Fossil Butte   by Eric Peterson   airs  Nov. 11, 2007     1:31 long                                

Today finds us a few miles west of Kemmerer, Wyoming at Fossil Butte National Monument. Now, most of Wyoming and indeed the world wouldn’t realize this, but this is a world famous site.

Now 50 million years ago this was the bottom of a freshwater lake, specifically called Fossil Lake. It was surrounded by a warm swampy subtropical forest. Now, that doesn’t sound like Southwest Wyoming, does it?  But remember that 50 million years is a very long time.  And Wyoming has undergone many changes over that time.

Well back then, the lake waters were warm and animal life was diverse and abundant. A broad range of fish inhabited the tributaries and the shallows and the deep water of Fossil Lake. Whatever sank to the bottom, dead fish, fallen leaves or whatever, was covered by thin layers of freshwater limestones - sedimentary rocks that preserved the creatures living there at that time.

The outstanding feature of these fossils is their detail. Many of the fish, for example, have not only their entire skeletons but their teeth and scales and skin as well. The “flakiness” of the sedimentary deposits makes exploration of the 200-300 feet of the fossil bearing rock very exciting, as one breaks apart the rock to expose a creature that last saw the light of day maybe 50 million years ago.

From the University of Wyoming Cooperative Extension Service, I’m Eric Peterson.