The Way Continental Drift Has Created Nowadays World
In modern day rhinoceroses, zebras and camels can be found on the continent of Africa, but did you know that these animals had roamed the plains of the United States? Approximately 12 million years ago during the Miocene and Pliocene epochs they could be found wondering the great plains of the mid-west.
The Bruneau-Jarbridge caldera in south west Idaho erupted about 12 million years ago creating a huge ash plume spanning almost a thousand miles. Covering parts of the plains with up to two feet of ash. This wiped out large populations of species to include the teleceras, a pre-historic relative of current day rhinoceroses’. The remains of these creatures can be found throughout the plains, however in northeastern Nebraska a large quantity was discovered in 1971 by paleontologist Michael Voorhies. It is currently called the Ashfall fossil beds and is now a historic park. It is believed that at this location there was a watering hole where animals had gathered seeking relief from the Bruneau-Jarbridge ash plume, however relief could not be found as death was eminent from the inhalation of ash. Ashfall Fossil Beds.
So how can rhinoceroses have once inhabited North America when they can only be currently found in Africa? It started 250 million years ago upon the super continent of Pangea. Modern day continents were once all connected on what is called Pangea. Coyne, C. M. Earth Science. North America was side by side with Africa and Europe with no ocean between. Relatively the same type of plant life and animals roamed this massive super continent.
The earth is covered in what is called tectonic plates that move and shift at different times. Each plate has different land masses and continents on them. Over the course of time, millions of years they have slowly moved centimeters at a time, separating what we now call our seven continents of North America, Africa, Europe, Asia, Australia, Antarctica and South America. Alfred Wegener was the one to come up with this theory of continental drift in 1912. Wegener first got his idea by noticing that landmasses on earth seemed to fit together like jigsaw puzzle. He then analyzed the rock, fossils and geological structures on each side of the Atlantic Ocean. He noticed that they were very similar and in some instances the same. It was not until about the 1960’s when the theory of continental drift interest increased. American geophysicist, Henry H. Hess proposed the forming of new oceanic crust being continually made by igneous activity at the crests of oceanic ridges, thus spreading the sea floor. This sea floor spreading integrated with the basis of tectonic plate theory lead some investigators, Jack E. Oliver and Bryan L. sacks to believe that earth’s surface is comprised of plates that float on a layer of partially molten mantle called the asthenosphere. When the plates separate and the new mantle material forms new ocean floor is formed it carries the continents with them. On the basis of this they concluded that Europe, Africa, North and South America were joined almost 200 million years ago.
In conclusion, this explains why we have some of the same fossils and rocks on a multitude of current day continents. If the Bruneau-Jarbridge caldera did not erupt 12 million years ago causing the extinction of many species in North America, we might very well have been able to go out on the plains of the mid-west and see rhinoceroes, zebras and camels wondering the grasslands like their pre-historic relatives once did.
