INTRODUCTION 
3 
views by members of the Expedition were examined, as 
well as a large number from other sources, and at least 
several hundred of these have yielded information as to 
glaciers and glaciation. 
In arranging the material for presentation it has been 
found convenient to make an arbitrary division of the 
history of glaciation, connecting such changes as appear 
to have occurred within a few hundred years with the ex¬ 
isting status, and classing all remoter changes with the 
geologic or Pleistocene series. This procedure is a matter 
of convenience only; it is not determined by a turning 
point in glacial history, but by a difference in the nature 
of the evidence by which the history is recorded. The 
direct observational record, for a few localities, reaches 
back a little more than a century, and inference from the 
age of trees extends a little farther; but for all earlier 
times the data are purely geologic and the changes have 
not been measured in years. 
Under this classification the heads of my principal chap¬ 
ters are Existing Glaciers and Pleistocene Glaciation . 
The changing relations of sea and land also receive atten¬ 
tion, but these are so closely connected with the problems 
of Pleistocene glaciation that they have not been given a 
separate place. Notes of a general character as to glaciers 
and their work are in part introduced along with local 
descriptions and in part assembled in a closing chapter. 
Route .— Through the greater part of the journey I re¬ 
mained with the main party, so that the red line on the 
route map (pi. i) shows my course with approximate 
accuracy. It seems necessary to mention here only a few 
deviations and details. Such dates as are of importance 
are noted in connection with the descriptions of individual 
glaciers. 
In Glacier Bay I spent a day and a half at Muir Gla¬ 
cier, and then, with Muir and Palache, visited Hugh Miller, 
