82 WILLIAMS— DEEP KANSAN PONDINGS IN 



valley and a slope washed by the scour; more assortment of the 

 gravel : not so many glaciated boulders of large size. The east side 

 shows a wide valley and protection from current ; more mixture of 

 the gravel : many large glaciated boulders. 



The ponding here was at least 200 feet below that above Emlen- 

 ton, and high gravel ridges are found in the slack areas behind pro- 

 jecting shoulders of the high blufifs about which the current wound 

 through the ponding. There are three such near Monterey, at vary- 

 ing elevations. 



The iceberg clay is again the deciding factor. At the last named 

 place it is 10 feet thick and with large boulders. The same are at 

 Blairsville Intersection, at Red Bank Junction, at Fairmount, and 

 they run to the tops of the ridges under conditions that show that 

 they are not a subsequent wash. The Kiskiminetas Valley, and that 

 of Red Bank Creek show terraces, bars, rock masses as large as a 

 small house, in clay with boulders and local gravel of sorts, and all 

 unite to tell of ponding in which Kansan gravels were dropped. 



Conclusion. 



The surface of Northwestern Pennsylvania resembles that of a 

 flat and much etched cone, with axis at Kane, and a fall of 1,000 

 feet to Foxburg in 42 miles on a southwest course. The Kansan 

 glacial margin spread southwestward about this apex and lay about 

 in the meridian when it crossed the mouth of Clarion River. The 

 passage of the lobe southward along the western border of Penn- 

 sylvania seems to have relaxed the activity of the portion capping 

 the Highlands of the state. The discharge was along the marginal 

 canyon between the glacier and the rising surface to the Alleghany 

 uplift. This canyon rested at times across the watersheds at Big 

 Bend, Thompson, Titusville, Foster and Emlenton, and induced 

 such depth of trenching of cols that the subsequent ponding was 

 able to complete the work. 



The clearance of the region from the Kansan glacier began at 

 the McKean-Potter Highlands in the Conewango Valley about 

 Warren. The trenching of the canyon therein was accompanied by 

 the settlement of the ice towards that valley trough, and the calving 



