232 GLACIAL FORMATIONS OF ERIE AND OHIO BASINS. 



again bordered by drift deposits at high altitudes. The rock shelves up to 

 a height of 150 feet above the river carry g-ravel deposits containing 

 Canadian rocks, which in places have a known depth of 30 to 40 feet. 

 The slopes and shelves up to a height of fully 300 feet above the river 

 carry scattering pebbles, among which an occasional Canadian rock is found. 

 It is not certain that the glacial boundary lies as far southeast as President, 

 no drift having been observed by the writer on the uplands in that vicinity, 

 but the high altitude of these glacial pebbles suggest ice occupancy. 

 Undoubted glacial deposits are found about 5 miles west of President, on 

 uplands bordering the Allegheny, at an altitude of more than 400 feet 

 above the stream. 



At Walnut Bend a rock shelf or point encircled by the Allegheny 

 River has received a heavy deposit of glacial gravel, one well indicating a 

 depth of 135 feet. The gravel exposed on the slopes is rather fine, pebbles 

 exceeding an inch in diameter being rare. The top of this gravel deposit 

 stands, by anex'oid, about 250 feet above the river. 



Above Oil City g-ravel appears on the slope north of the Allegheny up 

 to an altitude of fully 250 feet above the stream. It seems to have a depth 

 of 100 feet or more as exposed in gullies whicli cut down through it. South 

 of Oil City rounded pebbles, including an occasional Canadian bowlder, 

 appear on slopes up to a height of more tlian 300 feet above the stream. 

 It is thought, as indicated above, that the ice sheet covered the Allegheny 

 Valley in that vicinity. A rock shelf on the south side of tlie river is 

 shown by a well to carry 90 feet of drift. The well mouth is about 220 

 feet (aneroid) above river level. 



At Reno, about 3 miles below Oil City, several wells show a large 

 amount of drift on high shelves. One, on ground 265 feet above the river, 

 penetrated 132 feet of drift; one, on ground 30 feet lower, 122 feet; and 

 one, at an altitude of 200 feet above the river, 142 feet. This drift is 

 described as being a sandy gravel, and slight exposures indicate that it may 

 be a stream deposit. If so, the valley may once have been filled to the 

 level of the highest well, 265 feet above the present river level. 



An abandoned channel in the northeastern part of Franklin, discussed 

 in Chapter III and shown in PL VIII, received a large amount of drift, which 

 from well records appears to be of finer texture than that commonly displayed 

 in the Allegheny Valley, niuch of it being sand. The surface portion, how- 



