brooks.]  PLACER   MINING    IN    ALASKA  IN   1903.  47 
against  such  a  conclusion:  (1)  Though  considerable  prospecting  has 
been  done  in  this  region,  especially  along  Alsek  River,  whose  valley 
crosscuts  the  range,  gold  has  been  found  only  in  small  quantities;  this 
evidence  is,  however,  purely  negative;  (2)  the  extensive  glacial  erosion 
and  the  great  deposits  of  glacial  drift,  as  well  as  the  presence  of  many 
large  glaciers,  would  not  seem  to  present  favorable  conditions  for  the 
concentration  of  gold  in  placers. 
COPPER    RIVER   BASIN. 
Unconsolidated  Pleistocene a  gravels  and  sands  are  extensively  devel- 
oped in  the  Copper  River  basin,  and  many  of  these  are  auriferous. 
In  relatively  few  of  these  deposits  has  the  gold  been  sufficiently 
concentrated  to  be  of  commercial  importance.  The  Chistochina  dis- 
trict, in  the  northern  part  of  the  basin,  where  developments  have 
been  going  on  steadily  during  the  past  year,  is  the  only  one  which  has 
produced  any  considerable  amount  of  gold.  What  would  seem  to  be 
the  eastern  extension  of  the  gold-bearing  series  has  been  found  in  the 
headwaters  of  the  Tanana,  but  it  has  not  yet  been  proved  to  carry 
commercial  values.  Gold  has  also  been  found  to  the  west  of  the  dis- 
trict, but  up  to  the  past  summer  not  in  commercial  quantities.  Rumors 
of  important  discoveries  on  White  and  Slate  creeks,  which  are  said  to 
lie  in  the  upper  Sushitna  basin  reached  Valdes  late  in  the  summer,  and 
parties  are  said  to  be  now  en  route  to  these  diggings  with  dog  teams. 
These  placers  are  reported  to  be  drained  by  streams  flowing  into  East 
Fork  of  the  Sushitna,  and  to  lie  200  miles  from  tidewater.  What  is 
known  concerning  them  is  too  vague  to  permit  of  speculation  in  ref- 
srence  to  their  importance,  but  their  position  would  indicate  that  they 
ie  in  a  zone  which  elsewhere  has  been  found  to  be  auriferous. 
Little  has  been  heard  of  the  placer  fields  in  the  southern  part  of  the 
[e popper  River  basin.     These,  which  embrace  Nizina  River,  the  Tiekel, 
[j!md  the  Tonsina,  while  they  have  given  sufficient  indications  to  attract 
mning  men,  as  far  as  known  have  not  yielded  gold  in  commercial 
quantities  during  the  last  year. 
COOK    INLET    REGION. 
The  Turnagain  Arm  placers,  which  have  been  exploited  since  1895, 
ie  in  the  drainage  basins  of  streams  which  empty  into  the  head  of 
3ook  Inlet  both  from  the  north  and  the  south.  The  district  may  be 
eached  by  a  ten-days'  ocean  journey  to  Tyonok  or  Homer,  and  thence 
>y  small  steamer  to  Sunrise.  Most  of  the  placers  are  within  10  to  20 
niles  of  tidewater.  There  is  little  to  add  to  the  statements  concerning 
his  district  in  last  year's  report.6     The  improvements  have  been  of  a 
H 
aMendenhall,  W.  C,  and  Schrader,  F.  C,  The  mineral  resources  of  the  Mount  Wrangeii  district, 
in|laska:  Prof.  Paper  U.  S.  Geol.  Survey  No.  15,  1903. 
&  Brooks,  A.  H.,  Placer  gold  mining  in  Alaska  in  1902:  Bull.  U.  S.  Geol.  Survey  No.  213, 1903,  p.  48. 
Hi 
