PENNSYLVANIA AND DEPOSITS THEREIN. 77 



Creek in a sandy wash, there was found a cobble of red granite with 

 quarry face and edges ; but so pulverulent that it crumbled between 

 the fingers. In the same wash were pebbles of fresh crystallines. 

 These indicate deep ponding and floating ice. At Salamanca, Olean, 

 and other places along the old Allegheny Valley are broad terraces 

 at 1,500 feet. There are beach lines in the affluents of Kinzua 

 Creek at this elevation, and indications of ponding at this level about 

 Sheffield and Clarendon. 



Second Emlenton Ponding. 



The damming probably took place between this place and Fox- 

 burg, where the stream passes through the ridge with crests above 

 1,500 feet. The elevation of the water was between 1,430 and 1,480 

 feet, as shown by washes, beach-lines, etc., in the vicinity and at Oil 

 City, Sheffield, and in some of the Kinzua affluents. At Roystone 

 there is a swampy fan running from 1,430 to 1,480 feet. 



Our study will be limited to the sporadic gravels in the West 

 Sandy Creek Valley. These were thought to be remnants of a com- 

 plete valley filling, since excavated, as stated by G. F. Wright in 

 1894.^ This theory he abandoned — retaining however the idea of a 

 complete valley trenching, to the present rock floor before their depo- 

 sition. Leverett, in 1902,^ held the same view as to the trenching ; 

 but thought the gravels remnants of a complete filling. 



There are three terraces of these gravels, and Leverett states: 



In several places, notably at the bends of the river at Brandon, at a point 

 2 miles below Brandon, at Kennerdell, at Black's (Winter Hill Station), and 

 at Emlenton, there are deposits on the face of the gorge extending from the 

 river's edge up to heights of 200 to 300 feet or more above the stream. The 

 occurrence of this gravel at low places can not be accounted for by creeping 

 or landslides, since in some places, notably at Kennerdell and 2 miles below 

 Brandon, the gravels show clearly by their situation and bedding that they 

 have not been disturbed since the stream deposited them. 



The sole criticism is against the use of the word " gorge " for 

 the low slopes on which the gravels lie at Brandon and at Kenner- 

 dell. At the former the slope varies from 7 degrees at one end to 

 16 degrees where it ends : at the latter the slope is 10 degrees. As 

 would be the case when a torrent laden with glacial outwash trenches 

 so tortuous a valley as that of West Sandy Creek, there would be 



