The Upper Pennsylvanian and Lower Permian stratigraphic sequence in Canyonlands National Park contains about 40 flat-topped eolian sand bodies. Rhizoliths, burrows, and traces of former evaporites abound at the tops of these tabular genetic units. Upper surfaces of units were created by eolian deflation to the level of the groundwater table. Analysis of cross-stratification reveals that sands accumulated via migration and climb of relatively small dunes. Brief episodes of sand accumulation were triggered by regression and were terminated when upwind sand supplies were depleted. Upper surfaces of genetic units are diastems and represent much more geologic time than the rocks themselves.