Continental drift Permian era but failing to account for glaciation in India, Australia and South Africa. Geophysicist Jack Oliver is credited with providing seismologic evidence supporting plate tectonics which encompassed and superseded continental drift with the article "Seismology and the New Global Tectonics", published in 1968, using data collected from seismologic stations, including those he set up in the South Pacific. It is now known that there are two kinds of crust: continental crust and oceanic crust. Continental crust is inherently lighter and its composition is different from oceanic crust, but both kinds reside above a much deeper "plastic" mantle. Oceanic crust
Big Drift over the cliffsides or into dump trucks. The entire Going-to-the-Sun Road takes about ten weeks to plow, even with equipment that can move 4,000 short tons of snow an hour. By the first of June of each year, the Logan Pass visitor center can usually be reached by vehicle from at least one side of the Continental Divide. In 2011, due to abnormally heavy late winter and early spring snowfall, the Going-to-the-Sun Road did not open until July 13th, the latest opening ever due to snow. Big Drift The Big Drift is in Glacier National Park, in the U.S. state