THE METHOD
We brought the resulting 1340 records into FileMaker Pro, based on Carbon-14 dated material in each midden, and parsed the records out to the five (5) chronological categories shown in the chart below. This pilot analysis uses only perennial taxa from each category to avoid skewing the data toward short-term phases in which annuals may have thrived. Using the century-old “law of latitudinal equivalent in elevation” (Lowe 1972) from the Merriam Life Zone System , one degree of latitude = 77 meters (250 feet) elevation in Arizona, we added calculation fields to the database that brought each record into our study area and adjusted the elevation of the packrat midden in which the taxa were found. Each taxon’s highest and lowest actual occurrence became its elevation range.
The map calculator function in ArcView 3.2 (Spatial Analyst extension) distributed taxa across the study area’s two latitude ranges, 32 degrees to 33 degrees N and 33 degrees to 34 degrees N, as shown above. Each pixel in the digital elevation model has a one-square-kilometer resolution. These grids were merged and exported as images. Each taxon image was linked by time period in MultiSpec and a cluster analysis run using the number of taxa as the initial cluster solution.
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PALEO-ECOLOGY IN AN URBAN BASIN SYSTEM
Reconstructed Perennial Plant Communities in the Phoenix and Tonto Basins
2,000 Year Intervals from 14,000 bp to 4,000 bp
Steven Schmich, Archaeological Research Institute, and C. Michael Barton, Department of Anthropology, Arizona State University
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