Palynology, flora and vegetation of Hovenweep National Monument : implications for aboriginal plant use on Cajon Mesa, Colorado and Utah

Abstract

Pollen analytical studies of late postglacial alluvial and cultural sediments from the Hovenweep National Monument area on Cajon Mesa in southwestern Colorado and southeastern Utah provide a basis for reconstruction of Late Quaternary vegetation and a record of cultural disturbances to past vegetational patterns. Late postglacial deposits from the period of about A.D. 900 to A.D. 1300 contain fossil pollen rain evidence suggesting higher levels of available moisture and more mesic plant environments, followed by more xerophytic conditions, as compared with the environment of today reflected in the modern pollen rain and present distribution of the flora and vegetation of Cajon Mesa. The fossil pollen records from the earlier part of the period imply a more moist environment than at present through evidence of an extension of northern mesa woodlands and mesic plant elements over a greater portion of the mesa. Pollen records toward the end of the period indicate a drying trend reflected by an implied wider distribution of more xerophytic vegetation throughout the mesa. The analysis of pollen samples from aboriginal sites of Basketmaker and Pueblo Period cultural context provide data indicating use of cultigen and certain noncultigen plant taxa by prehistoric inhabitants of the area. The on- and off-site distribution of the pollen data and disturbance to certain floral and vegetational elements suggest it may be possible to identify plant use sites of aboriginal man prior to excavation, by use of a strategy of pre-excavation sampling and interpretation of floral and vegetational disturbance patterns..