Continental Drift

Subdecks (1)

Cards (88)

  • Pangaea
    The large landmass that included all of Earth's present day continents
  • Alfred Wegener was a German meteorologist and geophysicist who noticed the similarity in the coastlines of eastern South America and western Africa and speculated that those lands had once been joined together
  • Continental drift
    One of the earliest ways geologists thought continents moved over time, as hypothesized by Alfred Wegener
  • Wegener hypothesized that all of the modern-day continents had previously been clumped together in a supercontinent he called Pangaea
  • Wegener brought together several lines of evidence to support his theory of continental drift
  • Evidence of continental drift
    • Shape of the continents
    • Evidence from fossils
    • Evidence from landforms
    • Location of coal deposits
    • Evidence of climate
  • Wegener's theory of continental drift was rejected because his explanation was too weak and clashed with widely accepted ideas at the time
  • Alfred Wegener and his colleague Rasmus Villumsen died in a blizzard in Greenland in 1930
  • Almost 50 years later, Harry Hess confirmed Wegener's ideas by using the evidence of seafloor spreading to explain what moved continents
  • Seafloor spreading
    The continuous process of forming new igneous rock at midocean ridges by injection of magma that forms new seafloor
  • Sonar uses sound waves to detect underwater objects and determine underwater landforms and distances
  • Hess discovered the mid-Atlantic ridge and found the temperature near it was warmer, leading him to develop the theory of seafloor spreading
  • The ocean floor is difficult to explore due to the deep darkness, cold water, and high water pressure
  • The Earth does not get larger when new rock is added to the ocean floor at the mid-ocean ridge because the ocean floor is constantly being renewed
  • Continental crust is primarily composed of granite, a light-colored igneous rock rich in silica and aluminum.
  • Continental crust is thicker and less dense than oceanic crust, with an average thickness of about 35 km.