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GEOS 212: EXAM 1
chemical layering |
-crust 7-40km
-mantle 3000km
-core 3000km
|
lithosphere |
crust and uppermost mantle (strong)
-100km thick and has plates
|
asthenosphere |
uppermost mantle (weaker)
|
oceanic crust
continental crust |
~7km
~30km
|
divergent plate boundaries |
-spreading center at ocean ridge
-new plate created
-most of world's volcanism
|
rate of spreading |
=d/t (distance/time)
ex.
=7000km/140my
=50km/my
=5cm/yr (divide by 10)
|
subduction zones |
-plates are destroyed
-largest EQs and volcanoes
-deepest oceans
|
why do plates move? |
so Earth can release heat
|
ocean-continent |
-oceanic trench
-largest EQ's
-mountain belts
-volcanoes
|
ocean-ocean |
-oceanic trench
-largest EQs
-volcanoes
-island arch
|
4 settings of volcanoes |
1)spreading centers (80% is at ridges)
2)hot spots
3)subduction zones
4)continents pulling apart
|
shield volcanoes |
-hot spots (oceanic crust)
-Basalt (iron-rich)
-erupts continuously
-not explosive
-not hazardous
-lava flows
-magma is very hot and runny
-not steep sides
|
strato |
-subduction (continental crust)
-Andesite (iron-poor)
-rare erruptions
-explosive
-hazardous
-lava flows, ash/cinders, pyroclastic flows, bombs
-magma is less hot and stiff
-steep sides
|
transfer faults |
-plates slide past each other
-neither create nor destroy plates
-mostly in oceans but some on land
|
EQ depths |
shallow- all plate boundaries
deep- only in subduction zones
|
sediment cycle |
-make mountains
-rocks to sediments
-transport seds
-deposit seds on seafloor
|
physical weathering |
-wind
-freezing water expands to break rocks (often high elevation)
-desert: salts crystals expand to break rocks (often low elevation)
|
chemical weathering |
-rust
-chemicals disolving
|
making mountains |
-pull continents apart
-chain of subduction zone volcanoes
-colliding continents
-transform faults (with bends)
-hot spots
|
marine life (skeletons)--> |
calcite --> limestone
|
what is the sediment in deep water like? |
very thick
|
transporting sediments |
-rivers
-glaciers
-wind
|
seds from shore to deep water |
marine life (skeletons) <-- mud <-- sand
|
turbidite |
-submarine landslide
-sand, mud, skeletons
|
sand and dust blown from deserts |
covers much of deep sea floor= mud
|
skeletons of marine organisms (deep water) |
1)most abundant- plankton
-microscopic and floating
-mainly diatoms (plants with skeletons of quartz)
-most abundant organism on Earth
---phytoplankton-plants
---zooplankton- weak-swimming animals
2)2nd most abundant- coccoliths
-planktonic plants
-skeletons made of calcite
|
rock |
granite made of:
1)Quartz
2)Mica
3)Feldspar
|
quartz |
-oxygen (O)
-silicon (Si)
|
mica --> clay releases Fe and Mg |
-oxygen
-silicon
-aluminum (Al)
-iron (Fe)
-magnesium (Mg)
|
feldspar --> clay releases Ca, Na, and K |
-oxygen
-silicon
-aluminum
-calcium (Ca)
-sodium (Na)
-potassium (K)
|
what do volcanoes release into the atmosphere and seawater? |
-water
-hydrogen
-carbon dioxide
-chlorine
-sulfate
-oxygen (a little)
|
rivers |
1)headwaters to muddy water= sediments
2)floodplains
-water covers part of it every 10 years
-water covers all of it every 100 years
3)delta
|
headwaters |
-sediment=boulders and gravel
-minerals=quartz, mica, feldspar
|
floodplain |
-sediment=sand and mud
-minerals=quartz and clay
-water contains Fe, Mg, Ca, Na, K
|
mud turns into...
sand turns into... |
clay
quartz
|
know Chemistry of seawater table! |
know Chemistry of seawater table!
|
photosynthesis |
CO2 + H2O --> O2 +body tissues
|
respiration |
O2 + food --> CO2 +H2O
|
Chemistry of Life |
marine bodies (and humans)
-60% fluids
-20% skeletons and hard tissues
-20% soft tissues
main elements
-65% O
-18% C
-10% H
-3% N
-1.5% Ca
-.35% K
-.15% Na
-.05% Mg
-.25% S
|
1. Which of the following is not true about divergent plate boundaries |
-there is very little volcanism here.
|
2. The Nazca ridge has created about 4500 km of seafloor in 30 m.y. The spreading rate is about... |
-150 km/my
|
3. Which is not true about subduction? |
-continental plates only subduct beneath oceanic plates
|
4. Why do plates move? |
-it's the most efficient way for the earth to lose heat (spreading centers are hot, lots of volcanism)
|
5. Moving plates |
-Rate = distance / time
|
6. Which isn't true about shield volcanoes? |
-They are explosive/dangerous
|
7. What kind of volcano/setting is Hawaii? |
-Shield/Hot spot
|
8. What volcano is most likely to erupt? |
-St. Helens
|
9. What is true about Iceland? |
-it's a ridge
-associated with a hotspot
|
10. Average time between eruptions |
=time/#eruptions
|
11. The San Andreas Fault? |
-is a transform fault
|
12. The next really big EQ on the san Andreas Fault will likely happen? |
-It isn't possible to know, but probably within your lifetime
|
13. Shallow earthquakes occur on all plate boundaries, |
But deeps earthquakes only occur on subduction zones.
|
14. A large earthquake is possible someday in the Pacific NW because of the ? there |
-subduction zone
|
15. Which is a way to make mountains? |
-pulling continent apart
-chain of subduction zone volcanoes
-colliding continents
-transform faults
-hot spots
|
16. Freezing and thawing is a way to ? break down rocks into sediments. |
physically
|
17. Big boulders are most often found in which part of a river system? |
Headwaters
|
18. The correct order of ocean sediments with increasing distance from the shore is: |
-sand,mud,skeletons
|
19. Why so much more sediment on East coasts than west coasts? |
-the east coast is old, been sitting and waiting for river sediment to be dropped off. In the west, any sediment from the mountains goes under the trench and swept away under the continent (don't accumulate)
-east coast amazon river
|
20. The most abundant skeletons of marine life are ? |
-diatoms made of quartz
|
21. 3 main minerals in rocks |
-elements in rocks: Oxygen, silicon= main ones
|
22. The gas removed from seawater by coccoliths |
CO2
|
23. The main reason the oceans are warmer at the equator is |
-the Sun's energy makes a direct hit there
|
24. The main reason the oceans are blue is because |
-water strongly absorbs red light
|
where is the oldest sea floor? |
the edge of land/continents
|