STRUCTURAL RESULTS OF FAULTING. 181 



if the equation is referred to the asymptote and a hue parallel to the fault 

 line and crossing the asymptote at 274 feet west of the fault line, it becomes 

 for the natural unit, 



The natural unit of the west curve is 1,085 feet, and if it be referred 

 to its asymptote and a line parallel to the fault line and crossing the asymp- 

 tote at a point 143 feet west, its equation is 



y--\0\ 



The equation of the tangent for the Stitro section values shows that 

 the horizontal point of the east curve is at 2,840 feet from the fissure meas- 

 ured on a line parallel to the asymptote, and that of the west curve at 1,820 

 feet measured in the same way. The tangent to the east curve at the fault 

 makes an angle of 2G° with the horizontal, while the tangent to the west curve 

 makes an angle of 32°. This sudden increase of inclination immediately 

 west of the croppings is a familiar feature of the landscape in Virginia. 

 Had the diorite been separated into plates of the same thickness as those 

 of the east country, the two curves would have had a common tangent at 

 the croppings. 



The position of the points of greatest curvature presents no significant 

 peculiarity, so far as I am aware, and is expressed by a somewhat involved 

 loo-arithmic function. This point in the east curve is at a distance of 686 

 feet from the fault plane, measured on the asymptote. In the west curve 

 it lies at dr)l feet from the same plane. The values of the minimum radii 

 are 6,640 feet and 3,.'^)80 feet in the east and west curves, resi)ectively. 

 These radii are simply and directly proportional to the natural units of the 

 curves. 



Topography chiefly due to faulting. — The wcst CToppiugs of tlic CoMSTOCK, ffom the 

 Bullion to the Oph'n; are nearly horizontal, and the original surface, as has 

 Ijeen shown, sloped to the west at an angle of only two and a half degrees. 

 The theory of faulting propounded would therefore lead one to expect a 

 pretty close agreement between the contours of the faulted slope and those 

 of the west wall; for on the Sidro Tunnel section, at least, there is evidence 

 of but slight erosion. Such an agreement appears from a comparison of 



