'  COAL   BETWEEN    GALLINA   AND   BATON    SPRING,    N.    MEX.         339 
region.  It  forms  a  prominent  hogback  across  the  east  side  of  the 
Gallina-Raton  Spring  field.  The  outcrop  of  the  formation  enters  this 
field  at  a  point  5^  miles  N.  8°  E.  from  Gallina,  follows  along  the  foot 
of  the  Sierra  Nacimiento  in  a  north-south  direction,  and  passes  from  the 
area  mapped  near  Copper  City.  Coal  beds  occur  at  varying  intervals 
between  a  prominent  basal  and  a  capping  sandstone.  The  main  coal 
bed  of  the  area  is  just  below  the  top  sandstone. 
Lewis  shale. — The  Lewis  is  much  like  the  Mancos  in  appearance. 
The  only  point  worthy  of  mention  here  regarding  this  formation  is  its 
notable  change  in  thickness  across  the  field.  From  about  2,000 
feet  north  of  Gallina  it  thins  to  250  feet  on  the  Arroyo  Torrejon 
and  in  the  vicinity  of  Raton  Spring.  It  may  be,  however,  that  the 
lower  part  of  the  shale  in  that  region  is  replaced  by  sandstone  which 
has  heretofore  been  considered  Mesaverde. 
Laramie  formation. — The  Laramie  is  without  workable  coal  beds  at 
the  north  limit  of  the  field.  In  fact,  Schrader  a  maps  the  entire  area 
northward  to  the  Colorado  State  line  as  barren.  West  of  Gallina  the 
Laramie  and  underlying  Lewis  shale  disappear  beneath  unconform- 
able Eocene  beds.  The  next  point  to  the  south  at  which  the  Laramie 
shows  is  where  it  emerges  from  beneath  the  Puerco,  about  10  \  miles 
southwest  of  Cuba.  The  Laramie  strata  exposed  between  this  point 
and  Raton  Spring  are  coal  bearing,  the  coal  beds  increasing  in  thick- 
ness and  number  toward  the  west. 
TERTIARY    ROCKS. 
In  the  vicinity  of  Gallina  and  to  the  south  beyond  Lajara  the  varie- 
gated shales  of  the  Wasatch  rest  horizontal^  against  the  foot  of  the 
Sierra  Nacimiento,  covering  the  highly  inclined  strata  of  the  Creta- 
ceous and  lower  sedimentary  rocks.  The  W^asatch  bears  many 
fragments  of  vertebrates,  and  collections  were  sufficient  to  permit  its 
positive  identification. 
In  the  southern  portion  of  the  area,  along  the  mountain  foot  north- 
east of  Cuba  and  along  the  headwaters  of  Rio  Puerco,  the  Wasatch  is 
underlain  by  a  mass  of  variegated  and  bituminous  shale,  with  two 
beds  of  massive  sandstone.  The  sandstones  form  prominent  escarp- 
ments, the  upper  immediately  west  and  the  lower  about  10  miles  south- 
west of  Cuba.  The  entire  thickness  of  these  beds  is  about  800  feet. 
They  are  highly  inclined  along  the  mountains,  and  northeast  of  Cuba 
they  are  overturned  and  dip  toward  the  mountains  at  about  70°. 
The  high  dips  of  the  massive  sandstones  are  in  marked  contrast  to 
the  unconformable  horizontal  shale  of  the  overlying  Wasatch.  The 
prominent  sandstone  escarpments  swing  westward  from  Cuba,  the 
lower  being  traced  across  the  area  beyond  the  limits  of  the  present 
a  Op.  cit.,  p.  243. 
