Vegetation history of the deserts of southwestern North America; The nature and timing of the late Wisconsin-Holocene transition

Publisher Website
Google Scholar
Abstract
The Southwest is a region of mountains and basins in the southwestern United States and northern Mexico. Four major deserts are found in rainshadows of the Sierra Madre Oriental and Occidental, which enclose the Mexican Plateau, and of the Rocky Mountains to the east and the Sierra Nevada/Transverse Ranges to the west. The climate of these now-arid regions during the Wisconsin was greatly modified, although North America’s continental glaciers were distant. The global thermal regimes and general circulation of the atmosphere were evident in advances and retreats of alpine glaciers, fluctuating lake levels, and changing vegetation. The climate of arid North America is especially sensitive to changes in the general circulation of the atmosphere because important climatic variables, including rainfall and freezing temperatures, reflect air masses imported from both north-temperate and subtropical regions. In this chapter we summarize the evidence for vegetational and climatic history for the last 22,000 yr in the Southwest, primarily from the fossil middens of packrats (Neotoma sp.)