THE CATSKILL MOUNTAINS. H? 



age of 10 feet per mile for the distance from the iuteruational boundary to 

 the watershed north of the St. Lawrence. 



In New Jersey Prof John C. Smock's observations show that the 

 ice-sheet covered the highest point of the State, which lies near its most 

 northern angle, at an elevation of 1,804 feet. Its distance north from the 

 terminal moraine is about 31 miles. The New York Highlands and the 

 Shunemunk and Shawangunk mountains are also glaciated to their crests. 

 But in the Catskill Mountains Professor Smock finds that the glacial drift 

 and striae extend upward only to an elevation apprciximately 3,000 feet 

 above the sea.^ Their limit is thus 1,000 feet below the highest summits, 

 Slide ]\Iountain, the culminating point of this group, having, according to 

 Guj^ot's determination, an altitude of 4,205 feet. The distance from Slide 

 IMountain south to the terminal moraine on Staten Island at the sea-level is 

 105 miles. The ice-sheet in this distance had an average slope of nearly 

 30 feet per mile, or slight! 3^ less than a third of a degree; and a consider- 

 able area of the Catskills rose above its surface at its time of maximum 

 thickness and extent. 



Farther to the west the continental giacier stretched in a vast expanse, 

 unbroken by any projecting mountain or highland, to the basin of Lake 

 Agassiz, and, excepting a single group of hills which rose above it, I believe 

 that the same ice expanse continued to the Rocky Mountains, whose sum- 

 mits, as will be presently shown, appear also to have been wholly ice- 

 enveloped in the region of the Peace River and northward. 



The upper portions of the Cypress Hills, in southwestern Assiniboia, 

 of the Hand Hills, in eastern Alberta, and of the Three Buttes or Sweet 

 Grass Hills, in the north edge of Montana, rose above the glaciation which 

 spread di-ift on all the surrounding country. Mr. R. G. McConnell writes 

 of this region as follows : 



The western part of tbe Cypres.s Hills is entirely uiiglaciated, and must have 

 formed an island in glacial times projecting about 400 feet above the surface, as no 

 drift or other mark of glacial action was observed within that distance of the summit, 

 and as this part has a height of about 4,800 feet above tlie sea, this would give the 

 surface of the glacial sea or glacier, di.'^reganling- Post-Tertiary changes iu elevation, 



' Am. Jour. Sci. (3), Vol. XXV, j.p. 339-350, May, 1883. 



