180 Tin; rnr.xoMKNA of drift, or 



in respect to the course taken by drift. I have given the direction 

 of the bowlders only because it has been described in some parts 

 of the country where no strife have been noticed. 



I have met with one unique case of the abrasion of rocks by 

 the as^ency whicji has been described, that ought not to pass 

 unnoticed. In a liigh bank of gi*avel, at Fall River, in Massa- 

 chusetts, or rather just within the limits of Rhode Island, there 

 was uncovered a few years since, the largest bowlder of conglo- 

 merate rock that I have ever seen, w^eighing, as already stated, 

 more than ten millions of pounds. This was transported at least 

 a mile or two, across Taunton river, and driven against a hiU of 

 granite. There it lay immovable, and was subsequently worn 

 down several feet, and its surface striated by the continued opera- 

 tion of the same force by which itself was removed. This fact 

 indicates at least the long-continued action of that force. 



I have scarcely noticed one variety of effect produced by the 

 abrading agency under consideration, because I intended to de- 

 scribe it as a third class of the phenomena of drift, under the 

 name of 



3. Embossed Rocks. 



I employ this term as a synonyme of the Roches moutonnees^ 

 used by Saussure to describe those rocks in the Alps which pre- 

 sent a rounded and curled • appearance, from the passage over 

 them of glaciers. Upon reading Agassiz' description of these 

 rocks, I became satisfied that they are very common in this 

 country, and that, although they have received a slight notice in 

 the descriptions of the phenomena connected with drift, that im- 

 portance and prominence have not been given them which they 

 deserve. I am now satisfied that they are a far more permanent 

 memento of glacio-aqneous agency, than stritP ; and that often 

 they will enable us to prove that agency when striae and aU other 

 traces have disappeared. 



The most striking instance of the embossed rocks which I 

 have met is on Mount Monadnoc, in New Hampshire, to which 

 my attention was called by Mr. Jenkins, of this Association. 

 This mountain is a ridge of mica slate, passing into gneiss, which 



