An Overview of Plate Tectonics

What are plates in the past?

Many scientists have contributed to the theory of plate tectonics. One of the first was Alfred Wegener, who in the early 20th century hypothesized that the continents move over time. According to Wegener's hypothesis of "continental drift," all the continents were once grouped together to form a supercontinent that Wegener called Pangaea.Many scientists have contributed to the theory of plate tectonics. One of the first was Alfred Wegener, who in the early 20th century hypothesized that the continents move over time. According to Wegener's hypothesis of "continental drift," all the continents were once grouped together to form a supercontinent that Wegener called Pangaea.

What are tectonic plates and boundaries?

The theory of plate tectonics describes how Earth's tectonic plates move over time. Scientists use this theory to explain how major geological features form, what Earth looked like in the past, and why continents and oceans have changed position over time.Earth's core is extremely hot. As mantle rock above the core heats up, it rises and, as it moves away from the heat source, it gradually cools and sinks. There are three main types of plate boundaries: divergent, convergent, and transform. At convergent boundaries, plates move toward each other. At divergent boundaries, plates move apart. At transform boundaries, plates slide horizontally past each other.

What are transform boundaries?

Transform boundaries occur where two plates slide past each other. Large earthquakes often occur at transform boundaries. Friction between the moving plates may cause them to become temporarily stuck. Pressure builds up until the plates become unstuck. The sudden movement releases energy in the form of an earthquake.

What are convergant boundarys?

When two continental plates collide, crust in the plates buckles and rises upward. Approximately 55 million years ago, the plates containing present-day India and Southeast Asia collided. Over time plate movements at this convergent boundary formed the highest mountain range on Earth: the Himalayas. These mountains get higher each year as the plates continue to move toward each other.Oceanic crust is denser than continental crust.

What are divergant boundaries?

Where oceanic plates move apart, magma flows from the mantle to Earth's surface. The molten rock cools in the ocean water, forming new oceanic crust. This process is called seafloor spreading. The mid-Atlantic Ridge—a long system spreading centers along the center of the Atlantic Ocean—is an example of such a divergent boundary. Divergent boundaries also exist between continental plates. These plates form deep valleys called rifts as they move apart. Rift valleys are characterized by volcanic activity and hot springs.