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138 Cards in this Set
- Front
- Back
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Metamorphic Rocks |
-transformation of a pre-existing rock into another in the solid state -changes in the mineralogy and texture of the parent rock |
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Textural Changes |
-increased density -larger crystals -bounding of mineral grains |
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Mineralogical Changes |
prograde > low to high Retrograde > high to low |
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Heat |
Heat > Chemical Reaction > Recrystallization |
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Effects of Heat |
-conversion of minerals to new high temperature -release of fluids -materials for new crystals -rocks become weaker and easier to deform |
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Pressure |
Confining -equal stress, compact Differential -unequal pressure |
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Confining |
-minerals may recrystallize into more compact form |
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Differential |
-may result to flattening of rounded minerals -smaller poles -preferred orientation of elongate minerals -horizontal minerals will be oriented vertically |
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Chemically Active Fluids |
Catalyst -migration of mineral matter >re crystallization Metasomatism -exchange of ions between fluids and host rocks |
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Sources of Fluids |
-trapped in pores -dehydration of minerals -magmatic bodies -fracture along igneous rocks -minerals w/ water (Amphibole, Mica and other clay minerals) |
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Vermiculite |
-a mineral that expand when heated |
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Smectite |
-a mineral that doesnt expand when heated |
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Contact Metamorphism |
-thermal metamorphism -most rocks are baked by molten igneous rocks -metamorphic halo -resulting metamorphic rock depends on the original composition of the parent rock |
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Hydrothermal Metamorphism |
-hot, ion rich fluids circulating through cracks in rocks and precipitating minerals |
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Regional Metamorphism |
-most common, associated w/ mountain building -often results to foliated metamorphic rocks -high pressure in subduction zones -deformation |
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Dynamic Metamorphism |
-occurs along fault zones -invokes brittle rocks near the surface or ductile rocks at depth |
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Burial Metamorphism |
-usually due to massive volume of accumulated sedimentary or volcanic material -geothermal gradient confining pressure = recrystallization |
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Impact Metamorphism |
-impact from meteorites |
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Classification of Metamorphic rocks |
-Texture -Protolith -Mineralogy |
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Texture |
Foliated -pervasive planar structure. -nearly parallel alignment of minerals and/or compositional and mineralogical layering Non-Foliated -no preferred mineral orientation |
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4 kinds of Foliated |
-Slate -Phyllite -Gneiss -Schist |
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Metamorphic Grade |
-increases w/ increasing temperature and pressure |
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Non-Foliated |
Limestones>marble sandstorms > quartzile |
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Index Minerals |
-indicators of the metamorphic environment in which they are formed Chlorite Muscovite Biodite Garnite Staurolite |
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Rock Deformation |
-changes in the original shape, size or orientation of a rock body |
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Stress |
-force that deforms a rock |
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Strain |
-deformation of the rock |
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Compressional |
-squeezed |
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Tensional |
-pulling apart |
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Shear |
-slippage |
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Measuring Deformation |
Strike -azimuth of the line formed by the intersection of a layer interface or bedding plane wl the horizontal Dip -angle between the layer interface/bedding plane and the horizontal measured to the strike direction |
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Ductile Deformation |
-compressional stress may cause rocks to be deformed into a series of wrinkles or folds |
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Axial Plane |
-imaginary surface that divides a fold as symmetrically as possible |
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Fold axis |
-line made by the length wise intersection of the axial plane w/ beds in the fold |
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Types of Fold |
Anticline -Summit Syncline -Sags |
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Fracture |
-breaks in rocks |
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Joint |
feature along which no appreciable displacement has occurred |
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Fault |
joint with displacement -Dip Slip --normal or reverse -Strike Slip --Left(Sinistral) or right (dextral) -Oblique Slip |
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Ground Water |
-freshwater (non-saline) located underneath the earth's surface -97% Ocean -3% Fresh water --79% Glaciers --20% Ground Water |
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Zone of Saturation |
-open spaces are completely filled with water |
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Water Table |
-upper limit of zone of saturation/ground water |
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Zone of Aeration |
-pore spaces contain both air and water |
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Porosity |
-measures amount of water that can be held by rocks/sediments -%=volume of voids/ total volume of materials -voids between particles joints, faults, cavities and vesicles -affected by grain size, sorting and packing |
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Permeability |
-ability to transmit fluids -degree of interconnection of voids in the material |
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Aquifer |
-stores and transmits sufficient amount of water freely |
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Aquitard |
-stores but slowly transmits water |
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Aquiclude |
-stores but does not transmit water |
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Aquifuge |
-no porosity and no permiability |
