Problems Relating to the Neothermal Climatic Sequence

Abstract

The sequence of three phases (Anathermal, Altithermal, Medithermal) of the Postglacial or Neothermal temperature curve, although demonstrably a reality, has been used improperly to determine absolute dates and past climatic conditions from archaeological deposits. A review of the historic development of the concept of the three sequent Neothermal temperature phases reveals the assumptions on which absolute dating of these phases has been based. Analysis of the variable radio-carbon dates now available for deposits attributed to these phases in a number of different localities in North America indicates that these phases cannot be considered as universal time periods bracketed by definite absolute dates; and consideration of the ecological diversity within North America at any particular time, especially in the West, indicates that climatic conditions inferred for a given span of Neothermal time in one area cannot be projected into another area without direct independent evidence of the actual climatic conditions which existed in the second area at that time. It is suggested that Anathermal, Altithermal, and Medithermal be used not as time periods with fixed absolute dates or climatic periods with defined characteristics, but rather be considered as phases of the Neothermal temperature curve which in different ecological areas resulted in locally varying climatic conditions which must be determined by direct evidence, dated by independent means, and designated by local terms.