Post on 27-Jun-2015
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Sedimentary RockStudents will be able toDescribe how rocks are formedClassify the sedimentary typesList uses for this rock type
Changing Earth’s Surface
1. WeatheringPhysical breaking of rock
2. Mass WastingFalling due to gravity
3. ErosionRemoval by mobile agents (water, wind, ice…)
Weathering
Frost Wedging
Water expands 9% when frozen
Repeated cycles will break apart rocks
Weathering
Unloading
When pressure is released by exposure
Rock cracks in sheets when it expands
Weathering
Biological
Damage caused by roots and animals
Weathering
Chemical
Acid rain, pollution, …
Mass Wasting
Spheroidal
Erosion
Loss of material
usually loose soil
Sedimentary Rock
5% of Earth’s outer crust
High Value
Contains major energy resources
Contains fossil record
Formation
Compaction
Weight of material on top presses into rock
Cementation
Minerals enter spaces between to harden
Types
Clastic
Rock fragments squeezed together
Organic
Formed from remains of living things
Chemical
Formed from chemical during evaporation
Clastic
Shale
50% of all sedimentary rock
Made from tiny pieces of clay
Black due to abundant carbon (living)
Formed in oxygen poor area (swamp)
“prevents decay”
Sandstone
20% of all sedimentary rock
Small grains (wind or river)
Conglomerate
Large particles
Steep slopes or fast streams
Organic
Limestone
10% of all sedimentary rock
Mostly calcite
Skeletons of coral reefs
Accumulation of shells
Caves from minerals above
Coal
Many plant parts
Low oxygen formation (swamp)
High heat and pressure to solidify
Major source of US electrical energy
Chemical
Evaporites
Seawater and salt flats evaporate
Quiz
Homework
• Describe how sedimentary rocks are made