CHAPTER III. 



OUTLINE OF TIME RELATIONS OR GLACIAL SUCCESSION. 



In the progress of the studies of glacial deposits the complexity of the 

 glacial history has been gradual^ unfolded. After the abandonment of 

 the iceberg hypothesis, the early students approached the study with the 

 hypothesis of a single and practically continuous period of deposition, in 

 which the ice sheet at one time covered the entire glaciated area, This 

 period was supposed to have terminated with a single high stage of water, 

 attending the melting of the ice, which was termed the Champlain epoch. 

 It soon became apparent that this simple hypothesis could not be made to 

 cover the complicated glacial history. Evidences of a succession of reces- 

 sions and advances of the ice sheet have appeared, and a sharp controversy 

 has arisen concerning the importance of these oscillations, it being held by 

 some students that they are of minor importance and mai-k short or partial 

 retreats and advances in a single epoch of glaciation, while others have 

 contended for the necessity of recognizing two or more ice invasions 

 between which were very extensive and prolonged deglaciation intervals. 

 The studies upon which the present report is based have developed evidence 

 which, it is thought, has an important bearing upon the question in dispute. 

 The writer, like others who have studied this region, has been greatly 

 impressed with the evidence of prolonged intervals of deglaciation, and an 

 attempt will be made to set forth the nature of this evidence. 



The several sheets of glacial drift which this and neighboring regions 

 contain have received geographic names, as have also some of the inter- 

 glacial beds. Names of this class were proposed by Chamberlin as a sub- 

 stitute for time phrases which had arisen and which were of controverted 

 application. 1 They have already come into wide use in glacial literature, 

 and are employed by students who hold the divisions to be of minor impor- 

 tance as well as by those who consider them of great importance. The 



' See Geikie's Great Ice Age, third edition, 1894, pp. 754-774. Also Jour. Geol., Vol. Ill, pp. 

 270-277, and Vol. IV, pp. 872-876. 



