COAL  IN  NORTHWESTERN  COLORADO  AND  NORTHEASTERN  UTAH.       311 
PENNSYLVANIAX    ( UPPER    CARBONIFEROUS)    COAL. 
An  older  coal  than  any  heretofore  noted  in  northwestern  Colorado 
was  found  on  upper  Birch  Creek,  tributary  to  Burnt  Fork,  which  is 
in  turn  a  branch  of  Henrys  Fork  of  Green  River.  This  is  in  sec.  3, 
T.  2  N.;  R.  17  E.,  of  the  Salt  Lake  base  and  meridian,  Utah,  south 
of  Zeb.  Edward's  ranch,  and  occurs  in  rocks  of  the  same  age  as  the 
Pennsylvania  coal  measures. a  The  same  horizon  has  been  pros- 
pected at  intervals  for  several  miles  along  the  foothills  in  this 
locality,  but  the  coal  appears  to  be  of  rather  uncertain  value. 
The  coal  at  the  Edward  prospect  is  said  to  have  been  tested  by  the 
Union  Pacific  Railroad  Company,  and  the  report  has  spread  that  it 
proved  to  be  of  coking  quality.  The  specimens  seen  had  certainly 
withstood  exposure  to  the  weather  in  an  exceptional  manner.  Other 
reports  state  that  the  coal  has  been  used  in  a  local  forge,  where  it 
burned  very  well  and  gave  a  good  heat.  The  exposure  seen  was  in  a 
very  unsatisfactory  condition  for  examination.  Some  pits  had  been 
dug  in  a  heavily  wooded  slope,  in  a  block  of  strata  very  evidently 
slipped  from  a  point  higher  on  the  ridge  and  tilted  out  of  its  normal 
position.  The  beds  are  very  soft  and  broken,  but  nevertheless  some 
of  the  coal  is  still  hard.  The  coal  bed  is  very  irregular  and  at  no 
place  was  more  than  a  few  inches  of  coal  visible,  although  it  was  con- 
fidently stated  that  the  bed  was  3  feet  thick  at  the  bottom  of  the 
pit,  which  had  then  caved.  No  trustworthy  estimate  of  the  true 
character  of  the  bed  can  be  obtained  until  the  coal  is  found  in  place 
and  in  a  normal  position. 
It  is  reported  that  several  prospects  on  Burnt  Fork,  farther  west, 
show  the  same  bed  in  place  ;  in  these  it  is  much  thicker  but  is  not  of 
commercial  value,  being  carbonaceous  shale  rather  than  coal. 
These  beds  are  of  interest  as  affording  an  unusual  occurrence  for 
the  western  fields. 
MESAVERDE    COAL. 
4 
As  shown  on  PL  XX,  the  Mesaverde  formation  outcrops  at  Green 
River  near  the  center  of  the  broad  valley  area  north  of  Flaming 
Gorge,  and  just  north  of  the  mouth  of  Henrys  Fork.  Toward  the 
west  the  formation  is  evidently  cut  off  by  a  fault  near  Linwood  post- 
office,  on  Henrys  Fork.  East  of  Green  River  the  formation  may  be 
followed  as  a  long,  curved,  double  ridge  extending  up  the  broad  strike 
valley  north  of  the  mountains,  apparently  bending  southward  and 
abutting  against  the  mountain  mass,  and  possibly  terminated  there 
by  another  fault.  These  beds  were  not  examined  far  east  of  Green 
River. 
a  Fossils  collected  in  the  prospect  pit  were  examined  by  G.  H.  Girty,  who  has  made  the  age  determina- 
tion and  identified  the  following  forms:  Fenestella,2  sp.;  Lingulaf  sp.;  Spirifer  rocky montanus;  Pleu- 
rophorella  costata? ;  Edmondia  aff.  gibbosa;  Aviculipecten  hertzerif;  Aviculipecten  sp.;   Naticopsis  sp. 
