750 THE JOURNAL OF GEOLOGY. 



sented, must be regarded as a very stimulative contribution. The 

 writer of this note does not agree with him in the belief that the border 

 of the glacial drift is necessarily any more amenable to the morainic 

 method than other portions ; indeed, we think that European as well 

 as American experience has already shown that it happens to be less 

 so, as a major fact. The moraine-developing habit was most pro- 

 nounced during the later part of the glacial period. More than this, 

 we think it has been amply demonstrated that the border of the drift 

 was formed at different times, and that the moraines that are marginal 

 to it in one portion depart widely from it in other portions, one moraine 

 lying on the border in one region, and another in another region, and 

 that along a large portion of the border there is no conspicuous ridg- 

 ing of the drift. Nevertheless it is valuable to trace out any terminal 

 moraine, whether it borders the drift or whether it separates drifts 

 older from drifts younger, for it becomes, in any case, if successfully 

 done, a tangible datum line for correlation. 



Professor Lewis came to recognize, so far as England is concerned, 

 that there was an earlier drift outside the moraine he mapped. Con- 

 cerning this he says, p. 69 {Postscript added to abstract printed in 

 "Geological Magazine,''' November, 1887, p. 516) : "Since the paper 

 [Extra-Morainic Lakes of England] was read of which the above is an 

 abstract, I have found traces of the existence of a very much older series 

 of glaciers than those here described. 



"Since the period of these ancient glaciers, which in many places 

 were more extensive than the modern ones, earth movements have 

 occurred and erosion has removed almost all their deposits, and gener- 

 ally obliterated striae, so that the region subject only to the older 

 glaciation now resembles a non -glaciated area. 



"The glaciers and their bordering lakes, described above should 

 therefore be considered as belonging to the second or last glacial 

 epoch." 



And again, p. 390 : "Recently I had found in the 'fringe' region 

 of England evidence of a much more ancient glaciation ; so old 

 indeed that erosion had removed almost all the deposit and obliterated 

 the striae. Perched erratics occur above any possible lake. Is not 

 this still due to an old glacier, and the red clay to an extra-morainic 

 lake? Are they contemporary deposits? I find that the glaciers 

 of the first epoch came from more southern centres than those of the 

 second ice period." T. C. Ghamberlin. 



