C. D. Walcott — The Taconic System of Emmons. 313 



formably to the eastward. On the east they rest unconforma- 

 bly on the primary and, on the west, the Calciferous and Hud- 

 son terranes are represented as unconformably superjacent to 

 the Taconic slates. Dr. Emmons says : " This section may 

 be regarded as one of the best for exhibiting and proving the 

 entire independence of the Taconic System from the Primary 

 below and the New York system above." * 



Two sections published in 1859 f may be taken as express- 

 ing his latest views of the relations of the different parts 

 of the "Taconic System," in its typical area, with the 

 exception of the "Upper Taconic" and the Lower Silurian 

 (Ordovician), on the western side. In these sections, the 

 " Lower Taconic " forms a synclinal with the " Granular 

 Quartz " at the base and then the Stoekbridge limestone and 

 Talcose slates, respectively superjacent, the " Upper Taconic " 

 being entirely disconnected from the latter. He held the view, 

 from the first, that the eastward dip of the greater part of 

 the strata of the " Taconic System " resulted from successive 

 uplifts, " which, in consequence of the confined position of the 

 rocks, have often produced local foldings and plications of the 

 strata." X His view of the extent and character of the uplifts 

 was subsequently changed, as is shown by his representation of 

 the position of the sparry limestone in 1842,§ 1844§ and 1855. 



In the memoir of 1856 several sections were illustrated and 

 described to show the unconformity \>et ween the Taconic slate 

 and the Calciferous sandrock, and thus establish the inferior 

 position of the " Taconic System " to the Lower Silurian (Or- 

 dovician) strata. These sections will be spoken of again, under 

 the head of " Discussion and Comparison." 



Dr. Emmons correlated the u Taconic System " with the 

 Cambrian system of Sedgwick, in his first memoir of 1 842, in 

 the following words : | " The Taconic rocks appear to be equiv- 

 alent to the Lower Cambrian of Prof. Sedgwick, and are alone 

 entitled to the consideration of belonging to this system, the 

 upper portion [of the Cambrian — C. D. W.] being the lower 

 part of the Silurian System." ^[ * 



Again, in the memoir of 1 844-' 47, he says, when speaking 

 of the proposed abandonment of the Cambrian System by Eng- 

 lish geologists :".... were it not for a single fact, the 



* Loc. cit., p. 366. 



f Manual of Geology, p. 85, figs. 58 and 60. 



JGeol. X. V., pt. 2, p. 142, 1842. 



§ See Professor Dana, this journal, 3d Ser., vol. xxxiii, p. 415. 



|| Geol. N. Y., pt. 1, p. 163, 1842. 



T[Dr. T. S. Hunt (Am. Nat., vol.xxi, p. 124, 1887) interprets this passage to 

 prove that Dr. Emmons in 1842 correlated the upper portion of the Taconic with 

 the Lower Silurian of Murchison, but, as I read it, Dr. Emmons refers the Upper 

 Cambrian, not his Taconic, to the Lower Silurian. 



Am. Jour. Sct.— Third Series, Vol. XXXV, No. 208.— April, 1888. 

 19 



