eansome.]  COEUR    D'ALENE    DISTRICT,  IDAHO.  275 
season  of  1903  by  Mr.  W.  F.  Williams  and  during  both  seasons  by 
Mr.  W.  F,  MacDonald.  The  brief  account  of  the  general  geology 
included  in  this  preliminary  report  is  based  almost  entirely  upon 
Mr.  Calkins's  work. 
A  part  only  of  the  rock  and  ore  collections  made  in  the  field  dur- 
ing the  past  two  seasons  has  been  studied,  and  much  office  work 
must  be  done  before  the  final  report  on  the  district  will  be  ready  for 
publication.  The  present  summary  is  nothing  more  than  a  brief 
statement  of  the  progress  of  an  uncompleted  investigation  and  is 
essentially  provisional  in  character. 
GEOGRAPHY. 
The  area  which  may  be  conveniently  called  the  Coeur  d'Alene  dis- 
trict (although  for  purposes  of  record  and  administration  it  has  been 
divided  into  a  number  of  local  mining  districts)  is,  so  far  as  its  pro- 
ductive portion  is  concerned,  in  Shoshone  County,  Idaho.  It  lies 
almost  entirely  upon  the  western  slope  of  the  Coeur  d'Alene  Moun- 
tains," a  broad  and  rather  complex  member  of  the  main  Rocky 
Mountain  chain.  The  Coeur  d'Alene  Mountains  extend  from  Pend 
Oreille  Lake  on  the  north  to  the  headwaters  of  the  North  Fork  of 
the  Clearwater,  or  nearly  to  Lolo  Pass,  on  the  south.  The  eastern 
slope  of  the  range  descends  in  from  10  to  25  miles  to  the  valleys  of 
'Clark  Fork  and  the  Missoula  River.  The  western  versant  slopes 
as  a  broad,  dissected  plateau  down  to  the  basaltic  plains  of  Spokane 
and  eastern  Washington.  The  breadth  of  this  western  slope  is  50  or 
60  miles. 
The  Coeur  d'Alene  special  map,  outlined  in  fig.  1(3,  embraces  within 
its  eastern  border  part  of  the  crest  of  the  range,  which  here  forms  the 
boundary  between  Idaho  and  Montana.  It  includes  all  of  the  local 
lead -silver  deposits  of  importance,  with  the  exception  of  a  few  mines 
and  prospects  lying  just  outside  its  western  boundary.  None  of  these 
outlying  mines,  however,  are  at  present  active  producers. 
Wallace,  the  principal  town  of  the  region  and  the  seat  of  Shoshone 
County,  has  a  population  of  about  o,500.  It  is  situated  in  (he  south- 
central  part  of  the  district,  at  the  confluence  of  Ninemile  and  Canyon 
creeks  with  the  South  Fork  of  Coeur  d'Alene  River.  It  is  essen- 
tially a  supply  point  for  the  mines,  the  mining  population  being 
housed  for  the  most  part  in  the  smaller  towns  of  Wardner,  Mullan, 
Burke,  Mace,  Gem,  and  Murray. 
"This  group  of  mountains  is  on  some  maps  made  ;i  part  of  flic  Bitterrool  Range.  It 
seems  better,  however,  to  restrict  the  name  Bitterrool  as  Lindgren  has  done  in  his  recenl 
reconnaissance  paper  (Prof.  Paper  U.  S.  Geol.  Survey  No.  27)  to  th<>  range  separating 
the  drainage  basins  of  the  Bitterroot  and  Clearwater  rivers,  and  forming  a  southern  con 
tinuation  of  the  Coeur  d'Alene  Mountains. 
