c 
GOLD-BEARING    RIVER    SANDS    OF    N.  E.   WASHINGTON.  65 
river  was  evidently  determined  in  some  places  by  the  thickness  of  the 
overburden  and  in  others  by  the  thinning  out  of  the  pay  streak.  The 
gold  contains  some  large  flakes  worth  0.02  cent  and  much  fine  flour 
gold,  bringing  the  average  down  to  0.0067  cent.  The  pay  streak  prob- 
ably averaged  a  little  over  40  cents  to  the  cubic  yard.  A  sample 
tested  by  fire  assay  at  the  concentrating  pavilion  gave  16  cents  per  ton. 
The  upper  terrace,  100  feet  above  the  river,  presents  a  somewhat 
similar  section,  comprising  from  1  to  3  feet  of  iron-stained  gravel,  sand, 
and  clay,  resting  on  more  than  90  feet  of  cross-bedded  gravel  and  sand. 
Panning  tests  showed  that  the  upper  layer  carries  a  small  fraction  of  a 
ent  in  flour  gold  per  cubic  yard,  while  the  gravel  and  sand  below 
w  no  trace  of  gold. 
Wilmot  Bar  is  about  6  miles  farther  up  the  river,  opposite  Jerome 
post-office.  As  at  Sixmile  Bar,  there  are  two  terraces  here — one  20 
feet,  the  other  about  100  feet  above  the  river.  The  lower  terrace  is 
situated  just  below  a  series  of  rock  ledges  forming  an  obstruction  to 
the  current  somewhat  similar  to  that  at  Hell  Gate  and  the  concentra- 
tion of  gold  on  the  bar  is  probably  due  in  part  to  this  cause.  On  the 
lower  terrace  there  is  a  surficial  deposit  from  1  to  5  feet  thick  that  con- 
tains flour  gold  and  rests  on  open-textured  gravel  and  sand.  Panning 
tests  indicate  a  possible  value  of  10  to  14  cents  per  cubic  yard  on  the 
lower  bench  and  a  small  fraction  of  a  cent  per  cubic  yard  on  the  upper 
one. 
Rogers  Bar,  on  the  west  bank  of  the  Columbia  2  miles  below  the 
town  of  Hunter,  contains  approximately  1,500  acres  of  nearly  level 
land  that  lies  from  20  to  100  feet  above  high  water  and  extends  for  3 
miles  along  the  river.  It  includes  three  distinct  benches — one  30, 
another  75,  and  a  third  100  feet  above  the  river.  Near  the  middle  of 
the  bar  two  men  are  still  working  with  rockers  on  the  river  bank,  fol- 
lowing the  edge  of  the  water  as  it  falls.  They  report  that  the  best  pay 
is  found  on  bars  exposed  only  at  low  water.  Half  a  mile  below  their 
workings  there  is  a  low  gravel  bar  that  is  scarcely  above  the  level  of  the 
river  at  ordinary  stages;  this  was  nearly  all  worked  over  by  Chinese. 
A  miner  working  here  reported  that  under  favorable  conditions  he 
could  make  as  high  as  $3  per  day.  Near  the  lower  end  of  Rogers  Bar 
is  a  large  island  in  the  river  known  as  Hog  Island.  The  channel 
between  it  and  the  mainland  is  dry  at  low  water  and  its  bed  has  all 
been  worked  by  Chinese. 
The  section  of  the  deposit  forming  the  lower  terrace  at  Rogers  Bar 
is  as  follows: 
Section  of  lower  terrace  on  Columbia  River  at  Rogers  Bar. 
Feet. 
Sandy  silt 2-8 
Gravel  and  clay  (pay  streak) |— 1 
Open-textured  cross-bedded  sand  and  gravel. ,. , , , 20 
Bull.  315—07 5 
