288  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1905. 
The  upper  bench  of  coal  is  the  only  one  now  worked.  The  section  below  this  bench 
is  reported  by  Dexter  Brothers  to  have  been  proved  by  excavations  beneath  the  present 
workings.  The  coal  in  the  Dexter  mine  is  clear  of  shaly  impurities  or  tangible  sulphm 
compounds,  and  the  quality  appears  to  be  equal  to  that  of  the  Wasatch  coal.  The  Dextei 
coal  has  been  mined  to  a  small  extent  in  several  places  in  the  hollow  below  the  Dextei 
mine.  The  irregularities  in  the  position  of  the  outcrops,  as  indicated  by  the  abandoned 
mines  and  the  difficulties  said  to  have  been  encountered  in  mining  shows  that  the  strata  i 
have  suffered  considerable  displacement  by  faulting. 
Other  coals. — A  double  coal  bed  occurs  nearly  400  feet  above  the  Wasatch  coal,  but  is,  at 
the  present  time,  of  little  economic  importance.  The  coal  in  each  of  the  two  benches  is  reli- 
ably reported  to  have  been  mined  a  mile  north  of  Coalville.  Each  bench  is  3  to  A  feet  thick, 
separated  by  a  shale  bed  2  to  3  feet  thick.  A  coal  in  the  stratigraphic  position  of  this 
bed  has  been  prospected  in  the  north  slopes  of  Grass  Creek  Valley  near  the  south  side  of 
sec.  3,  T.  3  N.,  R.  5  E.  A  similar  double  seam  of  coal  occurs  stratigraphically  about  7001 
feet  higher  and  1,100  to  1,200  feet  above  the  Wasatch  coal.  In  the  early  development  of 
the  country  this  coal  was  mined  2  miles  west  of  Coalville,  in  see.  10,  T.  2  N.,  R.  5  E.  It 
is  reliably  reported  that  each  of  the  beds  is  2\  to  3  feet  thick  and  separated  by  U  to  2 
feet  of  shale.  A  coal  in  the  same  stratigraphic  position  was  mined  also  at  one  time  in  the: 
\VY.  ■  sec.  l.T.  2  X.,  R.  5  E. 
Quality  ofiht  coal.  The  Wasatch,  Grass  Valley,  and  Dexter  mines  now  in  operation  in 
the  vicinity  of  Coalville  yield  a  product  that  has  the  physical  properties  of  a  fair-grade 
bituminous  coal.  It  is  a  black  block  coal  of  medium  hardness.  A  sample  of  the  Wasatch 
coal  was  analyzed  by  Mr.  V.  M.  Stanton,  chemist,  Q.  S.  Geological  Survey  coal-testing 
plant .  St.  Louis,  Mo.  An  analysis  of  the  coal  at  Winterquarters,  one  of  the  most  extensive 
mines  in  i  he  Book  Cliffs  coal  field,  was  made  also.  The  Book  dill's  held  is  the  most  exten- 
sive in  the  Stale,  and  the  coal  has  been  successfully  used  both  for  steaming  and  domestic 
purposes  and  in  the  production  of  coke. 
Comparativt  analyses  of  coal  from  Coalville  <m<l  Winterquarters. 
Moisture 
Volatile  mat  ter. 
Fixi  'I  carbon . . . 
Ash 
Sulphur 
Coal- 
ville. 
\\  'int<*r- 
quarteB 
L3.92 
s.  10 
37.96 
)0. 21 
43.67 
45. 91 
4.45 
.",.  78 
1 .  03 
.86 
101.03 
100.86 
The  percentage  of  water  in  the  Coalville  coal  approaches  that  often  found  in  the  black 
lignites,  the  highest  grade  of  so-called  lignites.  Owing  to  the  abundant  mine  water  occur- 
ring in  the  mines  near  Coalville  and  the  shattered  character  of  much  of  the  coal,  it  is  possible 
that  a  small  amount  of  superficial  water  was  carried  in  the  sample  at  the  time  the  analysis 
was  made.  The  physical  characteristics,  its  behavior  on  exposure  in  the  atmosphere,  and 
its  utilization  show  it  to  be  a  bituminous  coal  well  adapted  to  domestic  uses. 
Conclusion. — The  coals  of  the  Weber  River  field,  other  than  the  Wasatch  and  Dexter 
beds,  are  of  little  immediate  economic  value.  The  interst  rat ilied  shales,  together  with  the 
difficulties  experienced  in  mining  incident  to  water  and  broken  strata,  have  prevented 
these  other  beds  from  competing  with  the  Wasatch  and  Dexter  coals.  The  Wasatch  and 
Dexter  beds  are  ample  in  thickness  for  successful  working,  and  the  quality  of  the  product 
compares  favorably  with  the  better  grades  of  bituminous  coals  of  the  Rocky  Mountain 
region.  The  difficulties  in  the  way  of  large  exploitation  of  these  coals  are  the  amount  of 
mine  water  and  the  fractured  nature  of  the  beds,  resulting  in  the  production  of  considerable 
quantities  of  slack. 
