176 T. C. Chamberlin — Diversity of the Glacial Period. 



this a distinct and important group. The very able paper by 

 Dr. James Geikie, already referred to, is a notable expression 

 of advanced opinion of this kind. Incidentally it indicates a 

 similar attitude on the part of some other European glacialists 

 of large and varied experience and of unquestioned ability, 

 and some American glacialists have indicated at least a hospit- 

 able attitude to similar views. A comparison of the actual 

 position of Dr. Geikie with that assigned him by Professor 

 Wright, and a comparison of the array of evidence which Dr. 

 Geikie advances with the treatment it received in the article 

 in the November number of this Journal is one of several 

 illustrations of the ground of my protest. 



5. There is an ulterior synthetic view to be based on a 

 previous exhaustive analysis to which every cautious student 

 of the subject looks forward as the ultimate interpretation. 

 This is an ulterior view because it is impossible to take such a 

 view at the present time, except in a crude prophetic sense. 

 The method may now be clearly seen but the data for its 

 realization are not at hand. The first step toward it is a 

 thoroughgoing analysis of the glacial complex into its con- 

 stituent deposits and the definite delineation of these both in 

 plot and in section involving the tracing out of the connections 

 and the correlations of the constituent sheets, the determina- 

 tion of the intervals that occur at different horizons and in 

 different sections of the country (for they are not the same 

 everywhere), and the evaluation of the nature and length of 

 the intervals and their climatic, orographic and other character- 

 istics. Then will come the final test of the unity views, in the 

 demonstration, or the failure to demonstrate, that episodes of 

 glaciation fill in the intervals and bind the whole into indi- 

 visible unity. Then will come, also, the final test of the 

 doctrines of duality or diversity in the establishment, or non- 

 establishment, of intervals which prolonged research has failed 

 to bridge, and which temperate faunas and floras show to be 

 necessarily interglacial intervals, unless there be brought into 

 the series the distant polar connections which are presumed to 

 exist in any case. It is in the interest of each of the classes,. 

 unless it be the archaic one, to press on analytical and discrimi- 

 native studies and to give to them and to their results full 

 recognition. 



Immediately following his general statement of the question, 

 Professor Wright remarks, "In approaching the subject, it is 

 important to notice the fact that Professor Chamberlin inaugu- 

 rated his induction as director of the glacial division of the 

 United States Survey by publishing a monograph of " The 

 Terminal Moraine of the Second Glacial Epoch" [correct title 

 " Preliminary Paper on the Terminal Moraine of the Second 



