Late‐Quarternary Paleoecology of the Cuatro Cienegas Basin, Coahuila, Mexico

Abstract

Two sediment cores drawn from springs in the Cuatro Cienegas Basin, a small desert valley in central Coahuila, yielded fossil pollen chronologies transgressing more than 30,000 radiocarbon years. Comparisons of modern pollen spectra from the basin floor with the fossil records indicate that vegetation ecologically equivalent, if not identical, to that now present has occupied the floor of the basin since mid—Wisconsin time. A highly—endemic fauna and a lack of geological evidence for large Pleistocene lakes in the area afford strong support for this interpretation, and suggest that aquatic and terrestrial habitats of the valley lowlands remained stable environments throughout the Quaternary, regardless of fluctuations in regional climate. Fossil arboreal and Compositae pollen sequences provide a means for making stratigraphic correlations between the cores, and are the first late—Quarternary palynoclimatic chronologies available from northeastern Mexico. Trends in those components of the fossil records indicate that regional climate was cooler and perhaps more moist during the last Pluvial than at present. It became progressively warmer and drier during late—Pluvial time, and approximated modern climate during the Holocene. Holocene Altithermal or Hypsithermal intervals were undetected, but may be obscured by gaps in the fossil records.