COAL   ON   SOUTHWEST   SIDE    OF   BIGHORN    BASIN,    WYO.  207 
valley  of  Cottonwood  Creek.  A  small  syncline  encompassed  by  coal 
beds  lies  in  the  southern  part  of  the  field  and  another  of  similar 
size  forms  a  spur  from  the  main  body  of  coal-bearing  rocks,  3  miles 
southeast  of  Gebo.  Further  details  of  the  structure  are  presented  on 
PI.  XL 
THE   COAL. 
GEOLOGIC  OCCURRENCE. 
In  the  western  part  of  the  Bighorn  Basin  coal  of  workable  thickness 
occurs  in  three  formations — the  Eagle,  Laramie  (?),  and  Fort  Union. 
The  Eagle  coal  occurs  mainly  at  one  horizon,  between  the  two  massive 
sandstones  comprising  this  formation.  Generally  this  coal  is  below 
the  limit  of  workability,  but  locally  it  is  of  sufficient  thickness  to  be 
of  importance.  There  are  a  number  of  small  mines  and  prospects  in 
the  Eagle  formation  throughout  the  field,  and  the  only  commercial 
mines  in  the  Bighorn  Basin  are  in  this  formation  in  the  vicinity  of 
Gebo.  In  one  of  these  mines  the  coal  locally  reaches  a  thickness  of 
11  feet. 
The  coal  beds  of  the  Laramie  (?)  formation  occur  in  rather  small 
lenses,  which  in  few  places  form  a  continuous  outcrop  for  more  than 
1  mile  and  which  are  workable  for  a  much  shorter  distance.  There 
is,  however,  northeast  of  Cody  an  exceptionally  extended  bed  which 
has  been  prospected  at  intervals  for  7  miles  along  its  outcrop  by  the 
Cody  Coal  Company  and  others.  Numerous  partings  of  bone  and 
shale  separate  the  beds  into  benches  generally  less  than  1  foot  thick. 
The  Laramie  ( ?)  coals  are  not  mined  at  present,  though  there  are  some 
abandoned  mines  and  many  prospects. 
The  Fort  Union  formation  contains  some  of  the  best  and  thickest 
coal  beds  in  the  western  part  of  the  Bighorn  Basin.  The  beds,  like 
those  of  the  Laramie  (?),  are  lenticular,  but  they  are  thicker  and  con- 
tain fewer  partings.  In  the  Mayfield  syncline  there  are  three  beds, 
one  of  which  is  reported  as  containing  32  feet°  of  good  coal.  The 
Black  Diamond  mine,  near  Meeteetse,  is  operated  throughout  the 
year  on  a  bed  of  coal  of  this  age. 
The  location  of  the  mines  and  prospects  and  sections  representat i ve 
of  local  conditions  arc  shown  on  PL  XI. 
GENERAL   MINING  CONDITIONS. 
There  are  a  few  commercial  and  many  small  mines  and  prospects  in 
the  area.  Three  of  the  largest  mines  located  near  Gebo  are  being 
extensively  developed  since  the  building  of  the  Burlington  Railroad 
into  the  field  during  the  fall  of  1007.  Two  small  commercial  mines 
near  Meeteetse  supply  the  local  trade  in  Grey  Bull  Valley.     Many 
a  During  the  fall  of  1907,24  Eeet  of  coal  in  a  single  bench  was  exposed  in  a  prospect  the  bottom  of  which 
was  filled  with  water.    Mr.  Mayfield,  who  owns  the  property-,  states  thai  the  total  thickness  is  32  feet. 
