PENNSYLVANIA AND DEPOSITS THEREIN. 79 



wall of West Sandy Creek, where a sharp ox-bow curve was made 

 to turn it upon itself in order to pass to Emlenton, is seen in the 

 great valley width, which is six times that at Kennerdell. With but 

 slight narrowing this width extends southward to Brandon. If 

 ponding obtained hereabouts it is evident that the velocity of the 

 current through it must have been proportionally slower at Brandon 

 than at Kennerdell. That there was ponding is shown by the clas- 

 sification of the pieces in the glacial outwash, and by the iceberg 

 clay capping. 



There are larger pieces in the Brandon gravel than in that at 

 Kennerdell, and the silty cap at the former is 8 feet thick, against 

 the 2 feet at the latter, measured at the same distance above the 

 stream. The smaller sizes are also carried to a higher elevation at 

 Brandon. The slower current there would produce a more profound 

 slackness of the water in sheltered areas than at Kennerdell, and 

 there would be less movement of the surface. It has been noted 

 that the shoulder of the ridge which holds the Kennerdell gravels 

 rises to 1,400 feet for 2 miles form its end. That which sheltered 

 the area at Brandon rose slightly above an average of 1,450 feet, 

 and in one place above 1,500 feet. The level of ponding was be- 

 tween 1,430 and 1,480 feet. The stream flowed through this along 

 the broader channel above Brandon, and parallel to the axis of the 

 ridge just described, which rose to or above the surface of the water. 

 At Kennerdell, on the contrary, as the current swept about the bend 

 where Pine Hill Run enters, it struck squarely against the stoss side 

 of the ridge which shelters the Kennerdell area, and its upper 30 to 

 80 feet crossed that area directly. Only its profound depths would 

 be suitable for deposition. 



We are now prepared to appreciate why the coarse gravel ex- 

 tends at Brandon between 930 and 1,200 feet: at Kennerdell, be- 

 tween 915 and 1,000 feet. The fine gravel with 50 per cent, of 

 silt, which tells of a slacker water, extends at Brandon between 

 1,200 and 1,300 feet: at Kennerdell, between 1,000 and 1,200 feet. 

 The wave-action upon the thin drift sheet is marked at Brandon up 

 to 1,400 feet; at Kennerdell all above 1,300 feet is swept away. 

 Lastly, the iceberg silt, which caps everything, and which marks 

 the slowness of the current at this end of the wasting of the Kan- 



