240        CONTRIBUTIONS   TO    IX'ONOMIC   GEOLOGY,   1907,   PART  II. 
were  taken  from  a  mine  and  a  prospect,  the  percentages  of  moisture 
and  ash  are  much  less  than  in  the  other  two,  which  were  taken  from 
surface  croppings,  and  the  calorific  values  in  British  thermal  units 
are  correspondingly  higher.  If,  as  it  seems  reasonable  to  believe,  the 
effect  of  weathering  on  these  coals  is  similar  throughout  this  rather 
small  basin,  the  Wasatch  coals  of  the  area  covered  by  this  report 
should  show  a  heating  value  of  more  than  10,500  British  thermal 
units,  and  they  should  be  considered  as  high-grade  subbituminous 
coals. 
HISTORY   OF  DEVELOPMENT. 
Coal  was  first  developed  in  this  region  by  the  Union  Pacific  Rail- 
road Company  in  1868,  in  sees.  24  and  25,  T.  21  N.,  R.  89  W.  Hay- 
den  a  makes  the  following  statement  concerning  the  operations  there: 
Near  Separation,  about  10  miles  west  of  Rawlings  Springs  [Rawlins],  a  coal  min? 
has  been  opened  with  a  bed  of  coal  11  feet  in  thickness.  I  am  inclined  to  believe 
that  it  is  really  the  same  bed  as  the  one  opened  at  Carbon,  and  also  near  Rock  Creek 
and  Coopers  Creek.  The  strata  dip  nearly  west  about  10°.  The  mine  has  been 
opened  from  the  summit  of  the  hill,  and  the  bed  followed  down  the  inclination,  so 
that  all  the  coal  will  have  to  be  taken  up  the  grade,  and  the  difficulties  in  drainage 
will  be  greatly  increased.  The  coal  is  of  most  excellent  quality.  There  is,  above 
and  below  the  coal,  the  usual  drab  indurated  clay.  Below  the  clay  is  a  bed  of  gray 
ferruginous  sandstone. 
This  mine  was  abandoned  in  a  short  time  on  account  of  difficulty 
of  mining  and  distance  from  the  railroad.6 
No  further  development  was  attempted  in  this  field  until  recent 
years.  Along  the  eastern  and  northeastern  border  several  small 
mines  have  been  opened  to  supply  coal  for  local  use.  In  sec.  22,  T. 
21  N.,  R.  88  W.,  a  mine  (p.  227)  was  opened  on  a  bed  of  coal  of  Mesa- 
verde  age.  The  bed  has  a  thickness  of  8  feet  4  inches  and  is  nearly 
vertical.  A  slope  was  driven  down  in  the  bed  with  an  inclination  of 
30°  until  water  was  encountered  at  a  distance  of  80  feet.  At  this 
point  work  was  abandoned  on  account  of  the  difficulty  of  mining 
economically  a  bed  so  nearly  vertical. 
Shallow  mines  have  been  opened  on  beds  of  Laramie  age  in  sec.  18, 
T.  25  N.,  R.  89  W.,  and  sees.  4  and  16,  T.  26  N.,  R.  90  W.,  from  which 
coal  was  taken  for  local  use,  but  these  have  been  abandoned.  In 
sec.  8,  T.  27  N.,  R.  89  W.,  two  mines  were  developed  on  separate  beds 
of  the  same  age  to  a  depth  of  about  100  feet  along  the  slope,  but  were 
abandoned  when  ground-water  level  was  reached.  A  new  mine  is 
now  being  opened  in  sec.  6,  T.  27  N.,  R.  89  W.,  by  Frederick  C.  Speyer, 
of  Split  Rock,  Wyo.,  in  a  16-foot  bed,  the  lower  of  the  two  just 
referred  to,  which  dips  26°  SW.  The  slope  is  being  driven  down  the 
dip  and  has  reached  a  distance  of  75  feet.  The  lower  10  feet  of  the 
coal  is  being  removed  and  the  remainder  left  for  a  roof.     The  coal 
a  Hayden,  F.  V.,  Repts.  U.  S.  Geol.  Survey  Terr,  for  1867,  1868,  and  1869,  1873,  pp.  97,  98. 
b  Lesqucreux,  Leo,  Rept.  U.  S.  Gcol.  Survey  Terr,  for  1872  ,1873,  p.  333. 
