During the 1950 and 1951 seasons, field parties of the Missouri River Basin Survey carried on a series of excavations in the vicinity of the Oahe dam near Pierre, South Dakota. Most of the work was done at two earth lodge villages, the Dodd site (39ST30) and the Phillips Ranch site (39ST14). On the basis of the archaeological material from the Dodd and Phillips Ranch sites, and from a series of previously excavated sites located within a thirty-mile radius of the Dodd site, it seems possible to set up a sequence of cultural complexes for the area, complexes which follow one another in time and which appear to represent a series of modifications in and accretions to the earliest one known for the area.

The Dodd site, located on the west bank of the Missouri River about six miles upstream from Pierre, provides the basis for the chronological seriation of the material.