46  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1904.         [  bull.  200. 
Crescent  belt  last  October  there  were  but  two  producing  mines  with 
one  quartz  mill  and  two  arrastres. 
The  most  continuous  activity  of  the  region  has  been  along  Wards 
Creek,  on  the  border  of  Genesee  Valley,  where  the  Gruss  mine  has 
been  in  operation  for  over  twenty  years.  Near  by  is  the  Five  Bear 
mine,  and  across  Genesee  Valley  is  the  Cosmopolitan,  from  which  most 
of  the  ore  was  obtained  years  ago  for  the  Coppertown  furnace. 
Beyond  are  the  Regal,  Engel,  and  finally,  in  Lights  Canyon,  the 
Superior  mine,  where  a  body  of  bornite  and  chalcopyrite  approxi- 
mately 00  feet  long,  40  feet  Avide,  and  3  feet  thick  has  been  removed. 
These  mines  and  several  smaller  ones  lie  in  the  Genesee  mining  belt, 
which  extends  from  Wards  Creek  N.  22°  W.  to  Lights  Canyon,  a  dis- 
tance of  about  15  miles.  While  conservative  estimates  place  the  total 
prod  net  ion  of  the  Crescent  belt  at  $6,650,000,  that  of  the  Genesee  belt 
has  been  estimated  at  $450,000.  At  the  present  time  in  the  Genesee 
belt  there  are  5  mines  active,  with  2  stamp  mills  and  3  arrastras. 
GENERAL  GEOLOGY   OF   INDIAN  VALLEY   REGION. 
The  Indian  Valley  region  has  three  topographic  parts:  (1)  The 
prominent  ridge  of  Grizzly  Mountain  and  Arlington  Heights,  on  the 
southwest,  made  up  largely  of  Silurian  and  Carboniferous  sediments: 
(2)  Kettle  Rock  Mountain,  on  the  northeast,  composed  of  pre-Ter- 
tiary  volcanic  rocks  and  granodiorite,  and  (3)  a  group  of  valleys  and 
lower  hills  in  the  middle  part,  containing,  besides  subordinate  masses 
of  volcanic  rocks,  a  great  thickness  of  Jurassic,  Triassic,  and  some 
Carboniferous  rocks. 
The  rocks  of  each  part  form  a  mass  which  may  be  called  a  block. 
The  middle  or  valley  block  is  separated  from  the  grizzly  block  on  the 
southwest  by  a  great  overthrust  fault  which  brought  the  Silurian 
limestone  in  Grizzly  Mountain  far  up  over  the  sandstones  of  Jurassic 
age.  On  the  northeast  of  the  valley  block,  where  it  adjoins  the  Ket- 
tle Mountain  block,  there  may  have  been  some  faulting,  but  it  is  not 
expressed  in  the  topography. 
Attention  has  already  been  called  to  the  fact  that  the  mines  of  the 
Indian  Valley  region  are  in  two  belts,  the  Genesee  belt  and  the  Cres- 
cent belt.  The  Genesee  belt  corresponds  approximately  to  the  contact 
on  the  northeast  side  of  the  valley  block  where  it  adjoins  that  of 
Kettle  Rock  Mountain,  but  the  Crescent  belt  of  mines  lies  a  short  dis- 
tance southwest  of  the  great  overthrust  fault,  wholly  within  the  block 
to  which  the  rocks  of  Arlington  Heights  belong. 
GEOLOGY  OF  CRESCENT  BELT  OF  MINES. 
The  Crescent  mining  belt  has  in  it  two  long,  narrow  masses  of 
granodiorite,  one  southwest  of  Taylorsville,  cutting  the  Paleozoic 
