8 STKATKiKM'HICAr. GKOLOGY. 



inch, and then reduced to alx)ut one hundred miles to the inch by pho- 

 tograpliy. Tlie area has ])ccn sufficiently extended to include all the 

 Canadian representations of the Labrador system. Outside of New Kng- 

 land, the geological boundaries have been copied from Logan's map of 

 1 869, as amended by Dawson's sketch of Nova Scotia and Prince Edwards 

 island, Prof. L. W. Bailey's and G. l\ Matthews's report upon New Bruns- 

 wick, and Alexander Murray's recent map of Newfoundland, The au- 

 thorities for New England arc my own maps and observations in the four 

 northern states, my father's map of Massachusetts of 1844, Pcrcival's 

 Connecticut, Jackson's Rhode Island, and a few isolated facts presented 

 by various authors. It is the first published attempt 'to subdivide the 

 crystalline and metamorphic formations of all this region. 



Looking at the map in the most general way, a fourfold division natu- 

 rally suggests itself. Plrst, the more ancient gneisses and granites, 

 embracing the Laurentian, Atlantic, and Labrador systems. Second, 

 the immense areas of hydro-micaceous and micaceous schists, which arc 

 here termed Pluronian. Third, an equally great expanse of clay slates 

 and all the known fossiliferous groups of the Paleozoic. Fourth, the 

 comparatively restricted patches of slightly inclined areas of Mesozoic 

 and Cenozoic age. All these divisions possess characteristics peculiar to 

 New England, those of the first two being the ones most important to us 

 in the discussion of the geology of New Hampshire. 



The first division is divided into four parts, — first and oldest, the 

 Lmirentian ; second, the Porphyritic gneiss and various undetermined 

 granites; third, the Atlantic; and fourth, the Labrado7'ian. The second 

 division cannot yet be well subdivided upon the map. The third consists 

 more largely of clay slates than anything else in the East, with all the 

 well determined Paleozoic formations of New York and Canada. These 

 slates arc grouped under the general term of Silurian and Cambrian of 

 the Atlantic area, in distinction from the same formation in the St. Law- 

 rence and Champlain valleys. These might be further divided, did the 

 scale of the map allow minuter representation. The outcrops of the 

 Devonian and Carboniferous are also distinguished from the preceding. 

 The fourth portion is easily divided into Triassic, Cretaceous, and the 

 capes and islands off southern New England, composed of Tertiary and 

 Alluvium. 



