The mounds are not burial mounds or mortuary sites, as no human remains have ever been found in them. They contain much charcoal and burned rock but few other artifacts. They lack plant or animal remains expected if they were food-processing sites or habitation structures. In the present study, we are focused on conducting a field census of the mounds for preservation purposes and on gathering basic descriptive data that better documents some of the morphometric and geophysical attributes of the mounds.
Prior to this study no one had made any real attempt to look for food remains to address the suite of economic hypotheses, or to study in detail the internal structure and history of a mound. To do this, we conducted limited test excavations by working off of reopened historical excavations in two mounds on the rocky High Banks that form eastern shore of Perch Lake. No food remains were found in the newly excavated samples despite a large and intensive archaeobotanical flotation effort in the field and in the laboratory, so we reject the series of economic hypotheses, including our own favored one. This is no small gain, however, as it places exploration and refinement of the other hypotheses on firmer ground.
Stratigraphic studies show that the mounds are planned, carefully-made geometric structures of earth and stone, internally complex but with sharply delineated outer margins. A Perch Lake mound was first a made earthen structure that later became the site of many subsequent burn episodes, in which much charcoal was produced when fires were extinguished under soil or stones. Few intact burn surfaces are preserved, as the soil and stones were subsequently reorganized in an act of mound building that would leave the mound in its very distinctive form. The two tested mounds were found to have been made at the sites of tree-tip, where pit-and-knoll disturbed soils were remolded into the ring-shaped form. Near-surface soil horizons in the area that would become the mound were also used for the earthen fraction of the rings, and their excavation may have served as the initial marking out of the mound space that would be maintained with subsequent use. Sixty seven new high resolution radiocarbon dates place construction and near continuous ritual use of these mounds minimally between 50 BC and AD 1425.