What Forms When Two Continental Plates Collide?

••• typo-graphics/iStock/GettyImages

About 45 million years ago, when the Eurasian continent collided with the Indian subcontinent, the Himalayan mountains formed. In plate tectonics, the scientific theory that explains the structure of the Earth’s crust and how it moves, the planet has roughly nine major plates and many smaller ones, arranged in puzzle pieces around the globe. These plates skate over the mantel of the Earth, an inner layer composed of rocks that surround the Earth’s core. As a unifying theory in geology, most geologists subscribe to plate tectonics as it helps them describe these changes that occur to the Earth’s crust.

TL;DR (Too Long; Didn't Read)

When continental plates collide, mountains form. The least understood of all tectonic boundaries, continental plates have greater density, sometimes reaching lower than the mantel. When these plates collide, it’s reminiscent of the force of two bulls butting heads. While some subduction can occur, the effects at these boundaries often include a wide-ranging and creased mountain range, intense crumpling, faulting and a condensed, thickened area inside the collision zone.

Convergent Plate Boundaries

Where plates meet in plate tectonics, three types of boundaries form: convergent, divergent and transform. Convergent boundaries include when two continental plates collide, two oceanic plates converge or when an oceanic plate meets a continental plate. Several events can occur. Generally, when the oceanic plate hits a continental one, the continental plate uplifts, and the oceanic plate goes beneath it or subducts. When two oceanic plates collide, the older, heavier plate usually subducts beneath the other.

The Himilayas, formed by the collision of two continental plates, is the highest mountain range in the world.
••• Jupiterimages/Photos.com/Getty Images

Continental and Oceanic Plates

Continental plates typically do not subduct beneath oceanic plates because of how thick and buoyant they are. Instead, continental plates typically bend, break and crumple, creating folds, thick creases and mountain ranges like the Andes, Swiss Alps and the Himalayas. Rocks trapped within the collision zone undergo changes because of the extreme heat and squeezing. Called metamorphic rocks, you can find slate, gneiss and schist in these mountain ranges. This includes the eroding Appalachians, which at one time stood as high or higher than the Himalayas, and formed when the North American plate collided with Gondwana, a super continental plate that included South America and Africa at one time.

Volcanoes and Mountains

In areas where oceanic plates collide with continental plates, volcanoes often form, like the volcanoes that circle the Pacific Ocean called the Ring of Fire. Along the Pacific Plate in the Northwestern United States, the Cascade Mountain range consists of several volcanoes formed by the oceanic plate subducting beneath the continental one. Transform boundaries also form, like the San Andreas fault zone, where the two sides of the fault move in opposite directions sliding past each other. The Pacific Plate on the west grinds horizontally to the southeast, while the North American plate moves northwest.

Related Articles

What Are Convergent, Divergent & Transform Boundaries?
Facts on Convergent Boundaries
Three Types of Stress on the Earth's Crust
How Does Pressure Affect Plate Tectonics?
Landforms Caused by Plate Tectonics
10 Facts About Plate Tectonics
What Are the Three Different Types of Convergent Boundaries?
Three Types of Boundaries Between Lithospheric Plates
Types of Geography Features at a Plate Boundary
Types of Rocks Found in the Himalayas
How Do Earthquake Activities Influence the Formation...
Three Types of Convergent Boundaries
Facts About the African Plate
What Landforms Are Formed at a Transform Boundary?
What Type of Plate Boundary Is the Aleutian Trench?
What Plates Interacted to Form the Paricutin Volcano?
What Kind of Eruption Would You Expect at a Rift?
What Best Describes the Relationship Between Earth's...
What Are the 4 Main Types of Landforms?
What Is the Primary Force That Causes the Seafloor...