Aerial photograph taking in the 1940s showing the Polvo site's setting in the Rio Grande valley. The site lies within the red circle on a high terrace overlooking the river. Just across the river in Mexico a wide band of gravel marks the dry streambed of a major tributary creek, Arroyo de Valle Nuevo (locally known as Arroyo de la Mula and Arroyo del Cañoucito). Most of its normal flow today is captured by dams and agricultural pumping upstream. In earlier times the arroyo would have been a more dependable source of water. The farmed areas are river floodplains (low terraces) with deep alluvial sediments. From Shackelford 1951. |