What are Tectonic Plates?

Tectonic plates are large plates of rock that make up the foundation of the Earth's crust and the shape of the continents. The tectonic plates comprise the bottom of the crust and the top of the Earth's mantle. There are ten major plates on Earth and many more minor ones. They float on a plastic-like part of the Earth's mantle called the asthenosphere. The plates are most famously known for being the source of earthquakes.

The tectonic plates are about 100 km (60 miles) in thickness, with continental plates tending to be thicker than oceanic ones. The composure of the two types of plate is also quite different. Oceanic plates consist of thicker basaltic rocks, compressed by the pressure of kilometers of water. Contintental plates have a lower average density, containing granitic rocks with a heavy composition of aluminum and silica.

The mantle underneath the tectonic plates is constantly recirculating, causing the plates to float around slowly in a process called tectonic drift. This process was described well by the theory of plate tectonics, which solved several scientific dilemmas about the distribution of species when it was introduced. When plates push up against each other, they create mountain ranges and volcanoes. Mt. Everest was created in this way.

Because the plates are so large, each wraps over a considerable portion of the Earth's surface, making them curved. This is a different shape than the flatness the word "plate" suggests.

Over time, plate tectonics has caused the world's continents to be reshaped. Every continent on Earth was once part of an ancient supercontinent known as Pangaea, and Antarctica was once located in a temperate climate. Marine fossils can be found on the peaks of the world's tallest mountains. The tectonic plates continue to move slowly, but it is unlikely that their movement will cause the world's face to change more rapidly than the growing technological influence of mankind will. One day the plates' great momentum and pressure might even be used as a source of geological energy.

Tectonic plates are massive, irregularly shaped slabs of solid rock that make up Earth's lithosphere. They float atop the semi-fluid asthenosphere and move due to the planet's internal heat. There are seven major plates and many smaller ones, constantly interacting and shaping the Earth's surface through processes like earthquakes and volcanic activity.

Tectonic plates move because of the intense heat in the Earth's core that creates convection currents in the mantle. These currents cause the semi-molten rock in the asthenosphere to flow, which in turn drags the overlying tectonic plates along. This movement is slow, averaging a few centimeters per year, akin to the rate at which fingernails grow.

When tectonic plates interact, they can converge, diverge, or slide past each other, leading to significant geological events. Convergent boundaries can form mountains or cause subduction, which might trigger earthquakes or volcanic eruptions. Divergent boundaries create new crust as magma rises, and transform boundaries can result in earthquakes as plates grind alongside each other.

While understanding tectonic plates helps identify regions at risk for earthquakes, predicting the exact timing and strength of an earthquake remains challenging. Seismologists use data from plate movements to estimate probabilities of future quakes, but the complex nature of the forces at work means that precise predictions are not yet possible.

Tectonic plates play a crucial role in the rock cycle by recycling crustal material. At divergent boundaries, new rock forms as magma cools. Convergent boundaries can push rock deep into the mantle where it melts and reforms. This constant creation and destruction of rock is fundamental to the ongoing process of the rock cycle.

Tectonic plates can influence climate over geologic timescales. Their movement alters the position and size of continents and oceans, which can change ocean currents and atmospheric circulation patterns. For instance, the formation of the Isthmus of Panama altered ocean currents and contributed to the onset of the Ice Age by affecting global heat distribution.