Plate Tectonics

Definition

The theory that the Earth's lithosphere is divided into large rigid plates that move over the semi-fluid asthenosphere, and whose interactions cause earthquakes, volcanoes, and mountain building.

Key points

• The lithosphere is broken into major and minor plates that move a few centimetres a year.
• Three boundary types: convergent (plates collide), divergent (plates move apart), and transform (plates slide past).
• Convergent collision of the Indian and Eurasian plates formed the Himalayas (young fold mountains).
• Divergent boundaries form mid-ocean ridges; convergent oceanic boundaries form trenches and volcanoes.
• Builds on the earlier theory of continental drift (Alfred Wegener).

Why it matters for CAPF

It explains the origin of the Himalayas, earthquakes, and volcanoes, all standard physical-geography facts, and links to disaster-management questions.

Common confusion

Plate tectonics (modern, mechanism with plates) versus continental drift (Wegener, earlier, lacked a mechanism); convergent versus divergent boundaries.

Parent note

geomorphology earth interior and plate tectonics