Following their discovery in the Colorado Plateau Province, denudation surfaces were recognized on the Atlantic slope and discussed by McGee (1888),[26] in a paper notable for the demonstration of the use of physiographic methods and criteria in the solution of stratigraphic problems. Davis (1889)[27] described the upland of southern New England developed during Cretaceous time, introducing the term “peneplain,” “a nearly featureless plain.” The short-lived opposition to the theory of peneplanation indicates that in America at least the idea needed only formulation to insure acceptance. It is interesting to note that surfaces now classed as peneplains were fully described by Percival (1842),[28] who assigned them to structure, and by Kerr (1880),[29] who considered glaciers the agent. In Europe “plains of denudation” have been clearly recognized by Ramsay (1846), Jukes (1862), A. Geikie (1865), Foster and Topley (1865), Maw (1866), Wynne (1867), Whitaker (1867), Macintosh (1869), Green (1882), Richthofen (1882), but all of them were looked upon as products of marine work, and writers of more recent date in England seem reluctant to give a subordinate place to the erosive power of waves. Americans, on the other hand, have been thinking in terms of rivers, and the great contribution of the American school is not that peneplains exist, but that they are the result of normal subaërial erosion. More precise field methods during the past decade have revealed the fact that no one agent is responsible for the land forms classed as peneplains; that not only rivers and ocean, but ice, wind, structure, and topographic position must be taken into account. The recognition of rivers as valley-makers and of the final result of stream work necessarily preceded an analysis of the process of subaërial erosion. The first and last terms were known, the intermediate terms and the sequence remained to be established. A significant contribution to this problem was made by Jukes (1862).[34] “... I believe that the lateral valleys are those which were first formed by the drainage running directly from the crests of the chains, the longitudinal ones being subsequently elaborated along the strike of the softer or more erodable beds exposed on the flanks of those chains.” Powell’s discussion of antecedent and consequent drainage (1875) and Gilbert’s chapter on land sculpture in the Henry Mountain report (1880) are classics, and McGee’s contribution[30] contains significant suggestions, but the master papers are by Davis,[31] who introduces an analysis of land forms based on structure and age by the statement: