Wednesday, October 14, 2009

Questions for plate boundries

1) Divergent boundaries -- where new crust is generated as the plates pull away from each other.
Convergent boundaries -- where crust is destroyed as one plate dives under another.
Transform boundaries -- where crust is neither produced nor destroyed as the plates slide horizontally past each other.
2) It means that plates are moving apart from each other. This happens because magma is pushing up from the mantle.
3) An example would be the Mid-Atlantic Ridge going through Iceland. The red triangles represent volcanoes in Iceland.
4) Where two plates move towards each other and collide.

5) a. oceanic-continental convergence


b. oceanic-oceanic convergence

c. Continental-continental convergence

6)
a. When an oceanic-continental convergence takes place, a deep trench on the floor of the ocean forms.
b. When an oceanic-oceanic convergence takes place, a deep trench on the floor of the ocean forms.
c. When a continental-continental convergence takes place, mountains are formed.
7) A transform boundary is when two plates are moving horizontally past each other and these boundaries usually cause small earthquakes or zig-zag plate margins an example in North America would be the San Andres fault zone in California.
8)
a. The Mid-Atlantic ridge is a divergent boundary with two oceanic plates
b. The Kuril Trench was made in a convergent boundary with two oceanic plates
c. The Philippines were formed in a convergent boundary with two oceanic plates. The Philippines are an island arc.
d. The East Africa Rift Valley was made in a divergent boundary, with two continental plates.
e. The Red Sea was a rift valley that got filled in with water. This means it formed a divergent boundary with two continental plates.
f. The Peru-Chile Trench is a convergent boundary with a continental and an oceanic plate.
g. The Aleutian Islands are an island arc, which means it was made by a convergent boundary with two oceanic plates.

Wednesday, October 7, 2009

Geologic Timeline Follow-up questions

1) On the Earth, you need oxygen, water and a source of food. Without those things, you would die because they are a necessity for life of a multi-celled organisms. That is why the Earth has "Goldilocks" conditions. Or perfect conditions for life to happen.
2) Archaeon Eon because that's when the Earth was born, oxygen started to fill the atmosphere, and the Earth's crust and oceans started to form. Those are all key events that led to the Earth being what it is today. Some of those are all also common ingredients for life to happen.
3) Not very significant at all because we haven't been here long enough to really change the pace of the Earth's development. However, we have managed to start to kill the atmosphere by polluting it with cars.