Volcanoes and Plate Tectonics/Earthquakes and Seismic Waves/Drifting Continents

Volcano

a mountain that form in Earth’s crust when molten material, or magma reaches the surface

Magma

A molten mixture of rock-forming substances, gasses, and water from the mantle

Lava

Magma when it reaches the surface

Volcanic belts along the boundaries of Earth’s plates

Where are volcanos found

Ring of fire

a major belt of volcanos

island arc

The volcanoes sometimes create a string of islands

hot spot

an area where material from deep within Earth’s mantle rises through the crust and melts to form magma.

A volcano forms above a hot spot when magma erupts through the crust and reaches the surface

Where volcanoes are found on Earth’s surface (2)

earthquake

the shaking and trembling that results from movement of rock beneath Earth’s surface

vibrations that are similar to sound waves that travel through Earth carrying energy released by an earthquake

What are seismic waves

focus

an area beneath Earth’s surface where rock that was under stress begins to break or move

epicenter

the point on the surface directly above the focus

Geologists use seismic waves to an epicenter

How is an epicenter located?

from past seismographic data, geologists have created maps of where earthwuakes occur around the world. The maps show that earthquakes often occur along plate boundaries

What patterns do seismographic data reveal

Wegener’s hypothesis was that all the continents were once joined together in a single landmass and have since drifted apart

What Was Wegener’s Hypothesis About the Continents

Continental Drift

Wegener’s idea that the continents slowly moved over Earth’s surface

Pangaea

The supercontinent or single landmass about 300 million years ago

fossil

any trace of an ancient organism that has been preserved in rock.