Fjords and Hanging Valleys, — Upham. 315 
der the vast weight of the ice-sheets, the lands were depressed 
to their present levels, or mostly even somewhat lower; tem- 
perate climatic conditions were thus restored, the ice being 
melted away; and the fjords testify to the depth of the land 
subsidence and marine submergence, accompanying the de- 
parture of the ice, and continuing to the present time. 
In some instances, however, deep valleys and discordance 
of their tributaries are doubtless to be explained by the dis- 
placement of faulted segments of the bed-rock, as noted by 
Crosby.* ' 
Further evidences of late Pliocene and early Pleistocene 
epeirogenic elevation of northern land areas and sea beds, 
shown by entirely submerged fjords or continuations of river 
valleys, and by beds of littoral marine shells dredged at great 
depths, have been adduced by Spencer, Hull, Brogger, Nan- 
sen, and others, including the present writer. Many years 
since, in 1889, in an appendix contributed to Wright's "Ice 
Age in North America," I reviewed the evidences then known 
of very high land uplifts as the principal cause of the Gla- 
cial period, tracing also the supposed relationship between the 
crust and interior of the earth which could admit of so great 
epeirogenic movements. No better explanation of the causes 
of glaciation seems to me to have been brought forward ; and 
it has gained new and strong support by the latest discussions 
of the origin of fjords and hanging valleys, in place of the 
distrust which in the minds of some students beset this view 
a few years ago. 1 , 
The early suggestion of Dana thus seems still sustained by 
advancing research, namely, that three grand continental 
movements of glaciated regions characterized the Glacial and 
Recent periods, first, great uplifts which induced the ice ac- 
cumulation ; second, subsidence of the ice-burdened lands, 
bringing again a mild climate and ending the Ice age; and, 
third, moderate reelevation, lifting coastal parts of the sea-bed 
to be again a land-surface. The epoch of great uplifts, doubt- 
less most prolonged far northward and far southward, was the 
time of deep fjord erosion, and ensuing lateral planation of the 
fjord cliffs by rasping ice, the little tributaries being left high 
above the wonderfully deepened main valleys. 
•"The Hanging Valleys of Georgetown, Colorado." Technology Quarterly, 
vol. xvl, pp. 41-50. March, 1903 ; also In the American Geologist, vol. zxxii, 
pp. 42-48, July, lOO.S. 
