In sea-floor spreading, molten material rises from the mantle and erupts

As the molten material cools and hardens at a mid ocean ridge, it forms new ________.

Old oceanic crust is more dense than new oceanic crust because it is _______________.

Most geologists think that the movement of Earth's plates is caused by __________________.

Place on the sea-floor where the oceanic crust bends downward into a deep-underwater canyon

Process where the ocean floor sinks beneath a deep-ocean trench and back into the mantle

The outermost solid layer of the Earth which has the least amount of pressure is called the

A break in the Earth's crust where rocks have slipped past each other, and they form along plate boundaries

The rigid rocky layer of the crust and upper mantle is called the:

The soft layer of the mantle that creates convection currents:

The supercontinent that existed about 300 million years ago

This person hypothesized that the sea floor is slowly creating new material and pushing the continents apart

This person hypothesized that all continents had once been joined together in a single landmass that has drifted apart

Which one of these is NOT a piece of evidence Alfred Wegener used to support his hypothesis about Pangaea?

Which one of these is NOT a piece of evidence Harry Hess used to support his hypothesis about sea-floor spreading?

This theory states that pieces of Earth's lithosphere are in slow, constant motion.

A plate boundary where two plates of the same density crash into each other

A plate boundary where one plate of a heavier density sinks under another.

Plate boundary where two plates slide past each other in opposite directions.

Plate boundary where two plates move apart and leave a gap where molten material often erupts.

A device that bounces sound waves off underwater objects to measure how far away they are.

Holes drilled several km into Earth's crust that provide direct evidence about Earth's interior

A source of indirect evidence that geologists use to learn more about the Earth's interior

Layer of the Earth with the most pressure; made of solid iron and nickel

Place where the magnetic field occurs; made of liquid nickel and iron

Rock with fine, dark texture that makes up the oceanic crust

Rock in the continental crust that is light in color and has a coarse texture

In the interior of the Earth, heat is transferred as soft rock flows slowly in cycles known as

When a heat source is removed from a fluid, convection currents in the fluid will...

When materials are heated they...