Plate Tectonics and Continental Drift

Voc Set 2

Asthenospherethe soft layer of the Earth

on which pieces of the lithosphere move; flowing portion of the upper mantle

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Did you know?The

asthenosphere◦flows like a liquid

◦breaks like a solid

(sort of like molten glass, but MUCH hotter)

Did you know?Temperatures in the asthenosphere:1400-3000 degrees celsius

(the surface of the Sun is about 5000 C)

Lithospherethe outermost layer of the

Earth, including the crust and uppermost, solid portion of the mantle

Did you know?

Lithosphere means “ball of stone” in Greek

Did you know?The lithosphere is a very thin

layer – only about 1000 km (620 miles) thick.

Ridge a line or range

of hills or mountains, or an elongated elevation on the ocean bottom

Did you know?The mid-ocean

ridges of the world are all connected to make one long mountain range?

It is about 60,000 km long – that’s 37,282 miles!

Trencha long, steep-

sided valley on the ocean floor that happens when one plate subducts under another

Did you know?The oldest

ocean floor crust is found at subduction zones, where old crust will be recycled back into magma.

Did you know?Trenches are

usually found near volcanic island arcs.

Examples:

Faulta break in

the Earth's crust where rocks will slide past each other

Did you know?Fault lines are

frequent sites of earthquakes.

Did you know?Fault lines are

frequent sites of earthquakes.

Rift Valleya long, deep

valley formed by two tectonic plates moving away from each other

Did you know?Parts of the East

African Rift Valley are called the “cradle of mankind.”

The remains of “Lucy,” an early hominid that lived 3.2 million years ago, were found there!