THE THEORY OF PLATE TECTONICS

_____ _________ the far-reaching theory that explains the large-scale forces that act inside the Earth to shape it’s surface

It is founded on _________ __________ of continental drift but further refined and expanded by evidence gathered from the ocean floor in the 1950s and 1960s.

As geology writer ____ ______ once said, “The whole world suddenly makes sense.”

Plate tectonics states that Earth’s rigid _____ shell

the ___________, is divided into a dozen or so large pieces plus a number of smaller ones.

Each piece of lithosphere is called a _________ _____ or, simply, a plate.

Plates are up to 100 km thick. True or false

Being slabs of lithosphere, tectonic plates consist of the uppermost core plus the crust. True or False

The plates ride atop the plastic _____________ below.

Some plates are large; others are small. True or False

Some are relatively immobile, while others are more active. True

The continents move only because they are embedded in the plates. True or False

The continents have the same boundaries as the plates. True or False

The North American Plate, for example, is much larger than the North American continent. True or False

Earth’s plates move in different directions at different speeds, ranging from _ cm per year to about 15 cm per year.

Plates pull apart, crash, merge, and separate from one another over geologic time. True or False

Plates that carry continents, such as the North American Plate, are slow movers, while oceanic plates, such as the Pacific Plate, tend to move much slower. True or False

Plates that carry continents, such as the North American Plate, are slow movers, while oceanic plates, such as the Pacific Plate, tend to move much _____.