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, 



