254  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY;   L905. 
Ft.  In. 
Shale,  brown,  carbonaceous l 
Shale  and  sain  1st  one LOO 
Shale,  brown,  carbonaceous 1 
Coal 1 
Shale,  brown,  sarbonaceous 1 
Shale 2 
Coal,  containing  much  fossil  resin 2 
shale,  brown,  carbonaceous 1 
Total  coal 21     6 
Section  of  coal  bed  at  Tiejen  prospect,  on  Seven  Lakes  road    17  miles  northeast  of  Thorek 
N.  Mex. 
Ft.  In. 
Shale,  carbonaceous 1 
Coal 1     3 
Shale,  arenaceous 11 
Coal .- 3     6 
Shale,  carbonaceous. 
The  coal  is  a  good  Mack  lignite  and  contains  much  fossil  resin,  resembling  in  this  resp< 
the  Monero  coal.  A  sample  was  taken  from  the  Tiejen  prospect  for  analysis.  The  mateiJ 
was  secured  by  making  a  cut  across  the  face  of  the  coal,  exclusive  of  the  parting  1 ',  inch 
in  thickness.  The  coal  was  crushed  and  quartered  down  to  a  quart  sample,  which  w 
scaled  air-tight  in  a  galvanized-iron  can  and  sent  to  the  laboratory  at  St.  Louis.  T 
result  is  shown  in  analysis  No.  10  of  the  table  on  page  258.  With  the  exception  of  t 
heavy  percentage  of  water,  this  analysis  compares  favorably  with  the  analyses  of  otl 
coals  of  I  he  Geld. 
GALLUP    DISTRICT. 
The  Gallup  district  extends  from  the  hogback  '■*>  miles  east  of  Gallup  westward  beyd 
Defiance,  a  distance  of  about   12  miles.     It  is  crossed  l>\   the  Atchison,  Topeka  and  San 
Fe  Uailway  and  is  the  oldest,  best  known,  ami  most  productive  district  in  the  held.  T 
coal-bearing  group  of  rocks  of  this  district ,  so  prominent  around  ( lallup,  lies  higher  in  t 
series  than  the  groups  that  form  the  hogback  east  of  Gallup.  Its  geological  horizon  li 
not  been  well  determined,  hut  from  some  fossil  plants  found  at  the  Weaver  mine,  north 
Gallup,  it  is  referred  to  the  upper  part  of  the  Montana  formation  and  is  probably  t 
same  as  the  upper  coal  groups  o(  the  Chico  Arroyo  and  Hosts  Butte  districts.  It  is  divid 
into  upper  and  lower  subgroups,  which  are  separated  by  about  ")tMI  feet  of  sandstone  a 
sandy  shale.  In  the  immediate  vicinity  of  Gallup  the  dips  are  from  2°  to  15°  NW.,  b 
the)  vary  in  direction,  as  the  rocks  are  gently  folded.  In  general  this  part  of  the  held  li 
the  structure  of  a  syncline  with  the  rocks  dipping  toward  the  center  from  each  side.  T 
synclinal  axis  is  known  to  extend  south  of  Gallup  into  the  Zuni  Plateau,  hut  this  area  \S 
not  examined  during  the  present  reconnaissance.  The  upper  subgroup  of  coal-beari 
beds  is  about  loo  feet  in  thickness  and,  a-  show  n  by  the  following  section,  based  in  part 
data  obtained  from  the  American  Fuel  Company  at  its  Gallup  and  Weaver  mines,  contai 
>ix  workable  beds  of  coal: 
Section  of  upper  coal  subgroup  at  /In   (lallup  and  Wearer  minis  ■',  miles  north  of  Galh 
X.  Mex. 
Sandstone.  Ft.  In. 
Coa  1 1 
Fire  clay 2 
Dirtycoal     bed  No.  1 3    (> 
Sandstone  and  shale 14 
Coal 6 
Fire  clay 7 
Coal     bed  No.  2 4    G 
Sandstone  and  shale 13  36 
Sandi  i 
Coal    bed  No.  3 4 
