Description: Fort Union Formation comes from the first geological epoch to follow the extinction of the dinosaurs. The Fort Union Formation covers much of Montana, eastern Wyoming, and the western Dakotas. It contains an extensive amount of minable coal, and has an extensive flora. It was a flora indicative of a lowland, sub-tropical to temperate climate. The depositional environment was both fluvial and lacustrine, with the fluvial deposits holding the most coal. This Dawn Redwood (Metasequoia) frond is of a genus that was first discovered in Korea over 60 years ago. The first living specimens were discovered in central China in 1944. The deeper brown color of the plant matter contrasts well with the lighter matrix, bringing out the detail.