SUMMARY OF THE DATA 427 



well number ], except that the ahnornial rocks were met at a slightly 

 greater depth. 



Neither tjie logs of the wells nor the samples tlierefrom showed igneous 

 rocks, but many horizons of slate were indicated. The rocks which drillers 

 indicate as slate, however, are generally hard shales, and such is probably 

 the case in these wells, as tlie \ogfi also show shales lying ])etween slates. 

 In each well rocks were cjiconntered which the drillers identified as mica. 

 These proved to be merely fine-grained sandy sliales carrying large quan- 

 tities of hydrated mica. Black limestones were indicated in the logs. 

 These were found to coiitain no calcium carboiiate, l)ut to Ije hardened 

 chloritized material containing hydrated mica. Tliey appear to have 

 been black shales. Botli the micaceous substances and tlie black rocks 

 have a distinctly soapy feel. 



The data given by the well logs make it appear rpiite probable that 

 alteration has affected the sediments beneath the anticline to a consider- 

 able extent, and that the alteration becomes deeper witli distance from 

 the Silver City ridge. In itself, however, the evidence of the wells is of 

 little value; but taken in connection with the actual fact of alteration it 

 is corroborative. 



SUMMATIY OF THE DaTA 



(1) Silver City ridge lies on the northeastern flank of a comparatively 

 high anticline, and on this flank there has been rather decided local 

 deformation of the strata. 



(2) In a narrow zone on the northeastern flank of the anticline the 

 Lawrence shales, which elsewhere are ])oorly cementer! sands and shales 

 of varied colors, are compact, hard rpiartzites of a gray or greenish color, 

 the green being due to the development of varial)le j^roportions of chlorite. 



(e3) The latan limestone, v^hich elsewhere than on the south face of 

 Silver City ridge is a compact s])lintery limestone in its upper division, 

 is there re])laced by a dai'k green earthy chert, or a lu'eccia from the same, 

 with the. chert making its first appearance in a purer and harder form. 

 as fillings in the cracks of the limestone, while the matrix of the })reccia 

 and, to a lesser degree, the fragments contain horidilende, epidote, and 

 chlorite whicli crystallized from solution at a time subsecpient to the 

 brecciation. 



(-1-) The Le lioy shales, whicli in the areas surrounding Silver City 

 ridge are poorly cemented yellow and gray sandy shales, on the south side 

 of the ridge are fine-grained, v.ell laminated, firmly cemented gray and 

 light green quartzites. 



