and the Taconic System* 379 



This is not their apparent order of superposition, but Dr. Emmons 

 conceives that the whole series has been inverted since its depo- 

 sition. In fact the schistose strata 5, 6, 7 and 8, pass succes- 

 sively beneath the magnesian slates and limestones, which in their 

 turn are overlaid to the east by the Green Mountain gneiss. This 

 latter formation Dr. Emmons regards as a primitive azoic rock, upon 

 which were successively deposited the members of the Taconic sys- 

 tem, commencing with the quartzite, which forms its base, and 

 crowned by the black andTaconic slates, which are now, from an im- 

 mense overturn, placed at the bottom of the series, while the ancient 

 gneiss lies at the top. It is hardly necessary to say that this sup- 

 position is wholly unwarranted by the facts. In the paper on 

 American geology already cited, we have shown that the apparent 

 succession of the rocks of the Quebec group is the true one. The 

 black slates are really at its base and successively overlaid by the 

 conglomerates, roofing slates, limestones and quartzites, and the 

 gneiss is a newer rock, being no other than the Sillery sandstone in 

 an altered condition, and as we have there shewn, entirely distinct 

 from the Laurentian gneiss. Dr. Emmons has fallen into an 

 error, similar to that of Prof. Nichol with regard to the gneiss of 

 the Scottish Highlands, so well refuted by Murchison, Ramsay and 

 Harkness, and has consequently been driven, in order to explain the 

 structure of the Green Mts. to admit not merely an upthrow with 

 Nichol, but a complete overturn of the whole palaeozoic series in 

 question. As to the geological age of this series, Dr. Emmons 

 maintains that his Taconic system occupies a position inferior to the 

 Champlain division of the New York system, and is consequently 

 beneath the Lower Silurian system of Murchison. As we have 

 before shown however, the fossils of the Quebec group prove it 

 to be the palaeontological equivalent of the Calciferous sand- 

 rock. The Stockbridge and sparry limestones, with their ac- 

 companying slates (excepting only 7 and 8,) we conceive to be 

 no other than the Quebec group, of which they have both the 

 stratigraphical position and the lithological characters. Dr. 

 Emmons has maintained that limestones of the age of the 

 Calciferous are found overlying the black slates, and has ap- 

 pealed to this in proof of the antiquity of the whole series, 

 of which he imagined these slates to form the summit, but 

 inasmuch as these slates are really older than the Quebec or 

 Calciferous strata, his argument falls to the ground. Mr. Billings 

 has lately found Conocephalites in the red sandrock of Highgate, 



