r80 NEW YORK STATE MUSEUM 



visited was nephelin syenite country, many peculiar rocks appear- 

 ing which have not yet been met with in the Adirondacks, nor^ 

 so far as can be judged from their prevalent trend and the pre- 

 vailing northeast strike in the western Adirondacks, are likely 

 to be found in New York. They lie too far west, and their pro- 

 longation across the boundary lies under Lake Ontario and the 

 Paleozoic rocks of western New York, in the writer's • opinion. 

 The Grenville limestones and associated gneisses were magnifi- 

 cently shown in the section visited. As has been noted by 

 numerous observers, they are lithologically indistinguishable 

 from the Adirondack elastics of series 2, and their field relations 

 are the same. As in the Adirondacks, they lie in wholly separate 

 belts or patches, which show always identical rocks lithologically,. 

 and which are therefore naturally classed together, though it is 

 utterly impossible to demonstrate that they are contemporaneous. 

 They are classed together because of their identity in appear- 

 ance and origin, the comparative nearness of the belts to one 

 another and the fact that they seem to represent a continuous 

 series of deposits in a single basin. In our present state of 

 knowledge, the ^ving of different names to the different belts 

 because of the fear that they may not be absolutely contempo- 

 raneous after all, seems to the writer an absurdity. It would 

 seem equally absurd to apply several local names to the different 

 Adirondack belts. Yet these rocks have been carried to the St 

 Lawrence in the Thousand Island region, on the New York side, 

 and can be, or have been, so carried on the Canadian side; the 

 strong probability being that outcrops on opposite sides of the 

 national boundary are no farther apart than the average distance 

 between belts in either district. There can be no question that, 

 if the boundary ran south of the Adirondack region instead of 

 north of it, the Canadian geologists would have unhesitatingly 

 included the Adirondack rocks in the Grenville. To use the term 

 Grenville for the Adirondack rocks brings out at once the univer- 

 sally remarked similarity between the two series, which is wholly 

 lost sight of, unless specially commented on, by the application of 

 a new name to them. There is no question in the writer's mind 



