

214 



PALEOZOIC TIME. 



shows the condition along it (at F) near the Falls of Montmorency 

 (M), east of Quebec. On one side there is the Trenton limestone 



Fig. 395 F. 

 4a M C 



(4 a), which is followed eastward by 4 b and 4 c, the Utica slate and 

 Hudson River slates, and 3 the Quebec group ; while on the other side 

 there is Archaean gneiss overlaid horizontally by fifty feet of Trenton 

 limestone. The fault is continued south-southwest through Vermont 

 into Eastern New York. (Another section illustrating it, by Mr. 

 Wing, and additional sections of the rocks of the limestone region, 

 may be found in volumes xiii. and xiv. (1877) of the American Jour- 

 nal of Science. 



4. The Width of the Region Disturbed. — On the west it extended 

 to the Hudson ; how far east is not ascertained, but possibly in some 

 parts to the Connecticut. The map (Fig. 395 G) shows a portion from 

 the more southern part of the region, spreading from Connecticut to 

 the Hudson, in Dutchess County, N. Y. The limestone comes to the 

 surface through folds or faults in^W principal belts (besides others of 

 less width), as exhibited on the map. The Great Central belt, east of 

 the Taconic range, terminates against the Archaean in Putnam County. 

 East of it there are two in Connecticut, separated by mica schist 

 and gneiss; and two in Dutchess County, separated by mica schist, 

 hydromica schist, and clay slate, passing south from the limestone belt 

 west of the Taconic range. The directions of the strike and dip are 

 indicated by the T-shaped symbols, the stem showing the direction of 

 dip. Trenton fossils have been found in Ancram west of the Taconic 

 range, and, farther southwest, along this more western limestone belt ; 

 and Hudson River fossils in the Poughkeepsie slates. As these slates 

 and limestone are thus continuous with those of the Taconic mountain 

 region, these fossils and those of Vermont show that the Taconic slates 

 are of the age of the Hudson River group. (For a further statement 

 of the facts, see American Journal of Science, xvii., 1879.) 



5. Other Effects of the Disturbance Lake Champlain valley 



was probably defined before the Silurian era began, by Archaean up- 

 lifts along the Green Mountain area ; but, if not, it dates from this 

 epoch, as suggested by Logan. It lies where unstable or oscillating 

 New England, through Lower Silurian time, hinged on to the stable 

 Archaean ; or, just where the heavy pressure during the era of disturb- 

 ance operated against the stable Archaean, as it folded up the thick 

 series of rocks to their bottom. 



