PREFACE TO FIRST EDITION. ix 



adequately survey so large a field. The writer is but one 

 of many investigators who have been busily engaged for 

 the past fifteen years (to say nothing of what had been 

 previously accomplished) in collecting facts concerning the 

 Glacial period in this country. My endeavor has been to 

 make the present volume a pretty complete digest of all 

 these investigations, and in carrying out that aim I have 

 had the generous assistance of the great array of careful 

 and eminent observers who have turned their attention to 

 the subject. So far as possible I have, by their permission, 

 given their results in their own language, and with due 

 credit. I hereby take occasion to express my obligations 

 for the help which they have, one and all, so courteously 

 rendered. 



The numerous maps accompanying the text have been 

 compiled from the latest data, as indicated in the abundant 

 foot-notes scattered throughout the volume. These render 

 it unnecessary to make here any more specific acknowl- 

 edgment of authorities. 



The volume is committed to the public in the belief 

 that it will meet a widely felt want. The accumulation 

 of facts for the past decade has been so rapid, and from so 

 many sources, that few persons have been able to keep 

 themselves informed of the progress made. And so great 

 has this progress been that we may now safely assume that- 

 future discussions will pertain mainly to the details of the 

 subject. We now know, from actual observation, the limits 

 and prominent characteristics of the glaciated area on this 

 continent. The Glacial age of North America is no longer 

 a theory, but a well-defined and established fact. 



It will become apparent also that, though the title of 

 the book is the " Ice Age in North America,'' it is really 



