_The Interpretation of Valleys._ _The Pioneers._ Desmarest (1725–1815) might be styled the father of physiography. By concrete examples and sound induction he established (1774) the doctrine that the valleys of central France are formed by the streams which occupy them. He also made the first attempt to trace the history of a landscape through its successive stages on the basis of known causes. His methods and reasoning are practically identical with those of Dutton working in the ancient lavas of New Mexico; and Whitney’s description of the Table Mountains of California might well have appeared in Desmarest’s memoirs.[5] The teachings of Desmarest were strengthened and expanded by DeSaussure (1740–1799), the sponsor for the term, “Geology,” (1779) who saw in the intimate relation of Alpine streams and valleys the evidence of erosion by running water (1786). The work of these acknowledged leaders of geological thought attracted singularly little attention on the Continent, and Lamarck’s volume on denudation (Hydrogéologie), which appeared in 1802, although an important contribution, sank out of sight. But the seed of the French school found fertile ground in Edinburgh, the center of the geological world during the first quarter of the nineteenth century. Hutton’s “Theory of the Earth, with Proofs and Illustrations,” in which the guidance of DeSaussure and Desmarest is gratefully acknowledged, appeared in 1795. The original publication aroused only local interest, but when placed in attractive form by Playfair’s “Illustrations of the Huttonian Theory” (1802), the problem of the origin and development of land forms assumed a commanding position in geological thought. Hutton was peculiarly fortunate in his environment. He had the support and assistance of a group of able scientific colleagues as well as the bitter opposition of Jameson and of the defenders of orthodoxy. His views were discussed in scientific publications and found their way to literary and theological journals. Hutton’s conception of the processes of land sculpture—slow upheaving and slow degradation of mountains, differential weathering, and the carving of valleys by streams—has a very modern aspect. Playfair’s book would scarcely be out of place in a twentieth century class room. The following paragraphs are quoted from it:[6] “... A river, of which the course is both serpentine and deeply excavated in the rock, is among the phenomena, by which the slow waste of the land, and also the cause of that waste, are most directly pointed out.