19 



and more important considerations confirm this view. The 

 northern or Salem area of this series is bounded everywhere 

 either by the sea or by rocks belonging to the Huronian system. 

 On the north, in Beverly, we have coarse Huronian granite, 

 such as is quarried in Quincy and Rockport ; while to the west 

 and south, in Peabody, Salem, and Marblehead, are dioriteand 

 fine-grained hornblendic granite, also Huronian. What, now, 

 are the geognostical relations of the Naugus Head series to 

 these Huronian terranes ? It underlies them. Everywhere, 

 along the boundaries of the Naugus Head areas, we find the 

 various members of this series penetrating and cutting through 

 the Huronian rocks. But the converse of this is never ob- 

 served. Nowhere, so far as my observations extend, does the 

 Naugus Head series appear to be cut by the adjoining Huronian 

 rocks ; nor by any member of the Huronian system ; nor, in 

 fact, by any rocks not easily referable, as already stated, to the 

 stratified portions of this series itself. In short, the Naugus 

 Head series appears to be, as it -were, at the bottom; and, 

 while it has been extravasated extensively through superjacent 

 formations, it is penetrated by nothing foreign to itself. The 

 relations of the Naugus Head series and the Huronian forma- 

 tion are best displayed in the cliffs along the shores of Beverly 

 and Manchester. Here the Huronian granite, already men- 

 tioned, is cut extensively by great dykes and eruptive masses of 

 rocks, both pyroxenic and feldspathic, clearly belonging to the 

 Naugus Head series ; the feldspathic dykes appearing, usually, 

 to be older and larger than the pyroxenic. But this granite, 

 although it has evidently been more or less fluent, is never 

 found cutting any member of the Naugus Head series ; and we 

 are thus forced to the conclusion that this series is older than 

 the granite. 



The Norian beds of Canada and Labrador were formerly 

 regarded as forming- part of the Laurentian, bearing the name 

 " Upper Laurentian" ; and, wherever their relations to the un- 

 derlying terranes have been observed, they lie directly upon the 

 Laurentian, never upon the Huronian or Montalban. The 



