, high productivity
climate
colder, worse at decomposing and moving water
-high latitudes of N. Hem composed of org. material in an undecomposed state
-fast soil devel. in tropical climates
topography
the surface slope and arrangement of a landscape
-steep slopes: erosion
-bottoms of steep slopes: accumulate material + deeper
organisms (soil)
plants: remove nutrients from soil and excrete organic acids
animals: burrow and mix, distibute organic and mineral matter
humans
time (soil)
older the soil, the more
soil horizons
the layers of soils formed as they develop
-composition depends on parent material, climate, and veg.
o horizon
-organic horizon
-surface of soil w/ organic detritus
-most pronounced in forest soils and in some grasslands
a horizon/topsoil
the top layer in a soil that is mixed
-the zone of organic material and minerals that have been mixed together
e horizon
-forms in some acidic soils
-the zone of leaching (eluviation) under the O horizon, or less often, the A horizon
-always above the B horizon
-transported materials (iron, alum, and organic dissolved acids), transported through and removed from the E horizon and then deposited in the B horizon
b horizon (subsoil)
-all soils have this horizon
-composed primarily of mineral material with very little organic matter
-if soil has nutients, they will be in this horizon
c horizon
the least weathered soil horizon, always occurs beneath the B horizon
-similar to the parent material of the soil
texture
(of soil) determined by the percentages of sand, silt, and clay the soil contains
permeability
(of soil) how quickly soil drains
-depends on texture
-sand: high, quick to drain and quick to dry, easy for roots of plants to penetrate
-clay: packed tightly together, low,
-silt: intermediate in size and ability to drain or retain water
clay particles
-contribute the most to the chemical prop of soil
b/c they have the ability to attract positively charged mineral ions (cations)
-have a negative electrical charge, cations are absorbed (held on the surface) by the particles
-cations can be subsequently released from the particles and used as nutrients by plants
cations
positively charged mineral ions
cation exchange capacity (CEC)
(the nutrient holding capacity)
-the ability of a particular soil to absorb and release cations
-a function of the types of clay particles present
-high: provide essential cations to plants
-more than 20% clay, high water retention, waterlogged soils
soil bases
calcium, magnesium, potassium, sodium
soil acids
aluminum, hydrogen
base saturation
a measure of the proportion of soil bases to soil acids, expressed as a percentage
?p. 225
fungi, bacteria, protozoans
3 groups of organisms that account for about 80-90% of biological activity in soils
-majority are detritivores (consume dead plant and animal tissues and recycle the nutrients they contain
soil degradation
the loss of some or all of the ability of soils to support plant growth
-caused by soil erosion (topsoil disturbance)
-compaction of soil
crustal abundance
the average concentration of an element in the crust
oxygen, silicon, aluminum, and iron
4 elements that constitute over 88% of the crust
ores
concentrated accumulations of minerals from which economically valuable materials can be extracted
-typc. characterized by the presence of valuable metals, but sand can also be considered to be them
metals
elements with properties that allow them to conduct electricity and heat energy and perform other important functions
-copper, nickel, alum.
disseminated deposits
ores that occur in much larger areas of rock, often in lower concentrations
concentrated deposits
deposits that occur as a result of their chemical or physical separation from other materials by water, in conjunction with the tectonic and rock cycles
-nonmetallic mineral resources (clay, sand, salt, limestone, phosphate
reserve
the known quantity of the resource that can be economically recovered
strip mining, open-pit mining, mountaintop removal, placer mining
surface mining
strip mining
type of surface mining
-the removal of "strips" of soil and rock to expose ore, used when the desired ore is relatively close to Earth's surface and runs parallel to it (sedim. materials, coal, sand)
-miners remove a large volume of material, extract the resource, and return the unwanted waste material to the hole created during mining
mining spoils/tailings
the unwanted waste material during mining
open-pit mining
the create of a large pit or hole in the ground that is visible from Earth's surface
-used when the resource is close to the surface but extends beneath the surface both horizontally and vertically
-copper mines
mountaintop removal
miners remove the entire top of a mountain with explosives
-coal
placer mining
the process of looking for metals and precious stones in river sediments
-use river water to separate heavier items
subsurface mining
-when the desired resource is more than 100 m (328 ft) below Earth's surface
-begins w/ a horizontal tunnel in the mountain side
-vertical shafts are drilled, elevators
-deepest: 3.5 km (2.2 miles) deep
-coal, diamonds, gold
11000
bw 1900 and 2006 coal miner deaths in US to fires and explosions
mining law of 1872 (general mining act)
act that regulated the mining of silver, copper and gold ore, as well as fuels, natr. gas and oil, on fed lands
surface mining control and reclamation act (1977)
act that regulated surface mining of coal and the surface effects of subsurface coal mining
-land should be minimally disturbed and reclaimed after mining is completed