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Unconfined Aquifer |
-Bounded at the bottom by a confining unit |
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Perched Aquifer |
-unconfined aquifer defined by a discontinuous confining unit |
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Confined aquifer |
-bounded at top and bottom by a confining unit |
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Spring |
-form when the water table, confined aquifer/groundwater bearing fractures and cavities intersects the ground surface |
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Potentiometric Surface |
-level to which water will rise in a well due to natural pressure |
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Artesian Wells |
-when confined ground water under high hydrostatic pressure us forced up to a level higher than the top of the aquifer |
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Karst Topography |
-landforms results from the solution of highly soluble rocks (carbonate, dotomite, gypsum, evaporites) by acidic ground water -takes place more rapidly at regions with higher temp, lush vegetation, intense microbiology. |
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Sinkholes |
-a small, shallow circular to oval closed depression formed by --downward solution of limestones from the surfaces --collpase of the root of a solution cavity |
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Cave |
-elongate cavity in limestone produced by solution aided by mechanical erosion of subterranean flowing water -speleogenesis -shape is directed lithology, by the pattern of joints, fractures and faults and by cave breakdown and evaporite weathering |
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Speleothems |
-secondary mineral deposits formed in caves |
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Problems with ground water |
-Pollution -saltwater intrusion -Land subsidence |
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Earthquakes |
-natural geologic phenomenon caused by the sudden and rapid movement or slippage of a large volume |
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Focus |
-origin of an earthquake at depth, point at the surface directly above the focus(epicenter) |
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Faults |
Active-10k years Potentially active-1.65 MyA Inactive-1.65 MyA |
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Elastic Rebound |
original position build-up of strain. Rupture or slippage. Release of Energy |
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Seismic Waves |
-energy is released during earthquakes |
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Body Waves |
-emanate from the focus in all directions through the interior of the earth. Gives character of the different layers of the earth |
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Primary Wave |
-solids and liquids -push-pull, faster |
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Secondary Wave |
-solids only, transverse, up and down |
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Surface Waves |
-travels along the paths restricted to earth's surface, directly affects us |
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Rayleigh Waves |
-cyclical up and downs |
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Love Waves |
-cyclical side to side |
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Seismographs |
-instrument that record earthquakes waves producing records of movement |
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Causes of earthquakes |
-tectonic earthquakes --related to deformation of earth's lithosphere -Volcanic Earthquakes --related to movement of magma causing fracturing of rocks -Human Activity --additional load, high pressure fluid pumping and underground nuclear testing |
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Intensity |
-Measure of ground shaking at a given locality based on the amount of damage -Modified Mecali Intensity Sclae |
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Magnitude |
-amount of energy released at the source of an earthquake |
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Richter Scale |
-magnitude of an earthquake estimate by measuring the amplitude of the largest seismic waves |
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Wave Frequency and wavelength |
-farther from the source, lower wavelength |
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Duration of Vibrations and distance from source |
-the longer the shaking and the closer the source, the higher the seismic wave amplitude and corresponding damage |
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Nature of the material upon which the structure rests |
-amplification and peak ground acceleration |
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Design of Structure |
-anti-earthquake |
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Earth's Age |
-6000 years (Bible) -cooling through conduction and radiation (Lord Kelvin) 224-40 my -rate of delivery of salts to the ocean (John Joly) 90-100 my -thickness of total sedimentary record divided by average sedimentation rate 1.6 by -amount of evolution of marine mollusks (Charles Lyell) 80 my -Radioactivity (Henri Becquerel) 500 my |
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Relative Dating |
-putting rocks and events in their proper sequence of formation -dating of rocks and rock units w/ the use of fossils and correlation of different strata. U |
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Uniformitarianism |
-former changes of the earths surface may be explained by reference to causes in operation |
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Law of Superposition |
-youngest strata (top) -oldest (Bottom) -undisturbed |
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Law of Original Horizontality |
-most layers are deposited horizontaly |
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Deformation of Originally Horizontal Beds |
-sedimentary beds which are inclined at an angle must have undergone deformation after they had been deposited |
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Law of Lateral Continuity |
-sediments would spread out until they thin out at the edge of the depositional basin, stop at a depositional barrier or grade into another type of sediments. |
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Laws of Cross Cutting Relationship |
-when a fault or intrusion cuts through another rock, the fault or intrusion is younger than the rocks which it cuts |
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Principle of Inclusions |
-the rock mass containing the inclusion is younger than the rock that provided the inclusion |
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Unconformities |
-any significant break in time within a strati graphic column |
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Angular Uniconformaty |
-tilted, folded sedimentary rocks that are overstain by younger |
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DIsconformity |
