190 Dale — Geology of the North End of the Taconic Range. 



Wolff to have occurred on Hoosac Mountain.* That explana- 

 tion of the relations about the Taconic range is now shown to 

 be erroneous. 



Then came the Ordovician folding which, here and as far 

 south as West Rutland, produced 1ST. 1 5-25 W . strikes, principally, 

 and which may have produced the N.15W. secondary cleavage 

 in the Cambrian slates, and must also have otherwise more or 

 less modified the Cambrian structure as well as the Cambrian 

 surface. The central part of the section shows the Cambrian 

 folding, and the ends of it the overlapping and the Ordovi- 

 cian folding. Denudation through long geological periods' 

 must account for the presence of only shred-like remnants of 

 the great mass of Ordovician argillaceous sediments and for the 

 severance of the northern extension of the schist from the 

 Taconic range, and, generally, for the exposure of the Stock- 

 bridge Limestone. The salient fact is the unconformity between 

 the Lower Cambrian and the Ordovician, which is masked in 

 the slate region of Washington Co., either by the parallelism in 

 the strike of the two foldings or by the effect of the later one 

 upon the earlier, but which was accentuated at the north end 

 of the Taconic range by the original divergence in the strike 

 of the two periods and is still shown in the dips. This uncon- 

 formity thus fully corroborates, stratigraphically, the time break 

 shown, paleontologically, by Mr. Walcott's fossil localities. f 



Although the Taconic controversy was settled long ago, and 

 has ceased to be of other than historical interest, as it was shown 

 by Dana, Walcott and the authors of Monograph XXIII, that 

 Ordovician rocks had been included by Ebenezer Emmons in his 

 Taconic System owing to the overlooking of faults, the mis- 

 taking of cleavage for bedding and insufficient exploration of the 

 areal relations, yet it is remarkable that at this late day it should 

 appear that his contention that there was an extensive forma- 

 tion, marked by a peculiar fauna, now known as Lower Cam- 

 brian, unconformably related both to the underlying gneisses 

 (pre-Cambrian) and to the overlying Lower Silurian rocks (Hud- 

 son, etc.), should be confirmed, at least for a part of the Taconic 

 region, for no trace of the unconformity shown by this paper 

 has yet been found along the Green Mountain border. Dur- 

 ing the Taconic controversy, however, conformable succession 

 of the Cambrian and Ordovician beds was supposed by the 

 opponents of Emmons to hold for the entire region.;}; 



* Geology of the Green Mountains in Massachusetts, by Kaphael Pumpelly, 

 J. E. Wolff, and T. Nelson Dale. Monograph, U. S. Geological Survey, 

 XXIII, 1894, pp. 14-18, 104. 



fOp. cit. Slate belt, pp. 163, 166. 



JKogers (Henry D.), this Journal (1), vol. xlvii, D., p. 152, 1844; Walcott 

 (Charles D.), op. cit. this Journal, vol. xxxv, 1888, p. 320. 



Pittsfield, Mass, December, 1903. 



