140 GLACIAL FORMATIONS OF ERIE AND OHIO BASINS. 



the two old divides just noted, one of which is crossed by French Creek 

 between Cambridge and Saegerstown, and the other between Saegerstown 

 and Meadville. The presence of these old divides makes it necessary to 

 give the stream a different course from Cambridge to the lake. The great 

 amount of drift in the region through which it must have passed has nearly, 

 if not quite, concealed the line of discharge, hence it is not possible at 

 present to trace the line tlirough to the lake. 



As indicated in the discussion of the Upper Allegheny, there is a possi- 

 bility that a small section of the Allegheny, together with the headwater 

 portion of Tionesta Creek and the lower course of Conewango Creek, 

 formerly discharged south westward into the upper part of Oil Creek drain- 

 age basin past Grrand Valle}^, carrying with it the lower courses of Broken- 

 straw and Little Brokenstraw creeks, as well as several smaller streams now 

 tributary to the Allegheny. This being the case, a much larger stream 

 than the present headwater portion of Oil Creek (above Titusville) dis- 

 charged through Muddy Creek channel. It seems more likely, however, 

 as suggested above, that the drainage of this section of the Allegheny was 

 northward through the Conewango. The valley at Titusville is nearly a 

 mile in width, and becomes gradually larger upon passing northwestward 

 along the line of the Muddy Creek channel, the width being nearly 2 miles 

 along the portion of French Creek between the mouth of Muddy Creek 

 and Cambridge. It is several times the size of the small valley which now 

 forms the lower course of Oil Creek. 



The headwater part of Oil Creek drainage basin was excavated to a 

 level below that of the lower part; that is, of the small drainage line south 

 of the divide. The valley floor at Titusville, as shown by numerous oil 

 wells, is only 1,100 feet above tide, and it falls to 1,034 feet in the Muddy 

 Creek channel, 7 miles northwest of Titusville,^ thus reaching an elevation 

 tion about as low as the lower Oil Creek reached at Oil City on the Middle 

 Allegheny, 18 miles below Titusville as the stream now flows. 



The old divide near Titusville is found to consist of a narrow ridge 

 situated but a short distance south of the line of the old upper Oil Creek. 

 It was apparently quite similar to the divide at the head of Pithole Creek, 

 a few miles east of Titusville, which almost overlooks the valley of a head- 

 water tributary of Oil Creek and yet stands about 400 feet above it. The 



iSee Carll, op. cit., pp. 357-358. 



