COAL  IN  NORTHWESTERN  COLORADO  AND  NORTHEASTERN  UTAH.       301 
river,  two  beds  at  about  the  same  horizon  have  been  opened.  In 
one  of  these  6  feet  4  inches  of  coal  has  been  mined,  leaving  about  1 
foot  3  inches  of  good  coal  in  the  roof.  A  bed  stratigraphically  about 
80  feet  lower  shows  3  feet  7  inches  of  good  coal  that  has  also  been 
worked. 
All  the  Mesaverde  rocks  of  the  Angora  district  are  steeply  tilted, 
forming  a  long,  narrow  hogback,  approximately  parallel  to  the  course 
of  White  River.  West  of  Angora  this  ridge  continues  for  several 
miles  to  the  region  where  the  influence  of  the  Raven  Park  anticline 
broadens  the  outcrop  of  the  coal-bearing  rocks  and  considerably 
enlarges  the  available  coal  field. 
The  coal-bearing  rocks  encircle  the  Raven  Park  anticline,  although 
the  more  important  coal  beds  are  completely  eroded  on  the  north  side 
of  it  between  the  Raven  Park  and  Blue  Mountain  folds.  The  coal 
rocks  dip  away  in  all  directions  from  Raven  Park  as  a  center  or  axis, 
for  a  greater  or  less  distance,  according  to  the  proximity  of  other 
folds  that  modify  this  simple  structure. 
DOUGLAS    CREEK    DISTRICT,   SOUTH    OF    THE    BASE    LINE. 
Location  and  extent. — The  coal-bearing  rocks  of  the  White  River 
field  are  continuous  south  of  the  base  line  in  the  vicinity  of  Raven 
Park,  forming  a  considerable  area  of  actual  croppings  of  the  principal 
coal-bearing  group  of  the  Mesaverde  formation  which  lie  mainly  in  the 
drainage  basin  of  Douglas  Creek  and  its  tributaries.  This  district, 
as  shown  by  Pis.  XVII  and  XVIII,  is  a  part  of  the  lower  White  River 
field,  and  the  division  along  the  base  line  is  arbitrary,  as  already 
explained. 
General  structure. — Structurally  the  Douglas  Creek  district  is  prob- 
ably continuous  with  the  Book  Cliffs  coal  field,  on  the  Grand  River 
side  of  the  Book  Cliffs  divide.  Between  these  two  fields  the  coal- 
bearing  rocks  are  buried  under  several  thousands  of  feet  of  overling 
strata  in  the  high  hills  of  the  Roan  or  Book  Cliffs  plateau. 
The  structure  of  the  district  is  perhaps  most  clearly  revealed  by  a 
general  view  from  the  high  escarpments  surrounding  the  valleys  and 
somewhat  broken  and  hilly  "parks."  The  bordering  escarpments 
expose  the  bare  ledges  of  the  Tertiary  strata  dipping  away  in  nearly 
all  directions  from  the  eroded  center.  In  passing  up  the  valley  of 
Douglas  Creek  southward  from  White  River  the  beds  at  first  dip 
south,  conforming  to  the  structure  of  the  Raven  Park  anticline.  Be- 
fore the  base  line  is  reached,  however,  they  assume  a  practically  hori- 
zontal position  and  t  hen  may  be  seen  to  rise  toward  the  soul  h,  approxi- 
mately a1  the  grade  of  the  streams.  This  structure  is  very  regular, 
and  with  the  exception  of  a  few  small  faults,  mentioned  in  a  following 
paragraph,  the  strata  continue  to  rise  gradually  southward  to  a  point 
about  3  miles  south  of  the  N  Bar  ranch,  which  is  situated  in  the  main 
