THE  COAL  FIELD  BETWEEN  DURANGO,  COLORADO. 
AND  MONERO,  NEW  MEXICO. 
By  James  H.  Gardner. 
INTRODUCTION. 
In  1905  a  reconnaissance  survey  of  the  area  between  Durango,  Colo., 
and  Monero,  N.  Mex.,  was  conducted  by  F.  C.  Schrader,a  assisted  by 
M.  K.  Shaler.  The  work  of  that  season  was  carried  on  too  rapidly  to 
permit  the  location  of  coal  boundaries  with  reference  to  land  lines, 
the  chief  object  being  a  hasty  determination  of  the  extent  and  value 
of  the  entire  San  Juan  coal  region  (Durango-Gallup  field).6  Since 
that  time  the  outcrops  of  the  coal  beds  from  Durango  to  Rio  Florida 
have  been  carefully  surveyed  by  Joseph  A.  Taff.c 
During  the  season  of  1907  the  writer,  assisted  by  William  J.  Reed 
and  Albert  L.  Beekly,  conducted  a  resurvey  of  the  field  eastward  from 
Durango  to  Monero,  N.  Mex.  It  seems  desirable  to  publish  a  brief 
review  of  this  area  in  connection  with  a  map  (PL  XXIII)  showing 
more  accurately  the  boundaries  of  the  coal-bearing  formations. 
GEOLOGY. 
STRATIGRAPHY. 
The  Cretaceous  formations  in  this  area,  from  the  base  upward,  are 
as  follows:  Dakota  sandstone,  300  (?)  feet;  Mancos  shale,  1,200  feet; 
Mesaverde  formation,  1,000  feet;  Lewis  shale,  1,600  feet;  and  Laramie 
formation,  700  feet.  Of  these  the  Dakota,  Mesaverde,  and  Laramie 
contain  workable  coal  beds  in  certain  regions.  In  the  area  consid- 
ered, however,  the  Dakota  coal  is  not  known  to  be  of  commercial 
value. 
The  Mesaverde  is  the  most  important  of  the  coal-bearing  forma- 
tions in  the  Durango  district,  containing  three  or  four  workable  beds 
of  excellent  bituminous  coal,  some  beds  locally  being  suitable  for  the 
a  The  Durango-Gallup  coal  field  of  Colorado  and  New  Mexico:  Bull.  U.  S.  Geol.  Survey  No.  285,  1906, 
pp.  241-258. 
&  For  a  description  of  the  west  side  of  the  field,  see  Shaler,  M.  K.,  A  reconnaissance  survey  of  the 
western  part  of  the  Durango-Gallup  coal  field:  Bull.  U.  S.  Geol.  Survey  No.  316,  1907,  pp.  376-426. 
cThe  Durango  coal  district,  Colorado:  Bull.  U.  S.  Geol.  Survey  No.  316,  1907,  pp.  321-337. 
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