Ceramic Petrography Laboratory

Research Results

Gila-Phoenix Petrofacies Model Summary

Elizabeth J. Miksa, Carlos Lavayen, and Sergio F. Castro-Reino

The quantitative petrofacies model for the middle Gila River basin started with work sponsored by the Western Archaeological Conservation Center and the Mesa Southwest Museum in the early 1990s (Miksa 1995b). Parts of the Phoenix model began in the early 1990s as well (Miksa 1995a), though sand samples for most of the Phoenix metropolitan area were not collected until the year 2000 and later (Miksa et al. 2004). Much of the Phoenix petrofacies model is coincident with that developed by Schaller (1994), though the model described here is based on an extensive network of sand samples. Schaller's model was based on a limited number of rock samples, which do not describe the full variation in the sand available as temper.

The Gila-Phoenix model as now defined covers drainages that are in the middle Gila River watershed and the lower Salt River watersheds (which drains into the Gila just to the west of Phoenix). Archaeologists generally describe this area as the "Phoenix Basin," though strictly speaking it is part of the Gila River basin in a hydrologic sense.

  • A map (Adobe PDF format) of the current Gila-Phoenix petrofacies model.

  • A list of the petrofacies (Adobe PDF format), their map designations, and short descriptions of their compositions.

  • A list of point count parameters (Adobe PDF format) in current use in the modeled region.

  • A cross-tabulation of samples (Adobe PDF format) collected and available in the combined middle Gila River and Phoenix basin, inventory (Excel 2000/XP format) of the sands, and point count data (Excel 2000/XP format) for the sands used in the discriminant analysis model.

  • A schematic diagram (Adobe PDF format) of the set of nested discriminant analysis models used to classify the sands.

  • A table of the point count parameters and calculated parameters (Adobe PDF format) used as variables in each of the discriminant analysis models.

  • A cross-tabulated table (Adobe PDF format) showing the sand discriminant analysis of the full discriminant analysis.

  • A flowchart (Adobe PDF format) showing how data are used to identify sand from each petrofacies.

  • A References Cited (Adobe PDF format) section.

  • A full report on the combined model, with application to ceramics from the Dutch Canal Ruin site (Miksa et al. 2004). Report (Adobe PDF format)

A detailed discussion of how these elements are developed and combined to create a petrofacies model can be viewed on the Ceramic Petrography Laboratory web pages.