BULL   MOUNTAIN   COAL  FIELD,    MONTANA.  69 
It  is  well  developed  at  the  southern  base  of  the  Bull  Mountains  proper, 
in  or  near  the  southern  and  southeastern  portions  of  T.  (J  X.,  K.  27  E. 
It  also  extends  westward  into  T.  6  N.,  R.  26  E.,  where  it  crosses  the 
main  divide  near  the  center  of  the  township,  and  is  exposed  at  the 
point  where  the  Roundup  road  crosses  the  summit  of  the  divide. 
From  this  point  it  turns  northward,  crossing  Dorrity  Coulee  near  the 
northeast  corner  of  this  township,  sweeping  northeastward  around  the 
northern  group  of  the  Bull  Mountains  and  swinging  back  into  the 
head  of  Fattig  Creek,  in  the  northeast  corner  of  T.  6  N.,  R.  27  E. 
Thence  it  extends  eastward,  probably  crossing  the  main  divide  in 
R:  28  E.  and  returning  to  connect  with  the  outcrop  on  the  south  side 
of  the  mountains.  The  eastern  portion,  however,  was  not  investi- 
gated during  the  last  season.  Throughout  the  area  studied  the  coal 
is  of  workable  thickness  except  in  T.  6  N.,  R.  26  E.  In  this  locality 
it  is  from  3  to  5  feet  thick  on  the  main  divide  in  the  south-central 
part  of  the  township,  but  as  the  outcrop  continues  northward  the 
thickness  decreases  to  2  or  3  feet  and  probably  less.  The  exposures 
in  this  locality  were  largely  concealed  by  grass  and  soil  so  that 
measurements  could  not  be  made,  but  in  fresh  cuts  the  bed  measured 
in  places  only  a  few  inches.  In  T.  6  N.,  R.  27  E.,  however,  the  coal 
has  a  thickness  ranging  from  8  to  15  feet,  the  eastern  portion  of  the 
township  showing  usually  15  feet  of  coal.  It  is  burned  at  some 
points,  but  it  is  believed  that  this  burning  extends  only  a  short  dis- 
tance back  from  the  outcrop  where  the  cover  is  reasonably  thick. 
The  Mammoth  bed  usually  carries  three  or  four  thin  partings,  whose 
relative  position  and  thickness  are  shown  in  the  following  section, 
measured  at  the  head  of  Fattig  Creek: 
Section  of  Mammoth  coal  bed  at  head  of  Fattig  Creek. 
Ft.     in. 
Coal 1   10 
Shale 3 
Coal 3  10 
Coal,  shaly 2 
Coal 2     1 
Shale  and  clay 6 
Shale,  coaly G 
Coal 2    7 
Shale 2 
Coal 3     3 
15    2 
At  a  point  in  sec.  30,  T.  6  N.,  R.  26  E.,  where  this  bed  measures 
8  feet  6  inches,  different  portions  of  it  were  sampled  for  analysis. 
The  lower  7  feet  gave  a  fuel  value  of  10,121  B.  t.  u.  in  the  sample 
as  received,  and  the  upper  remaining  portion  of  the  bed  over 
6,200  B.  t.  u. 
