Sand dunes at Monahans Sandhills State Park display a variety of dune forms that develop under a unique trimodal wind regime. Large expanses of unvegetated sand form akle dunes having reversing slip faces. Smaller dune forms in the park include wind-shadow, coppice, transverse, barchan, and parabolic dunes. Blowout dunes also occur in the heavily vegetated cover sands of the Pecos Plain surface. Seasonal wind regimes can be divided into three groups: summer, winter, and spring winds. Persistent summer winds from the south-southeast build long transverse dunes.