Several thousand stone tools have been found along the Imlay channel in eastern Michigan. The first were noticed in 1937, but it was not until 1952 that enough were accumulated to be very certain there was a people here before readvances of ice of the Wisconsin glaciation. The area is within that shown for the Cary Substage on the Glacial Map of North America (R. F. Flint, et al., Geol. Soc. of Am., Special Paper, No. 60, Pt. 1, 1945).

Opinions have varied among professionals who have seen this material, some thinking it is all natural, others, that some at least might be artificial, and George F. Carter who examined the largest sample, nearly 500 specimens, that it is all man-made. That many of these are artifacts could be demonstrated to anyone taking the trouble to examine the stones of this region. While many can be ruled out as possibly of natural origin, others cannot.