The 2,500 year old footprints of some ancient farmers and their children and dogs have been found perfectly preserved north of Tucson, Arizona (USA), roughly 800 kilometres east-southeast of Los Angeles. Dozens of prints depict the movements of several adults and at least one child, as they tended their crops and irrigation ditches. They are likely the oldest human tracks yet found in the North American Southwest.
     The barefoot tracks are distinct enough that the movements of specific individuals can be followed across the 15-square-meter field. The tracks were preserved by a sudden flood from a nearby creek soon after the prints were made, covering them in mica-rich sandy sediment, forming a kind of mineralised cast.
     The fields appear to date to the Early Agricultural Period, a span between about 2500 BCE and 50 CE when some of the Southwest's first farmers began cultivating crops.
     The fields, the shallow ditches around them, and even the small depressions where archaic farmers placed individual plants of corn and other crops may stretch far and wide throughout the area, says Jerome Hesse, project manager for SWCA Environmental Consultants, which is conducting the study, "So we've excavated a number of these planting depressions and will run samples for pollen and phytoliths to get a sense of what was being grown."
     The nonprofit 'Archaeology Southwest' is conducting 3-D photo scans of the site to create a digital model, and some of the prints have been cast with synthetic moulds, while others have been extracted completely to be sent to nearby museums. The site lies in the path of road construction.

Edited from Western Digs (21 January 2016)