Week 3 quiz - Plate tectonics 2

Question 1

All basalts younger than 700,000 years old ________.

Answer 1

have normal magnetic polarity

Question 2

Wegener’s idea of continental drift was rejected by American geologists because ________.

Answer 2

he could not conceive of a valid mechanism that would cause continents to shift positions

Question 3

Marine magnetic anomaly belts run parallel to ________.

Answer 3

mid-ocean ridges

Question 4

Deep-ocean trenches are found predominantly along the perimeter of the ________ .

Answer 4

Pacific ocean

Question 5

At a subduction zone, the downgoing (subducting) plate ________.

Answer 5

Is always composed of oceanic lithosphere

Question 6

The oldest basalts on the ocean floor are about ________ years old.

Answer 6

200 million

Question 7

Currently, most geologists ________.

Answer 7

agree that continental drift occurs due to mechanisms at work in the ocean basins and upper mantle

Question 8

A great boost in seafloor exploration and a greater understanding of seafloor bathymetry was a result of ________.

Answer 8

military needs in World War II

Question 9

Iceland is one of the few places in the world that is both above sea level and situated atop a ________ plate boundary.

Answer 9

divergent