Two buried soils have been identified in early and middle Holocene sediments at the Lubbock Lake site, a well-stratified archeological locality in Yellowhouse Draw, Lubbock County, Texas. The Firstview Soil formed in organic-rich lacustrine and sandy eolian sediments deposited from 11,000 to 8,500 yr B.P. The soil developed from 8,500 to about 6,300 yr B.P. and exhibits O-A-C and A-C profiles. The lacustrine facies (found along the valley axis) has a relatively high organic matter content, contains abundant silicified root remains, and commonly exhibits a gley horizon immediately below the A horizon, indicating that the soil formed in a marsh with the water table at or just below the surface. The soil becomes coarser-grained, better-drained, and weakly calcareous toward the valley margin, reflecting the facies change in parent material. The overlying Yellowhouse Soil formed in highly calcareous lacustrine sediments (along the valley axis) and sandy eolian material (along the valley margin), with deposition and pedogenesis occurring between 6,300 and 5,000 yr B.P. The soil exhibits A-C and sometimes A-B-C profiles. The relatively high organic matter content of the A horizon and minimal leaching of carbonate in the C horizon of the valley-axis facies suggest that the water table was high during pedogenesis. The valley-margin facies of the soil exhibits some evidence of clay illuviation. The contrasting field and chemical characteristics of the valley-axis facies of the two soils and the sedimentological data indicate a sudden change in the water geochemistry and local environmental change. Soils with morphologies, parent material, and age similar to that of the Firstview Soil are not common in valley fills on the Southern High Plains, whereas soils similar to the Yellowhouse Soil are widespread. These data indicate a regional climatic change toward conditions of increased eolian activity, reduced effective moisture, and possibly warmer temperatures.
ASJC Scopus subject areas
- Earth-Surface Processes