COAL.  TN  NORTHWESTERN  COLORADO  AND  NORTHEASTERN    UTAH.       313 
TERTIARY     (OAT.. 
Coal  beds  in  the  Tertiary  strata  have  been  noted  at  a  number  of 
localities  along  the  north  side  of  Henrys  Fork.  Outcrops  are  reported 
along  the  bluff  bordering  that  stream  for  a  distance  of  several  miles 
east  of  Burnt  Fork,  Wyo.,  and  the  coal  is  probably  continuous  for  a 
still  greater  distance,  although  no  further  information  on  this  point 
has  been  obtained. 
Some  exposures  of  these  beds  were  examined  3  or  4  miles  east  of 
Burnt  Fork  post-office,  along  a  road  in  a  little  gulch  leading  up  to 
the  mesa,  less  than  one-fourth  mile  from  the  creek  and  opposite  the 
Mass  ranch.  The  coal  is  exposed  at  several  horizons.  A  coal  bed 
near  the  lower  end  of  the  gulch  measured  2  feet  10  inches,  as  shown 
in  natural  outcrop,  and  although  considerably  weathered,  much  of  it 
was  a  clear,  glossy  black.  The  roof  is  a  sandy  and  calcareous  shale, 
alternately  thick  and  thin  bedded.  The  floor  is  a  brown,  woody  clay, 
which  is  evidently  softened  by  exposure.  The  beds  are  nearly  hori- 
zontal, the  dip  being  very  low  toward  the  north.  The  bed  is  evi- 
dently continuous  for  some  distance,  as  its  croppings  can  be  plainly 
traced  around  the  hillside.  The  coal  is  doubtless  subbituminous, 
although  this  statement  is  no  more  than  a  rough  estimate  based  on 
the  appearance  of  the  weathered  exposure. 
On  another  bed  exposed  100  yards  or  so  farther  up  the  gulch  a 
small  amount  of  digging  uncovered  2  feet  of  coal,  but  the  bed  is 
doubtless  somewhat  thicker.  A  prospect  drift  had  been  dug  at  this 
place  but  is  now  wholly  caved.  Some  very  perfect  impressions  of  a 
symmetrically  coiled  spiral  gasteropod  were  collected  from  the  roof 
of  this  coal  bed,  but  unfortunately  they  do  not  fix  the  geologic  age 
of  the  strata,  except  to  indicate  that  they  belong  to  the  fresh-water 
Tertiary.  The  coal-bearing  beds  are  very  probably  of  Wasatch  age, 
as  they  are  succeeded  by  strata  which  resemble  the  Green  River 
shales  and  sandstones,  and  these  in  turn  are  overlain  by  undoubted 
Bridger  beds  with  their  vivid  green  banding. 
Other  coal  beds  in  Tertiary  strata  were  observed  at  the  bank  of 
Green  River,  north  of  the  mouth  of  Henrys  Fork.  This  locality  is 
about  1.3  miles  N.  5°  E.  of  the  290  milepost  on  the  Utah- Wyoming 
line.  The  coal  was  very  poorly  exposed  and  could  not  be  shown  to 
be  of  workable  thickness  without  further  development.  A  collection 
of  fossils  from  neighboring  rocks  contain  some  fresh-water  shells 
resembling  clams  and  gasteropods  elsewhere  found  in  the  Wasatch, 
but  the  same  species  also  occur  in  later  Eocene  formations  of  this 
region. 
