Review The Hell Creek Formation, Montana: A Stratigraphic Review and Revision Based on a Sequence Stratigraphic Approach Denver Fowler 1,2 1 Badlands Dinosaur Museum, Dickinson Museum Center, Dickinson, ND 58601, USA;
[email protected] 2 Museum of the Rockies, Montana State University, Bozeman, MT 59717, USA Received: 12 September 2020; Accepted: 30 October 2020; Published: date Supporting Information 1. Methods: Lithofacies Descriptions Facies descriptions follow methodology laid out in Miall (1985). Descriptions mostly follow those of Flight (2004) for the Bearpaw Shale and Fox Hills Sandstone. Additional lithofacies are described for the Colgate sandstone, ?Battle Formation, an undivided Hell Creek Formation, and the lowermost 5–10 m of the Fort Union Formation. It was desirable to stay as close to Flight's (2004) definitions as possible in order to facilitate cross comparison between measured sections and interpretation; however I have also chosen to remain true to the intentions of Brown (1906) in keeping the Basal Sandstone (and associated basal scour) as the first unit of the Hell Creek Formation, rather than the tidal flats identified by Flight (2004). This analysis is not as concerned with the nature of the basal contacts as much as internal stratigraphy within the Hell Creek Formation itself, hence some of the stratal and facies relationships described by Flight (2004) were not directly observed by myself, but I have included them here to ease comparisons. 1.1. Bearpaw Shale The Bearpaw Shale is the basalmost formation considered in this study; as such only the uppermost 10–20 m have been observed in outcrop. In this upper 20 m or so, the Bearpaw Shale generally coarsens upwards, predominantly comprising shale with occasional interbedded sandstone.