1930

1. Plate Tectonics Timeline 1950- Earthquake patterns provide evidence of sea-floor spreading- Kiyoo Wadati and Hugo Benioff discovered a patern of earthquakes during the subduction process. The deeper the earthquake was the farther the focus. No earthquakes were recorded under 700km. The explanation of the patteren is called the subduction process. The slab gets heated when it gets deep. 1915-Theory of Continental Drift-Alfred Wegener formed a hypothesis that the continents were one formed toether. He called this giant continent Pangaea. Alfred Wegener had 3 groups of evidence to support his theory. Wegener found out that the same animal was found on different continents 5,000 miles apart. Wegener also found out that in Africa there was evidence of glaciers. 1920 1930 1940 1950 1960 1929- Wegeners hypothesis of Continental Drift was Dismissed People thought that his hypothesis was very wong. People just thought that he was crazy. Arthur Homes decided to experiment with the idea of continental drift. Homes thought that the thermol convection acted like a conveyer belt. No one payed attention to what Homes thought at the time. 1963- Theory of sea-floor spreading-Harry Hayes made the hypothesis that new ocion floors form at mid-oean ridges. Thenit moves slowly across the ocean basin. Then is sinks back into the mantle. Evidence emerged from sudy of the fracture zones. This offsets the section of tbe ridge. 1915-1963