200 THE JOURNAL OF GEOLOGY. 



must be judged, have been widely discussed. These criteria are 

 not new to the specialists who had earlier defined and used them. 

 But not until now had it been so clear to so large an audience 

 that the evidence concerning man's antiquity is primarily geo- 

 logical, and more than this, that it involves some of the nicest 

 and most particular questions with which geologists have to 

 deal. R. D. S. 



*** 

 The article of Mr. Leverett in this number gives occasion to 

 invite attention to certain errors that still linger in the literature 

 of the glacial period, and that are occasionally supplemented by 

 new ones of like nature. They grow out of the failure to dis- 

 tinguish between the Champlain depression and the earlier 

 depression during which the main silts of the Mississippi Valley 

 were deposited. A very large mass of evidence has been pre- 

 sented by different investigators under different auspices during 

 the past decade that seems to us to have completely demon- 

 strated a stage of elevation between the time of the main silt 

 depositions associated with the outer tract of drift in the interior 

 basin, and the time of the low -altitude formations of the St. 

 Lawrence basin of which the deposits of the Champlain valley 

 are the type. This stage of elevation embraced some of the most 

 important events of the glacial period. The two stages of 

 depression, we think, have thus been proved to be altogether dis- 

 tinct. In our judgment they were separated by a long interval 

 of time, but it is not important to insist upon this in this connec- 

 tion. The evidences of this elevation between the two stages of 

 depression embrace practically all the great glacial gravel trains of 

 high gradient that are found south of the St. Lawrence basin. The 

 nature and slope of these give clear testimony to the attitude of 

 the land at the time of their formation. It is not asserted that 

 there were not similar trains connected with the early stages of 

 the earlier invasion of the ice, but the evidence on this point is 

 as yet very scant. It certainly does not embrace the well-known 

 high - gradient valley deposits of the interior, for these lie in valleys 

 cut in the earlier drift and are connected with moraines that lie 



