What is the theory of the formation, structure, and movement of the earth's landmasses?

• A. Plate Tectonics
• B. Rocks
• C. Subduction
• D. Diamond

Answer: (A)

Plate tectonics explains how Earth's landmasses formed, how the crust is structured, and how it moves. The idea is that the outer shell of the planet is made up of rigid plates that ride on the partially molten layer beneath them. New crust is created at mid-ocean ridges, while older crust is recycled back into the mantle at subduction zones; when plates collide, pull apart, or slide past one another, continents and oceans are rearranged over geological time.

Movement comes from convection currents in the mantle that push and pull on these plates. This framework accounts for mountains built by collisions, earthquakes that occur along plate boundaries, and volcanoes that line certain margins. Supporting evidence is diverse: the coastlines of continents fitting together like a puzzle, similar fossils and ancient climates found on now-distant landmasses, and the magnetic strip patterns recorded in oceanic rocks that reveal past plate motions.

Other terms are parts of the bigger picture rather than the overarching theory itself. Rocks are the materials making up the crust, subduction describes one dynamic process at certain boundaries, and diamonds are minerals formed deep in the mantle under high pressure—related to geology but not the theory that explains how continents move.