Origin & evolution of Earth

Story hook

It is 1912. A 31-year-old German meteorologist, Alfred Wegener, stares at a world map and notices something his predecessors had dismissed for centuries — the coast of Brazil fits the bulge of West Africa like a puzzle piece. The matching geology, the identical fossils of Mesosaurus found on both shores of the Atlantic, the same Glossopteris flora across India, South America, Africa, Antarctica and Australia — none of it makes sense if the continents have always sat where we see them.

He publishes "Die Entstehung der Kontinente und Ozeane" ("The Origin of Continents and Oceans"), arguing that all land was once joined as a supercontinent he names Pangaea ("all land", Greek). Geologists laugh him out of the room — he cannot explain how continents would plough through solid ocean rock. Wegener freezes to death on the Greenland ice sheet in 1930, his theory still discredited.

Then, 1962, Harry Hess notices that the mid-Atlantic Ridge is a magma factory. 1963, Vine and Matthews find symmetric magnetic stripes either side of mid-ocean ridges — the seafloor is moving. By 1968, the world has a theory of plate tectonics that vindicates Wegener completely. The Earth, it turns out, is 4.54 billion years old, has assembled and dismantled supercontinents at least five times, and is still tearing itself apart and reshaping its face every day.

Why this matters for UPSC

Syllabus location: GS-I — World Physical Geography (origin and evolution of Earth, continental drift, plate tectonics). Asked 4-5 times in Prelims over the last 10 years; appeared in Mains 2014 (mid-ocean ridge), 2018 (plate boundaries and Indian geography), 2021 (origin of continents). High-yield factual zone — the dates, the discoverers, and the seven plates carry the marks.