146  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,   1903.  [bull. 225. 
of  canyons,  bowlder  belts,  lateral  and  terminal  moraines,  and  other 
glacial  features.  Many  of  these  are  well  developed  in  Lavigneur 
Canyon,  at  the  northwest  fork  of  Snake  Creek,  on  Bonanza  Flat, 
in  Empire  Canyon,  Walker,  Webster,  and  Woodside  gulches,  and 
Thaynes  and  White  Pine  canyons.  About  the  head  of  Bonanza  Flat 
certain  rock  knobs  and  walls  exhibit  excellent  polishing  and  striation. 
A  limit  of  advance  of  each  stream  of  ice  appears  to  be  indicated 
on  the  valley  bottoms  by  heavy  deposits  of  mixed  unsorted  soil  and 
rock  debris,  which  terminate  abruptly  downstream.  The  numerous 
bowlder  belts  typically  displayed  on  Bonanza  Flat  probably  mark 
different  positions  occupied  by  the  ice  front.  The  Lady  Morgan 
lakes,  two  small  ponds  just  west  of  the  Daly  West  shaft,  are  dammed 
back  by  a  moraine.  Collections  of  large,  disordered  masses  of  coarse 
rock  debris  simulating  cirques  at  the  extreme  heads  of  valleys  are 
best  shown  east  of  Clayton  Peak  and  northeast  of  Scott  Hill.  Further- 
more, glacial  material  composing  the  divide  at  the  head  of  Woodside 
Gulch;  the  flat-topped  lobe  between  Walker  and  Webster  Gulch  and 
Empire  Canyon;  the  narrow,  attenuated  spur  between  Woodside 
Gulch  and  Empire  Canyon,  and  the  straight,  narrow,  level  ridge  east 
of  lower  Thaynes  Canyon,  indicate  striking  changes  in  topography 
and  drainage  produced  by  glaciation. 
ECONOMIC  GEOLOGY. 
General  statement. — With  the  appearance  of  snow  in  the  fall  of 
1903  areal  mapping  and  study  of  special  surface  features  were  neces- 
sarily abandoned,  and  the  detailed  mapping  of  underground  geology 
and  examination  of  ore  deposits  were  undertaken.  A  large  portion  of 
this  work  has  been  finished,  yet  considerable  remains  to  be  done,  and 
field  work  on  this  is  now  being  carried  on. 
The  number  of  properties  in  the  district  is  relatively  small,  and  the 
record  of  the  camp  rests  upon  the  output  from  a  few  mines  which 
have  been  developed  very  extensively,  both  laterally  and  in  depth. 
The  work  of  studying  these  exposures  is  greatly  increased  by  the 
large  amount  of  complex  deformation,  through  faulting  and  intrusion. 
Although  this  work  is  at  present  incomplete  and  there  has  not  been 
suitable  opportunity  thoroughly  to  correlate  the  results  thus  far 
attained,  it  appears  that  conclusions  may  be  given  in  the  final  report  i 
which  will  not  only  aid  present  development,  but  should  materially  i 
benefit  future  exploration. 
The  high  rank  of  the  mines  of  this  district  among  the  dividend- 
paying  argentiferous  lead  mines  of  the  world,  the  progressive  meth- 
ods employed,  and  the  generally  prosperous  condition  of  the  camp 
were  briefly  outlined  in  the  progress  report  of  last  year.  Additional 
information  which  may  now  be  given  comprises  brief  general 
descriptions  of  development,  character  of  ores,  occurrence  of  ores; 
