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doubt that lines of fault, giving to the strata of sandstone, limestone 

 and slate, originally horizontal, an eschellon position, have occasion- 

 ed this repetition of the rocks of the ridge in the Mill mountain, pre- 

 serving their dip in the same direction; or more familiarly speaking, 

 these two ridges were thrown up from their horizontal position un- 

 der such an action of the dislocating force as not to elevate the rock 

 on the western side of each ; and, therefore, not to present any strata 

 having a counter or western dip. To present this principle, which 

 is familiar to geologists, in another point of view, the rocks of the 

 Mill, Brown, and North mountain, being rocks of sediment, and hav- 

 ing, therefore, been originally horizontal, or nearly so, formed one 

 continuous bed, the sandstone lying beneath, the limestone next, and 

 the slate upon the surface. The disturbing force throwing up the 

 sandstones of the North mountain, gave them a western dip, while 

 other forces dislocating the strata to the west, gave them the parallel 

 but not continuous positions which they now display. Instances of 

 this kind of disturbance are among the most usual in geology, and 

 would readily be inferred by those versed in the subject to have oc- 

 curred at the points here described, by a simple view of the profile 



itself. 



But it is thought that the explanation above given will aid the ge- 

 neral reader, for whom the report is chiefly intended, in understand- 

 ing the delineation of this portion of our line. West of the Mill 

 mountain to near the base of the Warm Spring mountain, we pass 

 over slates occasionally exposing the subjacent bed of limestone, but 

 throughout this valley scarcely a glimpse of the sandstone which lies 

 still lower can be had. At Bratton's Ridge, the limestone comes 

 boldly out with an eastern dip, and at some distance beyond, a turn 

 not delineated having occurred in the strata, the slate is seen dipping 

 in the opposite direction. This brings us to the little valley of the 

 Millboro' Sulphur spring, which here issues from the pyritous slate 

 — and now the slate is found dipping to the east until another change 

 brings up the limestone into view near the Blowing cave, and the 

 dip becomes west again ; after which, with several rolls or undula- 

 tions as seen in the Cow Pasture hills, it settles into an eastern dip, 

 which continues to the boundary of the slate near the base of the 

 Warm Spring mountain. Here limestone occurs dipping with the 

 slate, and this brings us upon the debris piled upon the skirts of this 

 lofty range. As the structure of the Warm Spring valley will re- 



