What is the average pH of the ocean?
A) 7.0
B) 7.5
C) 8.0
D) 8.5
Question 2
The magnetic striping of the seafloor is considered evidence of seafloor spreading and ____.
A) periodic interruptions in mantle convection
B) subduction occurring in rift valleys
C) changes in Earth's axis of rotation
D) periodic reversals in the polarity of Earth's magnetic field