BULL   MOUNTAIN   COAL   FIELD,   MONTANA.  71 
Section  of  Matt  coal  bed  in  sec.  6,  T.  6  N.,  R.  27  E. 
Ft.  in. 
Shale,  coaly 5 
Coal 2    6 
Coal  and  brown  shale 5 
Coal 7 
3  11 
At  a  distance  of  45  feet  above  the  Matt  coal,  and  usually  separated 
from  it  by  a  bed  of  sandstone,  occur  the  two  Bull  Mountain  coals 
(F  and  G  coals,  PI.  IV).  These  beds  are  very  persistent  and  in 
general  they  mark  the  base  of  the  high  bluffs  of  the  southern  Bull 
Mountain  mesas.  To  the  northwest,  however,  a  slight  dip  in  the 
rocks  brings  the  coals  down  100  feet  or  so  below  the  bold  bluffs  of  the 
northern  mesas.  These  coal  beds  are  usually  separated  by  only  15 
or  20  feet  of  sandstone  and  a  little  shale.  Accompanying  the  upper 
bed  and  lying  upon  it  is  generally  a  conspicuous  dark-gray  clay  shale 
20  to  30  feet  thick.  In  places  one  or  the  other  of  the  coal  beds  is  of 
insignificant  size,  but  generally  the  remaining  bed  is  of  workable 
thickness.  Thus  in  the  southeastern  half  of  T.  6  N.,  R.  27  E.,  usually 
only  one  of  the  coal  beds  measures  over  2  feet  thick,  and  this  is  in 
most  places  the  lower  bed.  In  the  northeastern  portion  of  the  town- 
ship, however,  both  beds  are  regular  and  of  workable  thickness. 
In  the  former  locality  the  thickness  ranges  from  2  to  5  feet,  the 
average  being  a  trifle  over  3  feet.  In  the  northeast  corner  of  the 
township  the  upper  bed  is  uniformly  2  or  3  feet  thick,  and  3^  feet 
in  T.  7  N.,  R.  27  E.  On  the  other  hand,  the  lower  coal  approaches 
3 J  feet  in  thickness  in  sec.  14,  T.  6  N.,  R.  27  E.,  and  from  this  point 
thins  in  both  directions,  being  2  feet  or  less  in  T.  7  N.,  R.  27  E. 
Partings  of  shale  are  not  numerous,  and  the  following  is,  perhaps,  a 
common  section  in  the  northeast  corner  of  the  township: 
Section  of  Bull  Mountain  coal  bed  in  sec.  13,  T.  6  N.,  R.  27  E. 
Ft.  in. 
Coal 2 
Shale,  brown 2 
Coal 2  4 
Shale  and  sandstone 12 
Coal 1  5 
Shale 3 
Coal 1  3+ 
17     7  + 
In  some  localities  one  or  the  other  of  these  beds  is  burned  on  the 
outcrop,  in  which  case  the  horizon  is  marked  by  10  or  12  inches  »l 
reddish  to  gray  ashes. 
Above  the  Bull  Mountain  coal  beds  the  section  of  rocks  presents  ;i 
series  of  thin  coal  beds  occurring  at  intervals  of  1 5  to  40  feet.  The 
Wescott  coal  (E  coal,  PL  IV),  about  100  feet  above  the  upper  Bull 
Mountain  coal,  is  the  next  higher  bed  to  reach  significant  thick] 
