alternative ideas on plate movement Flashcards
1
Q
why is there now other explanations for plate movement?
A
it is thought that it is not as simple as just convection currents
2
Q
what are the two forces that offer other explanations?
A
slab pull and ridge pull
3
Q
what boundary does ridge push occur at?
A
constructive
4
Q
what boundary does slab pull occur at?
A
destructive
5
Q
what is the ridge push theory?
A
when two plates move apart, the upwelling of material causes a boyancy effect and gravity acts on plates pushing them apart
6
Q
what is the slab pull theory?
A
a downward gravitational force that pulls the whole plate down as a result of a negative boyancy
7
Q
what type of boyancy occurs at ridge pull?
A
positive
8
Q
what boyancy occurs at slab pull?
A
negative
9
Q
how tall can ocean ridges staqnd above ocean floor?
A
2-3 km
