Paleoclimate
Van Devender and Spaulding and Spaulding et al. report that the well-documented pluvial epochs which occurred over much of the southwestern United States during the most-recent (Wisconsin) ice age may not have extended as far south as the Gran Desierto. It appears that the climatic regime of the past 150,000 years at this site has been one of gradually increasing aridity with current hyperarid conditions being firmly in place by at least 43,000 years ago.
As a minimum, it may be assumed that onshore coastal winds from the south were less important to sand movement when the Wisconsin shoreline was located 45 km seaward of its current position.
Read more about this topic: Gran Desierto De Altar