How many major tectonic plates are there on earth?

There are seven major tectonic plates on the planet that are further subdivided into dozens of smaller plates. Geologists do not always agree on how to subdivide the minor plates. Each plate is in motion relative to the other plates. read more

Just as there is no consensus about whether the Nazca Plate is a primary or secondary plate, there is no agreement about exactly how many tertiary plates there are, but scientists have identified about 58 of them. Theory of Plate Tectonics. Tectonic plates are great slabs of rock that form the Earth's top layer, called the lithosphere. read more

Tectonic plates are pieces of Earth's crust and uppermost mantle, together referred to as the lithosphere. The plates are around 100 km (62 mi) thick and consist of two principal types of material: oceanic crust (also called sima from silicon and magnesium) and continental crust (sial from silicon and aluminium). read more