University of Michigan Radiocarbon Dates IV

Abstract

The following is a list of radiocarbon dates obtained since the time of the preparation of Michigan list III. x The description of the essential features of our method of measurement as given in the introduction to list 111 applies to this list. The modern standards used were obtained from hardwood logs, and were of various ages from 75 to 150 years by ring count. These standards were sufficiently old so that no correction for the recent dilution of the atmospheric C1' is believed to be necessary in the dates reported here. The ages of carbonate sample are also calculated from modern wood as a reference standard, without any correction for isotope fractionation.

We are pleased to acknowledge the help of Miss Patricia Dahlstrom for the chemical preparation of the samples, and that of Mr. James J. Taylor for assistance in the preparation of the descriptions of the samples. We are indebted to the Michigan Memorial-Phoenix Project for the major part of the financial support of the laboratory.