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Minerals
Key Terms
84
Geology
Undergraduate 2
02/17/2010

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Term
geology
Definition
the study of the earth
Term
physical geology
Definition
looks at the materials that compose the earth & tries to understand the processes that operate on the surface and within the earth
Term
historical geology
Definition
tries to understand the origin of the earth & its development through time, & piece together a chronology of the physical & biological changes during the earth's history
Term
catastrophism
Definition
landscapes formed primarily by great catastophism
Term
uniformitarianism
Definition
the physical, chemical, & biological laws that operate today also operated in the geologic past
Term
Big Bang Theory
Definition
the universe began with a gigantic explosion where matter was created and flung part over an expanding volume of space
Term
nebular hypothesis
Definition
explains the formation of solar systems
Term
solar system
Definition
form when gas & dust come together in rotating clouds
Term
star
Definition
massive enough for nuclear reactions
Term
differentiation
Definition
heavy elements sank to the center & the light elements floated to the surface (core/mantle/crust)
Term
plate tectonics
Definition
unifying theory of geology that explains many of the earth's geologic processes & features
Term
lithosphere
Definition
earth's outer, rigid layer (strong)
Term
asthenosphere
Definition
partially, molten region of the mantle (weak)
Term
divergent
Definition
plates move apart, rocks created,seafloor spreading at mid-ocean ridges
Term
convergent
Definition
plates move together, rocks destroyed, subduction zones or moutain building
Term
transform fault boundary
Definition
plates slip past eachother, rocks neither created/destroyed
Term
isotope
Definition
atoms with the same number of protons but different number of neutrons
Term
ion
Definition
charged particles
Term
cation
Definition
atom loses a negative electron and becomes positively charged
Term
anion
Definition
atom gains a negative electron and becomes negatively charged
Term
noble or inert gases
Definition
elements that already have a filled outer shell are already chemically stable & electrically neutral so they don't react much
Term
mineral
Definition
naturally, occuring, inorganic, solid elements or compounds, with a definite composition and a regular internal crystal structure
Term
silicate mineral
Definition
made up of Si and O
Term
silicate tetrahedron
Definition
basic building block of silicate minerals
Term
rock cycle
Definition
interaction of plate tectonics and climate systems
Term
igneous rocks
Definition
form when magma rises, cools & crystalizes
Term
magma
Definition
hot melt made up of rock-forming materials and volatiles held in solution by pressure
Term
lava
Definition
magma that reaches the surface and loses its gases
Term
extrusive
Definition
(volcanic) from the earth
Term
intrusive
Definition
(plutonic) in the earth
Term
crystallization
Definition
liquid to solid, ordered & bonded
Term
melting
Definition
solid to liquid, no order or bonds
Term
Bowen's Reaction Series
Definition
how different minerals crystallize at different temperatures
Term
continuous reaction
Definition
Ca-rich plag changes to Na-rich plag by substitution in the plag mineral. If cooling is fast enough, complete substitution can't occur and you get crystals with Ca-rich interiors surrounded by zones of progressively more Na-rich plag
Term
discontinuous reaction
Definition
a mineral forms, then as temperature drops the mineral reacts with the magma to form a different mineral
Term
fractional crystallization
Definition
process of separation of minerals by differential crystallization; shows how one magma can generate several different igneous rocks
Term
volcano
Definition
the structure that forms from the accumulation of materials that erupts at the surface
Term
viscosity
Definition
measurement of the flow of magma (resistance to flow)
Term
fissure eruption
Definition
eruption of magma from a long crack rather than a single vent
Term
shield volcano
Definition
broad, flat shield-like shape formed from mafic/basalt lavas
ex. Hawaiian islands
Term
pahoehoe
Definition
hot, fluid lavas form a smooth, ropy texture as the top "crust" cools but lava underneath continues to flow
Term
aa
Definition
lavas that have lost their gases & thus are less fluid produce jagged, blocked, jumbled flows
Term
pillow lava
Definition
lava extruded underwater forms bulbous-shaped pillow lavas with a glassy surface and a coarser-grained, more slowly cooled interior
Term
volcanic dome
Definition
less mafic, more silica-rich lavas are more viscous so flow less readily. They're extruded and pile up close to the vent forming steep-sided domes, which often "stop-up" the vent
Term
cinder cone
Definition
form when pyroclasts fall close to the vent & pile up in symmetrical cone-shaped heaps
Term
pyroclasts
Definition
pieces of magma & rock that are flung out of volcano
Term
