Sedimentation, soil stratigraphy, and age of the Blackwater Draw Formation

The Southern High Plains of northwestern Texas and eastern New Mexico is mantled by a vast (more than 100 000 km²) sheet of Quaternary/eolian sediment locally as thick as 30 m. These sediments, which compose the Blackwater Draw Formation, generally fine from southwest to northeast, indicating the source area to be the Pecos river valley. As many as six well-developed buried soils, similar to the surface soil, occur in the formation and indicate episodic sedimentation separated by long periods of landscape stability. Presence of the 0.62-Ma-old Lava Creek B ash and the 1.4-Ma-old Guaje ash in the Blackwater Draw Formation shows that it accumulated throughout most of the Quaternary Period. -from Author