394  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1904.         [bui7L.  260. 
with  the  shales  and  thin  sandstones.  The  belt  of  country  so  char- 
acterized in  the  northern  part  of  the  Indian  Territory  coal  held 
lies  between  Neosho  River  and  a  line  drawn  through  Schulter, 
Wealaka,  Broken  Arrow,  Catoosa,  Claremore,  Chelsea,  and  thence 
northward  to  the  Kansas  line  a  few  miles  west  of  the  Missouri, 
Kansas  and  Texas  Railroad.  This  belt  of  country  might  well  be 
classed  within  a  single  formation.  In  southeastern  Kansas  it  is 
included  within  the  Cherokee  shales,  a  formation  of  shale  with  local 
thin  sandstones  and  limestones  interstratified,  and  containing  two 
workable  coal  beds  in  the  upper  part,  known  as  the  Wier-Pittsburg 
coals. 
The  Cherokee  shale  is  succeeded  by  the  Fort  Scott  limestone, 
which  has  been  traced  southwestward  across  Cherokee  Nation,  pass- 
ing near  Chelsea,  Claremore,  and  to  Arkansas  River  near  Wealaka. 
Its  approximate  outcrop  is  shown  on  the  map.  The  Fort  Scott  lime- 
stone becomes  thin  southward,  but  has  not  been  traced  south  of  the 
immediate  valley  of  Arkansas  River.  In  northern  Indian  Territory 
a  coal  bed  occurs  at  Broken  Arrow  beneath  the  limestone  and  near 
the  horizon  of  the  Wier-Pittsburg  coal  in  Kansas.  In  the  vicinity 
of  Henryetta  a  commercially  valuable  coal  bed,  known  locally  as  the 
Henryetta  coal,  occurs  below  the  horizon  of  the  Fort  Scott  lime- 
stone. Its  outcrop  has  been  traced  northward  beyond  Okmulgee,  and 
it  is  presumably  the  same  as  that  at  Broken  Arrow.  A  number  of 
thin  coal  beds  are  known  to  occur  lower  in  the  shales  in  northern 
Indian  Territory. 
The  coal  measures  rocks  which  lie  above  the  horizon  of  the  Fort 
Scott  limestone  crop  out  in  northwestern  Cherokee  Nation  and  west- 
ern Creek  Nation.  In  the  Creek  Nation  they  consist  of  an  alternating 
succession  of  sandstone  and  shale  formations  Avith  occasional  beds 
of  limestone  and  one  or  more  coal  beds  of  economic  importance.  The 
sandstone  formations  become  gradually  thinner  northward  and  the 
limestone,  as  a  whole,  thicker.  Two  or  more  of  the  limestones  become 
thick  enough  to  be  classed  as  formations  north  of  Arkansas  River, 
and  the  outcrops  of  those  best  known  are  mapped.  The  outcrops  of 
a  deposit  of  yellow  limestone  that  lies  above  the  commercially  valu- 
able Dawson  coal  have  been  traced  from  Tulsa  southwestward,  and 
its  mapping  will  aid  in  locating  the  outcrop  of  the  coal. 
STRUCTURE. 
The  structure  of  the  northern  part  of  the  Indian  Territory  coal 
field  is  simply  monoclinal,  the  rocks  being  tilted  about  N.  05°  W.  at 
locally  variable  inclinations  of  (>0  to  100  feet  per  mile.  This  applies 
more  particularly  to  the  rocks  occurring  west  of  the  Missouri,  Kansas 
and  Texas  Railroad.     East  of  this  railroad  the  rocks  are  involved  in 
