334 Sketch of the Geology of 



Slaty rocks, too, not unfrequently are so fissile, that 

 their edges can hardly be made to exhibit a smooth hard 

 surface by the action of water. But around Portland 

 they adhere so closely to each other, that their edges, 

 where worn, present as smooth and uniform a face as 

 sienite and trap rock ; while at the same time they are 

 much softer than the unstratified rocks. Hence the dis- 

 tmctness of the diluvial grooves under consideration. 

 And upon the whole, they are the finest examples that 

 have ever come under my observation. 



It is known to the Society, that Dr. C. T. Jackson 

 has recently examined geologically, the whole coast of 

 Maine ; and I take the liberty to quote here his testi- 

 mony on the subject of a northerly diluvial current. ^* I 

 discovered every where, in Maine," says he, in a recent 

 letter, " the fullest confirmation of your opinions respect- 

 ing the last great cataclysm ; and the boulders always 

 led me directly to their origin as I proceeded north. The i 



current was every where indicated to have been fi^om the 

 northwest towards the southeast. The details would 



too 



?> 



wiU 



soon be given to the public. 



gentleman, in connexion with Mr 



in then- Memoir on the Geology of Nova Scotia, give a 

 similar testimony in respect to the diluvial phenomena 

 of that country. We have now, then, an almost un- 

 broken series of observations on this subject, from the 

 extremity of Nova Scotia, to the western side of our 

 great lakes, a distance of from 1 200 tn 1 riOO miles : and 



local 



and 



waters from the north or northwest. In all cases, its 

 direction appears to have been to the east of south ; and 



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