ESS105 Unit 9

What is extrusive?

form on Earth’s surface, able to undergo weathering and erosion

What is intrusive?

form below Earth’s surface, unable to undergo weathering and erosion

What step in the rock cycle comes after magma and igneous rocks?

uplift

What is uplift?

the vertical elevation of rock in response to geological processes

Uplifted rocks undergo what?

denudation

What is denudation?

weathering and erosion which acts to reduce the amount of vertical elevation

correlation between uplift and denudation

where rocks are uplifted from processes such as mountain building, weathering, and erosion, they act to denude them, bring them back to sea level

uplift and crust

processes that thicken the crust will cause uplift

destructive margins and crust

destructive margins deform and thicken the crust, causing uplift

What are some ways to thicken the crust?

folding and faulting

What is folding?

over long periods are time the rocks are folded by compressive forces

What is faulting?

brittle failure of rocks where one block slides past another block. In thrust faulting (thrusting), older rocks are placed above younger rocks

examples of uplifted rocks that experience weathering and erosion

orogenic events (mountain building)

isostatic rebound

plate flexure

What is weathering?

physical or chemical breakdown of a rock in-situ

What is erosion?

breakdown and removal of material

What are the products of weathering and erosion?

either be physical bits of sediment/rock, or a solution carrying dissolved components

What categories can weathering be in?

biological, physical (mechanical), and chemical

example of biological weathering

roots can grow into cracks in the rock, get larger over time, then cause the rock to break

example of physical weathering

water enters crack in rock —> water freezes and expands widening crack —> ice melts and water go deeper into crack —> process repeats until rock splits

example of chemical weathering

cause mineral changes

ex. kaolinite (clay material) formed from the breakdown of feldspar and now is easily eroded than the original feldspar crystals

process of river erosion

hydraulic action

abrasion

attrition

solution

What is hydraulic action?

when water compresses trapped air, causing it to break off pieces of rock or other sediments

What is abrasion?

the result of friction between transported bedload and the riverbed

What is attrition?

the wearing down of transported sediments as they rub against each other

What is solution?

water can dissolve and carry away components that are soluble in water

example of landslide transport

transport distance: short

sediment grain size: large

diversity of grain size: high (poorly sorted)

angular or rounded: angular

diversity of minerals: high

example of river delta sediments transport

transport distance: long

sediment grain size: small

diversity grain size: low

angular or rounded: rounded

diversity of minerals: low

transport and maturity over a long distance

the long the transport distance the more rounded the grain becomes, the more uniformed in size (sorted), the less mineral diversity, and the more quartz rich

What does the term maturity mean?

maturity describes the textures and mineral compositions of the rock

formation of sedimentary rocks

weather and erosion —> transport —> deposition

What is deposition?

occurs when there is no longer sufficient energy to continue transporting the particles, this is followed by compaction and cementation - turning sediments into rock

What is compaction?

as more sediments accumulate above, clasts are forced closer together

What is cementation?

groundwater moves between the grains and leaves behind mineral deposits, bonding the grains to each other

Compaction and cementation together are called?

lithification

What is lithification?

turns sediment into rock

for isostasy, how do you find mass?

mass = density x volume

how do you find volume?

length x width x height