ANCIENT GLACIERS. 85 



the glacial movement in northern Pennsylvania could not 

 have been local, but that over the northern part of that 

 State there was distinct evidence of a continental move- 

 ment of ice whose centre was far beyond the Allegha- 

 nies. 



For example, we found that the evidences of direct 

 glacial action extended farther south upon the hills and 

 plateaus than they did in the narrow valleys, while every- 

 where on the very southern border of glacial indications 

 we found boulders that had been brought from the gra- 

 nitic region of northern New York or central Canada. 

 In eastern Pennsylvania we found indeed a terminal mo- 

 raine more or less distinctly marking the southern border 

 over the highlands. This was more specially true in 

 Northampton and Monroe Counties. 



In Northampton County it was very interesting to see 

 long lines of hills, a hundred or more feet in height and 

 lying several hundred feet above the Delaware Eiver, com- 

 posed entirely of glacial debris, much of which had been 

 brought bodily over the sharp summit of the Blue Eidge, 

 or Kittatinny Mountain, which rises as a continuous wall 

 to the northwest and is everywhere several hundred feet 

 higher than the moraine in Northampton County. The 

 summit of Blue Eidge, also, as far south as the glacial 

 movement extended, shows evident signs of glacial abra- 

 sion, some hundreds of feet evidently having been removed 

 by that means, leaving a well-defined shoulder, marking 

 the limits of its southwestern border. Eesting upon the 

 summit of the glaciated portion of the Blue Eidge, there 

 are also numerous boulders of Helclerberg limestone, which 

 must have been brought from ledges at least five hundred 

 feet lower than the places upon which they now lie. 



In Monroe County the terminal moraine marking there 

 the extreme limit of the ice-movement is upon an exten- 

 sive plateau of Pocono sandstone, about eighteen hundred 

 feet above sea-level, and five or six hundred feet lower than 



