Shaler.] 488 [April 21» 



two analyses by Mr. Sharpies, calculated for 1000 parts of the water. 

 I. is from a well eighty or ninety feet deep at the corner of Brookline 

 Street and Harrison Avenue, and II. from a well 170 feet deep at 

 No. 791 Tremont Street. 





I. 



II. 



Chi or id of Sodium 



1.184 



.530 



Chlorid of Calcium 



.060 



.023 



Chlorid of Magnesium 



.161 



.100 



Sulphate of Lime 



.122 



.105 



1.527 .758 



Note on the Geological Relations of Boston and 

 Narragansett Bays. 1 By N. S. Shaler. 



The indentation of Boston bay and harbor presents some striking 

 points of contrast with most of the fjords of our New England 

 coast. All other indentations of our shore have a general north' and 

 south trend, varying but little therefrom, and when varying turning a 

 little to the east of north, and south of west. This break in the 

 shores extends, however, in what seems at first to be a general east 

 and west direction. On closer inspection we see, however, that the 

 principal trends about the harbor and the neighboring bay are north- 

 east and southwest in their direction. I am therefore inclined to 

 think that this opening does not violate the general law of the. trends 

 along the coast, but that it only opens towards the north rather than 

 towards the south, as most of these fjords do. 



Looking more closely to the structure of this region, I have become 

 convinced that there is here a set of irregularly parallel faults run- 

 ning in a general northeast and southwest direction, the whole form- 

 ing something like a rude synclinal furrow, which may be compared 

 to those of the ordinary Alleghanian type. The subsidence of the 

 synclinal is accompanied by very great faulting, both in the direction 

 of the fold and transverse to it. On either side of this depression we 

 had anticlinals which are now obscurely marked on account of the 

 extreme degradation to which the region has been subjected. The 



1 In a forthcoming volume of the Coast Pilot, published by the U. S. Coast Sur- 

 vey, I shall discuss the geology of the shore between Boston and New York in a 

 general manner, under the general permission of the superintendent of the Sur- 

 vey, and give a part of the substance of that report in advance of the rest, as it 

 seems to me to have a somewhat important bearing on the studies of the coast 

 geology of New England. 



