What Causes Continents To Drift

The Himalayan Mountains were formed from continental drift.

Continents have been moving, slowly but surely, for as long as Earth has been in existence. The planet has a number of continental plates that shift and glide along Earth’s surface above the mantle. The area where these plates come in contact with each other can result in some extreme phenomena and geological features.

Pangaea

Roughly 225 million years ago in the Permian Era, according to scientists, there was a single, massive continent on the planet called Pangaea. This supercontinent can be thought of as a solved puzzle of today’s continents. The east coast of South America fits very well against the west coast of Africa, and the shorelines of eastern North America are made of similar materials as those of western Europe. Alfred Wegener first proposed the idea of continental drift in 1915, saying that each continent rested on a plate, drifting on top of a liquid core.

Plate Divergence

When two plates drift away from each other, known as plate divergence, the area between these two plates is filled with magma. This action only occurs under oceanic plates, so the magma is instantly cooled and hardened, contributing to a new section of crust. This new section, called a mid-ocean ridge, is like a seam in the ocean floor. There is a long ridge running roughly north-south along the Atlantic Ocean as a result of the North and South American plates separating from the Eurasian and African plates.

Convergence

The opposite of plate divergence is plate convergence. This is when two plates move toward each other, causing an ecosystem-altering collision. The Himalayan Mountains were formed when the Indian subcontinent collided with the southern edge of the Eurasian plate. These landforms are still colliding, and the tallest mountain on the planet, Mount Everest, continues to rise at a rate of about 2.4 inches per year. In other cases of convergence, one plate can actually slide under the edge of another plate in a process called subduction. When two oceanic plates collide, volcanoes can form as magma is pushed upward.

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Lateral Slipping

When two plates move in parallel directions, as residents of the west coast of the United States are well aware, pressure can build up and cracks can form. These cracks are called faults, and when enough pressure is created from the opposing movement of the two plates, energy is released in the form of an earthquake.