Geomorphic Surfaces and Soils in the Black Creek Valley, Johnston County, North Carolina1
- E. E. Gamble,
- R. B. Daniels and
- W. D. Nettleton2
The Black Creek Valley in the dissected upper Coastal Plain is a complex of geomorphic surfaces that ranges in age from Pliocene to Recent. Soils on the Pliocene surfaces are on the interstream divides and on old terrace remnants within the valley. They are classed as Paleudults. These soils are formed in relatively uniform sediments, have sola 2–4 m thick, little or no B horizon structure, and few clay films in the upper B horizon. Discontinuous phase plinthite is found in the middle B horizon. These soils have uniform profile characteristics, are easily mapped, and the delineations have few inclusions.
The soils on the late Pleistocene to Recent valley-side slopes and low terraces have sola less than 1.25 m thick and are classed as Hapludults. There is much variation in A2 horizon thickness, B horizon color, and texture. This arises from the variation of the sediments outcropping on the valley sides. Further variability is caused by Recent valley-side alluvium that has irregular distribution and unpredictable thickness. Regardless of their variability, these soils all have weak to moderate B horizon structure, common clay skins on ped faces, and no plinthite. They are best mapped as complexes because of their variability. A delineation contains many inclusions.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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