Roosevelt Platform Mound Study: Rock Island Complex


This report is the second site description volume for the Roosevelt Platform Mound Study, an eight-year archaeological research project in the Tonto Basin of central Arizona that began in April of 1989. It is funded by the Bureau of Reclamation, Department of the Interior and is conducted by the Office of Cultural Resource Management in the Department of Anthropology at Arizona State University. The work was performed under a permit from the Tonto National Forest.

The research was made necessary by plans to modify and raise the height of the Theodore Roosevelt Dam in the Tonto Basin. The original dam, completed in 1911, is used to store water and generate electricity for the Phoenix metropolitan area.

Most of the sites included in our investigation are located above the level of the original reservoir, at elevations between 2,120 and 2,200 feet. The modifications to the dam are designed to improve the structure for controlling floods. During such flood events, the reservoir has the potential of rising about 80 feet above its usual elevation of 2,120 feet, temporarily inundating many of the sites that are included in our study. As the flood waters are drained (generally in a matter of days), the water drops again to its normal level (or less, as water is used for municipal, irrigation, and power generating purposes).

The four sites reported in this volume are from the Rock Island Complex, which was not subdivided into management groups because of the small number of sites investigated. The fieldwork design estimated how many days of effort would be expended at each site, but these were only rough estimates and it was understood that the field directors would need to adjust the effort among sites as work progressed. In the Rock Island Complex, each archaeological site was approached as a decision-making unit controlled by the field director. As the work progressed, new objectives were identified.

The Rock Island Complex is located at the center of the basin, overlooking the confluence of Tonto Creek and the Salt River. Many of the prehistoric sites in this area now lie beneath the reservoir (Wood 1989; Hohmann and Kelley 1988). We conducted research at four sites in this complex, three of which in 1992 lay completely above the reservoir and one of which was inundated whenever the reservoir was at maximum capacity.

Cite this Record

Roosevelt Platform Mound Study: Rock Island Complex. ( tDAR id: 394035) ; doi:10.6067/XCV89P33MN

Temporal Coverage

Calendar Date: 1100 to 1450

Spatial Coverage

min long: -111.159; min lat: 33.677 ; max long: -111.129; max lat: 33.698 ;

Record Identifiers

Roosevelt Monograph Series(s): 4

Anthropological Field Studies(s): 33

Bureau of Reclamation Contract No.(s): 9-CS-32-06230

Resources Inside this Project (Viewing 1-14 of 14)


  1. Where the Rivers Converge, Roosevelt Platform Mound Study: Report on the Rock Island Complex (1995)


  1. Rock Island Complex Data, AZ U:8:400(ASM): Strata (1995)
  2. Rock Island Complex Data, Bass Point Mound: Strata (1995)
  3. Rock Island Complex Data: Decorated Ceramics from Screened Contexts (1995)
  4. Rock Island Complex Data: Groundstone from Screened Contexts (1995)
  5. Rock Island Complex Data: Lithic Artifacts from Screened Contexts (1995)
  6. Rock Island Complex Data: Lithic Material Types from Screened Contexts (1995)
  7. Rock Island Complex Data: Lithic Size Class Data from Screened Contexts (1995)
  8. Rock Island Complex Data: Plain Ware Ceramics from Screened Contexts (1995)
  9. Rock Island Complex Data: Shell Artifacts from Screened Contexts (1995)
  10. Rock Island Complex Data: Shell Taxa from All Contexts (1995)
  11. Rock Island Complex Data: Special Artifacts from Screened Contexts (1995)
  12. Rock Island Complex: Ceramic Bowl and Jar Data from Screened Contexts (1995)
  13. Rock Island Complex: Shell Taxa from Screened Contexts (1995)