INTERPRETATION OF LAND FORMS 123 



other will you arrive at a knowledge of things." But 

 the thorough-going "diluvialist" who believed that a 

 million species of animals could occupy a 450-foot 

 Ark, but not that pebbles weathered from rock or that 

 rivers erode, had no use for his powers of observation. 



Sporadic germs of a science of land forms scattered 

 through the literature of the seventeenth and eighteenth 

 centuries found an unfavorable environment and pro- 

 duced inconspicuous growths. Even their sponsors did 

 little to cultivate them. Steno (1631-1687) mildly sug- 

 gested that surface sculpturing, particularly on a small 

 scale, is largely the work of running water, and Guettard 

 (1715-1786), a truly great mind, grasped the fundamental 

 principles of denudation and successfully entombed his 

 views as well as his reputation in scores of books and vol- 

 umes of cumbrous diffuse writing. 



At the beginning of the nineteenth century a sufficient 

 body of principles had been established to justify the 

 recognition of an earth science, geology, and the 195 vol- 

 umes of the Journal thus far published carry a large part 

 of the material which has won approval for the new 

 science and given prominence to American thought. 

 From the pages in the Journal, the progress of geology 

 may be illustrated by tracing the fluctuation in the devel- 

 opment of fact and theory as relates to valleys and gla- 

 cial features, the subjects to which this chapter is devoted. 



The Interpretation of Valleys. 

 The Pioneers. 



Desmarest (1725-1815) might be styled the father of 

 physiography. By concrete examples and sound induc- 

 tion 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 his- 

 tory of a landscape through its successive stages on the 

 basis of known causes. His methods and reasoning are 

 practically identical with those of Button 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. 2 The teachings of 

 Desmarest were strengthened and expanded by DeSaus- 



