162 



southern border suggests the idea that the entire series, above the 

 granite, may be repeated in that direction, though covered, for 

 the most part, by the Montalban terranes. This theory places 

 the granite in the axis of a vast anticlinal fold of comparatively 

 low altitude and great breadth, and involving all the crystal- 

 lines of this region. The normal position, according to this 

 view, for the Naugus Head series, is in the axis of this anti- 

 clinal ; but the erosion of the granite has not apparently been 

 sufficient to expose it along that line. The exposure of this 

 series farther north is due, as already explained, to a system of 

 faults. 



This great regional axis is depressed toward the south-west, 

 allowing the Montalban strata to sweep directly across its 

 course ; the Huronian area of Massachusetts being entirely 

 surrounded, except seaward, by rocks of Montalban age. 

 South of the latitude of Worcester the strike of the Mont- 

 alban strata gradually shifts from north-east through north- 

 south to south-east, the terranes of this age passing with 

 the latter strike under the Carboniferous basin and Narra- 

 gansett Bay and reappearing in the Buzzard's Bay region with 

 an east-west strike. There are good reasons, as Prof. Hitch- 

 cock long ago pointed out, for believing that Cape Cod, as far 

 east as Brewster, and probably also the southern half of Cape 

 Cod Bay, are underlaid by gneiss. I am of the opinion that 

 could we trace these rocks we should find the strike bending 

 to the north-east, having doubled upon itself since leaving 

 Worcester, and proving the stratigraphic equivalence of the 

 gneisses of Essex and Plymouth Counties. 1 



Although appearing to die out south-westerly, there are good 

 reasons for believing that this fundamental axial line is con- 

 tinued north-easterly across the Gulf of Maine, reappearing 

 on the shores of the Bay of Fundy and, possibly, in Newfound- 

 land. The Naugus Head series is represented in New Bruns- 



i In the seoond volume of the recently published Report on the Geology of New 

 Hampshire, page 23, Prof. C. H. Hitchcock has desoribed a substantially similar con- 

 centric arrangement of the crystalline formations of south-eastern New England, having 

 the petrosilex and granite adjacent to the Boston basin as a centre or nucleus. 



