Geo Exam 2
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What is limestone
made of calicium carbonate found in marine environment. it makes fossils. The most abundant chemical rock.
What is Chert?
made of silica it is very smooth fine grained
What is gypsum?
Calcium sulfate evaporite found in arid environments. The most abundant evaporite.
what is rock salt?
Halite it forms in arid environments
What is Coal?
made of organic parts found in swamps
What are the 5 sedimentary structures that determine environment of deposition?
- Graded Bedding
- Ripple Marks
- Mud cracks
the deposition of sediment under wind or water. stratified rocks are layered. This is the Most important feature of sedimentary rocks.
beds deposited at an angle by wind or water. Eolian(wind) environment is where we find large-scale crossbedding. it indicates direction of wind or water
Define Graded bedding
the decreases of size of sediment upward through a bed. indicates sediments being deposited by turbidity currents in a deep marine environment
Define ripple marks and mudcracks
found in a tidal flat environment. after its all dried out.
What are the 6 environments of deposition
- River(fluvial)-small scale crossbedding
- wind(eolian)-large scale crossbedding
- Glacial(tillite)-angular, unsorted and unstratisfied
- Tidal Flat-ripple marks and mudcracks
- Lagoon/swamp-coal between layers of sanstone and shale
- Shallow Marine-limestone and fossils(deep marine shows graded beds)
What is a metamophic rock?
rock that has been changed due to Heat,Pressure, and Chemically active fluids.
What is Contact metamorphism?
High temperatures bake igneous rocks in a zone called an aureole.
what is regional metamorphism?
Both High temperatures and pressure deform rock. Generally at convergent plate boundaries
What are the 2 types of metamorphic rocks?
- Foliated(regional)-has layers
- Non-foliated(contact)-no layers
What is foliation?
having a definite Planar texture(layered)
where do most metamorphic rocks form?
In the roots of ancient mountin systems at convergent plate boundaries/subduction zones. (regional metamorphism)
What is spheroidal weathering
the rounding of rocks over long periods of time.
what is the most important factor influencing the rate of weathering?
climate, temperature and humidity
What is Talus?
the small rock debris that accumulates at base of cliff
Describe the 4 types of foliated rocks
- Slate-lowest grade,very fine grains, parent rock shale
- Phyllite-fine grains, kind of glossy, parent rock slate
- Schist-medium to coarse grain, scaly, parent rock Phyllite
- Gneiss-medium to coarse grain, compositional banding, parent rock Schist, Granite or volcanic rocks
Describe the 2 types of nonfoliated rocks
- Quartzite-came from sandstone(quartz)
- Marble-came from limestone(calcite)
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