What are tectonic plates and how do they shape Earth?

Tectonic plates are massive pieces of Earth's crust and uppermost mantle known as the lithosphere, which float across the ductile asthenosphere. Earth's rigid outer shell is fractured into several major plates and many smaller platelets that move slowly via mantle convection currents and gravity. Where these plates meet at convergent, divergent, or transform boundaries, they create geological activity such as earthquakes, volcanoes, and mountain ranges.

What we know

• Tectonic plates are pieces of Earth's crust and uppermost mantle collectively referred to as the lithosphere, measuring around 100 kilometers thick. [2]
• Earth's lithosphere is fractured into seven or eight major plates and many minor plates or platelets. [5]
• Tectonic plates consist of two principal types of material: oceanic crust dominated by mafic basaltic rocks and continental crust consisting of lower-density felsic granitic rocks. [2]
• Tectonic plate interactions are classified into three basic types of boundaries: convergent, divergent, and transform. [4, 5]

Still open

• The relative importance and interaction of proposed drivers for plate motion, such as active mantle convection, upwelling inside the mantle, and the tidal drag of the Moon, remain subjects of debate.

Where to go next

• how it workedHow do tectonic plates interact at their boundaries?
• the bigger pictureWhat is the broader scientific framework of plate tectonics?
• how we knowWhat are the specific articles and topics related to plate tectonics?
• whenHow does continental drift relate to modern plate tectonics?
• compared withDoes any other planetary body feature active tectonic plates?
• an unexpected connectionHow are Jupiter's icy moons connected to Earth's geology?Jupiter's moon Europa shows signs of ice crustal plates moving and interacting in a manner similar to Earth's plate tectonics.

Sources

• [1]list of tectonic plates (Wikidata Q1583739) · CC0 1.0
• [2]List of tectonic plates · CC BY-SA 4.0
• [3]Outline of plate tectonics · CC BY-SA 4.0
• [4]List of tectonic plate interactions · CC BY-SA 4.0
• [5]Plate tectonics · CC BY-SA 4.0