Paleosols of the Llano Estacada.

There are several paleo-landscapes associated with the Llano Estacada. The soils typically have thick Mollic or Ochric epipedon with well a developed argillic horizon. The soils also have a stage 4 to 6 petrocalcic horizon. It appears that some of these soils have developed within or from the petrocalcic horizons. The soils that have an Ochric epipedon classify as Paleustalfs, but similar soils with a Mollic epipedon do not classify as Paleustolls. Examples of such soils will be presented and proposed classification for the Mollisols will be presented. Chemical, micromorphology and mineralogy of several such paleosols will be presented. For example sepiolite and attapulgite is common in many of the petrocalcic horizons. The soils are not typically associated with nor influenced by lacustrine sediments. Possible source includes in situ formation from the weathering of smectitic minerals, but direct evidence is difficult.