Continental Drift, Seafloor Spreading, and the Birth of Plate Tectonics | Chapter 3 from Earth: Portrait of a Planet
Continental Drift, Seafloor Spreading, and the Birth of Plate Tectonics | Chapter 3 from Earth: Portrait of a Planet How did we discover that continents move and oceans grow? Chapter 3 of Earth: Portrait of a Planet by Stephen Marshak unravels the remarkable journey from early ideas of continental drift to the discovery of seafloor spreading, revealing the foundation of modern plate tectonics. For an expert podcast summary, watch the full video or explore this in-depth written breakdown below. Introduction: The Puzzle of Moving Continents In the early 20th century, most geologists believed continents and ocean basins were fixed. Alfred Wegener, however, noticed intriguing clues: the fit of coastlines across the Atlantic, similar rock layers and fossils on separate continents, and traces of ancient glaciers. Wegener’s hypothesis—continental drift—proposed that all continents once formed a supercontinent, Pangaea, that slowly split apart. Despite his compelling evidence, the s...