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112 Cards in this Set
- Front
- Back
geographic time scale order:
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eon, era, period, epoch
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uniformitarianism
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the same phyiscal processes active in the environment today have been operating throughout geologic time.
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relative time
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relative positions of rock strata above or below each other
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core's percentage of earth's mass and volume
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1/3 of its mass, 1/6 of its volume
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composition of inner core
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solid iron becaues of pressure, likely with silicon, oxygen and sulphur
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composition of outer core
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molten iron with less density than inner core
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what generates 90% of earth's magnetic field field and the magnetosphere
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outer core
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border between outer core and lower mantle
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Gutenberg discontinuity
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mantle's percentage of earth's volume
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80%
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mantle's composition
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oxides, silicates of iron magnesium. denser and more tghtly packed the deeper it gets
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lower & upper mantle's percentage of mantle's volume
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50%
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in the mantle, temperature increases or decreases?
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increases
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lithosphere
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uppermost mantle & crust
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asthenosphere
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plastic layer - pockets of increased heat from radioactive decay and susceptble to slow convective currents. least rigid part of mantle. 10% is molten in asymetrical patterns and hot spots. resulting slow movement in thiz zone distrurbs the overlying crust and creates tectonic activity
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boundary between crust and high-velocity portion of the lithospheric upper mantle
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moho discontinuity
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crust's % of earth's mass
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0.01%
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lithosphere
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entire crust and uppermost mantle
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composition of continental crust
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granite: crystalline and hihg in silica, aluminum, potassium, calcium, and sodium. sometimes called sial silica and aluminum. low in density.
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composition of oceanic crust
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basalt: granular and high in silica, magnesium, and iron. sometimes called sima - silica and magnesium. denser than continental.
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isostasy
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the crust is in a constant state of compensating adjustment, rising and sinking in response to its own weight on the asthenosphere
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isostatic rebound
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when the crust loses weight, it rides higher on the asthenosphere due to buoyancy
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endogenic system
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internal
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exogenic system
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external
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mineral
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an element or combination of elements that form an inorganic natural compound
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igneous
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forms from magma
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two types of igneous
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intrusive and extrusive
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intrusive:
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form by the crystallization of magma at a depth within the Earth. large crystal sizes, because cooling is slower within the earth and larger crystals can grow.
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intrusive
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form by the crystallization of magma at a depth within the Earth. large crystal sizes, because cooling is slower within the earth and larger crystals can grow. (granite)
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extrusive
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igenous formed at the surface of teh earth - lava, basalt, obsidian. smaller crystals.
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sedimentary
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form from other rocks as a result of weathering )
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lithification
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cementation, compaction, and hardening
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types of sedimentary rock
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clastic (conglomorate) or chemical (limestone, evaporites like salt
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stratification
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the building up of layers
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common types of sedimentary rock
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shale, coal, limestone, sandstone, siltstone, iron ore
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metamorphic rock
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forms from igneous or sedimentary rocks transformed bg pressure and /or temperature
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common meta rocks
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marble (cooked limestone), gneiss, quartzite, schist
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convection
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brings magma to the crust; the crust fractures and magma extrudes onto the sea floor
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divergent boundaries
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plates diverge at mid-ocean ridges. "constructional"
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transform fault
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plates move past each other literally between seafloor spreading centers
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convergent boundary
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plates converge, forming a subduction zone. coastal area features, mountains, volcanoes, and earthquakes. "destructional"
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ocean-continent boundary examples
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Cascade and Andes Mtns
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ocean-ocean boundary
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solomon islands, vanuagu, new caledonia
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continent-continent
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himalayan mtns
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relief
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vertical elevation differences in the landscape
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topography
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the undulations and configurations that give Earth's surface its texture; the heights and depths of local relief
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craton
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nucleus of ancient crystalline rock on which the continent "grows" with the addition of crustal fragments and sediments
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continental shield
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region where a craton is exposed at the surface
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terranes
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migrating crustal pieces of continental crust taht were forces against the edges of continental shields and platforms
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normal or tension fault
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occurs when rocks pull apart and move vertically along an inclined fault plane so that one "block" of rocks ends up lower than the other.
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hanging wall
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downward-shifting side of the tension fault, drops relataive to the footwall block
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reverse (thrust) fault
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compressional forces of convering plates force rocks upward along the fault plane
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folding
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convergent plates compress rocks, folding them like layers of thick fabric stacked flat on a table would bend if pushed at opposite ends
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anticline
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layers of folding that slope downward away from the axis
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syncline
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layers of folding that slope downward toward the axis
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strike-slip (shear) fault
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horizontal, lateral, plate movement along a transform fault
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right or left lateral
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depending on the motion perceived when you observe movement on one side of the fault relative to the other side
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fault plane
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the fracture surface along which the two sides of a fault move
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horst
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upward-faulted rocks
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graben
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downward-faulted rocks
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oceanic-continental orogeny
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pacific coast of the Americas and Rockies. folded sedimentary formations, with intrustions of magma forming granitic plutons. augmented by the capturing of displaced terranes cemented uring their collision with the continental mass.
