THE PHYSICAL GEOGRAPHY OF THE LANDS. 165 



for publication in the Quarterly Journal of the Geological Society, of 

 London, but had to find a place in the more modest Geological Maga- 

 zine (1867), whose pages it now honors. So signal indeed was this 

 victory that, in later years, the destructive work of the sea has been 

 not infrequently underrated in the almost exclusive attention given to 

 land sculpture by subaerial agencies. Truly, the sea does not erode val- 

 leys; it does not wear out narrow lowlands of irregular form between 

 enclosing uplands, as was maintained by some of the most pronounced 

 marinists in the middle of the century; but it certainly does attack 

 continental borders in a most vigorous fashion, and many are the 

 littoral forms that must be ascribed to its work, as may be learned from 

 Richthofen's admirable Tiihrer fur Forschungsreisende' (1886). As 

 this problem can not be further considered here, the reader may be 

 at once referred to the most general discussion of the subject that has 

 yet appeared, in an essay on 'Shoreline Topography* recently pub- 

 lished by F. P. Gulliver.* 



At about the time when the subaerial origin of valleys and escarp- 

 ments was being established in England, the explorations and surveys 

 of our western territories were undertaken, and a flood of physio- 

 graphic light came from them. One of the earliest and most important 

 of the many lessons of the West was that Playfair's law obtained even 

 in the case of the Grand canyon of the Colorado, which was visited 

 by the Ives expedition in 1858. Newberry, the geologist of the ex- 

 pedition, concluded that both the deep and fissure-like canyon and the 

 broader valleys enclosed by cliff-like walls "belong to a vast system 

 of erosion, and are wholly due to the action of water." Although he 

 bore the possibility of fractures constantly in mind and examined the 

 structure of the canyons with all possible care, he "everywhere found 

 evidence of the exclusive action of water in their formation." This 

 conclusion has, since then, been amply confirmed by Powell and But- 

 ton, although these later observers might attribute a significant share 

 of the recession of cliffs in arid regions to wind action. In a later 

 decade, Heim demonstrated that the valleys of the Alps were not 

 explicable as the result of mountain deformation, and that they found 

 explanation only in river erosion. By such studies as these, of which 

 many examples could be given, the competence of rivers to carve even 

 the deepest valleys has been fully established; yet so difficult is it to 

 dislodge old-fashioned belief that Sir A. Geikie felt it necessary to 

 devote two chapters in his admirable 'Scenery of Scotland' (1887) to 

 prove that the bens of the Highlands were not so many individual 

 upheavals, but that the glens were so many separate valleys of erosion; 

 and as able an observer as Prestwich, a warm advocate of the erosion 



* Proc. Amcr. Acad., Boston. 1899, 152-258. 



