German geophysicist Alfred Wegener first presents his theory of continental drift.
Alfred Wegener was a German meteorologist, polar researcher, and geophysicist who proposed the theory of continental drift in the early 20th century. His groundbreaking ideas challenged the prevailing scientific views of his time and laid the foundation for the modern theory of plate tectonics. Wegener’s work was instrumental in shaping our understanding of Earth’s dynamic geology.
Wegener’s theory of continental drift, first presented in 1912, suggested that the continents were not fixed in their positions but rather had drifted over time. He proposed that all continents were once part of a single supercontinent, which he named Pangaea, and that they had gradually drifted apart to their current positions.
Wegener supported his continental drift hypothesis with several lines of evidence:
Fit of the Continents: Wegener noticed that the coastlines of continents such as South America and Africa seemed to fit together like pieces of a jigsaw puzzle. This suggested that these continents were once connected.
Fossil Evidence: Similar fossilized plants and animals were found on continents that are now widely separated by oceans. For example, fossils of the extinct reptile Mesosaurus were found in both South America and Africa, indicating that these continents were once connected.
Rock Formations and Mountain Ranges: Wegener observed similarities in rock formations and mountain ranges across continents, such as the Appalachian Mountains in North America aligning with the Caledonian Mountains in Scotland and Scandinavia. This suggested a geological connection between these regions.
Paleoclimatic Evidence: Wegener also pointed out the presence of glacial deposits and evidence of past climates that were inconsistent with the current positions of the continents. For instance, he argued that coal beds found in Antarctica indicated that the continent was once situated in a much warmer climate.
Despite the compelling evidence, Wegener faced skepticism from the scientific community. One major challenge was the lack of a plausible mechanism explaining how continents could move across the Earth’s surface. Wegener suggested that the continents plowed through the ocean floor, but this idea was not well-received.
It wasn’t until the mid-20th century, with the development of plate tectonics theory, that Wegener’s ideas gained widespread acceptance. Plate tectonics provided a mechanism for the movement of continents by proposing that the Earth’s lithosphere is divided into rigid plates that float on the semi-fluid asthenosphere beneath them. The movement of these plates explained the observed phenomena associated with continental drift.