208         CONTRIBUTIONS   TO   ECONOMIC   GEOLOGY, 
small  mines  are  operated  chiefly  by  ranchmen  to  procure  fuel  for 
private  use. 
All  the  mines  are  operated  by  the  room  and  pillar  system.  They 
are  dry  and  contain  only  small  quantities  of  gas ;  hence  pumping  and 
safet}^  lamps  are  unnecessary.  Generally  the  coal  is  mined  by  "bear- 
ing in"  at  some  convenient  dirt  band  and  shooting  it  down  with  black 
powder.  Most  of  the  mines  employ  horse  haulage,  but  some  of  the 
more  recently  developed  mines  are  installing  cables  in  the  main 
gangways. 
COAL  FIELDS. 
To  facilitate  description  the  area  may  be  divided  into  four  fields, 
which  in  a  general  way  coincide  with  four  drainage  basins.  Except 
for  minor  modifications  they  also  agree  with  divisions  adopted  by 
Eldridgea  and  Fisher.6  They  are  the  Cody  field,  Meeteetse  field, 
Grass  Creek  field,  and  Gebo  field.  A  possible  fifth  field  includes  the 
valley  of  Clark  Fork,  but  as  that  region  contains  only  one  abandoned 
mine  and  no  exposures  of  coal  that  promise  future  development  it  is 
not  treated  in  this  report. 
CODY   FIELD. 
The  Cody  field  lies  mainly  in  the  Shoshone  River  valley.  It  is 
limited  on  the  south  by  the  Meeteetse  Rim  and  to  the  north  extends 
a  short  distance  beyond  the  divide  which  culminates  in  Heart  Peak. 
In  this  district  coal  occurs  in  the  Eagle  and  Laramie  (?)  formations. 
It  has  been  mined  from  the  Eagle  at  the  Allison,  Schwab,  and  Wiley 
mines  and  from  the  Laramie  ( ?)  at  the  mine  of  the  Cody  Coal  Company. 
Allison  mine.— The  Allison  mine  is  located  in  the  NE.  \  SE.  \  sec. 
25,  T.  55  N.,  R.  102  W.,  on  the  east  side  of  Skull  Creek,  a  branch  of 
Pat  O'Hara  Creek.  An  entry  has  been  driven  for  about  100  feet  on 
beds  which  dip  23°.  One  room  has  been  opened  from  the  entry  and 
about  250  tons  of  coal  taken  out  for  use  at  neighboring  ranches.  It 
is  a  good  subbituminous c  coal  suitable  for  domestic  purposes.  The 
coal  lies  beneath  a  thin  shale  bed,  which  in  turn  is  covered  by  a  massive 
sandstone.  Section  No.  2  on  PI.  XI  shows  the  character  of  the  bed 
at  the  mine  where  the  most  favorable  conditions  are  presented.  The 
bed  is  thinner  along  the  strike  on  both  sides  of  the  mine. 
Navine  mine. — The  Navine  mine,  3 J  miles  northeast  of  Cody,  for- 
merly supplied  a  domestic  trade  in  the  Shoshone  Valley.  The  mine 
is  now  abandoned  and  the  roof  so  badly  caved  that  a  section  of  the 
bed  could  not  be  measured,  and  the  previous  extent  of  the  mine  was 
not  determined. 
aEldridge,  G.  H.,  Bull.  U.  S.  Geol.  Survey  No.  119,  1894,  p.  54. 
b  Fisher,  C.  A.,  Prof.  Paper  U.  S.  Geol.  Survey  No.  53,  1906,  p.  46. 
cThe  name  subbituminous  has  recently  been  adopted  by  the  United  States  Geological  Survey  for  the 
class  of  coal  above  the  brown  lignites  and  below  the  bituminous  coals— the  class  generally  called  ' '  black 
lignite." 
