This monograph represents the state of the art in investigations of pollen and vegetation calibration in North America and is not likely to be surpassed soon. The Delcourts and Webb have brought together both published and a large amount of their own unpublished modern pollen data from Canada and the United States, east of the 105th meridian (a total of 1684 samples of surface duff, surface lake and bog sediments, and moss polsters).