Unit 2E B Plates of the Earth

2. Plates of Earth

The surface of Earth is made up of large sections called plates Vocabulary: plates A large section of Earth’s crust

These plates are like pieces of a puzzle that fit together There are about 20 plates that make up Earth’s crust

The seven major plates are the: Pacific North American* South American African Eurasian Australian Antarctic

The plates of the crust rest on the hot liquid rock of the mantle below them

The plates move slowly all the time They are carried along as the melted rock in the mantle moves

Most plates move from ¼ inch to 4 inches a year

Plates can move in several ways They can move toward each other They can move away from each other They can slide past each other

When two plates move toward each other, or converge, one plate is pushed down below the other

Movement of Earth’s plates toward each other Vocabulary: converge Movement of Earth’s plates toward each other

When plates under the continent collide, edges of the plates crumple and are pushed up

A deep ocean trench is then formed Vocabulary: trench A deep valley formed when two plates under the ocean floor collide

Mountains such as the Himalayas and Andes were formed when 2 plates converge

When this occurs under the ocean it is called seafloor spreading When plates move away from each other, or diverge, molten rock is forced upward to form new land When this occurs under the ocean it is called seafloor spreading

Movement of Earth’s plates away from each other Vocabulary: diverge Movement of Earth’s plates away from each other

The deepest place on Earth called the Mariana Trench was formed with diverging plates

In other places, plates grind past each other and is called transformation

Movement of Earth’s plates against each other Vocabulary: transformation Movement of Earth’s plates against each other

The line where two plates pass each other is called a fault Vocabulary: fault A line where two plates of Earth’s crust pass each other (transform)

Strain is produced on the rocks on both sides of the fault Many earthquakes occur along faults