ch10 geol 100

Why are the patterns showing the age of the seafloor symmetrical in the Atlantic Ocean but not the Pacific Ocean?

spreading along the Atlantic ridge added seafloor to plates on both sides subduction has consumed large areas of old oceanic crust in the Pacific

What processes can occur in front of or behind some island arcs?

trench rollback and back-arc rifting

What is a popular model for the formation of an atoll?

a volcanic island forms and subsides

In the Atlantic Ocean, where is the oldest oceanic crust?

abyssal plain next to the continents

If you were looking for graded beds, where would be a good place to start?

in a submarine fan

What has happened to the Pacific Ocean in the last 200 million years?

it became smaller as the Atlantic Ocean opened

If you drilled into an oceanic plateau, what would you most likely find?

large amounts of basalt derived from melting in the mantle

What are some uses of magnetic reversals?

matching the patterns of reversals in a rock sequence to the magnetic time scale studying magnetic stripes on the seafloor calculating rates of seafloor spreading

How do most oceanic islands and seamounts form?

they are constructed by volcanic eruptions that first occur under water

What causes the seafloor to deepen across a typical continental slope?

thinning of continental crust because of normal faults a transition from continental crust to oceanic crust