Which part of the subduction zone is indicated in this image? ...

[Chelseaamend]

Which part of the subduction zone is indicated in this image?
 
  A) Deep-ocean trench
  B) Forearc basin
  C) Volcanic arc
  D) Back-arc basin

Question 2

Is there data to suggest there was more accretion in the distant past (4 billion years ago) or the more recent past (50 million years ago)? Explain.
 
  What will be an ideal response?

[mcabuhat]

Answer to Question 1

Answer: D

Answer to Question 2

Answer: There was more accretion in the past because there was more radioactive decay in the past. When the Earth was younger, there were more unstable radioactive isotopes that were going through the decay process. The radioactive decay would provide the heat necessary for convection. So, with more isotopes and more decay, more heat would be produced. More heat produced means more convection, which means faster plate motion.

[Chelseaamend]

Thanks for the timely response, appreciate it

[connor417]

Excellent