COAL  TN  NORTHWESTERN  COLORADO  AND  NORTHEASTERN   UTAH.       809 
Measurement  of  Mancos  coal  as  mined  near  Vernal. 
• 
Section. 
George 
Gray  mine. 
Joe  Rich     A.  N.  Tim- 
mine,        othy  mine. 
C.  C.  Rich 
mine. 
Coal 
Ft.  in. 
i  m 
11 
7 
2 
6i 
Ft.  in.         Ft.  in. 
2    3                   ll1. 
2?*.  in. 
1    6* 
10 
Bone 
9 
% 
11 
3i 
6* 
8| 
10 
3* 
114 
5h 
6 
Coal 
y 
Bone 
4* 
9 
Coal 
Bone 
*' 
4 
Coal 
4 
Total  coal . . . 
3  10£ 
5     7 
4    6!            43 
6 
3  4* 
4  11 
Total  bed 
' 
The  roof  is  white  sandstone  at  each  mine;  the  floor  at  the  Gray 
and  Timothy  mines  is  bone. 
The  coal  bed  at  the  Gibson  mine,  north  of  Vernal,  that  in  the  pros- 
pects near  the  Pollard  mine,  on  Brush  Creek,  northeast  of  Vernal, 
and  that  at  the  Bowen  mine,  farther  south  on  Brush  Creek,  east  of 
Vernal,  all  show  much  resemblance  to  the  sections  given  above, 
especially  in  the  character  of  bony  beds  and  partings  contained, 
although  the  actual  thicknesses  vary  considerably  from  place  to  place. 
Quality  of  the  coal. — As  may  be  seen  by  reference  to  the  analyses 
the  coal  from  this  field  is  of  very  much  the  same  quality  and  degree 
of  efficiency.  It  is  similar  to  the  average  Mesaverde  coal  of  the 
Meeker  district,  and  is  distinctly  inferior  to  the  coals  of  the  New- 
castle and  Glenwood  Springs  districts.  The  abundance  of  bony 
material  in  the  bed  is  the  chief  disadvantage  and  interferes  rather 
seriously  with  economical  mining. 
The  variation  along  the  outcrop  of  the  bed  is  very  slight,  probably 
not  greater  than  that  which  is  likely  to  occur  in  almost  any  coal 
bed.  The  only  apparent  exception  is  found  in  the  mine  due  north 
of  Vernal,  which  had  not  been  worked  for  some  time  when  the 
sample  was  taken  and  the  coal  of  which  had  evidently  deteriorated 
somewhat  by  exposure  to  the  air. 
The  lower  limit  of  efficiency  of  high-grade  bituminous  coals,  as 
shown  by  calorimetric  determinations,  is  approximately  12,000 
British  thermal  units,  so  that  the  best  of  the  coals  in  this  region 
fall  just  within  that  class. 
Demand  and  market. — The  coal  directly  available  in  this  field  is 
moderate  in  amount,  especially  when  compared  with  the  extensive 
coal  fields  in  the  adjacent  parts  of  Colorado.  The  local  demand  is 
already  a  considerable  factor,  probably  as  much  so  now  as  it  will  be 
later,  when  the  coming  of  a  railroad  ,may  open  up  competition  with 
the  larger  fields  to  the  east. 
