Dr, Hioit on the Tacoiiic System of Emmons. 79 



imagines a great overturn of the whole series in question. In 

 this we have been misled by the language of Mr. Emmons, 

 which has caused him to be misinterpreted by others as 

 well. In speaking of the succession of rocks, he uses the term 

 "inverted strata," and Mr. Barrande has spoken of the " overturn 

 (renversement) of the whole system." Mr. Marcou, apparentlv as 

 the interpreter of Emmons, speaks of the strata in question as 

 having been " overturned {renversees) on each side of the crys- 

 talline and eruptive rocks which occupy the centre of the chain, 

 presenting thus a fan-shaped structure, and all the accidents which 

 accompany a complete overturn of a whole system of strata," so 

 that in going eastward towards the centre of the chain, we find 

 that the most recent strata appear to be placed beneath the most 

 ancient, "in consequence of an overturn {renversement).'''' Comjytes 

 Rendus de VAcad. xliii. 804. 



Now in justice to Mr. Emmons it should be said, that despite 

 his use of the expression " inverted strata," he has never main- 

 tained any inversion or overturn, as a careful examination of his 

 descriptions will show. (Taconic St/stem. p. 17). He supposes 

 that during the accumulation of the Taconic rocks, the gneiss 

 which formed the eastern limit of the basin was progressive^' 

 elevated, so as to successively bring the older members above the 

 ocean from which the sediments were being deposited ; and that 

 the upper parts of the formation, such as the black slates, were 

 thus confined to a narrow basin, and never extended far eastward ; 

 at the same time he conceives that denudation may have removed 

 large portions of the upper beds. At a subsequent period a series 

 of parallel faults, with upthrows to the eastward, is supposed to 

 have broken the strata, given them their eastward dip, and caused 

 the older beds to overlap the inner ; thus giving rise not to an in- 

 version of the strata, but to an apparent inverted succession. Now 

 we find in Canada abundant evidence that the slates which Em- 

 mons regards as the newest, are really near the base of the series, 

 and cannot consequently admit his hypothesis to explain an order 

 of things which we conceive to have no existence. 



The careful study of the region in question shows, that although 

 such a great upthrow and overlap does bring the Quebec group to 

 the surface from beneath the higher rocks, to the east of this fault 

 undulations, overturns, and downthrows to the eastward, diversify, 

 with eastern upthrows, the structure of this complicated region. 

 The gneiss of the Green Mountains, like that of the Scottish High- 

 lands and like the granite of the summits of the Alps, is the newest 



