Parent materials and stratigraphy of a doline in the Valley and Ridge Province

A variety of contrasting parent materials have been preserved within a ridgetop doline in the Valley and Ridge Province of eastern Tennessee. These materials, related to current and past slope processes, were differentiated based on morphologic properties. Matrix color and texture and the nature and content of chert fragments were particularly important in this discrimination. The doline rim was host to several distinct parent materials, including: (i) Copper Ridge residuum, (ii) mixed ancient alluvium and colluvium, and (iii) ancient toeslope colluvium. Mass wasting and fluvial processes emplaced these “ancient” materials, which currently have no source area, during the late Pliocene or early Pleistocene. The doline sideslopes contain parent materials composed of stacked layers of cherty colluvium that are late Pleistocene and Holocene in age. These colluvial deposits were derived from upslope residual and “ancient” toeslope colluvial soils via recent mass wasting. Parent materials in the doline center have a completely different morphologic character than upslope deposits. A silty material, possibly late-Wisconsinan loess eroded into this doline during the Holocene, is devoid of chert fragments. These materials have been sorted and deposited by active slope wash and originated from either locally derived loess deposited on upper doline sideslopes, the A and E horizons of soils located upslope, or both. At 1.3 m these silty materials rest directly on a buried A horizon (2Ab) that has been radiocarbon dated to 9170 ± 140 years before present (YBP). Beneath this buried surface, alternating layers of thick noncherty and thin cherty silt loam materials represent cycles of late Quaternary landscape stability and instability.