-strata on either side of the unconformaty are essentially parallel |
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Paraconformity |
-Beds above and below are parallel and the unconformity is identified by some evidence such as lack of certain diagnostic zone fossils |
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Non conformity |
-older metamorphic or igneous rocks are overlain by younger sedimentary rocks |
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Principle of Faunal Succession |
-fossil organisms succeed one another in a definite and determinable order |
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Correlation |
-to show correspondence in character and in stratigraphic position -based on similarity of lithologic and paleontologic features |
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Fossils |
-remains -bones/shells -traces -must be 10 k old |
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Fossils |
-Rapid Burial --tar -Protective Cover --amber -Possession of hard parts --bones |
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Preservation of unaltered body parts |
-hard parts -soft tissues |
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Chemical Alteration |
-carbonization -recrystallization -replacement -permineralization -petrifaction |
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Imprints of hard parts in sediment or trace fossils |
-mold -cast -borings and burrows -coprolites --tae -gastroliths --smooth. polished stones found in the abdominal cavities of dinasours |
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Oldest Fossil |
-3 year old female -africa |
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Philippines (south palawan) |
-Tabon Man -22 k year old |
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Uses of fossils |
-tracing the evolutionary history of extinct as well as living organisms -recontructing paleoclimates and paleoenvironment -providing the source of energy resources |
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Absolute Dating |
-Numerical Dating -utilizing radioactive isotopes |
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Radioactive Isotopes |
-Isotopes, variants of the same atom but with diff. mass # -undergo spontaneous breaking apart(decay) of certain unstable atomic nuclei |
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Half-Life |
-the length of time required for one half of nuclei of radioactive isotope to decay |
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Consideration |
-type of rock -mineral present in the rock and isotope available in it -relative age of rock |
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Geologic Time Scale |
-history of the earth is broken up into a hierarchical set of divisions for describing geologic time untis |
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Pleistocene |
-10000 ya -last ice age |
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Cretaceous-Tertiary |
-65 mya -Extinction of dinasours |
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Permian-Triassic |
-250 mya -extinction of 96% of marine life |
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Carboniferous |
-300-370 mya -proliferation of plants |
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Devonian |
-460 mya -proliferation of fish |
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Cambrian |
-542 mya -explosion of life |
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Pre-cambrian |
-542-4.6b -no life |
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Earthquake signs |
Seismic Gaps Radon Emissions Fracioluminescence Animal Behavior Frog Migration |
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Mass Wasting |
-downslope movement of rock, regolith and soil under the influence of gravity |
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Factors of mass wasting |
-Slope -Water -Soil Cover -Geologic Features |
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Slope |
-materials resting on flat surface will not move under -gt>gp=mass wasting |
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Angle of repose |
-steepest angle at which a pile of unconsolidated grains remain stable and controlled by frictional contact between grains -for dry materials, the angle increases with increasing grain size. 30-37 |
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Soil Cover |
-Soil is more unconsolidated and water percolating down may reach its contact with bedrock. This surface may serve as a sliding plane -thicker soil cover, greater volume of unconsolidated material |
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Geologic Features. |
-type of rock -presence of joints or fractures |
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Trigger of mass wasting |
-Ground Shaking -Excessive rainfall |
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Classification of mass wasting |
Movement -Fall -Topple -Translational Slide -Slumps -Flow Water content and rate -creep -Solifluction -Earth Flows -Debris Flow -Grain Flow -Mud Flow -Debris Avalanche Type of material -rock -solid -debris |
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Fall |
sudden movement of rock, seperated along fractures or bedding planes. no fluid. |
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Topple |
blocks of material fall over as a unit, similar to falling dominos |
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Translational Slide |
rocks and debris slide down a pre-existing surface |
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Slumps |
downward rotation of rock occurs along a concave-upward curved surface |
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Flow |
materials behave in a fluid manner |
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Creeps |
very slow, usually continuous movement of regolith down slope |
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Solifluction |
distinctive lobes on hill slopes, where the soil remains saturated with water for long period of time |
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Earth Flows |
fine grained materials that form a thick slurry and have a fluid motion. |
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Debris Flows |
higher velocities than solifluction and results of heavy rain causing saturation of the soil |
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Grain Flow |
usually form in relatively dry material |
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Mud Flow |
-highly fluid, high velocity mixture of sediment and water that has a consistency ranging bet. soup-like and wet concrete
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Debris Avalanche |
very high velocity flow of large volume mixtures of rock and regolith that result from complete collapse of mountainous slope |
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Measures |
-chicken wires -concrete cover -retaining wall -coconet -weep holes -benching -rock barriers |
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Measures |
-Hazard Maps -Monitoring -Deep-Root Vegetation |