composite volcano
Definition
built up in alternating layers as pyroclasts then lava then pyroclasts, etc. are erupted over a long period of time. This produces a large, steep-sided cone
Term
caldera
Definition
large depression in volcano
Term
pluton
Definition
classified based on shape (tabular or massive)
Term
orientation
Definition
concordant or discordant
Term
tabular/massive
Definition
flat/ big blob
Term
concordant/ discordant
Definition
parallel/ cut across
Term
characteristics: sills/ dikes/ batholiths
Definition
sills: tabular, concordant
dikes: tabular, discordant
batholiths: massive, discordant
Term
partial melting
Definition
produces a magma that is more felsic than parent rock
Term
spreading zone
Definition
along mid-ocean ridges where sea floor spreading occurs (fluid)
ex. Iceland
Term
convergence zone
Definition
when an oceanic plat is subducted beneath a continental plate, mafic rock & wet sediments are carried down & partial melting occurs to produce intermediate magma. (intermediate)
Term
intraplate volcanism
Definition
a "hot spot" or mantle plume in the middle of a plate. Hot spots under oceanic crust give mafic magma, under continental crust remelting of more silica-rich rock give a more felsic magma. (thick)
Term
weathering
Definition
disintegration & decomposition of rock at or near the surgace of the earth
Term
erosion
Definition
incorporation & transportation of material by a mobile agent, usually water, wind or ice
Term
mass wasting
Definition
transfer of rock material downslope under the influence of gravity
Term
physical weathering
Definition
rock is broken into smaller & smaller pieces but each retains the characteristics of the original material. This gives many small pieces from a single large one. It is important to not that breaking increases the surface area available for chemical weathering, thus speeding it
Term
frost wedging
Definition
water expands as it freezes, producing a tremendous outward force.
Term
unloading
Definition
when erosion exposes large igneous bodies, concentric slabs of rock begin to break loose.
Term
exfoliation domes
Definition
caused by continued weathering which causes layers to break off
Term
organic activity
Definition
bacteria, plants burrowing animals, and humans can all break up rock.
ex. roots grow into cracks and as they grow, wedge rock apart.
Term
chemical weathering
Definition
processes that alter the internal structure of minerals by removing and/or adding elements
Term
acid rain
Definition
rain in the atomosphere dissolves some carbon dioxide but can also react with other compounds to form strong acids
Term
partical size
Definition
more exposed surface means faster weathering
Term
mineral composition
Definition
some minerals are more resistant than others under similar conditions. Silicate minerals weather is about the order they crystallize (Bowens Reaction series).
Term
climate
Definition
temperature and rainfall: weathering is most rapid in warm, wet climates (tropics) where chemical weathering is easy.
Term
regolith
Definition
a layer of rock & mineral fragments produced by weathering
Term
soil
Definition
a combination of mineral and organic matter (decayed plants and animals called humus), water, and air. (part of regolith that supports the growth of plants)
Term
soil profile
Definition
soil-forming processes operate from the surface downward so there are variations in the composition, texture, structure and color which occur at varying depths & become more pronounced with time.
Term
horizons (o,a,b,c)
Definition
different zones/ layers of soil
Term
O horizon
Definition
mainly organic matter, upper part primarily plant litter, lower part partially decomposed organic matter (humus) where plant structures cant be identified
Term
a horizon
Definition
"topsoil"- largely mineral matter but lots of biological activity, humus generally present
Term
a horizon
Definition
"topsoil"- largely mineral matter but lots of biological activity, humus generally present
Term
b horizon
Definition
"subsoil"- much of the material removed from A is deposited in B, so the B horizon is called the "zone of accumulation". More fine clay particles in B enhance water retention. If there is lots of clay, you get hardpan, a dense, impermeable layer. B has much less living organisms/organic matter than A but more than C
Term
c horizon
Definition
partially altered parent material and little if any organic matter. The parent material is easily recognized even if its radically altered in the solum.
Term
solum
Definition
true soil
Term
soil formation (parent material)
Definition
bedrock or unconsolidated deposits, type of material and its rate of weathering
Term
soil formation (time)
Definition
more time gives a thicker soil layer that is less like the parent rock
Term
soil formation (climate)
Definition
most important; determines whether physical or chemical weathering will be dominant.
Term
soil formation (slope)
Definition
influences the water content & the amount of erosion
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