Continental Drift and Geological Evidence

The oceanic crust is thin yet​ ​ (a)   , and the Continental crust is thick but ​ (b)  

• dense
• Less dense

What observation about the shapes of continents was an early clue to the idea of continental drift?

• The similar mountain ranges found on different continents.

• The way Africa and South America appear to fit together.

• The presence of identical plant fossils across continents.

• The discovery of shark teeth in high mountain ranges.

Which theory did Alfred Wegener propose in the 1910s?

• Seafloor spreading

• Plate tectonics

• Continental drift

• Mantle convection

Why did many scientists initially reject the theory of continental drift?

• They believed land could rise and fall to connect continents.

• There was no known mechanism strong enough to move continents.

• Fossil evidence did not support the idea of connected landmasses.

• The maps available at the time were not accurate enough.

What tool did scientists develop to map out the ocean floor?

• satellite imagery

• AI images

• Sonar mapping

• paintings

What mineral found in the ocean floor provides evidence of Earth's magnetic field reversals, supporting seafloor spreading?

• Quartz

• Feldspar

• Magnetite

• Calcite

What method did NASA use with the LAGEOS satellite to measure continental drift?

• Using GPS signals to track plate movement.

• Bouncing lasers off reflectors on the satellite to measure distances.

• Analyzing seismic waves generated by earthquakes.

• Directly observing plate boundaries from space.

How do scientists determine that widely separated mountain ranges were once part of the same continuous range?

• By comparing the types and ages of rocks found in those ranges.

• By analyzing the fossil records found in the mountains.

• By observing current seismic activity along the mountain ranges.

• By studying the erosion patterns caused by ancient rivers.

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What geological evidence helps scientists reconstruct the past positions of continents by indicating their orientation relative to Earth's magnetic poles?

• The presence of ancient coral reefs.

• The distribution of specific fossil types.

• Paleomagnetism, recorded in rocks containing magnetite.

• The age of oceanic crust.