﻿362 J. O. Branner — Thickness of the Ice in Northeastern 



Art. XLT. — The thickness of the Ice in Northeastern Pennsyl- 

 vania during the Glacial Epoch ; by John 0. Branner. 



The thickness of the ice in northeastern Pennsylvania dur- 

 ing the Grlacial epoch was supposed, from such evidences as 

 those who have studied the region were able to find, to have 

 been indicated by the absence of striae, bowlders or ice-worn 

 fragments above an elevation of 2,200 feet above tide, upon the 

 sides of the highest hills in that part of the State. These high 

 points are Sugar Loaf peak, Ararat peak and Elk Mountain. 

 The first two are the straggling continuation of the Lacka- 

 wanna coal basin beyond where the Moosic range and the 

 Lackawanna mountains coalesce. They are in Wayne County, 

 almost upon its boundary with Susquehanna County, and 

 about sixteen miles north and a little east of Carbondale. The 

 summit of Sugar Loaf is 2,450 feet, and of Ararat peak 2,600 

 feet above tide, according to Professor I. C. White, who has 

 reported upon this region.* Elk Mountain is in Susquehanna 

 County, about ten miles north and a little west of Carbondale. 

 It culminates in a pair of peaks known as North and South 

 Knobs, which are respectively 2,700 and 2,575 feet above tide 

 according to Professor White's measurements. 



These several peaks are the highest points in the northeastern 

 part of the State, and stand up boldly above the surrounding 

 country, the valleys being eroded away about them to a depth 

 of from 500 to 1,500 feet. 



Professor I. C. White refers in several places to the absence 

 of evidence that these peaks were covered by the ice, and they 

 are spoken of, both by himself and by Professor H. C. Lewis, 

 as having stood out like islands above the ice of the glacial 

 epoch. Speaking of Ararat and Sugar Loaf, Professor White 

 says:f "These summits, which probably existed as elevated 

 hills in preglacial times, were left as islands in the ice moving 

 southward, and escaped the universal abrasion to which every 

 other portion of the township was subjected ; for no appearance 

 of drift or glacial scratches can be found on their sides or sum- 

 mits." In another place (ibid., p. 25) he speaks of "such iso- 

 lated peaks as Elk Mountain, Ararat, and Sugar Loaf — the 

 summits of which were islands in the Mer de Glace, and thus 

 escaped its action." On the same page he says: " 2,200 feet 

 above tide is the greatest elevation at which I have observed 

 direct evidence of glaciation, either in the shape of morainic 

 dehris or striated rock surfaces. All higher summits which I 



* Report G5 of the Second Geological Survey of Pennsylvania, 

 f Report Go, Second Geol. Survey of Pa., pp. 158, 159. 



