476 PROCEEDINGS OF THE ACADEMY OP [1892. 



Professor Lewis in bringing the ice border down to Green Creek on 

 the north side of Knob Mountain, in Orange township. (G. 7, p. 

 217.) Thus it appears that the section between Bloomsburg and 

 Berwick (Am. Jour. vol. 135, pp. .376, 464), upon which Mr. 

 McGee depends for proof of his Columbia submergence of 500 feet 

 in this region, is within the attenuated border or fringe, as I had 

 surmised, and hence fails to prove what he supposed. 



On passing over into the valley of the Lehigh, we first drove 

 from the Glen Summit Hotel to Hazleton, during which we satis- 

 fied ourselves that there are no glacial deposits much farther south 

 than the terminal moraine, as there marked by Professor Lewis at 

 Drums, where a short distance to the south, the outcropping coal 

 measures form a bold obstructing wall several hundred feet above 

 the valley of Nescopec Creek. But the region beyond is so broken 

 up by raining operations, and with the disintegrating debris of the 

 Pottsville Conglomerate, that I should not put entire confidence in 

 such investigations as I was able to make. 



In the broad anticlinal valley crossed by the Lehigh, between 

 Mauch Chunk Mountain and Blue Ridge, however, the opportunity 

 for crucial tests is as good as could be desired. Here we found 

 that the evidence of direct occupation by glacial ice extended at 

 most only a few miles beyond the moraine, as marked on Lewis's 

 map. Extensive drives up the valley of Big Creek, near the 

 mountain north from Weissport, across the valley both of Big 

 Creek and Aquanchicola Creek to the Lehigh "Water Gap, as well 

 as south from Lehighton, up and across the valley of Mahanoy 

 Creek, demonstrated to my satisfaction that glacial ice had never 

 extended to within ten miles of the Lehigh at this point. At 

 Lehighton, however, there is a well defined pebbly terrace rising 

 about 75 feet above the river. The material is well rounded, and 

 mixed with yellow sand and clay. These terrace deposits do not 

 appear above that level anywhere between Lehighton and the 

 Water Gap, either on the Lehigh or on its tributaries. But on the 

 gentle slopes of Mauch Chunk and Big Creek Mountains there are 

 many pebbles which have evidently been brought down in the slow 

 process of erosion. These are collected at various heights in special 

 quantity in front of the openings into the mountains effected by the 

 side streams, and in many cases clearly represent ancient deltas 

 when the whole drainage was at a higher level. 



