Geoarchaeology, a discipline that incorporates various methods from earth sciences in the investigation of archaeological sites, is well suited to examine the complex relationship between humans and their environments in the past. This talk featuring Rachel Cajigas, of the University of Alabama, will review two case studies (La Playa in Sonora Mexico, and Creighton Island Shell Ring in Georgia), each from very different, but dynamic erosional environments, where a multi-scalar, multi-technique, geoarchaeological methodology was utilized to characterize how ancient humans modified their environments in significant ways during the Late Archaic period.