Continental Drift Theory Video Lecture - Geography for UPSC CSE

Ans. Wegener used multiple lines of evidence including matching rock formations and mountain ranges across continents, fossil distribution patterns showing identical species on separated landmasses, and similar climate indicators like glacial deposits. He proposed that continents drifted apart over geological time, though he couldn't explain the mechanism driving continental drift theory initially, which limited acceptance of his hypothesis.

Ans. Continental drift theory explains how continents move across Earth's surface, but didn't specify the mechanism. Plate tectonics, the modern framework, reveals that Earth's lithosphere comprises rigid plates moving over the mantle. Plate tectonics validates Wegener's continental drift concept while providing the physical process-seafloor spreading and subduction-that actually moves continents and causes geological phenomena.

Ans. The complementary fit of African and South American coastlines strongly supported continental drift theory, suggesting these continents once formed a supercontinent called Pangaea. Matching geological structures, identical fossils, and similar rock types on both continents confirmed they were previously joined. This coastline alignment remains one of Wegener's most compelling pieces of evidence for continental movement and continental drift hypothesis acceptance.

Ans. Identical fossils of plants and animals appear on continents now separated by oceans, impossible through natural migration. Mesosaurus, a freshwater reptile, found only in South America and Africa, couldn't have crossed saltwater. Glossopteris ferns and Lystrosaurus reptiles existed on multiple southern continents. This fossil evidence demonstrates continental drift occurred, as these organisms couldn't have dispersed across vast ocean barriers, supporting Wegener's continental movement hypothesis.

Ans. Glacial deposits and striations appear in present-day tropical Africa, South America, and India-regions too warm for ice sheets. Under continental drift theory, these landmasses occupied polar positions within Pangaea during the Carboniferous period. When continents are repositioned on paleomagnetic maps to their ancient locations, glacial evidence aligns logically around a single ice sheet. This glacial distribution pattern provides crucial support for the continental drift mechanism and large-scale crustal movement.