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Few workers have reported previously on features of ancient valleys in western Nebraska. Six sites in the southern Nebraska Panhandle, ranging in age from Oligocene to Middle to Late Pleistocene, illustrate the characteristics and variability of Cenozoic paleovalleys. The dimensions of these paleovalleys vary from less than 0.1 km to more than 1.0 km in width and from less than 1.0 km to more than 100 km in length. Relief is as much as 35 m in outcrop. Four of the examples have valley sides that are nearly vertical. Potholes and other scour features occur at one site. Remnants of tributaries are present at a second site. A third locality has bedrock-incised channels that are similar to features produced experimentally in flumes.
The fills in these paleovalleys include colluviumlike sediments along valley sides and flood plain and channel silts, sands, and gravels derived from local and distant sources. Locally derived boulders more than 1 m in diameter occur in fills close to the sides of some of these valleys.