354  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,   1903.  [bull. 225. 
Section  of  Eades  mine  near  Middleton,  Wyo. 
J      .  Ft.     In. 
Dark-gray,  compact  clay 2      0 
Impure,  coaly  shale 1       0 
Coal 4      0 
Thermopolis  district. — This  district  is  located  on  the  west  side  of 
the  Bighorn  Basin,  about  12  miles  north-northeast  of  Thermopolis,  and 
a  few  miles  below  the  mouth  of  Kirby  Creek.  The  formation  consists 
of  alternating  layers  of  massive,  gray  sandstone,  sandy  shale,  and  clays 
belonging  to  the  basal  sandy  series,  with  an  increased  amount  of  shale, 
and  a  locally  developed  clinker  bed  occurring  immediately  below  the 
principal  coal  seam  of  the  district.  This  is  the  only  clinker  bed  thus  far 
observed.  The  dip  of  the  beds  is  17°  north-northeast.  The  Jones  mine 
was  opened  in  this  district  in  the  summer  of  1889,  but  the  output  was 
small  for  the  three  following  years,  scarcely  exceeding  200  tons  a  year. 
Since  1900  the  annual  output  has  increased  to  1,000  tons,  but  as  yet 
only  a  small  part  of  the  field  has  been  Avorked  and  the  present  pro- 
duction of  this  locality  could  be  increased  many  times.  Operations  have 
now  ceased  at  the  Jones  mine  and  a  new  opening  has  recently  been  made 
by  McDonald  &  Cottle.  The  principal  bed  is  9  feet  thick,  overlain  by 
a  bed  of  sandy  clay  of  variable  thickness.  Above  this  is  another  coal 
bed  5  feet  thick.  In  the  McDonald  &  Cottle  mine  the  sandy  clay 
reaches  a  minimum  thickness  of  2  inches,  which  practically  unites 
the  2  seams,  giving  a  total  thickness  of  14  feet.  This  is  the  thickest 
coal  deposit  thus  far  observed  in  the  Bighorn  Basin.  Five  other 
closely  adjacent  beds  occur,  4  below  and  1  above  the  11-foot  bed;  3 
of  the  lower  beds  are  said  to  be  workable.  The  uppermost,  outcrop- 
ping 25  feet  below  the  McDonald  &  Cottle  vein,  is  3  feet  thick  and 
apparently  of  good  quality.  The  total  thickness  of  the  various  beds 
exposed  within  close  vertical  range  is  approximately  30  feet.  The 
material  is  a  bright,  firm,  free-burning  variety  of  lump  coal.  It  gives 
a  brown  streak,  breaks  in  blocks,  and  does  not  crumble  easily  on 
exposure.  The  analysis  shows  a  rather  high  per  cent  of  fixed  carbon 
and  moisture,  and  only  a  small  amount  of  ash.  At  the  McDonald  & 
Cottle  mine  the  following  section  was  taken: 
Section  of  the  McDonald  <&  Cottle  mine  near  Thermopolis,  Wyo. 
Ft.  In. 
Coal 5  0 
Dark-gray,  sandy  clay 0  2 
Coal 9  0 
An  area  of  1  square  mile  underlain  by  a  coal  bed  14  feet  thick 
would  contain  7,000,000  tons  of  coal,  an  amount  far  exceeding  the  total 
product  of  the  Red  Lodge  mines  during  the  past  fourteen  years. 
Of  course  there  is  always  a  loss  in  working,  and  in  an  area  of  broadly 
lenticular  coal  deposits  allowance  must  be  made  for  a  certain  amount 
