252 National Geograjphic Magazine. 



existing stream from its once independent parts. The Juniata of 

 to-day consists of headwaters acquired from Ohio streams ; the 

 lake in which the river once gathered its upper branches is now 

 drained and the lake bottom has become a mountain toj) ; the 

 streams flow around the margin of the lake, not across its basin ; 

 a short course towards Lewistown nearly coincides with the 

 original location of the stream, but to confound this with a precise 

 agreement is to lose the true significance of river history ; the 

 lower course is the product of diversion at least at two epochs 

 and certainly in sevei'al places ; and where the river now joins 

 the Susquehanna, it is suspected of having a superimposed course 

 unlike any of the rest of the stream. This is too complicated, 

 even if it should ever be demonstrated to be wholly true, to serve 

 as material for ordinary study ; but as long as it has a savor of 

 truth, and as long as we are ignorant of the whole histoiy of our 

 rivers, through which alone their present features can be right- 

 fully understood, we must continue to search after the natural 

 processes of their development as carefully and thoroughly as 

 the biologist searches for the links missing from his scheme of 

 classification. 



44. Provisonal Conclusion. — It is in view of these doubts and 

 complications that I feel that the history of our rivers is not yet 

 settled ; but yet the numerous accordances of actual and deduc- 

 tive locations appear so definite and in some cases so remarkable 

 that they cannot be neglected, as they must be if we should 

 adhere to the antecedent origin of the river courses. 



The method adopted on an early page therefore seems to be 

 justified. The provisional system of ancient consequent drainage, 

 illustrated on fig. 21, does appear to be sufl!iciently related to the 

 streams of to-day to warrant the belief that most of our rivers 

 took their first courses between the primitive folds of our moun- 

 tains, and that from that distant time to the present the changes 

 they have suffered are due to their own interaction — to their own 

 mutual adjustment more than to any other cause. The Susque- 

 hanna, Schuylkill, Lehigh and Delaware are compound, composite 

 and highly complex rivers, of repeated mature adjustment. The 

 middle Susquehanna and its branches and the upper portions of 

 the Schuylkill and Lehigh are descendants of original Permian 

 rivers consequent on the constructional topography of that time ; 

 Newark depression reversed the flow of some of the transverse 

 streams, and the spontaneous changes or adjustments from imma- 



