The correlation of the Trenton strata of the central portions of the States of Tennessee and Kentucky with the deposits of the same age in other regions has been accomplished in a general way, but there is considerable difference of opinion as to the equivalence of the subdivisions. Through the aid of a grant from the income of the Shaler Memorial fund at Harvard University, I was able to spend two weeks on this problem, and as a result have come to look upon it in a way somewhat at variance from any solution I have seen in print and also from my own preconceptions, obtained from the study of the literature.
I am greatly indebted to Mr. Wilbur A. Nelson, the State Geologist, for much assistance in Tennessee, and to Prof. Arthur M. Miller for similar courtesies in Kentucky.
The work of Professors A. . . .