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presented in the profile. A similar direction of the strata is also 

 seen in the range of the North mountain in Rockbridge and else- 

 where, but as exhibited in the section of Brown's ridge and the Mill 

 mountain, the dip is east. The rocks composing the North moun- 

 tain at the place represented in the section, are chiefly sandstones ot 

 different hues and textures, with a reddish shale appearing towards 

 the eastern base. Ascending by the eastern side, after passing these 

 shales, we meet with red and gray sandstones ; then deep red sand- 

 stone with occasional seams of a shale interposed, to near the sum- 

 mit, where we find a heavy stratum of white pinkish sandstone ex- 

 posing an extensive bared surface, which dips N. W. On the west- 

 ern side following the winding of the spurs, the pinkish variety of 

 rock is succeeded by gray, and thence tracing the mountain to its 

 base, the red and gray varieties appear with changing dip, such as 

 would be explained by the structure indicated in the profile view of 

 this side of the mountain. Pursuing a western course, we find slate 

 dipping to the west for some distance from the flank of the mountain, 

 but assuming an eastern dip as we approach the base of Brown's 

 ridge, where a bed of limestone, with a correspondent dip occurs, 

 after which we come upon the gray and reddish sandstones com- 

 posing that ridge, which also dip in the same direction. 



There being no reason for doubting the identity of the rocks in 

 the North mountain and Brown's ridge, we are led to infer, that im- 

 mediately at the base of the former there exists a western dipping 

 limestone similar to that with eastern dip at the base of the ridge, 

 but not having detected it in consequence of its being concealed by 

 the fragments of rock collected there, it is not indicated in the figure. 

 The series of rocks thus far, commencing with that which in the ho- 

 rizontal disposition, must have been the lowest, would, therefore, be 

 sandstone, limestone, slate ; and this order we shall find prevailing 

 for some distance farther west. The sandstones of Mill mountain, 

 like those of Brown's ridge, dip east, and are separated from the for- 

 mer by an intervening valley of slate, the western portion of which 

 is seen dipping in conformity with the rocks of the Mill mountain, 

 but in the eastern part no rocks in situ could be seen on account of 

 the mass of fragments by which they were covered up. From the 

 precipitous escarpments of the two ridges here described, the appa- 

 rent identity of those rocks of which they consist, and other striking 

 circumstances in the features of the valley, there can be but little 



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