ikving.]  OURAY   DISTRICT,   COLORADO.  77 
determined  even  by  the  most  careful  methods  of  assay,  and  since 
almost  any  rock  in  a  mineralized  region  in  the  neighborhood  of  ore 
deposits  may  contain  values  equal  to  or  slightly  in  excess  of  this 
amount  the  inference  seems  justifiable  that  no  gold-bearing  lodes 
existed  prior  to  the  deposition  of  the  conglomerate.  The  purely 
negative  results  shown  by  these  samples  seem  also  to  afford  to 
those  interested  in  mining  in  this  region  a  strong  reason  for  the 
exercise  of  extreme  caution  in  the  exploitation  of  these  Eocene 
gravels. 