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oceanic-oceanic orogeny
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indonesia, japan, philippines, kurils, aleutians. deformation and metamorphism of rocks and granitic intrusions.
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continental-continental
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intense folding, overthrusting, faulting, uplifting. crush and deform marine sediments and basaltic oceanic crust. Alps and Himalayas
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tilted fault-block mountain range
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normal fault on one side produces a tilted landscape of great relief. slowly cooling magma intruded and formed granitic cores. after uplfit and removal of overlying material, the masses get exposed. Sierra Nevada and Tetons. in later stages of orogeny.
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appalachians
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eroded, fold-and-thrust. dating to the formation of Pangaea and the collision of Africa and North Africa. Alleghany orogeny
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pyroclasts (tephra)
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pulverized rock and clastic materials of various sizes ejected during an eruption
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volcanic location #1
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continent-ocean or ocean-ocean convergence subduction zones
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volcanic location #2
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rifting and sea-floor spreading centers
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volcanic location #3
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hot spots
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effusive eruptions
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relatively gentle, large lava volume, low-viscosity, very fluid, forms dark basaltic rock (low silica and high in iron and magnesium). gases escape easily, little tephra.
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shield volcano
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volcano from effusive eruptions, gently sloped
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Elastic Rebound Theory
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as plates on opposite sides of a fault are subjected to force and shift, they accumulate energy and slowly deform until their intenral strength is exceded. then the rocks snap back to their original undeformed shape.
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mafic lava - effusive or explosive?
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effusive. high in the heavier elements, like MAgnesium. commonly at sea-floor spreading centers. rocks like basalt.
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felsic lava - effusive or explosive?
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explosive. lower percentage of the heavier elements, like FELDspar. rocks such as granite.
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explosive eruptions
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high in silica and aluminum. thicker and more viscous. more tephra.
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lahar
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mud, water, pyroclasts
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pyroclastic flow
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tephra and gas
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geomorphology
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the science of landforms, their origin, evolution, form, and spatial distribution
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denudation
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any process that wears away or rearranges landforms, caused by movign water, air, waves, ice, and gravity
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dynamic equilibrium model
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the balancing act between tectonic uplift and erosion
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geomorphic threshold
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the at which there is enough energy to overcome the resistance against movement
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slopes
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inclined surfaces that form the boundaries of landforms
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slope parts
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upper waxing (increasing) slope near the top, confex surface curving downward - free face, downsloped debris slope, waning slove, pediment - brad, gently sloping erosional surface
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potential enrgy of position
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disequilibrium between relief and energy created by uplift
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potential energy
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energy stored
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kinetic energy
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energy in action
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weathering
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break up and dissolution of rocks
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physical weathering
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mechanic processes
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physical weathering type #1
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frost (freeze-thaw) action
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frost-wedging
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ice enters rock openings, expanding and splitting rocks. (joint-block separation)
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physical weathering type #2
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pressure-release jointing
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pressure-release jointing
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plutons are uplifted, the covering regolith is eroded, the pluton is exposed as a batholith, and without the pressure of burial, layers of the batholith peel off (SHEETING and EXFOLIATION PROCESS)
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chemical weathering
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decomposition and decay of the rock due to chemical alteration from water
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regolith
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broken up rock
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chemical weathering type 1
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spheroidal weathering - water penetrates joings and fractures, dissolving weaker minerals and cementing materials
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chemical weathering type 2
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oxidation - some metallic elemnts combine with oxygen, such as rusting. seen in deserts.
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chemical weathering type 3
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dissolution - when a mineral dissolved into solution. water is the universal solvent and dissolves carbon dioxide, creating carbonix acid, which dissolves limestone. increased because of acid precipitation.
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rock joints
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fractures in rock that occur without displacement of the sides, efore physical or chemical weathering
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karst topography
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where there is chemically weathered limestone with poorly developed surface drainage
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how does karst topography form?
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groundwater percolates through limestone along joints and bedding planes, dissolving limestone and creating caverns at and below the water table.
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sinkholes
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collapsed features caused by the weigh tof the overlying surface collapsing in on the caverns below. coalesce to form larger depressions.
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tower karst
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karst area in late stage of development. tectonic uplift + tropical erosion.
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4 types of mass movement
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fall, slide, flow, creep
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fall
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rock fall that falls through the hair and hits a surface.
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slide
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landslide: sudden rapid movmeent of a cohesive mass of regolith and badrock that is not saturated with moisture. translational or rotational.
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flow
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high moisture content slides
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creep
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persistent mass movement of surface soil
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two types of slides
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translational or rotational
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translational slide
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movement along a planar (flat) surface rougholy parallel to the angle of the slope
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rotational slide
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surface material moves along a concave surface
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talus slope
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cone-shaped pile of irregular broken rocks from a rock fall
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pluton
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an intrusive igneous rock (called a plutonic rock) body that crystallized from magma slowly cooling below the surface of the Earth
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batholith
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large emplacement of igneous intrusive (also called plutonic) rock that forms from cooled magma deep in the earth's crust
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