New Mexico Geological Society Annual Spring Meeting — Abstracts

The small dune field referred to as Los Medanos, located 25 miles southeast of Carlsbad, New Mexico, provides an excellent opportunity to observe the migration rates of eolian features. The field, covering approximately 0.6 km², consists of active transverse and parabolic sand dunes indicating consistent west-southwest winds. Barchan and barchanoid forms are less abundant. Eolian fornlations typically caused by more complex wind patterns, such as reversing, seif, or star dunes, are absent. Bare areas found among central interdune spaces demonstrate a limited amount of sand in relation to the amount potentially transported by local winds. Los Medanos is located adjacent to a much larger set of dunes stabilized by vegetation. These dune areas are likely sources for the active dunes.

Annual to semi-annual aerial photographs of Los Medanos since the early 1980s show that dunes are fomting and migrating in recent years. From 1990 to 1996, dune crests shifted west-southwest a total of 78 m over the 6-year period. Active perimeter dunes containing more vegetation move more slowly than formations in the center. Mesquite and other small trees, located sparsely throughout the field, develop roots from the trunk as they are buried by advancing dunes. As the dunes continue to migrate, exposing the vegetation, roots develop bark. The mesquite and other trees may be helpful in understanding dune movement beyond the photographic record.