122 
ALASKA GLACIERS 
greater part of the inside passage, and our examinations 
about Sitka occupied several days. An excursion to 
White Pass gave a view of a canyon at the head of a 
fiord, and of uplands at 2,000 to 2,500 feet altitude, but 
the higher summits were seen only from stations at or 
near sea-level. 
Direct observation of the uplands was afterward supple¬ 
mented by the study of photographs. The U. S. Coast 
and Geodetic Survey and the Canadian International 
Boundary Commission have used the camera freely in con¬ 
nection with topographic surveying, and I was so fortu¬ 
nate as to have access to their series of pictures. The latter 
organization spread a web of triangulation over all the 
mainland portion of southeastern Alaska, and from each 
of the mountain peaks occupied as stations photographed 
the entire horizon, using the views afterward for the con¬ 
struction of contour maps. Their album thus represents 
the upland in a systematic and thorough way and is emi¬ 
nently adapted to physiographic study. (See page 6.) 
In this, as in other districts of Pleistocene glaciation, it 
is evident that the Pleistocene sculpture is superposed on 
an earlier sculpture, chiefly aqueous; and in the discus¬ 
sion of the work of Pleistocene glaciers it is necessary to 
consider the pre-Pleistocene condition. I find it conve¬ 
nient to begin with that consideration. 
Pre-Pleistocene Topography 
So far as we saw the indurated rocks, and so far as we 
know them from the descriptions of others, they are either 
igneous or metamorphic. The igneous rocks are almost 
wholly intrusive. The metamorphic exhibit various de¬ 
grees of alteration, but all are so folded or squeezed that 
the planes of structure make large angles with the hori¬ 
zon. The general strike is believed to be parallel to the 
coast, but there are few direct observations of strike. In- 
