In definitions of the postglacial readaptation in eastern North America, attempts have been made to apply a single standard to the entire area. Such definitions are inadequate since a number of environmental zones existed in the region during late glacial and early postglacial times. These consisted of a periglacial zone with a fairly high carrying capacity supporting a cold-climate hunting adaptation; a zone of closed boreal forest with a relatively low carrying capacity; and a region of broadleaf and southern forests with a relatively high carrying capacity for a mixed gathering-and-hunting base. In the southeast there is a gradual transition from formally defined Paleo-Indian to Archaic culture, although both groups, if separation is possible, had potentially the same subsistence base. In the northeast there is a low population density hiatus between two periods of higher population density.

A series of radiocarbon dates from Younge Tradition sites in southwestern Michigan indicates that previous age estimates for the four suggested phases were too conservative. Corn agriculture was practiced throughout the Younge Tradition time range as indicated by an A.D. 700 date for the Sissung site (20 MR 5).

In an attempt to compare a large number of fluted points in the Eastern United States, metric data were coded on punch cards and analyzed statistically. A sample of fluted points from Virginia was tested in a trial study. It was found that some attributes showed significant but predictable clustering. The variation in fluting pattern between geographical areas within the state was significant.

In 1953 it was suggested that bifurcate-stemmed projectile points might serve as a horizon marker in the southwestern United States. Since then material has been reported which indicates that this is also true for the eastern United States. There are two types of bifurcate-stemmed points: a larger form which may be older than 5000 B.C. and a smaller form which appears to be more recent.

A statistical examination of Paleo-Indian projectile points and bases from the Holcombe (Michigan) and Scharbauer (Texas) sites shows that basal modification, thinning to fluting, is distributed throughout the range of thickness. It is possible that fluted points were considerably thicker before fluting, but this is untestable and, since the present populations have a normal distribution, seems unlikely.