Recent studies of the cores from four drill holes at the White Sands dune field in New Mexico demonstrated that the eolian sand body below the present active dunes ranges in thickness from 23 to 34 ft in the area tested. It consists of one to two older generations of dune and associated interdune deposits, which rest on playa and fluvial deposits. Relatively thick sheets of clean, well-sorted dune sand are separated from one another by thin zones of darker colored interdune deposits. In vertical sections of test trenches and in cores, these interdune deposits appear as thin zones of tan or buff, poorly sorted, subparallel strata between relatively thick units of white cross-stratified sand. The interdune deposits are buried by the advancing foresets of the encroaching dunes and their thickness is limited by the time of exposure. The subsurface dune deposits are relatively thin as compared to the active surface dunes. This difference in thickness apparently results from the beveling or truncation of dunes by the migration of interdune areas.
