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Crosby and Barton— Carboniferous in Massachusetts. 419 
The precise locality is the place marked on the map as Rock- 
dale, in the southeastern corner of the town of Norfolk. In this 
neighborhood there are many large, bold ledges of conglomerate 
and sandstone, as well as of the underlying granite; and this 
is, on the whole, the best exposure of the rocks which the belt 
affords. The fossils are found only in a small-pebbled or 
arenaceons conglomerate which lies near the top of the first or 
conglomerate series; and their occurrence along several lines 
of strike has assisted us in arrivingat a knowledge of the struc- 
ture of the region, the beds being clearly thrown into a series 
of closed folds. The fossils seem to consist wholly of the 
molds of Sigillaria, though many of them are so imperfect 
that, for aught that we could determine, they might be Cala- 
mites or Lepidodendron. The coarse texture of the rock has 
been unfavorable for the preservation of the finer and more 
characteristic features of the bark. till, in several cases, 
enough remains to show that the specimens are unquestiona- 
so formed having been probed to a depth of twenty feet or 
more. About thirty molds in all have been observed. 
Although fossils have been found at only this one locality, 
yet we are not persuaded but that, having learned what kind 
of impressions are to be looked for, close observation would 
discover them at other points. Certainly, there is nothing pe- 
Culiar in the character of the rock at Rockdale; and we fee 
that the fossils occurring here, taken in connection with the 
lithological and stratigraphical evidence already referred to, 
afford ample proof of the equivalence of the Norfolk Count 
series and the conglomerate and sandstone underlying the coal- 
measures in the main Narragansett basin; and Hitehcock and 
Lesquereux have already satisfactorily referred these lower 
Narragansett beds to the horizon of the Millstone Grit. It is 
worthy of note, too, that the descriptions given by Dawson in his 
‘Acadian Geology ” of the Millstone Grit series of New Bruns- 
wick and Nova Scotia apply very closely to the rocks in ques- 
tion; and since our coarse conglomerate rests immediately 
upon the crystallines, it is apparent that Dawson’s Carbonifer- 
ous limestone and lower coal-measures, which taken together 
represent the Subcarboniferous of the Appalachian region, are 
probably entirely wanting in Massachusetts and Rhode Island. 
