First excavated in 1956–57, the LoDaisKa Archaeological Site south of Morrison is a rockshelter that contains evidence of about 7,500 years of human occupation, from the Paleo-Indian period (before 6000 BCE) to the Early Ceramic (150–1150 CE). The site is especially significant for three main reasons: it was one of the first sites in the Rocky Mountain foothills to be professionally excavated, it helped establish the cultural chronology of the foothills region, and it launched the careers of the important Colorado archaeologists Henry and Cynthia Irwin.
Early Foothills Archaeology
The Rocky Mountain foothills region west of Denver received little professional archaeological attention before the 1950s. In 1931–32 the University of Denver archaeologist Etienne B. Renaud performed a reconnaissance of the region and found evidence of several prehistoric sites, but other than that the area was explored mainly by local amateurs.
The most extensive amateur investigations in the foothills were performed by LoDaisKa Bethel. She noted a promising prehistoric rockshelter at the base of a large Fountain sandstone formation on Otto Sanger’s ranch, about a mile south of Morrison in the valley between the hogback and the foothills, and guided the young siblings Henry and Cynthia Irwin to the site. Denver natives trained in archaeology and attending college at Harvard, the Irwins performed a test excavation at the site in 1956. The next summer they followed up with a full excavation.
The main rockshelter at the LoDaisKa site measures fifty feet long, thirteen feet deep, and thirteen feet high. The Irwins dug down more than seven feet deep and found more than a thousand artifacts representing multiple short-term occupations. The artifacts included stone projectile points, scrapers, and knives as well as pottery fragments and worked bone. The Irwins also detected twelve hearths and three storage cists.
Radiocarbon dating showed clear evidence of human activity at the LoDaisKa site from about 2880 BCE, in the Middle Archaic period, until 990 CE, in the Early Ceramic period. In addition, a Plano projectile point found nearly nine feet below the surface in conjunction with charcoal, ash, and burnt bone indicated at least one earlier occupation around 7000–6000 BCE, in the Paleo-Indian period.
The most puzzling discovery at the site was a group of several corn cob fragments and corn kernels in the layer dating to 2880 BCE. The corn was probably intrusive, meaning that it actually belonged to a more recent occupation than the layer in which it was found, but if not, these Archaic corn remnants would be among the earliest identified in the Southwest.
Working without the benefit of other foothills excavations for comparison, the Irwins attempted to situate the LoDaisKa site within a framework of alternating occupations by Plains and Great Basin cultures. Recent research has suggested that the foothills experienced its own cultural development that was related to but not entirely dependent on that of nearby regions. The LoDaisKa site was probably used by small groups of hunter-gatherers who practiced limited agriculture during some periods. Extended family groups may have frequented the site during seasonal migrations between the mountains and the plains. Beads, pendants, and gaming pieces suggest that ceremonial and leisure activities took place at the site.
In 1959 the Irwins published a lengthy report about the site. A few years later they used the questions that emerged from their LoDaisKa excavation to help guide their work at the Magic Mountain site near Golden. The Irwins’ excavations at LoDaisKa and Magic Mountain helped establish a cultural and chronological framework for foothills archaeology that has been the basis for all later work in the region.
The LoDaisKa site was backfilled after the 1957 excavation. Today it is still on the Sanger family ranch, which has changed little in the decades since the rockshelter was excavated. The site was listed on the National Register of Historic Places in 2003.