1883. 29 Trans. N. V. Ac. Sci. 



At the southern portion of the range, where it trends off decidedly 

 toward the southwest, the glacial movement nearly conformed to the 

 course of the valley, the upper part of the sheet scraping obliquely 

 over the summit of the range. 



The main body of the coarser detritus, gneiss, quartzyte, etc., from 

 the Adirondacks, Helderbergs, and Catskills, borne along through the 

 Hudson valley, was mainly diverted through the stronger glacial 

 current which swept down the Wallkill valley. The approximate coin- 

 cidence of the movement of the ice with the course of that valley, as 

 well as the low planes — within or beneath the ice — at which the foreign 

 boulders were borne or shoved along, have been the two causes which 

 appear to me to have permitted little or none of this northern material 

 to cross the Shawangunk range, even through its lowest gaps. 



DISCUSSION. 



Prof. D. S. Martin gave some account of the glaciation observed 

 by him during a visit to Lake Mohonk, near the northern end of the 

 range. At this point the cap of Oneida conglomerate is not less than 

 three hundred feet in thickness. The hotel rests upon it, at the shore 

 of the lake, which is 1,200 feet above the sea level, and it forms a 

 continuous mass extending up to the summit of Sky-Top (-altitude, i ,500 

 feet). He had observed the same form of bright red weathering at 

 this locality. Near the lake, the fresh horizontal surfaces of the white 

 quartzyte are polished like a slippery floor, which is even difficult to 

 walk upon. He had obtained specimens of the conglomerate, showing 

 pebbles sliced off by the glacial action. 



Mr. C. Van Brunt stated that the modified till was universally 

 distributed, with boulders, over the area on the west of the range up 

 to its northern termination. At that point particularly he had observed 

 the shoulders of the ridges to be remarkably ground and scratched. 

 He inquired whether the great masses of the conglomerate, loosened 

 or detached a^ong the escarpment, might not have been pushed away 

 by the pressure of the ice. 



Dr. N. L. Britton stated that he had visited the southern exten- 

 sion of the range, at High Point, which has an altitude of 1,700 to 

 1,800 feet. There also a small pond occurs, which is extremely shal- 

 low. The glacial striae ran very nearly to the southwest. Not a single 

 boulder of extraneous material was observed in the vicinity, except a 

 small flat pebble of Helderberg limestone, which was found at a point 

 about 300 feet below the summit. 



Prof O. P. Hubbard inquired how the deep excavation of Lake 

 Mohonk had been probably effected. 



Dr. JULIEN replied that, judging from the general accounts of the 



