166. W. N. THAYER 
plateau immediately adjacent to the coast. This tract was eroded 
to the condition of a peneplain and later uplifted and dissected 
into its present form. Local subsidences following the uplift 
drowned the lower courses of certain master-valleys, notably those 
of the Sacramento and Columbia rivers. 
Although a large part of the Canadian division of the Coast 
Ranges has not been studied or mapped, a survey of the literature 
and maps available shows how similar are its topographic features 
to those in the United States. The topography of this division 
also represents a dissected peneplain, with residuals rising above 
the general level. This region was extensively glaciated during 
the Pleistocene epoch, and many topographic features were devel- 
oped which are not found farther south, such as smoothed and 
rounded mountains, scoured and terraced valleys, fiords, and super- 
posed streams. However, when large areas are considered the’ 
topographic features appear to be analogous to those of the United 
States. A noteworthy similar feature is the coastal peneplain 
developed along the western margin of Vancouver Island. Asso- 
ciated with this are also wave-cut terraces, such as characterize the 
coastal peneplain in the United States, and in places a very irregu- 
lar coast line due to later depression. 
It is difficult to compare the topography of the Alaskan division 
of the Coast Ranges with that of the United States on account of 
the pronounced effect of Pleistocene and Recent glaciation, particu- 
larly in the mountains of the Alexander Archipelago and the 
St. Elias Range. However, two conditions necessary to link this 
division to the remainder of the Coast Ranges have been definitely 
established. The mountains of Kodiak Island and the Kenai 
Peninsula present an upland surface which can scarcely be inter- 
preted as other than the remnants of an ancient peneplain,’ and 
there is abundant evidence of instability dating from early Tertiary 
to the present time. Another correlating feature may be found 
in the course of Alsek River across the St. Elias Range. This is 
probably an antecedent stream course, analogous to those of the 
Columbia and Sacramento rivers. The course of Copper River 
1A. C. Lawson, Univ. Cal. Bull., I, 242-44. 
2C. H. Clapp, op. cit., pp. 282-84. 3 A. H. Brooks, op. cit., p. 272. 
