SHERIDAN    COAL   FIELD,    WYOMING.  129 
of  aneroid  barometers,  the  determinations  of  thickness  of  strata  are 
only  approximately  correct. 
With  respect  to  the  occurrence  of  coal,  this  member  may  be  sepa- 
rated into  three  divisions.  From  the  base  upward,  through  nearly 
800  feet  of  rock,  there  are  at  least  seven  workable  beds  of  coal.  These 
coal  beds  are  exposed  principally  in  the  valley  of  Tongue  River,  and 
for  convenience  of  reference  and  economic  discussion  they  will  be 
termed  the  Tongue  River  coal  g  [wip: 
Tongue  River  coal  group. — T  owcsj  workable  bed  of  this  group 
is  known  as  the  Carney  bed.  It  ccurs  in  two  benches  in  the  Tongue 
River  Valley.  The  upper  bench  is  4  feet  6  inches  thick,  and  the  lower 
between  10  and  11  feet.  The  two  benches  are  separated  by  a  thin 
parting  of  shale. 
The  next  workable  bed  occurs  about  86  feet  higher  in  the  section 
on  Tongue  River,  and  is  ^nown  locally  as  the  Monarch  bed.  This 
bed  also  is  divided  into  two  benches.  The  upper  one  is  reported  to 
be  nearly  10  feet  thick  and  to  Tutain  partings  of  shale.  The  lower 
bench  is  18  to  22  feet  thick,  as  ported  from  drill  prospecting  and 
mine  working.  Part  of  the  coi  left  for  roof  in  mining  until  the 
pillars  are  robbed,  therefore  a  full  section  of  the  coal  could  not  be 
seen.  A  large  part  of  the  rock  between  the  Carney  and  Monarch  coal 
beds  consists  of  white,  massive  sandstone.  In  the  bluffs  of  Tongue 
River  at  Carneyville  the  sandstone  is  nearly  60  feet  thick.  A  variable 
thin  shale  lies  between  it  and  the  Carney  coal,  and  a  thicker  bed  of 
shale  separates  it  from  the  Monarch  bed  above. 
Nearly  1 20  feet  above  the  Monarch  coal  bed  there  is  another  bed, 
known  as  the  Dietz  No.  3  coal.  This  is  not  exposed  directly  above  a 
known  outcrop  of  the  Monarch  bed,  its  identity  being  determined 
from  records  of  drilling  and  structural  conditions  between  Monarch 
and  the  junction  of  Goose  Creek  and  Tongue  River.  A  prospect  near 
the  mouth  of  Goose  Creek  exposes  6  feet  of  the  Dietz  No.  3  bed,  and 
it  is  reported  to  be  12  to  14  feet  thick  in  prospect  drillings.  The  rocks 
between  the  Monarch  and  Dietz  No.  3  coals  consist  of  bluish  shale 
and  thin-bedded  and  shaly  drab  sandstone. 
Another  coal  bed,  known  as  the  Dietz  No.  2,  lies  about  100  feet 
above  the  Dietz  No.  3.  Its  known  thickness  is  8  to  9  feet,  and  it  is 
reported  to  thicken  locally  to  14  feet.  Dietz  coal  bed  No.  1,  the  fifth 
in  the  Tongue  River  coal  group,  counting  from  the  base,  occurs  100 
to  115  feet  above  Dietz  bed  No.  2.  This  bed  is  8^  feet  thick  near 
Dietz,  and  is  succeeded  by  an  upper  bench  18  inches  to  2  feel  thick, 
with  a  gray  shale  of  the  same  thickness  intervening.  The  same  bed 
is  exposed  in  the  bluffs  of .  Tongue  River  near  the  mouth  of  Goose 
Creek.  The  rocks  separating  the  Dietz  coal  beds  consist  of  yellow  to 
brown  sandstone,  bluish  shale,  and  brown  carbonaceous  shale  in  beds 
of  variable  thickness.     Certain     hick  sandstone  beds  between  Dietz 
71497— Bull.  341—01) 9 
