86 MAN AND THE GLACIAL PERIOD. 



the crest of the Alleghany Mountains, a short distance to 

 the north. The moraine hills are here well marked by 

 the occurrence of circular lakelets and kettle-holes (such 

 as have been described as characteristic of the shores and 

 islands bordering the south of New England) ; by the 

 occurrence of granitic boulders, which must have been 

 brought from the Adirondacks or Canada; and by the 

 various other indications referred to on a previous page. 



As already intimated, the instructive point in our ob- 

 servations is the fact that, between Kittatinny Mountain, 

 in Northampton County, and Pocono plateau, in Monroe 

 County, there is a longitudinal depression, running north- 

 east by southwest, parallel with the ranges of the moun- 

 tain system, which is here about a thousand feet below the 

 respective ridges on either side. This, therefore, is one of 

 the places where we should have expected a considerable 

 southern extension of the ice, if it had been largely due to 

 local causes. Now, while there is indeed a gradual south- 

 ern trend down the flanks of the mountain, yet, upon reach- 

 ing the axis of the valley, there appears at once a very 

 marked change in the character of the deposit, and the 

 influence of powerful streams of water becomes manifest, 

 and it is evident, upon a slight inspection, that we have 

 come upon a line of drainage which sustained a peculiar 

 relation to the continental ice-sheet. 



From Stroudsburg, near the Delaware Water- Gap, to 

 Weissport, on the Lehigh Eiver, a distance of about thirty 

 miles, the valley between the mountains is continuous, and 

 the elevation at each end very nearly the same. But about 

 half-way between the two places, near Saylorsburg, there 

 is a river-parting from which the water now runs on the 

 one hand north to Stroudsburg, and thence to the Dela- 

 ware River, and on the other hand south, through Big and 

 Aquonchichola Creeks, to the Lehigh Eiver. The river- 

 parting is formed by a great accumulation of gravel, whose 

 summit is about two hundred feet above the level of the 



