250  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,   L905. 
The  workable  beds  occur  in  the  Mesaverde  formation,  which  is  exposed  in  the  lower  dip 
slopes  of  a  prominent  hogback,  in  which  the  beds  arc  upturned  at  angles  varying  from  20° 
to  40°. 
In  the  north  end  of  the  field,  near  the  Elvado-Gallina  road,  a  natural  outcrop  shows  the 
following  section  of  the  coal  beds: 
Sic/ion  of  coal  beds  near  Elvado  mad,  l  >  miles  north  of  Gallina,  .V.  Mex. 
Ft.  In. 
Sandstone 40 
Sha  le :< 
Coal 1    6 
Shale 4 
Coal f>     (i 
Shale,  carbonaceous 6 
Coal 1 
Shale 25 
Three  miles  west  of  Gallina  the  same  rocks  are  exposed,  and  the  following  section  was 
measured: 
Section  of  coal  beds  3  miles  west  of  Gallina,  X .  Mex. 
Ft.    In. 
Sandstone 20 
Shale \-2 
Coal :*i 
Shale 50 
Coal 2    9 
Shale,  with  five  coal  beds  ranging  from  :i  to  12  inches  thick 100 
A.s  1  lie  coal  beds  incline  to  1  he  west  from  t  he  hogback,  which  limits  1  he  field  on  the  east* 
the\  pass  beneath  the  surface  of  an  open  valley  or  sage-brush  Hat  nearly  LOO  miles  in  area] 
extent,  and  since  the  dip  generally  decreases  toward  the  center  of  the  basin  the  coal  bed! 
can  probably  he  reached  at  a  moderate  depth  by  shafting,  an  important  point  in  the  pro- 
spective economic  development  of  the  district.  An  ample  supply  of  t  i  in  her  suit  a  hie  for  mini 
ing  purposes  may  he  found  on  Gallina  Mountain  near  by,  and  thus  all  natural  conditions 
arc  la\ orable  for  economic  mining. 
All  the  coal  beds  so  far  described  in  this  district  occur  in  the  Mesaverde  formation,  hut 
the  Laramie  '  also  contains  coal,  a-  shown  by  the  outcrop  of  a  bed  of  good  coal  L2  to  15 
inehe-,  1  hick  7  miles  norl  h  of  ( lallina.  This  is  notewort  hy  as  being  (he  first  good  coal  found 
in  the  Laramie  (  '.)  formal  ion  south  of  Xa\  a  jo  River. 
\  \ci\iik\  10    DISTRICT. 
The  Nacimiento  district  flanks  the  west  base  of  the  Sierra  Nacimiento,  and  extends  from 
north  of  Lajara  nearly  to  San  Miguel,  below  Senorita,  a  distance  of  about  1<>  miles.  In 
genera]  the  coal-bearing  locks  dip  steeply  to  t  he  west ,  hut  in  come  local  it  ies  f  hey  are  over] 
turned  and  dip  in  the  opposite  direction.  Between  Lajara  and  Cuba  they  ar.  exposed 
on!\  in  the  heads  of  deep  canyons  or  cirques,  cut  through  the  overlying  Tertiary  and  the 
talus  and  wash  along  the  base  of  the  mountains. 
Near  the  site  of  the  old  Copper  City  Murllci,  however,  3  miles  east  of  Cuba  and  2  miles 
north-northwest  of  Senorita,  the  hogback  formed  by  the  Mesaverde  is  exposed  and  the  fol- 
lowing sect  mil  w  as  measured: 
Section  of  coal  !»</  mar  site  of  old  Copper  City  smelter,  .'  m>l<s  north-^northwest  of  Senorita, 
N.  Mex. 
Ft.  In. 
Sandstone 3 
Shale,  brown  carbonaceous 2 
Coal 1 
Shale,  brown  carbonaceous 2 
Coal .r>     G 
Shale 2 
Sandstone 4    (i 
