270 
CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1904.         [bull.  260. 
There  are  two  railroads  into  the  district.  A  branch  of  the  North- 
ern Pacific  Railway  leaves  the  main  line  at  Missoula,  Mont.,  follows 
the  Missoula  River  to  the  mouth  of  the  St.  Regis  de  Borgia  River  and, 
turning  up  that  stream,  enters  the  district  by  way  of  Lookout  Pass 
and  Mullan.  From  Wallace,  branches  of  the  Northern  Pacific  extend 
up  Ninemile  and  Canyon  creeks. 
From  the  west  the  district  is  entered  by  the  Oregon  Railway  and 
Navigation  Company,  with  connections  at  Harrison,  on  Coeur  d'Alene 
Lake,  with  steamers  operated  in  conjunction  with  the  Northern  Pa- 
Fig.  16. — Index  map  showing  position  of  Coeur  d'Alene  district. 
cific  and  electric  lines  from  Spokane.     The  Oregon  Railway  and  Nav- 
igation Company  also  has  a  branch  up  Canyon  Creek  to  Burke. 
RELIEF  AND   DRAINAGE. 
The  elevations  in  the  district  range  from  6,826  feet  on  the  summit 
of  Mount  Stevens,  near  the  Idaho-Montana  boundary,  to  2,250  feet; 
on  the  South  Fork  of  the  Coeur  d'Alene  River,  west  of  Kellogg.  The 
region  as  a  whole,  seen  from  a  commanding  point,  has  the  aspect  of  a 
deeply  dissected,  rolling  plateau,  sloping  very  gently  westward  from 
(he  divide  near  the  eastern  edge  of  the  district.  Although  it  is  prob- 
able that  the  present  mountainous  topography  lias  been  carved  by 
erosion  from  a  former  uneven  plateau,  no  vestige  of  this  old  surface 
remains  in  the  complex  of  steep  ridges  and  deep  narrow  valleys  and 
ravines  that  constitute  the  Coeur  d'Alene  Mountains.     The  ridges 
