2004 Denver Annual Meeting (November 7–10, 2004)

Paper No. 19
Presentation Time: 1:30 PM-5:30 PM


WILKINS, David, Geosciences, Boise State Univ, 1910 University Drive, Boise, ID 83725, dwilkins@boisestate.edu

The Coral Pink Sand Dunes is the site of ongoing research into changes in the aeolian system state of a small active dune field. Repeat aerial and ground photography of the dune field use photos acquired in 1937 and 1960 to compare features observed in those scenes with more recent photos acquired in 1997 and 2003. The paired ground-based photos record an increase in vegetation and an expansion of stabilized dune surfaces in the image foreground from 1937 to 2003. Similar observations are made from the aerial photos acquired in 1960 and 1997 – these also indicate contraction of the active dune field in response to expanding and encroaching vegetation-stabilized dune margins.

Using the model put forward by Kocurek and Lancaster (1999), the dune field is experiencing a change in system sediment state. Given the compact nature of the dune field, it is hypothesized to have formed through a contemporaneous influx in the middle to late Holocene from a source wash to the west. As that influx diminished, lagged influx from sediment stored at the southern end of Sand Wash Canyon supported further dune development and activity. Since 1960, however, precipitation in the region has been more variable from the previous 30 years — the wet years have seen an increase in amplitude while the dry years have been as dry as before. This has resulted in a change to an availability limited sediment state in the dune field and a change in the number and distribution of dunes as nearest neighbor analysis of the dune crests shows the dunes have become more clustered since 1960. These data indicate dune activity may be sensitive to minor changes in climate.