| Colluvium is a transported parent material which covers about one-quarter of the land area in central Pennsylvania. However, soils formed in colluvium have not been adequately investigated. The first objective of this study was to ascertain the characteristics of colluvial deposits in the unglacial portion of the Ridge and Valley Province, while the second objective was to assess soil development, specifically, fragipan and argillic horizon formation.; Colluvial soils were investigated to depths of 3 to 4 m in footslope positions along four major ridges. Landforms observed included rock-armored solifluction lobes and terraces. On the basis of differences in color, texture, rock fragments, and clay-free and silt-free contents a parent material stratigraphy consisting of three upper brown layers (designated as the UBn1, UBn2, and UBn3 layers), a red layer (Rd layer), and an underlying lower brown layer (LBn layer) was proposed for colluvium in footslope positions. All of the UBn layers had 10YR to 7.5YR hues and had a combined thickness of 1 to 2 m. Most Rd layers were truncated in situ Pre-Wisconsinan paleosols that had 5YR 5/6 to 2.5YR 5/8 soil colors, highly weathered sandstone rock fragments (10R to 2.5YR hues), truncated, buried, and compacted paleoargillic horizons (with 10 to 12% argillans), and field-identified stone lines.; In the UBn layer there was a surficial argillic horizon that had 2.0 to 6.7% argillans, illuvial/eluvial horizon ratios for the total clay content of 1.2 to 2.4 and for the fine/total clay ratio of 1.2 to 3.5. These data indicated that the colluvial footslopes have been stable since Wisconsinan time. The landforms, paleosols, and degree of present-day soil development indicated that there have been multiple periods of colluviation associated with cold glacial environments that were interpreted with periods of landscape stability.; Fragipans were 1.5 to 2.5 m thick, occurred only in the UBn3 and Rd layers, and were morphologically best expressed in the UBn3. However, bulk density was greatest in the Rd layer, indicating that the denseness of colluvium was not due to fragipan genesis. |
