Surface Denudation of the Gypsum Plain, West Texas and Southeastern New Mexico

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Conference Proceeding

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The Castile Formation crops out in Eddy County, New Mexico and Culberson County, Texas, covering more than 1500 square kilometers. The region contains more than ten thousand reported surficial karst features, including closed depressions, sinking streams and caves, with surface karren dominating exposed rock surfaces. A standard gypsum tablet study was conducted over the region for two years to delineate the rate of surface denudation across Castile outcrops of the Gypsum Plain. Fifty five sites were monitored with triplicate gypsum tabs that were deployed for four month intervals. Rates of surface denudation were calculated based on mass loss of gypsum tabs and compared with weather data collected at three control locations within the study area. Surface denudation rates exceeded 50 centimeters per thousand years (cm/ka) in some areas with an average denudation rate of more than 30 cm/ka. Greatest rates of denudation occurred during late summer and fall, in association with the monsoon season, while the lowest rates occurred during late spring and early summer. The Castile Formation is bounded by the Guadalupe Mountains to the northwest, Delaware Mountains and Apache Mountains to the west and southwest, Glass Mountains to the southeast and Rustler Hills to the east; orographic effects of these features contribute to a complex pattern of surface denudation associated with shifting seasonal climate patterns. True denudation within the gypsum plain varies from models developed from standard tablet studies due to variations in surficial deposits; however, standard tablet studies provide a quantitative measurement of the rate at which the gypsum plain is evolving.


Shaw, M.G., Stafford, K.W., and Tate, B.P., 2011. Surface denudation of the Gypsum Plain, west Texas and southeastern New Mexico. U.S. Geological Survey Karst Interest Group Proceedings, Fayetteville Arkansas, April 26-29, 2011, Scientific Investigations Report 2011-5031, U.S. Geological Survey, Reston, VA, p. 104-112.



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