Stratigraphy and Parent Material Relationships of Red Substratum Soils on the Allegheny Plateau

Red (2.5YR 4/6 to 4/8) and brownish yellow (10YR 6/6 to 6/8) subsoils were studied in the Sweden soils (tentative classification: fine-loamy, mixed, frigid Typic Hapludult) and the Dekalb-Cook-port-Nolo catena (loamy-skeletal, mixed, frigid Typic Dystrochrept, coarse-loamy, mixed, frigid Typic Fragiuquult, and coarse-loamy, mixed, frigid Typic Fragiaquult, respectively) on the unglaciated Allegheny Plateau. The red subsoil horizons are interpreted to be a pre-Wisconsinan paleosol formed in colluvium and residuum that were derived from acid sandstones of the Huntley Mountain and Pottsville Formations mantling the plateau summits. The paleosol horizons are buried by 1 to 2 m of brown, sandy colluvium of Wisconsinan age, but can be clearly distinguished by an increase of clay content, higher free iron oxide content, extensive weathering and rubification of sandstone rock fragments, and strongly expressed argillic horizons. In the Cookport and Nolo soils, the paleosol occurs beneath a fragipan, with a stoneline marking the surface of the paleosol. The paleosol has been truncated, since A and E horizons are not preserved in the profiles. The paleosol horizons vary in color and iron oxide mineralogy across the catena sequence. The paleosol horizons of the Sweden and Cookport soils morphologically resemble pre-Wisconsinan till-derived soils of the Susquehanna Valley. From this study, only one pre-Wisconsinan paleosol could be identified in the periglacial deposits of the Allegheny Plateau; it has been tentatively correlated with the Sangamon Interglacial. Three separate colluvial deposits were recognized on the plateau summits. Contribution from the Dep. of Agronomy, the Pennsylvania State Univ. Paper no. 7990 of the Journal Series of the Pennsylvania Agric. Exp. Stn., University Park.