Final answer:
Tectonic plates are composed of Earth's crust and the uppermost part of the mantle. The crust consists of oceanic crust, made mostly of basalt, and continental crust, primarily composed of granite. These plates move due to mantle convection and shape the planet's surface through various geological processes.
Step-by-step explanation:
Tectonic plates are large segments of Earth’s lithosphere, which includes the crust and the uppermost part of the mantle. The crust itself comes in two varieties; oceanic crust, mostly composed of basalt, and continental crust, primarily composed of granite. Both basalt and granite are types of igneous rocks, which form as molten rock cools and solidifies.
The movement of tectonic plates is a fundamental concept in geology, comparable in importance to natural selection in biology or gravity in physics. Driven by mantle convection, these plates shift and move, interacting at their boundaries which can lead to geological events like earthquakes, volcanic eruptions, and the creation of mountain ranges. This interaction not only shapes our planet's surface but also helps regulate the Earth's temperature by transporting heat from the interior towards the cooler exterior, acting as a global cooling system.
The concept of tectonic plates also explains the presence of different types of topography across the planet’s surface including rift zones, subduction zones, and various fault lines. While most visualize plate boundaries as straight lines, they can actually be curved or segmented due to the spherical shape of the Earth.