Memoir 186 Stratigraphy and Paleoenvironments of Late Quaternary Valley Fills on the Southern High Plains

Abstract

The dry valleys or "draws" of the Southern High Plains (in northwestern Texas and eastern New Mexico), headwater tributaries of the Red, Brazos, and Colorado Rivers, contain late Quaternary sediments that accumulated over the past 12,000+ years. A few previous, scattered stratigraphic investigations of the draws strongly suggested synchroneity in late Quaternary depositional and soil-forming events and regionwide environmental changes. This volume reports on a systematic study conducted from 1988 to 1992 aimed at better documenting the late Quaternary geomorphic evolution and stratigraphic record of the draws, investigating their paleoenvironmental significance, and determining whether there were synchronous, regional, geomorphic, and soil-forming events in these dry valleys. The work focused on the past 12,000 years because most of the valley fill dates to this time, but older deposits occur locally and were investigated as well.Most of the research was in Running Water, Blackwater, and Yellowhouse Draws (tributaries of the Brazos River), and Sulphur and Mustang Draws (tributaries of the Colorado River), with additional coring on McKenzie, Seminole, Monument, Monahans, and Midland Draws (all tributaries of the Colorado). Approximately 410 cores and exposures at 110 localities were studied. Samples collected from these sections underwent a variety of sedimentological and pedological analyses. Age control is provided by 53 new radiocarbon ages and scores of ages already available from several archaeological sites. Efforts also were made to recover pollen, phytoliths, molluscs, insects, ostracodes, and vertebrate faunal remains, and stable-carbon isotope trends were determined for four sites.Several geomorphic processes and features exerted some influence on late Quaternary drainage development. Quaternary jointing and subsidence controlled drainage patterns around the margins of the Southern High Plains, particularly on the northern edge (Red River system). Major segments of most draws roughly parallel paleodrainages on the buried Tertiary erosion surface. Factors influencing the older drainage likely influenced development of the present drainage. Segments of Running Water, Blackwater, and Sulphur Draws also probably follow ancient drainageways that once connected the plains with the mountains to the west. Most of the draws intersect paleolake basins or extant lake bains, which may have exerted control on drainage development by directing water to paleotopographic lows or by overtopping and interconnection of basins.The last phase of incision by the draws began after 20,000 yr B.P. but before 12,000 yr B.P. and aggradation began ca. 12,000 yr B.P. Valley fill predating this final incision is common locally and includes alluvial sand and gravel (stratum A) and lacustrine carbonate (stratum B). Eolian sheet sand with strong pedogenic modification (stratum C) accumulated on the uplands adjacent to some reaches during valley aggradation. on July 20, 2015 memoirs.gsapubs.org Downloaded from 2V. T. HollidayAfter ca. 12...

Mineralogical maturity in dunefields of North America, Africa and Australia

“…However, this mechanism would require not only long periods of dune stability, but also relatively humid paleoclimates, such that chemical weathering would proceed at a rate rapid enough to deplete feldspars over a Quaternary time scale. Long-term paleoclimate records from nearby loess-paleosol sequences in Colorado and Nebraska and the morphology of paleosols in the Blackwater Draw Formation (which spans the past 1.4 Ma) indicate that the Great Plains region has probably been semiarid to subhumid for a long time (Holliday, 1989(Holliday, , 1995Muhs et al, 1999).…”

Human (Clovis)–gomphothere (Cuvieroniussp.) association ∼13,390 calibrated yBP in Sonora, Mexico

“…Due to the extensive erosion, the mechanism causing the impoundment of stratum 4 is unknown. The strata 3-4 sequence is very similar in lithology and chronology (discussed below) to the Paleoindian geoarchaeology at the Lubbock Lake and Clovis sites (7-10) and other localities on the Southern High Plains (10,11). No weathering was observed in upper stratum 3 and the weathering characteristics of the bone are similar both where it was buried by upper stratum 3B and where it was buried by stratum 4.…”

The lithology of Ogallala gravels and hunter‐gatherer procurement strategies along the Southern High Plains eastern escarpment of Texas, USA

“…A high-density and more predictable high-quality water sources could be found along this ecotonal edge (Brune, 1981;Holliday, 1995). The escarpment edge would have provided natural shelter, wood occurred in higher abundance, and a higher biological diversity existed in flora and fauna.…”