Approximately 52 million years ago, in what is now Kemmerer, Wyoming, there was a massive lake. This lake was home to many fish, reptiles, and amphibians.

As these creatures died, their bodies were covered with small pieces of dirt and rocks (sediments) that preserved the structure of their bones. Over time, these sediments built up and created sedimentary rock that we find fossils in today.

The “fossil lake” as it is called also went through different weather events. Many believe there was volcanic activity near the lake. This created ash that gives some sedimentary rock a special color. Different “layers” of fossils are dug up, and these layers differ in rock color, flakiness, and species found in them. These layers were created with shifts in weather events, climate, and differences in age.