70  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,    1903.  [bull. 225. 
that  there  is  more  ground  to  be  worked  by  drifting'  methods.  So  far 
as  could  be  learned,  less  development  work  had  been  done  than  on 
Pedro  Creek. 
Clear y  Creek  and  its  tributaries. — Clear y  Creek  flows  in  a  north- 
easterly and  finally  northerly  direction  to  the  Chatanika.  Its  general 
characters  arc  similar  to  those  of  Pedro  Creek.  It  flows  in  an  unsym- 
metrical  valley  bounded  on  the  east  by  a  rather  steep,  wooded  slope. 
On  the  other  side  a  bench  a  quarter  of  a  mile  or  more  in  width  rises 
gradually  from  an  elevation  of  15  to  20  feet  above  the  creek  flat  to  the 
foot  of  the  wooded  slope  on  the  left. 
The  tributaries  of  importance  are  Chatham  and  Wolf  creeks.  Chat- 
ham is  about  a  mile  in  length,  heads  in  the  divide  opposite  Twin  Creek, 
and  flows  in  a  northerly  direction  in  a  narrow  valley,  which  has  a 
stream  flat  about  300  feet  in  width  at  its  mouth. 
The  headwaters  of  Wolf  Creek  have  formed  an  amphitheatral  depres- 
sion in  the  divide  between  it  and  Fairbanks  Creek.  The  main  creek 
is  about  li  miles  in  length,  and  flows  in  a  rather  open  valley,  which 
expands  to  a  flat  a  quarter  of  a  mile  in  width,  merging  with  that  of 
Cleary  about  a  mile  below  the  mouth  of  Chatham. 
Below  the  mouth  of  Wolf  Creek  the  valley  of  Cleary  widens,  rather 
steep,  wooded  ridges  approach  it  closely  on  the  west,  the  stream  flat 
on  the  east  becomes  more  thickly  wooded,  and  rises  gradually  until  at 
a  distance  of  about  a  mile  from  the  stream  it  merges  into  the  base  of 
the  wooded  ridges.  Cleary  Creek,  6  miles  below  Wolf,  flows  into  the 
Chatanika. 
The  bed  rock  is  mostly  mica-schist  and  quartzite-schist;  hornblende- 
schists  occur,  and  a  granitic  rock  of  apparently  intrusive  character  is 
found  near  the  head  of  Chatham. 
Work  is  in  progress  on  Chatham,  Wolf,  and  the  portion  of  Cleary 
from  Chatham  to  a  point  a  half  mile  or  more  below  the  mouth  of 
Wolf.  Claims  are  being  prospected  along  Chatham ,  and,  at  the  mouth, 
mining  is  carried  on  by  the  open-cut  method.  Sufficient  work  has  not 
been  done  to  determine  the  average  thickness  of  the  gravels  or  the 
average  value  and  extent  of  the  pay  dirt.  The  material  on  bed  rock 
varies  from  4  to  20  feet  in  thickness,  and  the  covering  of  muck  con- 
stitutes in  some  cases  a  considerable  proportion  of  this.  The  gravel  is 
composed  mostly  of  schist,  and  has  been  found  to  yield  values  ranging 
from  1|  cents  to,  in  exceptional  cases,  -10  cents  to  the  pan.  The  gold 
is  generally  fine,  but  nuggets  have  been  found  up  to  a  value  of  $5. 
The  gold  near  the  head  of  the  stream  is  rough. 
On  Wolf  Creek  the  covering  on  bed  rock  is  from  4  to  10  or  more 
feet  thick.  The  gravels  are  composed  of  quartzite-schist  and  this  is 
the  rock  which  outcrops  on  the  rim  of  the  amphitheater  at  the  head  of 
the  creek.  The  open  -cut  method  is  used  and  very  little  ground  is  found 
to  be  frozen.     The  gold  is  generally  in  the  lower  portion  of  the  graved 
