296 



QUICKSILVER DEPOSITS OF THE PACIFIC SLOPE. 



The line of contact, on the other hand, is marked by many irregulari- 

 ties. In the following diagram (Fig. 1 1) the line a h is the contact as it wonld 

 appear were a horizontal [)lane passing through it at the mean elevation of 

 3,800 feet. The line c d .shows the intersection of one of the Chico strata 

 with the ;3, 300-foot level. The stratum for which this subterranean contour 

 line was dednced was followed almost continuously for the entire distance 

 shown, a closely adjacent stratum being sometimes substituted for a short 

 distance. Other strata were mapped as far as they could be followed, in 

 several cases for over half a mile. The curvature was in all cases similar and 

 the conformity was absolute. In comparing this figure with the geological 

 map it is of course to be remembered that the contact on the latter is laid 

 down as it appears on the actual surface, while in the tigure it is represented 

 as it would appear were the country a horizontal })lane. At one point the 

 line of the figure is still further modified. The steep hill immediately south 

 of the Hacienda or Bell tunnel is not wholly in place. A large landslide 

 has begun here and an immense mass of metamorphic material has moved 

 northward past the solid contact. For this movement allowance has been 

 made in drawing: the fiojure. 





Fig. U. a h contact bi'tween metamorphic rocks and Chico beds redaoed to intersection with a horizontal plane ; c d, 

 strike of a Chico stratum reduced to intersection with a horizontal piano. 



The structure is evidently consistent with a non-conformity. It is also 

 conceivable that the entire mass of strata was laid down conformabl}" and 

 that the disturbance and metamorphism ceased abruptly at the line repre- 



