Assessing the chronology of post-contact rock art on the northern Plains via multivariate statistical comparison with Blackfoot biographic art

Rock art can provide an important source of data on the past lives of individuals and the societies to which they belonged. However, rock art does not generally become part of the stratigraphic record, which has the unfortunate consequence that it may be decontextualized from its archaeological and/or historical context, thus limiting its potential contribution to wider anthropological debates. We introduce a method for assessing the chronology of post-contact rock art sites from the northwestern region of the North American Great Plains through multivariate statistical comparison with dated examples of Blackfoot robe (biographic) art. Our analysis of four rock art sites indicates dates that are broadly consistent with previous dating assessments, but helps sharpen their chronology, which has important consequences for these sites with regard to their position in debates relating to the post-contact era history of the region. As is the case for any chronological technique (especially indirect), the method we describe is primarily a guide that should ideally be used in conjunction with other methods, although our analyses demonstrate it can be a valuable tool nonetheless. Although the applicability of the method is illustrated here using sites on the northwestern Plains, we are confident that it could be modified for use in other areas.