Two Medicine Formation

The Two Medicine Formation is a geological formation that extends across northwestern Montana and southern Alberta, dating to the Late Cretaceous period. It consists primarily of sandstone and contains distinct layers of river and delta deposits sandwiched between marine shale above and nearshore sandstone below.

The formation was first scientifically documented in 1914 during a geological survey, establishing its geological significance. This early work laid the foundation for all subsequent fossil discoveries and our understanding of the Cretaceous period in this region.

The formation holds numerous dinosaur remains, particularly the Maiasaura specimens found at Egg Mountain, which revealed how these animals lived together in groups. Visitors can observe fossils preserved within the rock layers at various discovery sites.

The formation spans two states and provinces, so visitors should plan which sections they want to explore before traveling. The western sections are particularly known for fossil discoveries and are generally more accessible than remote eastern areas.

In some areas, the fossil deposits are so dense that paleontologists continue discovering new remains as they expose the layers. This ongoing productivity makes the site an active research area where scientists regularly uncover fresh insights about prehistoric life.

Location: Montana

Location: Alberta

Part of: Montana Group

GPS coordinates: 48.07420,-112.29900

Latest update: December 7, 2025 19:24