;H2 The American GeohxjisI . May.ih'j? 
The continuity and uniformity of the great drift terrane of 
the Puget sound basin, and especially the absence of anything 
like local moraines toward axial parts of the basin, tend along 
with positive evidence to prove that the mass of its mate- 
rial cannot have been accumulated and distributed by gla- 
ciers alone, local to the bordering mountains. Proofs of the 
existence of powerful glaciers are ample throughout the Cas- 
cades, as well as of their important though subsidiary part in 
the physical history of the region. The existing glaciers of 
Mt. Ranier are obviously survivals of an extensive system of 
Cascade glaciers of whose morainal material the present basin 
of the sound was the catchment. Further facts and consider- 
ations, however, sustain a belief that, practically independent 
of the glaciation of the Cascades, and inferential!}' also of the 
Olympics, the axial part of the basin has been occupied by a 
confluent ice-sheet gathered mainly from the northeast. 
Tracks have been indicated, particularly by Dr. G. M. 
Dawson, of a vast development of this description whose 
neve gathered in the lofty mountain region between the 55th 
and 59th parallels, and which covered summits of the interior 
of British Columbia upwards of 7,000 feet in hight. Above 
the main river valleys and other principal depressions there 
is abundant evidence to prove that it stood over 6,000 feet 
with a thickness of 2,000 to 3,000 feet a')Ove the higher tracts 
of that province. To this commanding development of ice 
has been given the name of Cordilleran glacier. Projections 
have been traced southeastward as far as the 48th parallel. 
and southwestward as far as the southern extremity of Van- 
couver island, where separate the great orographic valleys 
occupied by the straits of Georgia and Fuca.* 
It has also been shown by Dr. Dawson that the deep sculp- 
turing of the Pacific slope of the Coast range of British Col- 
umbia has been mainly effected through the agency of local 
glaciers which occupied the elevated beds of Pliocene rivers 
at an epoch when that range stood at a much higher altitude 
than at present. The range, as likewise concluded, presented 
a barrier to further advance of the Cordilleran glacier toward 
the sea, except at certain gaps through which the ice mass 
*Dawson op. cit. p. 28 ; Geol. Mag. (1888) V, 347 : VI, 350 ; Amer. 
Geol. 1890, 153: Willis, Bull., U. S. G. S., No. 40, 1887. 
