THE  lllll  MOUNTAIN  COAL  FIELD,  MONTANA." 
By  L.  H.  Woolsey. 
INTRODUCTION. 
The  preliminary  report  on  the  coals  of  a  portion  of  the  Bull  Moun- 
tain field,  Montana,  here  presented,  is  based  on  a  detailed  survey 
made  during  the  summer  of  1907  by  R.  W.  Richards,  H.  Bancroft, 
and  the  writer.  The  progress  of  the  work  was  materially  aided  by 
the  assistance  and  hospitality  of  the  residents  and  of  various  com- 
panies interested  in  the  field,  for  which  acknowledgment  can  be  made 
Dnly  in  this  general  way. 
The  investigation  was  undertaken  for  the  purpose  of  classifying  by 
legal  subdivisions  of  40-acre  tracts  the  public  lands  as  coal  land  or 
noncoal  land.  The  area  covered  in  this  manner  comprises  a  strip  of 
country  approximately  two  townships  wide,  bordering  the  south  side 
of  Musselshell  River  and  extending  from  the  vicinity  of  Shawmut, 
Meagher  County,  to  the  Bull  Mountains.  The  western  and  larger 
part  of  this  area,  or  that  lying  roughly  between  Shawmut  and  Golden 
Creek,  probably  contains  no  coal  of  commercial  importance.  Two 
thin  coal  beds  were  found  in  the  Eagle  sandstone  near  Crawford's 
coal  bank,  on  Fish  Creek,  near  CavhTs  ranch,  and  elsewhere,  but  they 
average  only  23  inches  in  thickness,  including  a  parting  of  shale  7  to 
12  inches  thick.  The  Judith  River  formation  also  contains  a  few 
thin  beds  of  coal,  ranging  from  6  to  32  inches,  but  the  beds  are  com- 
monly lenticular  or  split  by  thin  partings  of  shale.  No  coal  beds 
are  known  to  occur  between  this  formation  and  the  Eagle,  above 
described,  and  between  the  former  and  the  coal  beds  of  the  Fort  Union 
formation  in  Bull  Mountain  no  coals  of  value  were  observed.  Thus, 
in  the  hilly  country  between  the  lower  course  of  Painted  Robe  Creek 
and  Golden  Creek  indications  of  coal  were  observed  at  only  five  or 
six  horizons,  and  these  beds  carried  12  inches  or  less  of  coal  or  coaly 
shale. 
The  western  part  of  the  country  surveyed  may  therefore  be  disre- 
garded in  a  discussion  of  commercial  coal  fields.     On  the  other  hand, 
a  A  full  report  on  this  coal  field  is  in  preparation  and  will  be  published  as  a  separate  bulletin. 
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