U S GEOLOGICAL SURVEY 



MONOGRAPH XXVHI, PL X 



F!C. 1. RKrOMPUSl'JL) ROCK, l!t:SKMi'>I, IXC. C.K.WITK, FROM WEWE SLATE 

 FIG- L:. KKRRL'C.IXOCS SIAMO Sl.ATK, SHOWING OX'KRTHRFST FAFl.T 



