116  CONTRIBUTIONS   TO    ECONOMIC    GEOLOGY,   1907,   PART   II. 
by  the  entire  thickness  of  the  Colorado  shale;  hence  no  information 
could  be  obtained  concerning  the  thickness  of  the  coal  bed.  Work- 
able coal  is  found  only  in  a  very  narrow  strip  to  the  north  of  the 
outcrop  along  the  base  of  the  Judith  Mountains  and  a  small  area  on 
the  south  side  of  Warm  Spring  Creek. 
In  the  southern  part  of  the  Warm  Spring  Creek  district  there 
appears  to  be  but  one  bed  of  coal,  which  splits  to  the  north  into  three 
members,  that  number  having  been  observed  in  exposures  near  Deer 
Creek.  The  coal  bed  varies  greatly  in  character  and  thickness  in  the 
district,  so  that  no  representative  section  can  be  given.  It  is  usually 
about  30  inches  thick  and  is  underlain  and  overlain  by  clay.  Near 
Warm  Spring  Creek  the  coal  bed  thickens  locally  to  43  inches  and 
occurs  in  two  benches  with  a  4-inch  bone  parting  between. 
Development. — The  Mace  mine,  in  the  NW.  J  sec.  32,  T.  17  N., 
R.  19  E.,  is  the  chief  producer  of  the  Warm  Spring  Creek  district. 
The  greater  part  of  the  coal  obtained  in  this  mine  is  taken  by  wagon 
to  Kendall,  a  town  outside  of  the  territory  mapped,  in  the  gold- 
mining  district  of  the  North  Moccasin  Mountains.  The  Nevin  mine, 
in  the  SE.  \  sec.  7,  T.  16  N.,  R.  19  E.,  yields  a  small  tonnage.  An 
abandoned  mine,  owned  by  the  New  Year  Mining  Company  and 
formerly  furnishing  that  company  with  fuel,  is  located  near  the  New 
Year  mill,  in  sec.  10  of  the  same  township.  The  workings  of  this 
mine  are  being  kept  in  repair,  in  view  of  possible  resumption  of  metal 
mining  in  the  district.  There  is  an  abandoned  mine  about  half  a  mile 
east  of  the  Mace  mine,  and  another,  known  as  the  Fergus  mine,  is 
located  near  the  center  of  sec.  20,  T.  17  N.,  R.  19  E. 
M'DONALD    CREEK   DISTRICT. 
General  conditions. — The  largest  district  in  the  Lewistown  field 
containing  workable  coal  is  that  to  the  south  of  the  Judith  Mountains, 
the  greater  part  of  it  lying  near  the  headwaters  of  McDonald  Creek. 
The  northern  limit  of  the  district  is  defined  by  the  coal  outcrop  along 
the  base  of  the  Judith  Mountains.  The  outcrop  along  South  Fork  of 
McDonald  Creek  marks  the  southern  boundary  east  of  the  McDonald 
Creek  divide.  West  of  this  divide  the  coal  does  not  extend  south  of 
the  Lewistown-Forest  Grove  wagon  road,  and  along  the  outcrop 
between  the  divide  and  the  mines  above  Lewistown  workable  coal 
does  not  appear  to  be  present.  The  producing  area  along  Big  Spring 
Creek  affords  no  data  regarding  the  extent  of  workable  coal  in  any 
direction  except  to  the  south  and  southeast,  so  that  it  can  not  be 
stated  definitely  that  this  area  is  in  reality  a  part  of  the  McDonald 
Creek  district.     In  the  present  paper,  however,  it  is  so  treated. 
The  eastern  limit  of  the  McDonald  Creek  district  also  is  indefinite. 
East  of  Forest  Grove  the  coal  outcropping  along  McDonald  Creek  indi- 
