248 The American Geologist. 
April, 1905 
named^John river, near the 152nd meridian, and thence extended 
in a nearly due north course through three and a half degrees of 
latitude, traveling by canoes, by portage over the Anaktuvuk pass, 
and again by canoeing down the river of that name and the Col- 
ville river to its mouth, with travel thence along the coast of the 
Arctic ocean through fourteen degrees of longitude west to Cape 
Lisburne. the northwestern corner of Alaska. 
On this route the frontal ranges of the Cordilleran belt trend 
nearly east and west, occupying a width ot about 100 miles, with 
peaks of 6,000 feet altitude above the sea. To the north a country 
of rolling plains, the analogue of the Great Plains east'of the 
Rocky mountains in the United States, stretches some 80 miles 
in width, and is succeeded by a nearly fiat low tundra of about 
the same width, adjoining the ocean. 
The Yukon basin, as the author remarks, seems comparable 
with the great Interior Basin of the western United States; and it 
may be further added that th^" southern curving mountain ranges 
of Alaska, culminating in Mts. St. Elias and Logan, Wrangell, and 
McKinley, and continuing onward southwesterly in the Alaska pen- 
insula and Aleutian islands, are clearly correlative with the Sierra 
Nevada and Coast ranges of our Pacific states. 
Here the longest mountain series of all the world passes from 
the western to the eastern hemisphere. Beginning at Cape Horn 
and running in the Andes and Cordilleran belts along the western 
sides of South and North America, the same grand orographic 
features reach forward, beyond Bering strait, through Kamtchatka, 
the Kurile islands, Japan, Formosa, the Philippines, Borneo, and 
Celebes, all the series from Patagonia to the East Indies being 
nearly in the same great circle and having together a length of 
about 240 degrees. 
Metamorphic rocks, principally sedimentary, regarded as of 
Silurian, Devonian, and Lower Carboniferous age, form the moun- 
tain belt crossed by this exploration. It is thought that the meta- 
morphism resulted ♦from the processes of the mountain building, 
which "seem to have been in progress intermittently since Middle 
Paleozoic time, and are probably still going on." 
Northward, the plains bordering the mountains consist of Cre- 
taceous and Tertiary formations, the former also having a large 
development southward in the Koyukuk basin, and the latter under- 
lying the tundra region next to the coast. 
Glaciation here during the Pleistocene period was not of a 
continental character comparable with the vast ice sheet of British 
America and the northern United States; but it was far more ex- 
tensive than has been heretofore supposed. The mountains were 
not overridden by moving ice, but were the gathering ground of 
thick snow and ice fields, whence broad piedmont glaciers, similai 
to the Malaspina glacier south of Mt. St. Elias, stretched many 
miles outward to the north and south, into the Colville and Koyukuk 
