Where the Rivers Converge, Roosevelt Platform Mound Study: Report on the Rock Island Complex

This report is the second site description volume for the Roosevelt Platform Mound Study. This volume describes the four sites investigated in the Rock Island Complex by the Roosevelt Platform Mound Study. It also presents some of the analyses and integrated conclusions that address the project's research objectives established by the Bureau of Reclamation and Tonto National Forest archaeologists and outlined in our research design. This volume primarily describes a single large site, U:8:23/177, with the three remaining sites reported much more briefly. Although knowledge of prehistoric life in what we now call the Rock Island region of the Tonto Basin is limited, our investigations at Bass Point suggest the appearance of the platform mound there was sudden and without precedent. Its initial construction and subsequent remodeling were carefully planned, which is indicated by the selection of its location as well as by aspects of its construction. We do not know exactly why the platform at Bass Point was constructed, but we do know it was a place where people lived. Rooms that could have been used as residences were built on top as well as at its base. But the construction of the platform required the assistance of others living elsewhere. It is the ability to engage outsiders to build a platform, and the authority to reside on it, that differentiated the occupants of platforms from others in their community, perhaps signaling their differing role in society. We believe this differentiation was the result of a formalization of leadership. Evidence for the expansion of the platform and its storage facilities suggest that, over time, the accumulation of surplus goods became important. Surpluses could have been exchanged or redistributed locally in order to maintain the leadership position held by those living at the mound. 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. 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.