118 JULES MARCOU ON THE TACONIC OF GEORGIA 



ficatioii is vei-y confused and the dip ol" strata, which at tlic foot of tlie ravine is only 10 

 to 20° Ibr the Trenton Ihnestone, increases i-apidly to 30" and 40" for the Utica shites, and 

 to 60° and ahnost perpendicular for the Taconic slates. 



Messrs. Logan and Selwyn have given sections in 1861 : "Considei-ations relating to 

 the Quebec group" (^Canadian ISfataralist and Geol ogisf. May, ^g. 1), and also in 1881: 

 "Descriptive sketch of the physical geography and geology of the dominion of Can- 

 ada," Montreal, fig. 1, of the Montmorency Falls extending to the Orleans island. Both 

 consider all the strata between Montmorency and the eastern part of Orleans island as 

 Ti-enton limestone, Utica and Lorraine (Hudson River), and Calciferous and Chazy 

 (Quebec group) with two large faults. Mr. Sehvpi goes so far as to find three large 

 faults, one on each side of Orleans island. Those diagramatic sections of supj)Osed struct- 

 ure are only speculative and have been used to settle the relations of strata of very 

 doubtful age, and proved to be very embarrassing in the altei-ed and finally adopted 

 classification of the Canada survey. 



Very small and limited local landslides, on the southern edge of the band of Trenton 

 limestone and Utica slates, have been taken for a big fault. As soon as Logan saw that 

 it was unpossible to maintain any longer the age of the red sandrock, as Oneida conglom- 

 erate and upper Hudson Kiver group, he had recourse at once to faults, which sti'angely 

 enough he had filled totally to see during twenty years; and he did not hesitate to submit 

 the strata in discussion to the most complicated folding, overlapping, upheaving and 

 breaking. Fault upon fault with all sorts of disturbances was vised most freely, in or- 

 der to sustain lus "Quebec group," instead of accepting openly the "Taconic system;" 

 the only result was to create more confusion, of what was already confused enough. 



These examples show sufficiently the enormous pressure exerted on all the Taconic 

 rocks of Vermont and Canada, prior to the deposits of the Champlain system or true 

 Cambrian. If there was on the western line of contact of the red sandrock with the 

 slates and lenticular masses of limestone a great overlapping fault, as the slates, according 

 to that view, have been forced under the magnesian limestone, they ought to have up- 

 heaved and raised more or less strongly the upper lip of the fault. The natural result 

 would have been that, at the contact of the red sandrock, the beds would have been 

 raised almost perpendicularly, as represented on Plate 13, fig. 9. But, on the contrary, 

 at Georgia, fig. ], at St. Albans' bay, at Swanton, fig. 3, at Highgate Fall, fig. 6, and 

 at Highgate Springs, the red sandrock or magnesian limestone are considerably less 

 raised, dipping only from 2° to 8°; when farther east, at some distance from the supposed 

 fiiult, their dip is from 12° to 16°. At Swanton and at Highgate Falls, they lie almost 

 horizontally on the slates and on the lenticular masses of magnesian limestone, and pre- 

 cisely at points where the most ^^owerful forces must have acted in order to fold and 

 contort, as they did, the beds of the Phillipsburg group. The conclusion that the red 

 sandrock at Highgate Falls was deposited after the dislocation and break, and over the 

 contorted strata of the Phillipsburgh group is unavoidable. The red sandrock at the 

 fall, and on the left bank of the Missisquoi river, is of Potsdam age, lying in discordance 

 of stratification over the Phillipsburgh group. 



The tendency to explain every stratigraj)hical and ])aleoiitological difticultj^ by a fault 

 is natural enough, but must be checked by direct observations; and all the objections 



