Plate Tectonics and Large – Scale System Interactions

Introduction to Earth’s Crust

• Solid rocks make up plates.

• A thinner layer of partially molten rock lies beneath the plates.
• This thinner layer is constantly being passed by the plates.

If you look at a map of the world, you may notice that some of the continents fit together like a piece of a puzzle.

Types of Plates

Oceanic and continental tectonic plates are the two main types.

An oceanic plate is a tectonic plate at the ocean’s bottom.

The continental plate is the thick part of the Earth’s crust that forms the continents.

Continent: A continent is a large area of solid land.

There are seven continents on Earth. Asia, Africa, North America, South America, Antarctica, Europe, and Australia are listed in order of size.

Explanation:

Plate Tectonics

• The plate movement on the crust causes them to collide, pull apart, or scrape against each other.
• The plates interact at their boundaries as they move.
• Each type of interaction causes a particular set of Earth structures or “tectonic” features.
• The word tectonic refers to the deformation of the crust due to plate interaction.

The three kinds of plate boundaries are:

• Divergent
• Convergent
• Transform

Divergent Boundaries:

• The plates move apart from each other.
• When they move, the melted rock (magma) beneath the plates rises.
• This magma, or melted rock, cools as it rises and creates new crust.
• In short, as the plates move apart, new material is spewed out to fill up the gap.

Convergent Boundaries:

• Convergent boundaries are formed when plates move in the same direction.
• In this situation, one plate’s edge could slide beneath another and be damaged. Or the two plate edges could rise up and create mountains.

• Examples of convergent boundaries that form mountains, e.g., the European Alps and the Himalayas.

Transform Boundaries:

• In transform boundaries, plates slide past each other.
• Most of the transform boundaries are located in the ocean where they oppose spreading ridges and cause a zigzag pattern between the plates.

Where Do Earthquakes and Volcanoes Occur?

• Along plate borders, earthquakes and volcanoes are common occurrences.
• At the borders of the Pacific Plate, there are many earthquakes and volcanoes happen. Hence that area is known as the Ring of Fire.

• The three types of plate boundaries are divergent, convergent, and transform.
• Each of these different boundary movements and slipping can result in an earthquake.

Continental Drift

• For hundreds of millions of years, the plates have been moving across the surface of the Earth.
• The continents on the plates move together with them. We refer to this movement as continental drift.