Hell Creek Formation

The Hell Creek Formation is a well-known geological group of rock layers in North America that dates back to about 66 to 66 million years ago, during the late Cretaceous and early Paleocene periods. It is famous for preserving fossils of dinosaurs like Tyrannosaurus rex and Triceratops, as well as ancient plants and other creatures. These rocks provide critical insights into the environment and life just before the mass extinction that ended the dinosaurs. The formation spans parts of Montana, North Dakota, South Dakota, and Wyoming, making it a key site for studying that pivotal moment in Earth's history.