why was the general mining law of 1872 created
designed to encourage mineral exploration and the mining of hardcore minerals (such as gold, silver, copper, zinc, nickel, and uranium) on US public lands and to help develop the then sparsely populated west
the general mining law of 1872
under this law, a person or corporation can file a mining claim or assume legal ownership of parcels of land on essentially all US public land except parks and wilderness
why is the earth referred to as a dynamic planet?
the earth we live on is constantly changing as a result of processes taking place on and below its surface
list three pieces of evidence which show that the earth is constantly changing
every now and then the solid earth under our feet shakes, rattles, and rolls during an earthquake
the earth erupts like a punctured boil when a volcano forms
or awakens after a long geological sleep
crust
the outermost and thinnest zone of the earth
consists of the continental crust, which underlies the continents, and the oceanic crust- which underlies the ocean basins and covers 71% of the earth's surface
core
the earth's innermost zone
intensely hot- contains a solid inner part, surrounded by a liquid core of molten or semi-solid material
outer core
liquid core consisting of molten or semi solid material
inner core
solid inner part of the core
tectonic plates
fifteen huge rigid plates
the flows of energy and heated material in the mantle convection cells cause them to move extremely slowly across the earth's surface
these thick plates are composed of the continental and oceanic crust and the rigid, outermost p
mantle
thick solid zone that surrounds the core
most of the mantle is solid rock, but under its rigid outermost part is a zone- the asthenosphere- of very hot, melted rock that flows and can be deformed like soft plastic
lithosphere
a combination of oceanic and continental crust, and the rigid, outermost part of the mantle
asthenosphere
under the lithosphere- consists of very hot, molten rock which flows and can be deformed like soft plastic
what causes the tectonic plates to move?
the flows of energy and heated material in mantle convection cells
how fast do the tectonic plates move?
extremely slowly
how is the formation of mountains related to tectonic plates?
over the course of earth's history, continents have split and joined together as tectonic plates have very slowly drifted thousands of kilometers back and forth across the planet's surface
as tectonic plates collide, break apart, and slide by one another
volcanoes
natural hazards such as earthquakes and volcanoes are likely to occur at plate boundaries
the lithospheric plates have three types of boundaries
1) divergent plate boundary
2) convergent plate boundary
3) transform fault
divergent plate boundary
the plates move in opposite directions
convergent plate boundary
the plates are pushed together by internal forces
transform fault
plates slide and grind past one another along a fracture (fault) in the lithosphere
most transform faults are located on the ocean floor but a few are found on land
erosion
the process by which material is dissolved, loosened or worn away from one part of the earth's surface and deposited elsewhere
weathering
consists of the physical, chemical, and biological processes that break down rocks and minerals into smaller particles that can then be eroded
types of weathering
physical
chemical
biological
physical weathering
also known as mechanical weathering
a large rock mass is broken into smaller fragments- it resembles what happens when you hammer a rock into small pieces
the most important agent of mechanical weathering is frost weathering- in which water collects in th
chemical weathering
one or more chemical reactions decompose a mass of rock
most chemical weathering involves a reaction of rock material with oxygen, carbon dioxide, and moisture in the atmosphere and on the ground
biological weathering
the conversion of rock or minerals into smaller pieces through the action of living things
example- lichens produce acids which can chemically weather rocks
example 2- roots growing and rubbing against rock can physically break it into smaller pieces
minerals
an element or inorganic compounds which occurs naturally and is solid with a regular internal crystalline structure
a few minerals consist of just one single element but it is extremely rare- (gold, silver, diamond (carbon) and sulfur)
rock
a solid combination of one or more minerals that is part of the earth's crust
some kinds of rock, such as limestone and quartzite, contain only one mineral, but rocks usually consist of two or more minerals
examples of rocks
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the rock cycle
the earth's crust contains igneous, sedimentary and metamorphic rocks that are recycled by the rock cycle
igneous rock
forms below or on the earth's surface when molten rock (magma), wells up from the earth's upper mantle or deep crust, cools and hardens
although they are often covered with sedimentary rock or soil, igneous rocks constitute the majority of the earth's cru
examples of igneous rock
granite (formed underground)
lava rock (formed aboveground when molten lava cools and hardens)
sedimentary rock
forms from sediment produced when existing rocks are weathered and eroded into small pieces- then transported by water, wind, or gravity to downstream, downwind or downhill sites
these sediments are deposited in layers that accumulate over time and increa
examples of sedimentary rock
limestone (formed from the compacted shells, skeletons, and other remains of dead organisms)
sandstone and shale (formed from pressure created by deposited layers of sediment)
lignite
bituminous coal (derived from plant remains)
metamorphic rock
forms when preexisting rock is subjected to high temperatures (which may cause it to melt partially) , high pressures, chemically active fluids, or a combination of these agents
these forces may transform a rock by reshaping its internal crystalline struc
examples of metamorphic rock
anthracite ( form of coal)
slate (formed when shale and mudstone are heated)
marble (produced when limestone is subject to extremely high temperatures)
rock cycle definition
the interaction of physical and chemical processes which change rock from one type to another over millions of years is known as the rock cycle
it is the slowest of the earth's cyclic processes
what does the rock cycle accomplish
it concentrates the planet's nonrenewable resources on which we depend
without the earth's incredibly slow rock cycle, we would not exist
nonrenewable mineral resource
a concentration of naturally occurring material in or on the earth's surface which can be extracted and processed into useful materials at an affordable cost
over millions and billions of years the earth's geological processes have produced numerous non f
ore
