[en] Results of the Tascotal survey area portion of the detailed geochemical survey for Trans-Pecos, Texas are reported. Field and laboratory data are presented for 337 groundwater and 611 stream sediment samples. Statistical and areal distributions of uranium and possible uranium-related variables are given. A generalized geologic map of the survey area is provided, and pertinent geologic factors which may be of significance in evaluating the potential for uranium mineralization are briefly discussed. Groundwaters containing greater than or equal to 80.0 ppB uranium were detected in three areas largely producing from acidic volcanoclastics in the south central portion of the survey area. High specific conductance and an association of lithium, selenium, and sodium were observed in these areas of anomalously high uranium. High uranium/specific conductance, uranium/boron, and uranium/sulfate ratios are also associated with areas of the highest uranium concentrations. Alkalinities in these areas were noted to be highly variable over short distances within the same hydrologic unit. Stream sediments containing greater than or equal to 2.57 ppM soluble uranium are located in the southwestern and the north and south central portions of the survey area. High U-FL/U-NT and low thorium/U-NT values are observed with sediments derived from acidic volcanics in the southern portions of the survey area. In areas of anomalously high uranium, an association of above background concentrations of thorium, lithium, potassium, beryllium, and zirconium were noted. In view of these data, areas containing the Buck Hill Volcanic Series, the Mitchell Mesa, and Tascotal Formations provide the best possibilities of an economical uranium deposit