166        CONTRIBUTIONS   TO  ECONOMIC  GEOLOGY,   1907,   PART  II. 
basin  to  the  Pryor  Mountains,  through  which  it  passes  in  another 
deep  canyon,  ultimately  reaching  Yellowstone  River  in  central 
Montana.  In  the  Bighorn  Basin  the  river  occupies  a  broad,  alluvial 
valley,  bordered  by  wide  terraces  which  are  extensively  cultivated 
wherever  irrigation  is  practicable. 
In  all  the  coal  fields  described  in  this  paper,  except  the  Silvertip 
field,  the  topography  is  gently  rolling  or  hilly.  The  Laramie  coal 
bed  in  the  Basin  field  south  of  No  Wood  Creek  outcrops  in  the  valley 
of  Sand  Creek,  which  would  furnish  a  convenient  route  for  a  spur  of 
the  Chicago,  Burlington  and  Quincy  Railroad.  The  same  coal  bed 
on  the  north  side  of  No  Wood  Creek  is  readily  accessible  because  it 
lies  under  an  undissected  plain.  The  workable  part  of  the  Fort 
Union  coal  bed  in  the  Basin  field  lies  beneath  a  gravel-covered  ter- 
race. The  Laramie  coal  in  T.  50  N.,  R.  93  W.,  outcrops  in  a  sharp 
ravine  and  is  not  easy  of  access. 
The  coal  district  south  of  Lovell,  in  T.  55  N.,  R.  96  W.,  is  a  hilly 
area  from  which  the  coal  will  probably  be  removed  only  by  wagon. 
In  the  northern  part  of  the  Garland  field  the  coal  bed  lies  beneath 
a  high  plain,  largely  covered  by  coarse  gravel,  but  in  the  southern  half 
of  T.  57  N.  the  coal  outcrops  near  the  top  of  a  high,  eastward-facing 
escarpment.  In  T.  56  N.  the  outcrop  is  again  in  the  low  country  of 
gentle  relief  that  characterizes  the  southern  part  of  this  field. 
The  Silvertip  field  is  an  anticline  in  which  the  coal  encircles  an  open 
valley  known  as  the  Elk  basin.  On  the  east  side  of  the  field  the  coal 
outcrops  in  westward-facing  cliffs.  On  the  west  side  the  coal  outcrops 
generally  in  the  second  hogback  ridge.  Here,  as  well  as  at  the  north 
end  of  the  field,  the  coal  bed  dips  beneath  a  region  of  deeply  cut  val- 
leys and  high  hills.  The  largest  of  these  valleys,  that  of  Silvertip 
Creek,  furnishes  a  direct  and  feasible  route  for  a  railroad  connecting 
with  the  Yellowstone  Park  Railroad  below  Beljry. 
The  outcrop  of  the  coal  bed  of  the  Bridger  field  north  of  Clark  Fork 
follows  an  eastward-facing  escarpment  of  Eagle  sandstone.  In  sev- 
eral places  this  escarpment  is  broken  by  the  small  valleys  of  eastward- 
flowing  transverse  streams,  in  which  the  coal  is  more  readily  accessi- 
ble; yet  there  is  no  place  on  the  outcrop  of  the  coal  bed  north  of 
Bridger  that  could  not  be  reached  by  a  short  spur  from  one  of  the  two 
branches  of  the  Northern  Pacific  Railway.  The  coal  bed  south  of 
Bridger,  in  T.  7  S.,  R.  23  E.,  outcrops  in  rolling  hills  in  the  northern 
part  of  the  township  and  in  high  ridges  in  the  southern  part.  The 
isolated  area  of  workable  coal  on  the  south  edge  of  T.  8  S.,  R.  24  E., 
is  in  a  high,  rugged  cliff  facing  toward  Jack  Creek.  The  proposed 
Scribner-Fromberg  branch  of  the  Burlington  Railroad  would  pass 
down  Jack  Creek,  about  2  miles  from  the  coal  outcrop. 
Horseback  travel  over  the  region  is  easy,  and  there  are  many  roads 
over  which  wagons  may  be  taken.  Timber  is  limited  to  deciduous 
trees,  growing  along  the  alluvial  plains  of  the  rivers,  and  to  a  few 
