Abstract
Introduction THE play of meteoric agents on the surface of the land is universal, and there is a constant tendency to the production of the forms characteristic of their action. All other forms are of the nature of exceptions, and attract the attention of the observer as requiring explanation. The shapes wrought by atmospheric erosion are simple and symmetric, and need but to be enumerated to be recognised as the normal elements of the sculpture of the land. Along each drainage line there is a gradual and gradually increasing ascent from mouth to source, and this law of increasing acclivity applies to all branches as well as to the main stem. Between each pair of adjacent drainage lines is a ridge or hill standing about midway and rounded at the top. Wherever two ridges join there is a summit higher than the adjacent portion of either ridge; and the highest summits of all are those which, measuring along lines of drainage, are most remote from the ocean. The crests of the ridges are not horizontal, but undulate from summit to summit. There are no sharp contrasts of slope; the concave profiles of the drainage lines change their inclination little by little, and they merge by a gradual transition in the convex profiles of the crests and summits. The system of slopes thus succinctly indicated is established by atmospheric erosion under the general law of the interdependence of parts. It is the system which opposes the maximum resistance to the erosive agents.
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References
From a paper by Mr. G. K. Gilbert in the "Fifth Annual Report of the Geological Survey of the United States for 1883–84." (Washington, 1885.)
"Leçons de géologie pratique"; tome premier; septième leçon, "Leviées de sable et de galet," pp. 221–52.
"Sul moto ondoso del mare e su le correnti di esso specialmente su quelle littorali pel comm." Alessandro Cialdi. Roma, 1866.
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The Topographic Features of Lake Shores 1 . Nature 34, 269–270 (1886). https://doi.org/10.1038/034269a0
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DOI: https://doi.org/10.1038/034269a0