Holocene Soils in Eolian Sediments of Bailey County, Texas

Abstract Three Holocene geomorphic surfaces and their associated soils and sediments are recognized in sandhills of Bailey County, Texas. Fairview sediments are related to the activities of man since about 100 years B.P. The Muleshoe (100–4,000 years B.P.) and Longview (4,000–7,000 years B.P.) sediments accumulated as a result of erosion initiated by severe droughts in the Holocene. Typic Ustipsamments and Alfic Ustipsamments are the most common Holocene soils in the study area; Psammentic Haplustalfs also occur, but are less common. The Alfic Ustipsamments have two or more continuous clay bands and the Typic Ustipsamments do not. Clay bands occur sporadically in Muleshoe sediments, but continuously in Longview sediments. Argillic horizons and the Psammentic Haplustalfs occur in some of the Longview sediments and in all of the sediments next older than Longview, which may date from latest Pleistocene or earliest Holocene time. Muleshoe sediments 1‐ to 2‐m thick are underlain by buried argillic horizons in many places, and some soils in these areas have been classified elsewhere as Grossarenic Paleustalfs. Thus, some of the soils so classified actually consist in part of buried soils. Clay in the clay bands is thought to have been deposited from clay in suspension on slowing of downward movement of the wetting front. Some clay apparently moves through the upper bands at times of deeply penetrating moisture and then accumulates in bands beneath as the wetting front slows its downward movement. Lateral movement of soil water is also important in the thickening and lateral spread of some bands. Clay accumulation in the bands gradually decreases soil permeability through time, and clay starts to accumulate between bands as well as in them. Since latest Pleistocene or possibly earliest Holocene time, enough clay has accumulated between some of the bands that they are partially obscured.