THE   COAL  FIELD   BETWEEN  GAILINA  AND   RATON 
SPUING,  NEW  MEXICO,  IN  THE  SAN 
JUAN  COAL  REGION. 
By  James  H.  Gardn  i  ;  i  ; . 
INTRODUCTION. 
The  San  Juan  coal  region  (Durango-Gallup  coal  field) a  is  a  basin  of 
more  or  less  circular  outline,  with  an  area  of  about  13,500  square 
miles,  about  one-seventh  of  which  lies  in  Colorado  and  the  remainder 
in  New  Mexico.  The  region  receives  its  name  from  San  Juan  River. 
The  two  chief  coal-producing  localities  are  Durango,  in  the  extreme 
southwestern  part  of  Colorado,  on  the  Denver  and  Rio  Grande  Rail- 
road, and  Gallup,  in  New  Mexico,  on  the  Atchison,  Topeka  and  Santa 
Fc  Railway.  The  San  Juan  coal  region  is  the  inner  coal-bearing 
portion  of  the  San  Juan  Basin. 
During  the  season  of  1905  a  reconnaissance  survey  around  the  east 
side  of  this  region  was  made  by  F.  C.  Schrader,  assisted  by  M.  K. 
Shaler.  Work  was  begun  at  Durango,  Colo.,  and  carried  in  an  easterly 
direction  to  Monero,  N.  Mex. ;  thence  southward  in  New  Mexico  via 
Elvado,  Gallina,  and  Cuba,  to  Cabezon;  and  thence  westward  to 
Gallup. 
In  the  season  of  1906  M.  K.  Shaler,  assisted  by  the  writer,  con- 
ducted a  reconnaissance  survey  around  the  opposite  side  of  the  region. 
Work  was  tied  to  that  of  the  previous  season  at  Durango,  and  the 
outcrop  of  the  coal  formations  was  mapped  around  the  west  side  of 
the  region  and  connected  with  that  of  Schrader  at  Gallup.  The  coal- 
bearing  formations  mapped  in  each  survey  are  the  Mesaverde  and 
Laramie,  of  Upper  Cretaceous  age,  as  classified  by  Cross6  in  the 
vicinity  of  Durango. 
In  the  reconnaissance  of  Schrader  in  1905  the  outcrops  of  the 
Mesaverde  and  Laramie  formations  were  found  to  he  roughly  parallel, 
a  Schrader,  F.C,Thc  Durango-Gallup  coal  field  of  Colorado  and  New  Mexico:  Bull.  U.S.  Geol.  Survey 
No.  285, 1906,  pp.  241-258.  Shaler,  M.  EC,  A.  reconnaissance  survey  of  the  western  pari  of  the  Durango- 
Gallup  coal  field  of  Colorado  and  New  Mexico:  Hull.  U.  S.  Geol.  Survey  No.  316,  L907,  pp.  H76-426. 
fr Cross,  Whitman,  La  Plata  folio  (No.  60),  Geologic  A.tlas  U.  S.,  U.  S.  Geol.  Survey,  1899. 
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