\ 



V 



76 ' Causes of Geological Change 



I apprehend, however, that the dynamics of the north- 

 east storms that prevail upon our coasts, is usually under- 

 rated. One has only to look at the naked sienitic rocks 

 of Cape Ann, to be satisfied that they have been subject 

 to a very powerful and long continued aqueous agency. 

 But from the statements of several intelligent gentlemen, 

 I am satisfied that one cannot justly appreciate the power 

 of these storms without witnessing them. I am informed 

 by Mr. Benjamin Haskell, who resides at Sandy Bay, on 

 the northeast side of Cape Ann, that on Flat Point, in 

 that vicinity, where the slope of the shore is very small, 

 at the distance of nearly one hundred feet inward from 

 high water mark, there lies "what a farmer would call a 

 winnow of boulders,^' evidently thrown up by the waves ; 

 and some of them weighing from fifteen to twenty tons. 

 One of them, which weighs twenty-eight tons, has been 

 driven southwesterly one hundred and six feet, across a 

 considerable depression ; so that it must have been ele- 

 vated in its course not less than ten feet- 



In the great hardness and unstratified structure of the 



(and 



) 



have so successfully resisted this powerful agency, while 

 the softer and stratified rocks that once occupied Boston 

 harbor have given way before it. 



PURGATORIES. 



I find the name Purgatory applied, in their vicinity, to 

 several extensive perpendicular excavations in the rocks 

 of New England. The most extensive one occurs in 

 Sutton, Massachusetts. It is a vast chasm nearly half a 

 mile long, in gneiss ; and its walls are for the most part 



"S 



