Poster Number 27
See more from this Division: Joint Sessions
See more from this Session: Desert Pavements and Vesicular A Horizons (Posters)
Abstract:
Surface characteristics studied included: (1) the abundance of overturned clasts , (2) exposure of underlying AV horizon, (3) clast size, and (4) roughness at the 1-10cm scale. Alluvial fans near Yuma, AZ were studied with ages ranging ~10-25 ka (2A) and ~125-400 ka (3B). Grid point-counts were made to characterize the size distribution as well as frequency of overturned clasts. High-resolution spectral measurements were made at a range of heights above the surface (1-500cm) to determine the scale of spectral variability.
Approximately 20-40% of the pavement clasts had been overturned at some time after varnish formation. The older the fan, the greater the potential for increased rubification (overturned clasts) exposed on the surface. Also, younger fans have larger mean clast sizes (higher variability) resulting in an increase of cast shadows, and a higher spatial scale of variability 60-80 cm (vs 10-20 cm for the 3B surface). These result in different spectral signatures that may be used to map different age pavements using remote sensing data.
See more from this Division: Joint Sessions
See more from this Session: Desert Pavements and Vesicular A Horizons (Posters)