450 SCIENTIFIC RECORD FOR 18-3. 



euce of large included fragments of these. The slates and flags of the 

 Primal series are described by Fontaine as sometimes talcose, pearly, or 

 nacreous in character, and as changing to kaolin by decay. They in- 

 clude large masses of limonite, and in some cases harder quartzose beds 

 are charged with specular iron. The upper 500 feet of the series consists 

 of shales, often kaolinized, containing both limonite and manganese- 

 oxide, and graduating into the overlying magnesiau limestones of the 

 Auroral division of Eogers, which with the underlying Primal makes 

 up the Taconian series. The great Appalachian belt of pre Cambrian 

 rocks, to which the Blue Ridge belongs, was overlaid in many other parts 

 of its extent by strata of Paleozoic age, as is well known, and the rela- 

 tions of these give evidence that important movements of the region 

 occurred at intervals until after the close of the Paleozoic period, and in 

 many cases involved in folds portions of Paleozoic strata, thus giving a 

 deceptive appearance of infra-position. The fractures which often accom- 

 pany these folds still afford passage in many cases to thermal waters, and 

 such waters, in past times, by their action upon the strata along their 

 course have produced local changes by the development of crystalline 

 minerals; a phenomenon alluded to above, which has been adduced as an 

 evidence of the Paleozoic age of the true crystalline schists. 



The organic forms from Bernardston, Mass., have lately been studied 

 by Whitfield, who describes them as occurring in " metamorphic sandy 

 shales," and also in an underlying bed of crystalline limestone. In the 

 limestone he finds two species of Favosites not certainly identified, a form 

 resembling Syringopora, and stems of criuoids of large size. The sandy 

 shales called by Dana " laminated quartzites " have yielded to Whitfield 

 species of Strophomena, Spirifera, and Rhynchonella, etc., besides a form 

 of Petraia. From all these he concludes that the limestones are Silurian, 

 probablj- of Niagara age, while the shales are of the age of the Chemung 

 or Middle Devonian. It is remarkable that these two rocks, which at 

 Bernardston immediately overlie each other, are separated by so wide an 

 interval in time; a fact testifying to great strati graphical irregularities 

 in the region. 



The fossiliferous limestones of Littleton, N. H., also intimately asso- 

 ciated with crystalline schists, have in like manner been examined by 

 Whitfield, who reaches the conclusion that these, including Halysites 

 catenulata, Favosites Niagarensis, Astrocerium vennstum Hall, and Pen- 

 tameras nysius are, like those of Bernardston, of Middle Silurian age, 

 and probably belong to the Niagara. 



NORTH AMERICAN CAMBRIAN. 



In a late communication *to the Boston Society of Natural History, 

 Hunt proposes to consider the Cambrian rocks of the great North 

 American basin as represented in four typical areas : (1) the Appala- 

 chian, (2) the Adirondack, (3) the Mississippi, and (4) the Cordillera 

 area. To the first of these belongs the great thickness of much dis- 



