The Green River Formation, an Eocene geological formation, records the sedimentation of a group of intermountain lakes. The sediments are deposited in fine layers and present a continuous history of 6 million years. Within the Green River Formation in southwest Wyoming, is an area known as Fossil Lake where two distinct zones of lime muds are particularly noted for preserving a variety of complete and detailed fossils. The most productive zone, called the split fish layer, consists of a series of laminated lime muds about 6 feet thick which contains abundant fish and other fossils.
PETRIFIED WOOD – INDONESIA
Petrified wood from Indonesia is from ancient teak (hardwood) trees that are approximately 20 million years old. Minerals present in the mud and water prior to and during the petrification process give it its color. Petrified wood is a 3-D fossil which is the result of permineralization and replacement. These processes take place at the same time and involve the flow of groundwater, rich in dissolved minerals through the wood.