Pleistocene Ecology and Biogeography of 

 North America' 



Paul S. Martin 



Geochronology Laboratories, 

 University of Arizona, Tuscan 



Uuring the past ten years, the related fields of 

 Pleistocene chronology, biogeography, palynology, and prehistory 

 have experienced vigorous growth. This growth may be attributed in 

 part to methods of isotope dating, fresh interest in periglacial 

 geomorphology, the application of pollen stratigraphy to archaeo- 

 logical and chronological problems, and increased appreciation of 

 "vertebrate microfossils." Students of animal and plant distribution 

 find themselves increasingly committed to archaeological and 

 geological data. The information exchange is mutual and poses a 

 challenge in interdisciplinary communication. For attempting to 

 unify Pleistocene concepts within archaeological, biological, geologi- 

 cal, and climatological specialities we are especially indebted to 

 Braun (1955), Clark (1952), Deevey (1949, 1953), Flint (1957), 

 Frenzel and Troll (1952), and Moreau (1955). In North America 

 Dillon's mapping of Pleistocene life zones (1956) has filled something 

 of a vacuum in the area of biogeographic reconstruction. 



My present purpose is to identify some of the problems that 

 appear important in the terrestrial ecology and biogeography of 

 North America during the late Pleistocene. This project follows the 

 logical principle advocated by Deevey (1949) that students of 

 plant and animal distributions are obligated to consider the Pleisto- 

 cene before working backward. To do so does not mean ignoring or 

 neglecting the instructive record of Tertiary environment and life. 

 The adopted course, however, is based on the belief that Pleistocene 

 climatic change was not confined to the glacial border. Until 

 proved otherwise, the more useful working hypothesis is that 



' Contribution No. 9 of the Program in Geochronology, University of Arizona. 



375 



