•.mj,r.^-^i-^. 



MAINE. — NEW HABIPSIIIIIE. 



383 



■s 



lilhological characters. All geologists, therefore, who use the name Iliiro- 

 nian, of necessity practically adopt this principle, though perhaps insensibly. 

 We do not claim that a talcose rock can never be found in any other system 

 than the Huronian. nor that gneiss may never be interstratilied with the hydro- 

 micas. Professor Dana's recent paper shows that gneisses, quart^^ites and lime- 

 stones are interstratified in the Lower Silurian of western New England. . . . 

 In no instance would we claim that mineral character is suthcient to distin- 

 guish systems without a study of the relations of the strata. We may some- 

 times generalize, and believe that rocks of similar mineral character nuist be of 

 the same age, but such speculations always provide for confirmation by a study 

 of the strata." (Proc Am. Assoc. Adv. Sc, 1873, XXII. pp. IGO, 167.) 



Wc shall see that in New Hampshire Prof. Hitchcock relied en- 



tirely on lithological evidence, 

 advocated. 



evidently not following the views hero 



In his paper on Granites and Granitic Vein-stones Dr. Hunt referred 

 many of the granites (gneisses) and mica schists of Maine to the Terra- 

 novan or Wliite Mountain series, but on litbological grounds. (Am. 

 Jour. Sci. 1871, (3) L p. 182.) 



In two more recent papers by Messrs. Hitclicock and Huntington 

 certain rocks in Nortliern Maine are regarded as Laurentian and Huro- 

 nian, if not Montalban; but this decision rests solely on litbological 

 evidence, not the slightest proof being given that the rocks in question 

 may not be much more recent than the Azoic, and of the same instead 

 of different ages. (Proc. Am. Assoc. Adv. Sci., 1873, XXIL pp. 205- 

 214; 1877, XXVL pp. 277-28G.) 



Thus far no evidence lias been given that proves the prc-Silurlan ago 

 of any rocks in this State, all the evidence thus far advanced being 

 based exclusively on lithological characters. 



NEW HAMPSHIRE. 



In this State we have principally to do with the writings of Messrs. 

 Hunt, Huntington, and Hitchcock, tlicse being the geologists who have 

 especially interested themselves in establishing subdivisions in the sup- 

 posed Azoic rocks of that State. It is in the publications of Prof. 

 C. H. Hitchcock, State Geologist of New Hampshire from 18G0, how- 

 ever, that wc fmd the larger part of that which touches the questions 

 here before us. 



