244         CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,    1907,    PART   II. 
the  Great  Divide  Basin  field  (PL  XII),  or  with  the  map  of  the  east- 
central  Carbon  County  fields/  both  of  which  were  plotted  about 
balance  lines  intersecting  near  their  own  centers.  When  the  entire 
Wyoming  area  of  the  Little  Snake  River  field  shall  have  been  sur- 
veyed, a  final  report  will  be  published,  accompanied  by  a  complete 
contour  map. 
.  The  writer  wishes  to  acknowledge  the  receipt  of  valuable  infor- 
mation and  assistance  from  the  Union  Pacific  Railroad  Company; 
E.  Lambert,  county  surveyor,  Carbon  County;  W.  S.  Smith,  M.  W. 
Dillon,  L.  Calvert,  A.  Stratton,  and  others. 
GEOGRAPHY. 
The  coal  field  drained  by  Little  Snake  River  extends  from  the 
Sierra  Madre  westward  to  and  partly  into  the  Red  Desert,  and  from 
the  summit  of  the  Elkhead  Mountains  of  Colorado  northward  to  the 
divide  between  the  Pacific  and  Great  Divide  Basin  drainages,  a  few 
miles  south  of  the  Union  Pacific  Railroad. 
The  area  discussed  in  this  paper  is  located  near  the  middle  of  the  south- 
ern boundary  of  the  State.  It  extends  along  the  Union  Pacific  Railroad 
from  Rawlins  to  Red  Desert  station,  and  southward  to  Little  Snake 
River  between  Baggs  and  Dixon.  It  comprises  all  except  the  south- 
east corner  of  the  Wyoming  portion  of  the  Little  Snake  River  field,  as 
well  as  that  part  of  the  Great  Divide  Basin  field  which  lies  south  of 
the  Union  Pacific  Railroad  and  east  of  range  96.  It  joins  along  the 
Union  Pacific  Railroad  with  the  work  of  E.  E.  Smith  in  the  Great 
Divide  Basin  field  (pp.  220-242),  at  the  northwest  corner  with  that  of 
A.  R.  Schultz  in  the  Rock  Springs  field  (pp.  256-282) ,  and  at  the  north- 
east corner  with  the  mapping  of  A.  C.  Veatcha  in  1906  in  the  Kindt 
coal  basin.  It  is  separated  by  the  Elkhead  Mountains  from  the 
Yampa  field  mapped  by  Fenneman  and  Gale  in  1905.6 
The  eastern  part  of  the  area  consists  of  high  plateaus  and  ridges 
cut  by  deep,  rocky  canyons.  West  of  this  is  a  depression,  in  places  a 
simple  valley,  elsewhere  a  broad  area  of  low,  irregular  relief.  It  is 
followed  by  a  series  of  hogbacks  and  low  transverse  ridges  which  in 
the  north  end  of  the  field  give  place  gradually  to  the  broad,  com- 
paratively level  expanse  of  gentle  dip  slopes,  dry  lake  beds,  and 
alkali  flats  forming  the  eastern  border  of  the  Red  Desert.  The  level 
expanse  is  terminated  on  the  west  by  the  brilliant  red  and  white 
escarpment  of  the  Laney  Rim,  and  on  the  south  by  the  highly  colored 
bluffs  which  extend  eastward  from  Flat  Top  Mountain  and  which 
south  of  the  mouth  of  Red  Creek  form  the  western  boundary  of  the 
a  Veatch,  A.  C,  Map  of  the  coal  fields  of  east-central  Carbon  County,  Wyo. :  Bull.  U.  S.  Geol.  Survey 
No.  316,  1907,  PI.  XIV. 
b  Fenneman,  N.  M.,  and  Gale,  H.  S.,  The  Yampa  coal  field,  Routt  County,  Colo.:  Bull.  U.  S.  Geol. 
Survey  No.  297,  1906. . 
