Quaternary history and landscape development of some tributary drainage basins north of Chaco River
Larry N. Smith
Topography in the northeastern tributary watersheds to the Chaco River is characterized by either subplanar alluvial surfaces or badland topography. The Alamo and Ah-shi-sle-pah watersheds contain extensive badland topography, whereas the Coal Creek and Tsaya basins are characterized by broad alluvial surfaces. Correlation of geomorphic surfaces between the drainage basins allows comparison of the responses each basin had to baselevel falls. The two oldest geomorphic surfaces extended beyond present-day drainage divides; drainage divides and the resulting proportions of sandstone and mudrock bedrock lithologies were inherited during the incision of these surfaces. Three younger geomorphic surfaces formed during periodic downcutting of the drainages. The character of drainage-basin evolution during regional dissection is a function of initial basin shape, relative relief of the drainage basin, distribution and proportion of mudrock to sandstone bedrock units, and distribution and preservation of sandy surficial deposits. Sandstone outcrop, elongate low-relief morphology, and accumulation of extensive sandy surficial deposits reduced sediment yield and downcutting in the Tsaya basin. Extensive badland development in the Ah-shi-sle-pah basin was augmented by the dominance of mudrock bedrock in the basin, a high drainage-basin relief ratio, and minimal preservation of sandy surficial deposits.
- Smith, Larry N., 1992, Quaternary history and landscape development of some tributary drainage basins north of Chaco River, in: San Juan Basin IV, Lucas, Spencer, G.; Kues, Barry S.; Williamson, Thomas E.; Hunt, Adrian P., New Mexico Geological Society, Guidebook, 43rd Field Conference, pp. 391-398.