rock containing enough of one or more metallic minerals to be mined profitably
differentiate between identified and undiscovered mineral resources
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identified resources
deposits of a nonrenewable mineral resource with a known location, quantity, and quality, or whose existence is based on direct geologic evidence and measurements
undiscovered resources
potential supplies of a nonrenewable mineral resource expected to exist on the basis of geologic knowledge and theory but with unknown specific locations, quantities or qualities
reserves
identified resources from which a usable nonrenewable resource can be mined profitably at current prices
other resources
undiscovered resources and identified resources not classified as reserves
discuss the methods used by geologists to find mineral resources
mining companies use numerous different methods to find promising mineral deposits
1) aerial photos and satellite images may reveal protruding rock formations (outcrops) associated with certain minerals
2) planes can be equipped with radiation-measuring e
most published estimates of a supply of nonrenewable resources refer to
reserves- reserves can increase when new deposits are found or when higher prices or improved mining technology make it more profitable to extract deposits that were previously too expensive to extract
theoretically, all other resources could be converted
aerial photos and satellite images
can show protruding rock formations (outcrops) associated with different minerals
radiation-measuring equipment
planes can be equipped with radiation-measuring equipment to detect deposits of radioactive minerals such as uranium ore
magnometer
measures changes in the earth's magnetic field caused by radioactive minerals such as iron ore
gravimeter
measures differences in gravity produced by differences in density between an ore deposit and the surrounding rock
surface mining is for
shallow deposits
deep deposits are removed by
subsurface mining
what is overburden? spoils?
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underground methods used for identifying mineral deposits
1) drilling a deep well and extracting core samples- scientists can use sensors in existing wells to detect electrical resistance or radioactivity to pinpoint the location of oil or natural gas
2) seismic surveys- scientists detonate explosive charges and
chemical analysis of underground water and plants
to detect deposits of underground materials that have leached into nearby bodies of water or have been absorbed by plant tissues
surface mining
mechanized equipment strips away the overburden of soil and rock and usually discards it as waste material called SPOILS
surface mining extracts...
90% of the non fuel mineral and rock resources
60% of the coal (by weight) that are used within the United States
the type of surface mining depends on what two factors
1) the resource being sought
2) the local topography
types of surface mining
open-pit mining
area strip mining
contour strip mining
mountaintop removal
open-pit mining
machines dig holes and remove ores (such as iron and copper), sand, gravel, and stone (such as limestone and marble)
area strip mining
may be used where the terrain is fairly flat
a gigantic earthmover strips away the overburden, and a power shovel digs a cut to remove the the mineral deposit
the trench is filled with overburden, a new cut is made parallel to the previous one
this proces
contour strip mining
used on hilly or mountainous terrain
a power shovel cuts a series of terraces into the side of the hill
an earthmover removes the overburden, a power shovel extracts the coal, and the overburden from each new terrace is dumped onto the one below
unless th
mountaintop removal
another surface mining method
explosives, massive shovels and huge machinery called draglines remove the top of a mountain and expose seams of coal underneath
the resulting waste rock and dirt are pushed into the nearest streams and valleys below
downside of mountaintop removal
causes considerable environmental damage
subsurface mining is used for
deep deposits
removes metal ores and coal that are too deep to be extracted from surface mining
miners dig a deep vertical shaft, blast subsurface tunnels and chambers to reach the deposit, and use machinery to remove the ore or coal and transport it to t
compare surface and subsurface mining in terms of environmental degradation, cost, and danger to human life
subsurface mining disturbs less than one tenth of the land that surface mining does and usually produces less waste material
however, it leaves much of the resource in the ground and is more dangerous and expensive than surface mining
hazards of subsurfac
negative effects of using mineral resources
extracting, processing, and using mineral resources can...
-disturb the land
-kill miners
-erode soils
-produce large amounts of solid waste
-pollute the water, air and soil
how can mining harm the environment
scarring and disruption of the land surface
the Department of the Interior estimates that at least 500,000 surface-mined sites dot the U.S. landscape, mostly in the west - cleanup cost estimates are in the tens of billions of dollars
another problem is th
summarize the seven steps in the life cycle of a natural resource
1) surface mining
2) extraction of the metal ore
3) separation of the ore from gangue- (the ore typically has two components: the desired metal and the waste material called gangue)
*removing the ore from the gangue produces piles of waste called TAILINGS
what do environmentalists fear is the greatest danger for continually increasing our consumption of mineral resources?
the major problem is the environmental damage caused by the extraction, processing and conversion of nonrenewable mineral resources to products
the three steps of mining
exploration and extraction
processing
use
the future supply of a resource depends on
how available and affordable it is, and how rapidly that supply is being used
a resource is economically depleted when
it costs more to find, extract, transport and process the remaining deposit than it is worth
what are the five choices when a resource becomes economically depleted?
1) recycle or reuse existing supplies
2) waste less
3) use less
4) find a substitute
5) do without
depletion time
the amount of time it takes to use up a certain proportion -usually 80%- of the reserves of a mineral at the given rate of use
how do rising prices affect the availability of a resource
a rising price for a scarce mineral resource can increase supplies and encourage more efficient use
geologic processes determine the quantity and location of a mineral resource within the earth's crust
economics determines what part of the known supply is
why and how are prices kept artificially low?
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