What is now a high mountain desert with alternating deep vast valleys and buttes was a tropical paradise some 50 million years ago.
Large freshwater lakes often occupied these vast basins for many millions of years.  The ancestral Wind River Mountains, Uinta Mountains, and Bear River Range rose above the basins.  Soft sedimentary stone layers wrapped up and over the mountain cores we now see, causing the shapes and sizes of the ancestral ranges to be much different. Seasonal torrential rains poured across Wyoming’s Eocene-Age lush green semi-tropical landscape.

 
Grasses and many of the plants we take for granted had yet to evolve.  Large quantities of the soft sedimentary material eroded down the slopes of the ancestral mountains and into the lake basins.

From generations of work and research in this world class fossil deposit and through cooperative ventures with research and educational institutions from around the world, we are well into understanding the ancient lake system and its paleoecology (the relationship between ancient life and their environments).