STRATIGRAPHY & SEDIMENTOLOGY IN THE UPPER HELL CREEK FORMATION

The Hell Creek Formation which outcrops in various localities in the states of Montana, North Dakota, and South Dakota has long been of interest to paleontologists and geologists alike. Geologists are likewise interested in this formation due to the K/T boundary being marked by what is often referred to as the z-coal, because it is the youngest bed of coal yet known to exist. However, along with this distention the z-coal also contains considerable amounts of shocked quartz and iridium (a rare earth element abundant in meteorites). Yet with all this interest in the formation, few sedimentological or stratigraphic studies of the Upper Hell Creek Formation have been conducted. Preliminary background research revealed that this formation was deposited by a Cretaceous fluvial system that flowed easterly into the Western Interior Seaway which extended from the present day Arctic Ocean to the Gulf of Mexico. The marine Breien member of Hell Creek Formation was formed by a short re-advancement of this seaway. Given the above factors, the goal of this project was to fill in this piece of the scientific puzzle by providing the world with scientific data concerning the stratigraphy and sedimentology in the upper Hell Creek Formation. Such data concerning this Maastrichtian Age formation hold countless clues to earth history and environment of the age. The study area chosen for this project is located on The Silhouette Angus Ranch on the outskirts of Jordan, MT. The stratigraphic column featured in figure 1 of this report is taken from field research conducted at a locality on this ranch known informally to the research team as Ice Cream Butte. All data for this portion of the study was collected by careful measurement of the described units with both a tape measure, and a clinometer. These measurements were then recorded in a field notebook and transferred into computer software to produce the stratigraphic section shown in figure 1 of this report.