BOB HIRSHON (Host):
North America’s formative years. I’m Bob Hirshon and this is Science Update.
Long before the Rocky Mountains were born, a great sea stretched deep into North America from the west, reaching all the way to present day Missouri. New research published in the journal Nature Geoscience suggests the sea formed about forty million years more recently than was thought. University of New Mexico geologist Karl Karlstrom and his colleagues dated radioactive material found in zircon crystals in a layer of the Grand Canyon.
KARL KARLSTROM (University of New Mexico):
They define this rapid flooding across North America around 500 to 505 million years ago, and the reason that flooding took place probably was North America was breaking apart from other continents within the super-continent of Rhodinia.
The work fills in important details about the formation of North America, and the evolution of marine life whose fossils are found throughout the continent. I’m Bob Hirshon for AAAS, the Science Society.
Story by Bob Hirshon