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22 Cards in this Set
- Front
- Back
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Sedimentary Processes |
-we care b/c they cause landslides, used in construction, and affects agriculture -most common rock type on earths surface -all fossils, oil and coal, come from sedimentary rock |
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Forming Sedimentary Rock |
-Parent Rock: preexisting rock...doesnt matter what type of rock -Weathering: break down process Physical vs. Chemical |
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Physical Weathering |
-Plant roots: busting rock down into smaller pieces, when trees push through sidewalk -Frost Wedging: ice to wedge apart rocks, fill cracks w/ water freeze them and it breaks apart, pot holes |
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Chemical Weathering |
More common in many enviornments Bowen reaction series flipped... Quartz reacts the slowest, Olivine reacts the fasted |
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Chemical Weathering w/ water |
-Feldspar + H2O+ H2CO3 -> Kaolinite + Dissolved ions -Saprolite formation: no strength, rotten rock, generic rock that has been extensively weathered |
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Erosion |
type of chemical weathering take sediments somewhere else requires energy water/wind/gravity/ice |
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Deposition |
type of chemical weathering setting sediment down Basin: is any place you can deposit sediment accommodation space: is how much space before basin is filled like ocean floor or pot holes subsidence: is the weight of sediment forces basin floor down layers are strata and beds built up in layers of sediments can cause loop to form |
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Lithification |
compaction: squeeze layers together keep piling layers up Cementation: nature ground water will "glue" these sediments together... whatever is dissolved in water will stick together and act ad cement |
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Detrial (Clastic) Sediment |
made up of little class of sediment Sorting: how uniform are the grains? Rounding: are sediments round, moderately round, or not at all round? longer they are transported= better sorting and rounding |
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ID Clastic Rocks |
grain size is key sand= sandstone silt= siltstone |
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Chemical Sediments |
never worry about rounding or sorting form via chemical reactions dissolution and reprecipitation Salt water evaporation |
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ID Chemical Rocks |
usually composed of 1 major mineral type halite= rock salt quartz= chert economically viable |
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Biogenic Sediments |
deals w/ biology pieces of something that used to be living creature common kinds are chalk, limestone, coal, shell |
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Mass Wasting (landslides) |
We care b/c its a natural hazard types are based on: material (snow, ice, rock, mud,sediment) type of movement (roll, slide, fall, flow) speed (sudden, quick, slow) |
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CASE STUDY- Huascaran |
1970 earthquake disloged an ice block 1 mile long x 1/2 mile wide x 1/2 mile deep covered 11 miles in 5 minutes killed 20,000 in the town of Yungay VERY DANGEROUS |
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Slope destabilization |
angle or response: steepest angle with stability more steep= more unstable average w/ huge variation is 35 degrees lack of/excessive moisture= unstable lack of/excessive vegetation= unstable |
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Slow Mass Wasting |
Creep: slow mass wasting carrying something downhill over years |
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Causes of Mass Wasting |
unstable slopes do not automatically have a landslide occur need a trigger (thunderstorms,earthquakes, landscaping) |
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Risk assessment |
risk assessment maps have to update how likely is it for this to occur? |
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Prevention |
drainage control... get rid of the water decrease slope grades... even out slopes building codes... don't build in unsafe area retaining walls... walls protecting area rock bolts... driving bolts to rock to pin it down |
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Prevention Cost |
expensive to build/ implement changes but damage is more costly est. return is $10-$2000 per $1 set on prevention |
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CASE STUDY- Thistle, UT |
1983 slide caused $200 million in damage Deemed preventable if $0.5 million had been spent on drainage systems |
