No. 2. — On the Geology of the Cambrian District of Bristol Councy, 
Massachusetts. By N.S. SHALER. 
[Published by Permission of the Director of the U. S. Geological Survey.] 
Preliminary Note. 
For a number of years I have been engaged in an incidental manner 
in studying the geological structure of the great synclinal district to 
which [ have given the name of “the Narragansett Basin.” This 
geological field, extending from the southern part of Narragansett Bay 
in Rhode Island to the region of the granitic hills which includes the 
Blue and Sharon Hills of Massachusetts, and eastwardly to the region 
occupied by the town of Hanover in Massachusetts, is mainly under- 
laid, as is well known, by rocks of Carboniferous age. My principal aim 
has been to determine the geological history of this Carboniferous sec- 
tion. Incidentally, it has been necessary to make some study of the 
deposits which lie below the level of the Millstone Grit. In these latter 
inquiries I found it necessary to do a good deal of work on the exten- 
sive series of more or less metamorphosed ancient rocks which lie be- 
tween the western border of Rhode Island and the western edge of the 
Coal Measures, from Greenwich, R. I., to Wrentham, Mass. This 
inquiry, although incomplete, has developed certain facts of consider- 
able interest, which it appears to me should be made public before the 
‘preparation of my final report on the Narragansett Basin, which can- 
not be finished for some time to come. The most interesting of the 
many results which I have obtained in this Pre-Carboniferous series 
of rocks consists in the discovery of an extensive series of Cambrian 
deposits, containing a tolerably abundant and fairly determinable set of 
fossils. The discovery of these beds not only enables us to fix the age 
of an extended section of rocks, but to ascertain a number of facts 
which have a great importance with reference to the general history of 
this portion of the continent. 
Several geologists have observed the fact that between Providence, 
R. I., and Wrentham, in Massachusetts, we have an extensive develop- 
VOL. XVI. — NO. 2. 
