These exceptional Sycamore leaf fossils (Platanus wyomingensis) come from the Green River Formation of the early Eocene (approximately 50,000,000 years old). 

The Green River Formation consists of layers upon layers of sediments deposited in a basin, situated between the Rocky and Uinta Mountain ranges of Colorado, Wyoming, and Utah. As mountains are created through tectonic processes, the forces of erosion work to break them down, causing massive amounts of sediment to build up along their bases. The fine-grained shale, deposited in lake bottoms, offers some of the best environments for fossil preservation. The Green River is well-known for excellent preservation of fish, insect, plants, and other creatures that lived both on land and in the water. 

The Dunn-Seiler Museum recently received a generous donation of thousands of Green River fossils from a graduate of the MSState Geology program, Barry McMullen. Stay tuned for more fossils from the McMullen Collection!