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National Geogra^phio Magazine. 



transverse gap, EB, in the next higher hard bed, and there 

 rejoining the diminished representative or survivor of the 

 original axial or synclinal stream, GB. 



lY. Terminology of rivers changed by adjustment. — A special 

 terminology is needed for easy reference to the several parts of 

 the streams concerned in such an adjustment. Let AB and 

 CD, fig. 14, be streams of unequal size cutting gaps, H and G, in 

 a ridge that lies transverse to their course. CD being larger than 

 AB will deepen its gap faster. Of two subsequent streams, JE 

 and JF, growing on the up-stream side of the ridge, JE will have 

 the steeper slope, because it joins the deeper master-stream. The 

 divide, J, will therefore be driven towards AB, and if all the 

 conditions concerned conspire favorably, JE will at last tap AB 

 at F, and lead the upper part, AF, out by the line FEGD, fig. 15, 



Fig. 14. 



Fig. 15. 



through the deeper gap, G. We may then say that JE becomes 

 the divertor of AF, which is diverted y' and when the process is 

 completed, by the transfer of the divide from J, on the soft rocks, 

 to a stable location, H, on the hard rocks, there will be a short 

 inverted stream, HF ; while HB is the remaining beheaded 'portion 

 of the original stream, AB, and the water-gap of AB becomes a 

 wind-gap, H. It is very desirable that geographic exploration 

 should discover examples of the process of adjustment in its 

 several stages. The preparatory stage is easily recognized by the 

 difference in the size of the two main streams, the difference in 

 the depth of their gaps, and the unsymmetrical jDosition of the 

 divide, J. The very brief stage of transition gives us the rare 

 examples of bifurcating streams. For a short time after capture 

 of the diverted stream by the divertor, the new divide will lie 

 between F and H, in an unstable position, the duration of this 

 time depending on the energy of the process of capture. 



