The Northern Rocky Mountain Front, a Pre-Contact Frontier

Abstract The Front Ranges of the Northern Rocky Mountains formed until recently a porous boundary – a frontier – repeatedly crossed for trade, subsistence, or warfare, and where Plains and Plateau/Rockies information networks overlapped. In this paper we investigate changes in network orientations and boundaries during the pre-contact period through the lens of projectile point morphologies and raw materials, using the case study of the Billy Big Spring Site in the Blackfeet Indian Reservation, Montana. This site contains numerous points, the majority of which were recovered in chronostratigraphic context, which range from Late Paleoindian to Late Precontact. They include types and raw materials alternatively typical of the Rockies/Plateau, the Front Ranges, and/or the Plains. Variation in the projectile point record at Billy Big Spring is representative of the wider Front Ranges in which, for most of the pre-contact period, information networks overlapped and formed a porous boundary akin to that observed in the recent past. Pre-contact changes in the nature and location of this boundary can in turn be related to major environmental and demographic events that occurred in the region.