Geologic Time Scale and Brief History of Life on Earth

north of the tropics was almost entirely ocean, and most of the world's land was collected into. the southern super-continent Gondwana. Throughout the Ordovician, Gondwana shifted towards the South Pole and much of it was submerged underwater. The Ordovician is best known for the

  Earth, Scale, Time, Life, Brief, History, Geologic, Tropics, Geologic time scale and brief history of life on earth