Cretaceous Fossil Rock
April 04, 2008
My nephew collected this rock from the top of Provo Peak in Utah. So how did a rock full of fossilized sea animals, including sponges, shells, and worms, end up at the top of a mountain over 11,000 feet (3,353 m) in elevation? In the Late Cretaceous period, 99 to 65 million years ago, much of what is now North America was divided from the Gulf of Mexico to the Arctic by an inland sea -- a shallow sea filled with abundant marine life. Over millions of years, sediment filled the sea and pressure from the Pacific Plate lifted the land upward, forming lofty mountain chains. Eventually, the fossil filled sediment was incorporated into the flanks as well as the summits of many of these mountains. Erosion now works to bring more and more of the fossil record to the surface.