Campbell — Changes in the Drainage of Virginia. 23 



fig. 1) although the easier course would have been to join the 

 river east of this fold. This cross anticline, pitching rapidly 

 northward, has arched the strata in such a manner that the 

 conglomerate, at this point, extends much beyond its general 

 line of outcrop. Guest river originally flowed across this 

 projecting point without coming in contact with the hard 

 stratum, but in later ages it has removed the softer rocks and 

 reached the main conglomerate. The stream has slowly mi- 

 grated down the' slope of the hard bed, forming a great north- 

 erly bend at the point where the axis crosses the river. No 

 such formidable barrier intersects the course of Yellow creek, 

 but in the measures above the conglomerate there are many 

 hard sandstones which would doubtless have a tendency to 

 shift the course of the stream. 



The acute angle made by Guest river itself at Norton is 

 equally remarkable and cannot be explained by the present 

 course of the river, since there is nothing to prevent this 

 stream from avoiding Norton altogether and joining the river 

 near the mouth of Yellow creek. If Guest river were a 

 mature stream this would certainly have been accomplished 

 and Yellow creek also would have been shifted to the east- 

 ward in accordance with the present conditions. But the 

 system is not adjusted to the surrounding conditions ; it has 

 the marks of immaturity, of adjustment to conditions which 

 no longer exist and which were radically different from the 

 present. 



The divide between Powell and Guest rivers is no more 

 conspicuous than that between any two tributaries of the same 

 stream ; but being quite narrow it has the appearance of ex- 

 ceeding them in altitude. The country is essentially a deeply 

 dissected plateau with the water partings standing at or near 

 the original surface. Along the northern side of Stone and 

 Powell mountains there is a valley due to the combined effect 

 of a line of outcrop of soft shale and great disturbance of the 

 strata in the uprising of the Powell Yalley anticline. This 

 valley has been accentuated by the work of the rivers under 

 consideration, for they have naturally availed themselves of 

 the most favorable location and have carved deep channels 

 throughout most of its extent. In view of these structural 

 facts, we might expect to find a low gap in the divide between 

 the two drainage basins, but it is even lower than would be 

 expected. Furthermore a distinct channel across it is still 

 visible and a deposit of white sand and clay rests upon its 

 highest point at Norton. 



Thus it seems certain that at no very remote time, geologi- 

 cally speaking, there w T as a large stream flowing across this 

 divide ; it seems equally certain that the direction in which it 



