302  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1905. 
CONCLUSION. 
With  the  possible  exception  of  one  or  two  coal  beds  occurring  in  the  high  land  west 
Pleasant  Valley  all  the  coals  of  value  known  at  the  present  time  in  the  Book  Cliffs  field  a 
found  in  the  lower  part  of  the  coal-bearing  strata  and  near  the  base  of  the  Laramie  form 
tion.  At  no  locality  investigated  was  it  found  that  the  entire  coal-bearing  section  hi 
been  thoroughly  prospected.  The  beds  in  the  lower  part  of  the  series  are  the  more  co 
veniently  situated  for  exploitation  and  were  found  usually  of  ample  thickness  for  profital 
working.  For  these  reasons  the  attention  of  the  prospector  and  miner  has  been  devot 
to  them.  At  every  locality  investigated  for  more  than  100  miles  in  the  Book  Cliffs  fie 
coals  ranging  from  3  to  20  feet  in  thickness  were  found  where  the  lower  part  of  the  secti< 
of  the  coal-bearing  series  had  been  carefully  prospected. 
The  coals  in  the  different  parts  of  the  field  are  remarkably  uniform  in  their  physic 
characteristics.  They  are  black,  moderately  hard,  and  usually  massive.  Occasional  sha 
partings  occur  in  the  bed,  but  one  or  the  other,  and  sometimes  both,  benches  are  sufficient 
thick  to  be  profitably  mined. 
The  composition  of  the  coals  in  various  parts  of  the  field  and  in  several  beds  varies  b 
little,  in  SO  far  as  proximate  chemical  analyses  show.  The  fuel  ratios  in  the  14  sampl 
analyzed  range  between  the  extremes  of  1 .00  and  1.46.  The  content  of  sulphur  is  remar 
ably  low  and  uniform.  The  coking  property  of  the  coals  has  been  tested  in  but  few  Iocs 
it  it-s,  and  of  these  only  the  coals  mined  at  Sunnyside  are  known  to  be  coked. 
