Convergent plate boundaries form where lithospheric plates collide along their boundaries with each other. Such collisions cause extensive deformation at the Earth’s crust, leading to the formation of volcanoes, the lifting of mountain ranges and the creation of deep oceanic trenches. Convergent plate boundaries are also characterized by extensive earthquake activities, which occur along the sections of the Nazca-Pacific convergent boundary in Chile and Peru, for example.
When continental plates and oceanic plates move together along their boundaries, the collision creates huge amounts of energy, releasing gigantic quaking tremors that cause deformation of the Earth’s crust. Different plates are independent of each other and move together at different relative speeds. However, they are still interconnected in that the collision of two plates will still have an effect on other plates not directly involved in the collision.
Types of Convergent Boundaries
The three principle types of convergent plate boundaries are oceanic-continental convergence, oceanic-oceanic convergence and continental-continental Convergence. Oceanic-continental convergence occurs where an oceanic plate converges with a continental plate and subducts under it. An oceanic-oceanic convergent plate boundary occurs when one oceanic plate becomes subducted under another, resulting in the creation of a deep oceanic trench. Finally, a continental-continental convergence plate boundary occurs when two continental plates collide head-on. In such a collision, neither plate becomes subducted since continental rocks are light and resist downward motion. The collision pushes rocks either upward or sideways.
Characteristics of Convergent Boundaries
Oceanic-continental plate boundaries are characterized by a mountain range, where the continental plate lifts up over the subducting oceanic plate, bordered by a deep subduction trench on the side of the oceanic trench. Oceanic-oceanic converging boundaries result in the creation of undersea volcanoes. Over millions of years, lava erupting along the boundary builds up on the ocean floor until a submarine volcano rises above sea level to become island volcanos, which become arranged in chains to form an island arc. Continental-continental convergent boundaries are often characterized by mountain building events, such as in the Caledonian Orogeny, which brought the British Isles together.
Examples of Convergent Boundaries
An example of an oceanic-continental plate boundary is the subduction of the Pacific plate below the Nazca plate on the west coast of the Americas, which formed the Andes mountains. A current example of an oceanic-oceanic plate boundary is the Marianas Trench, which resulted from the Philippine Plate subducting under the Pacific Plate. An example of a continental-continental plate boundary is the collision of the Indian Plate with the Eurasian plate, which resulted in the formation of the Tibetan Plateau and the Himalayan mountain range.
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