A chronostratigraphic re-evaluation of the Tusayan Dunes, Moenkopi Plateau and southern Ward Terrace, Northeastern Arizona

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Abstract
Optical dating of the Tusayan Dunes of northeastern Arizona indicates that at least three distinct late Holocene phases of aeolian reactivation took place in the area, partly upon pre-existing, Pleistocene linear dunes. The reactivation phases occurred approximately 400, 2000–3000, and 4700 years ago. We hypothesize that the large discrepancy in age between the basal and upper parts of the linear dunes relates to the reactivation of only the linear ridge crests, leaving an undisturbed plinth. If so, linear dunes hold a potential for preserving long-term records of successive aeolian depositions. Evidence of regional alluvial-fill episodes and palaeoclimatic data for the area indicate that sediment supply, in addition to aridity and effective sand-transporting winds, is a key factor in determining the timing of aeolian reactivation.