Earth Science Unit 9

The hypothesis that the continents slowly move across Earth's surface

The name of a single land mass that broke apart 200 million years ago and gave rise to today's continents.

A deep valley along the ocean floor beneath which oceanic crust slowly sinks toward the mantle

A device that determines the distance of an object under water by recording echoes of sound waves

The process by which molten material adds new oceanic crust to the ocean floor

A trace of an ancient organism that has been preserved in rock

An undersea mountain chain where new ocean floor is produced; a divergent plate boundary

Scientist who hypothesized that all the continents were once connected and had many pieces of evidence, but no mechanism for the movement.

American geologist who studied mid-ocean ridges. Studies showed that continental drift happens through plate tectonics and sea floor spreading.

Vibration of Earth due to the rapid release of energy in the crust.

The point within Earth where an earthquake starts.

The location on the surface of Earth where the earthquake was centered.

Fractures in Earth where movement has occurred.

First seismic waves felt, cause a back and forth motion.

Second seismic waves felt, cause a rolling motion.