10  CONTRIBUTIONS   TO   ECONOMIC   GEOLOGY,  1907,  PART  II. 
7.  A  party  under  the  direction  of  Alfred  R.  Schultz  made  a  survey 
of  the  coal  fields  exposed  on  the  north  flank  of  the  Rock  Springs  dome, 
an  uplift  near  the  center  of  the  Green  River  Basin,  which  brings  to 
the  surface  lower  and  more  valuable  coal  beds  than  are  present  in  the 
surrounding  region.  The  field  mapped  is  represented  by  area  No.  14 
on  PL  I. 
Colorado. — Only  three  geologic  parties  were  at  work  during  the 
summer  of  1907  in  the  State  of  Colorado.  The  fields  examined  by 
them  are  as  follows: 
1.  A  party  under  the  leadership  of  Hoyt  S.  Gale  continued  the 
mapping  of  the  northern  rim  of  the  Uinta  Basin  from  the  Danforth 
Hills  to  Vernal,  Utah,  and  then  made  a  hurried  reconnaissance  of  the 
Henrys  Fork  field,  north  of  Uinta  Mountains.  The  former  is  the  west- 
ward extension  of  fields  surveyed  by  Mr.  Gale  in  1906  and  by  Messrs. 
Fenneman  and  Gale  in  1905.  The  territory  examined  is  represented 
by  area  No.  15  on  PL  I. 
2.  A  party  under  the  direction  of  Willis  T.  Lee  made  an  examina- 
tion of  the  southern  rim  of  the  Uinta  Basin  from  Grand  Junction  to 
Somerset.  This  is  generally  known  as  the  Grand  Mesa  field,  and  is 
represented  as  area  No.  16  on  PL  I.  Generally  the  coal  beds  are 
inaccessible  at  the  present  time,  but  in  the  vicinity  of  Somerset  a 
branch  line  of  the  Denver  and  Rio  Grande  Railroad  extends  into  the 
coal  field  and  development  has  begun. 
3.  A  party  under  the  leadership  of  James  H.  Gardner  examined 
the  Durango  coal  field  from  Durango  eastward  to  Lumberton,  N.  Mex. 
In  1905  a  hurried  examination  was  made  by  F.  C.  Schradera  of  the 
eastern  rim  of  this  basin,  but  no  detailed  mapping  of  the  outcrop  of 
the  coal-bearing  formations  was  attempted.  Accordingly  during  the 
last  season  Mr.  Gardner  made  a  resurvey  of  the  outcrops  for  the  pur- 
pose of  more  definitely  locating  them  with  reference  to  public-land 
corners,  and  of  determining  the  coal  resources  of  the  field.  The  area 
surveyed  is  represented  by  No.  18  on  PL  I. 
New  Mexico.— -In  New  Mexico  only  two  coal  fields  were  examined 
during  the  summer  of  1907.  These  are  located  on  the  margin  of  the 
San  Juan  River  basin,  as  follows : 
1.  A  party  under  the  direction  of  James  H.  Gardner  resurveyed 
the  southeastern  rim  of  the  basin  from  Gallina  to  Raton  Springs,  as 
indicated  by  area  No.  17,  PL  I.  This  had  previously  been  examined 
by  Mr.  Schrader  in  1905,  but  not  with  sufficient  care  to  classify  the 
land. 
2.  Mr.  Gardner  also  mapped  the  southern  rim  of  the  basin  from 
Gallup  to  San  Mateo.     (See  area  No.  19,  PL  I.) 
Utah. — In  Utah  the  coal  fields  are  fairly  well  known,  except  those 
in  the  southern  part  of  the  State,  which  have  been  attracting  so  much 
attention  in  late  years  that  it  seemed  advisable  to  examine  them. 
a  Bull.  U.  S.  Geol.  Survey  No.  285,  1906,  pp.  241-258. 
