416 Crosby and Barton—Carboniferous in Massachusetts. 
Art. XLITL— Eatension of the Car <6 a ous Formation in Massa- 
chusetts ;* by W. O. CrosBy and G. H. Barron. (Con- 
tributions bom the Geological Department of the Massachu- 
setts Institute of Technology: No. L) 
THE Carboniferous strata of Massachusetts and Rhode Island 
are all found within the limits of what is known as the Narra- 
gansett basin ; the well-marked geological basin holding Boston 
and its environs ath. in our opinion, entirely filled with rocks 
of Primordial a The northern and western boundaries of 
the Na rasitiett Bost have about the latitude and longitude, 
respectively, of the northeast corner of Rhode Island, tending 
to form a right angle at this point. But the angle is not closed, 
for the basin gives off a long, narrow branch or arm here which 
sweeps first in a northeasterly and then in an easterly pgs 
to Braintree in Massachusetts, where, at a distance o 
than twenty-five miles from its origin, it nearly, but oS bAUEY 
not quite, sae with the Boston basin. The nearest out- 
crops in the two basins are about two miles apart, are entirely 
dissimilar Ngislabloally and are certainly widely separated in 
time. The intervening ground is a thick deposit of drift, and, 
although its contours are not unfavorable to the theory that 
the basins communicate, yet it is probably underlaid by gran- 
ite, which is the predo minant tnderigiag rock of all this re- 
gion. This elongated arm of the Narragansett ace lies wholly 
within the limits of Norfolk County; and, hence, it has re- 
ceived the local designation of the Norfolk Catinty’ basin. Its 
breadth varies from a small fraction of a mile to two and one- 
third miles; and it is Me in the middle part, being very 
much contracted toward eac 
four months of field and laboratory work,. performed chiefiy b y Mr. Barton, and 
formed ie thesis for graduation i in the Class of 1880 of the Massachusetts pin baat 
tute of nolo acknowledge our great obligations to Professo 
W Niles for material om rende many ways, and also to He. 
Jobn Cummings and W. T. Hart of the New York and N 
Railroad for free Fisoesniine while engaged upon the field-work. 
