Figure 3. Kernel density distributions of historical, pre-1140 A.D., and post-1140 A.D. maize in Chaco Canyon (a) and soil and water 87Sr/86Sr sources (b).
The dotted line represents the strontium isotope ratio for a single ponderosa tree stump found in the West Court of Pueblo Bonito (JPB-99). Maize from both time periods overlaps with strontium isotope ratios from the Chaco watershed, though maize dating after 1140 A.D. has more cobs with higher values than found within the canyon and in the selected source data set.