PHYVSIOGRAPHIC EXTENSION OF UNITED STATES 163 
been studied in detail, but it is supported in a general way by 
numerous geologists who have studied portions of the northwest 
coast of North America. Dawson,’ Ransome,’ and Clapp’ tenta- 
tively place the mountains of Vancouver and Queen Charlotte 
islands in the province with the Coast Ranges, and Willis and Smith* 
are definitely committed to the idea. Bancroft’ says that the 
system of the Coast Ranges is continued northward along the coast 
of Alaska in the mountainous islands of the Alexander Archipelago, 
and that these islands express the probable continuity of a range 
that formerly bridged all gaps existing between the Olympic 
Mountains of Washington and the St. Elias group of Alaska. 
Brooks® continues the system northward, connecting the Alexander 
Archipelago with the St. Elias group and that group, through the 
Chugach Mountains, with the mountains of the Kenai Peninsula 
and Kodiak Island. 
The four more or less dissimilar divisions of the Coast Ranges 
in the United States have this in common—they represent dissected 
peneplains. Topographically they consist of individual ridges, and, 
excepting the Klamath Mountains, they follow the contour of the 
coast with considerable parallelism between them. The tops of 
the ridges are generally flat and the upland has a rolling, mature 
character, with peaks rising here and there above the general level. 
These peaks are residuals or monadnocks that resisted erosion 
during the first cycle. Diastrophism and vulcanism have con- 
tributed something to the present topography, but, though locally 
prominent factors, they have been generally subordinate to erosion. 
The drainage of the Coast Ranges is a reliable index to the 
causes that have produced the present topography. The larger 
westward-flowing streams, that is, those which cut across the ranges 
to empty their waters directly into the Pacific, are without excep- 
tion antecedent. They have preserved the courses which they 
tG. M. Dawson, Bull. Geol. Soc. Am., XII, 61. 
2 F, L. Ransome in Problems of American Geology (Yale University Press), p. 359. 
3C. H. Clapp, Geol. Survey Canada, Guide Book No. 8, Part III, p. 280. 
4 Bailey Willis and G. O. Smith, U.S. Geol. Survey, Folio 54. 
5 J. A. Bancroft, Geol. Survey Canada, Mem. 23, p. 18. 
5A. H. Brooks, U.S. Geol. Survey, Prof. Paper 45, pp. 27-42. 
