Geology

study of dynamic processes that occur on earth's surface and interior

Core

most interior portion of the earth; extremely hot; solid inner core surrounded by liquid core of molten or semisolid material

Mantle

surrounds core but underneath the crust; mostly solid rock upper part but under this is the athenosphere made of melted, pliable rock that flows

Athenosphere

part of mantle made of melted rock; lies under solid rock portion of the mantle (closest to the core)

Crust

outmost and thinnest zone of the earth

Continental Crust

area of crust that is under land mass or continents as well as continental shelf of oceans

Oceanic Crust

area of crust that is under oceans; makes approximately 71% of earth's surface

Convection Cells

large volumes of rock material move in loops (hot goes up and forms new crust and gets pushed to side; cool moves across surface of earth and eventually back down to be reheated and remelted); causes plate tectonic movements

Tectonic Plates

dozen or so huge plates of crust move across surface of earth due to heating and cooling associated with Convection Cells

Magma

molten rock; material that tectonic plates "float" on and move along due to Convection Cells

Lithosphere

solid earth composed of crust and solid rock portion of the upper mantle (above the athenosphere)

Convergent Plate Boundary

two tectonic plates come together; can cause subduction - continental plate rides over and pushes oceanic plate down; also can cause mountain bulding when two continental plates collide and push each other up toward sky; creates mountains

Subduction

specific example of convergent plate boundary where more dense ocean plate is runs into less dense continental plate and the ocean plate is pushed back down into mantle

Subduction Zone

area where subduction takes place

Trench

occurs when two ocean plates converge

Divergent Plate Boundary

oceanic plates move away from one another; usually creates oceanic ridges from molten rock (magma) that flows up from the resulting cracks

Oceanic Ridges

created from divergent plate boundaries of oceanic plates; creates higher peaks and deeper canyons than the tallest mountains found on earth's surface

Tranform Fault

plates slide and grind past each other along a fracture or fault; ex: San Andreas Fault; usually cause earthquakes and volcanoes

External Processes

geologic changes based directly or indirectly on energy from sun or gravity (instead of heat in the earth's interior); ex: weathering, erosion, storm events, flooding, etc.

Internal Processes

geologic changes based directly or indirectly on heat from earth's interior; ex: volcanism, earthquakes, plate tectonics, etc.

Weathering

physical, chemical, biological processes that break down rocks and minerals into smaller particles and help build soil

Physical / Mechanical Weathering

large rock material, soil, or minerals are broken into smaller pieces

Frost Wedging

type of physical / mechanical weathering; water collects in spaces of rock, expands as it freezes, and breaks pieces of the rock off into smaller pieces

Chemical Weathering

chemical reactions "decompose" rocks, minerals, soil; oxygen, carbon dioxide, and moisture usually play a role; process accelerated by high moisture and high temperatures

Biological Weathering

conversion of rock, minerals, soil into smaller pieces by actions of living organisms; ex: lichens living on rocks produce chemicals that weather the rock; ex: roots growing into and rubbing agains rocks can break them into smaller pieces

Erosion

process where material is dissolved, loosened, or worn away from one part of the earth's surface and deposited elsewhere

Glaciers

slow flowing bodies of ice

Mass Wasting

rock and soil mass becomes detached from underlying material and move downhill due to gravity; ex: mudslides, avalanche, rockslides, mud flows, etc.

Mineral

element or inorganic compound that occurs naturally and is solid with a regular internal crystalline structure; ex: gold, silver, salt, quartz

Mineral Resource

concentration of naturally occuring material in or on earth's crust that can be extracted and processed into useful materials at an affordable cost

Fossil Fuels

type of mineral resource; ex: coal, oil, natural gas

Metallic Minerals

type of mineral resource; ex: aluminum, iron, copper

Nonmetallic minerals

type of mineral resource; ex: sand, gravel, limestone

Identified Resources

deposits of nonrenewable mineral resource with a known location, quantity, or quality and existence is based on geologic evidence and measurement

