Date of Award


Document Type


Degree Name

Master of Arts (MA)




Approximately 580 ft of the Sentinel Butte Formation (Paleocene) is exposed within this study area. A stratigraphic and sedimentologic study of these exposures was done in order to gather new information about the formation, to interpret paleodepositional environments, and to possibly develop an overall depositional model.

Stratigraphic analysis identified four major sand units within the study area, separated by intervals of mudstone and lignite. The lowermost sandstone unit is identified as the Basal Sandstone (Royse 1967). All of the sandstone units exhibit sedimentary structures that suggest a fluvial source for their deposition. They tend to be laterally consistent and when mapped show a meandering trend. This along with the existence of floodplain and back swamp deposits in close proximity to these sands leads to the hypothesis that this interval of Sentinel Butte sediments were deposited by a meandering fluvial system.

Sedimentologic analysis of the Basal Sandstone determined that it should be classified as a medium-grain (Wentworth) litharenite (Folk, 1980). The analysis of the upper sand showed that this unit should be classified as a fine-grained (Wentworth) litharenite to sublitharenite. The basal sand textural analysis produced mean grain size of 2.18tj>, while the upper sand showed a mean grain size of 3.05