Morphology of Late Holocene Soils at the Lubbock Lake Archeological Site, Texas

Abstract

AbstractThree soils have been identified in late Holocene deposits at the Lubbock Lake site, a well‐ stratified archaeological locality on the Southern High Plains. The soils have been informally named and their ages firmly established by radiocarbon dating. The soils formed in quartzose, sandy loam to sandy clay loam, dominantly eolian sediments with illite and mixed‐layer illite‐smectite clay mineralogy and lesser amounts of smectite and kaolinite. The Lubbock Lake Soil formed in material deposited between 5000 and 4500 yr BP and has had 4500 yr to form or, where buried, 3500 yr. The soils exhibits mollic and ochric (buried) epipedons, cambic and argillic and, in some positions, a partically gleyed B horizon, and Stage I or II, often multiple, calcic horizons. It is classified as either a Calciustoll, Haplustoll, Haplustalf, or Ustochrept. The Apache Soil formed in sediments deposited from 800 to 450 yr BP and is 450 yr old where not buried and 200 yr old where buried. The soil usually has a mollic epipedon but in some buried situations it is ochric. The B horizon is normally cambic but sometimes qualifies as argillic. Secondary carbonate accumulation, sometimes qualifying as calcic, commonly attains a Stage I morphology. The Apache Soil is classified as either an Ustochrept, Haplustoll, Calciustoll or possibly minimally developed Haplustalfs. The Singer Soil formed in sediments deposited from 250 and 100 yr. BP, allowing 100 yr for soil formation. The soil has an ochric epipedon and either a C, Bw, or a cambic horizon. Weak Stage I carbonate horizons are common but never qualify as calcic. The Singer Soil is classified as an Ustorthent. These three soils define a chronosequence that will allow a study of pedogenesis in Holocene sediments in a semiarid environment. The discovery of soils elsewhere on the southern High Plains of similar age, parent material, and landscape setting to the Lubbock Lake Soil and possibly the two younger soils, indicate that these late Holocene soils will be useful stratigraphic markers and dating tools.