Undiscovered Resources

potential supply of mineral resource assumed to exist based on geologic knowledge and theory but unknown specific locations, quality, and amounts

Reserves

identified resources from which a usable nonrenewable mineral can be extracted profitably at current prices

Other Resources

undiscovered resources and identified resources not classified as reserves

Rock

solid combination of one or more minerals that is part of earth's crust

Ore

rock that contains large concentration of a particular mineral (often metal) and can be mined to extract the desired mineral

High-Grade Ore

rock that contains fairly large amount of desired mineral

Low-Grade Ore

rock that contains smaller amounts of desired mineral

Igneous Rock

forms below or on earth's surface when molten rock (magma) wells up from the earth's upper mantle or deep crust then cools and hardens; ex granite, lava rock

Sedimentary Rock

forms from sediment produced when existing rocks are weathered and eroded into small pieces, transported by water, wind or gravity downstream, downwind, or downhill; layers deposited over time are compressed and form new rock; ex: sandstone, shale, dolomite, limestone

Metamorphic Rock

forms when preexisting rock is exposed to high temperatures, high pressure, chemically active fluids, or a combination of these; ex: coal, slate, marble

Grade

the percent metal content of an ore

Surface Mining

method used to extract surface deposits or shallow deposits of minerals; ex: open pit, strip, mountain top removal

Subsurface Mining

method used to extract deep deposits of minerals

Overburden

soil and rock that cover the valuable mineral / ore to be extracted during surface mining

Spoils

discarded waste material that is heaped up from overburden that has been removed during surface mining

Open-Pit Mining

type of surface mining where expansive holes are dug down, each hole smaller than the next so as to "terrace" the surface mine

Strip Mining

type of surface mining useful for removing mineral deposits that lie close to surface in large horizontal beds

Area Strip Mining

type of surface mining used when terrain is fairly flat

Spoils Banks

highly erodible hills of rubble and mining waste; often susceptible to weathering and erosion by wind and water

Contour Strip Mining

type of surface mining used on hilly or moutainous terrain; series of terraces cut into side of hill

Highwall

wall of dirt left in front of highly erodible bank of soil and rock after contour strip mining takes place

Mountaintop Removal

type of surface mining where explosives, tall power shovels (20 stories high) move top of mountains off to extract coal; waste rock and dirt often dumped into streams and valleys below leading to flooding problems and toxic waste water

Surface Mining Control and Reclamaation Act of 1977

requires mining companies to restore (reclaim) most surface-mined land by grading and replanting it

Reclamation

replacing disturbed land that has been surface-mined by grading and replanting the area

Subsidence

settling and sometimes collapse of land that is above an underground mine

Acid Mine Drainage

when rainwater seeping through min or mine wastes carries sulfuric acid (a waste product from bacteria respiring aerobically using iron sulfide minerals found in spoils) to nearby streams and groundwater

Ore Minerals

valuable metals part of ore that needs to be extracted from the gangue

Gangue

waste material found with ore that needs to be removed from the ore minerals; then usually piled off to the side in piles called tailings

Taillings

piles of solid waste from the gangue that was seperated from the ore mineral

Smelting

roasting ore to release the valuable metals

Cyanide Heap Extraction

spraying toxic cyanide salts on huge open-air heaps of crushed ore to chemically remove valuable ore; ex: used to remove 85% of world's gold from ore

Depletion Time

how long it takes to remove a certain proportion of (usually 80%) the reserves of a mineral at a given rate of use

Biomining

use naturally occuring or genetically modified microorgansisms (often bacteria) to extract a particular mineral / metal

Ecoindustrial Revolution

shift in thinking over next 50 years that will involve changing industrial processes to better mimic natural processes and ecosystems

Resource Exchange Webs

having industries interact with one another and be situated near each other so wastes of one manufacturer can become raw materials for another

Brownfields

abandoned industrial sites that can be rehabilitated and developed

Biomimicry

trying to get industrial processes to mimic the natural world; ex: recycling, using wastes to create new products, reusing abandoned land

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