66  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,    L906,  PART    I. 
The  section  in  the  next  higher  bench  is  similar excepl  that  the  under- 
lying gravel  contains  more  sand  and  there  is  a  greater  thickness 
exposed.  On  the  lower  bench  flour  gold  to  the  value  of  1  to  50  cents 
per  cubic  yard  was  found  in  the  pay  streak,  and  a  much  smaller 
amount  disseminated  through  the  overburden.  Tests  by  fusion  at  the 
concentrating  plant  gave  somewhat  higher  values  and  would  seem  to 
indicate  that  there  is  a  considerable  amount  of  finer  gold  which  could 
not  be  saved  by  ordinary  panning.  In  some  instances  traces  of  plati- 
num were  reported  by  the  assayer,  but  the  amount  was  not  deter- 
mined. No  gold  was  found  on  the  uppermost  terrace,  which  as  noted 
lies  100  feet  above  the  river.  The  bars  below  the  level  of  ordinary 
high  water  carry  values  in  gold  somewhat  higher  than  those  of  t lie 
terraces,  the  indicated  value  being  more  than  30  cents  per  cubic  yard. 
The  colors  of  gold  at  Rogers  Bar  have  an  average  value  of  about 
0.0012.")  cent  and  the  samples  contained  at  least  one  color  worth  0.01 
cent. 
Blue  Bar,  situated  on  the  right  bank  of  Columbia  River,  about  4 
miles  above  Hunter,  consists  of  a  terrace  from  100  to  1,000  feet  wide 
and  20  feet  above  the  river.  Opposite  t  he  bar  in  t  he  river  lies  Blue  Bar 
Island,  with  an  area  of  about  100  acres.  Mining  was  done  by  Chinese 
at  the  upper  end  of  this  island,  as  well  as  at  the1  vd^c  of  the  terrace, 
to  which  water  was  brought  in  a  ditch  from  a  small  stream  known  as 
St  ia\  Dog  ('reek.  The  section  of  the  deposit  making  up  the  terrace 
at  Blue  Bar  is  approximately  as  follows: 
Section  on  Columbia  River  at  Blva  liar. 
Fa  i. 
Sandy  loam \-l 
[ron-stained  gravel,  containing  some  clay  i  pay  streak  i i-^ 
Open-textured  gra"\  >-\  and  Band 15 
Nearly  all  the  gold  is  confined  to  the  pay  streak,  though  scattering 
colors  can  be  found  in  the  overburden.  The  results  of  panning  this 
pay  streak  indicate  values  ranging  from  less  than  a  cent  to  6  cents 
per  cubic  yard.  Samples  tested  by  fusion  at  the  concentrating  pavil- 
ion yielded  from  2  to  41  cents  per  ton. 
Two  miles  above  Blue  Bar,  near  Turtle  Rapids,  a  bench  60  feet 
above  high  water  extends  along  the  river  for  several  miles.  Old 
Chinese  workings  here  expose  a  nearly  barren  layer  of  sandy  silt  sev- 
eral feet  thick,  resting  on  a  pay  streak  a  few  inches  thick,  consisting 
of  gravel  and  clay,  below  which  is  open-textured  gravel  and  sand. 
These  old  workings  indicate  that  the  pay  streak  was  followed  back 
from  the  river  bank  until  the  overburden  became  too  thick  to  permit 
further  mining  in  that  direction.  Some  of  the  original  pay  dirt  was 
panned,  indicating  an  approximate  value  of  30  cents  per  cubic  yard, 
one  pan  containing  upward  of  300  fine  colors  of  gold,  the  average 
value  of  which  was  0.00143  cent. 
