VERMONT AND WESTERN MASSACHUSETTS. 



455 



Jban ' or ' White Mountain series ' in New Hampshire, and regarded of pre- 

 Silurian age, are here included, and are hence nothing but altered Hehlerberg 

 sediments. It is hence far from true tliat ' the crystalline rocks of the Green 

 Mountain and AVhite Mountain series ' and ' the whole of our crystalUne schists 

 of Eastern North America are not only pre~Silurian, but pre-Cambrian in age. ' " 



In the same article (p. 341) Professor Dana further remarks : 



^ 



■' Lithological evidence of a geological age among metamorphic rocks of dis- 

 tant TCij'L.is is in general worse than worthless. It is easy to use, and presses 

 itself on the mind most insinuatingly when a conclusion is eagerly Avanted. 

 .... I have further found that the Earth did not finish up its metamorphic 

 work in pro-Silurian time, or even by the epoch closing the Primordial, as it 

 did not its mountain-making." 



For the field evidence upon which Professor Dana founded his con- 

 clusions, the reader is referred to the original article. 



In the lleport of Progress of the Canada Geological Survey, for the 

 year 1873-74, Mr. Selwyn remarks that considerable doubt and uncer- 

 tainty have been thrown upon the labors of Sir William Logan by arti- 

 cles from the pen of Dr. Hunt. These articles appear to the present 

 head of the Canada Survey to indicate that the earlier views of Dr. 

 Hunt in regard to the true stratigraphical positions of the rocks in 

 Eastern Canada had undergone an almost entire revolution. This 

 change of opinion is said by Mr. Selwyn to have been based, so far as 

 he could understand it, on lithological comparisons exclusively, and he 

 thus expresses his views in regard to that kind of evidence : 



"Whether the relative ages of great masses of crumpled and metamorphic 

 strata can l)e thus dctcruiined apart from, or in the absence of pala)ontological 

 and stratigraphical evidence, is a question which, as a stratigraphist of thirty 

 years' experience, I should decidedly answer in the negative. The degree and 

 character of tlie metamorphism and mineralization which a group of strata 

 exhibit, cannot be relied on as certainly indicative of geological antiquity, aud, 

 as tending to strengthen this opinion, the recent researches of Mr. Pichardson 

 i\\ Bi'itish Columbia liavc shown that epidotic, chloriLic and serpentiuous rocks, 

 Aviih crystalline limestones and magnetites, are as characteristic of upper pala;- 

 ozoic, and perhaps also of even later hn-mations when they have been subjected 

 ^1 an equal amount of plication and folding, as they are of the ohU^st pal-cozoic 

 aud protozoic strata, such as those of Eastern Canada and the New Eu-dand 

 Slates." 



In 1875 Prof. J. P. Lesley stated that in Pennsylvania the ITuronian 



or Green Mountain series was seen to overlie the AVhite IMountain 



scries; while he unqualifiedly placed both series in Vermont aud New 



Hampshire below the Potsdam. (Second Geological Survey of Pennsyl- 

 vania, D., pp. ij^^ Q^,) 





II! 



