Monday, November 5, 2007
106-7
Soil Development and Soil-Landscape Relationships in the Presidio Bolson, Texas.
Susan Casby-Horton1, Nelson A. Rolong1, and B. L. Allen2. (1) USDA-NRCS, 101 South Main Street, Temple, TX 76501, (2) MS 42122, Texas Tech University, Texas Tech University, Plant, Soil Department, Lubbock, TX 79409-2122
Soil morphology in the Presidio Bolson in Trans-Pecos, Texas , shows increasing soil development (and soil age) with increasing elevation and closer proximity to the flanking Chinati Mountains . Basin fill parent sediments include coarse-grained fan alluvium on basin margins with gypsiferous mudstone and interbedded fine-grained sandstones in the basin center. Subsequent excavation of this bolson fill, corresponding to integration of the bolson into Rio Grande drainage, resulted in stepped, abandoned erosional surfaces. At least four geomorphic surfaces are present in the area. Soil-landscape relationships are strongly influenced by both the tectonic history of the basin and sedimentary facies distribution.