77 



Till' gradients of the different series vary in about tlie same way on 

 tlie tliroe fcirlcs. tliongli tliere is not perfect agreement. The general rela- 

 tions are shown Iiy Fig. 3. viz.: 



(1) The recent terraces above the point of junction of the forks 

 agree (inite closely in gradient with that of the stream to which they 

 are adjacent. 



(2) The older terraces have lower gradients than that of the 

 adjacent stream. 



One series, the Hftli, has a surface almost horizontal so far as the 

 West Fork is concerned ; but its extent ahmg this fork is limited to about 

 three-fourths of a mile. When considered as a part of the corresponding 

 series along INIiddle Fork with a total extent of nearly six miles, it agrees 

 in general with the older terraces in having a distinct gradient, but less 

 than that of the stream at present. The terrace profiles shown in Fig. 3 

 may suggest that the lower and upper parts of the third series do not 

 belong together, since the degiee of slope is so noticeably different. It 

 cannot, of course, be considered as settled beyond question, yet the work 

 in the Held indicated so strongly that the two portions are part of the 

 same scries that the correlation was made as here given. 



In most cases the remnants belonging to a given series are found part 

 on one side, part on the other side of the stream. n only a few cases 

 are remnants of the same series found on both sides of the stream at a 

 given point. 



n exi)lanation of the profile of the West Fork it should perhaps be 

 remarked that the Falls indicated are due to a diversion of the stream 

 from a part of its natural channel for water-power purposes, which has 

 forced it to abandon a part of its former course and re-enter its valley 

 at a ]ioint where the slope is steep and formed of outcropping bed rock. 

 The terraces of series (1) and (2) are. therefore, plainly not to be cor- 

 related, although the height of (2) above the stream bed above the Falls 

 is about the same as that of (1) above the stream bed below. 



Terraces Within the Gorge. 

 W^ithin the part of the main valley which is canyon-like, extending 

 from a little north of the city of Richmond to a point about two miles 

 south, are two well marked terrace levels, an upper and a lower, indicated 

 in prolile on Fig. 3 by (A) and (B) respectively, and shown on Fig. 2 by 

 solid black (upper), and obliquely lined (lower), areas. At neither level 



