;;7^  OONTEIBUTIONS    TO    ECONOMIC    GEOLOGY,   1903.  [bull. 225. 
Enochkin  Bay,  where  the  rocks  are  inclined  southeastward  at  an  angle 
of  28  .  The  greatest  dip  at  the  northern  end  of  the  field  is  between 
hal!'  a  mile  and  a  mile  southeast  of  the  entrance  to  Chinitua  Bay, where 
it  is  from  25°  to  45°  SE.  On  the  western  flanks  of  this  anticline  the 
dip  is  about  17°. 
'The  nature  of  the  undulations  at  the  crest  can  be  seen  in  the  cliffs 
on  the  .'listen i  side  of  Enochkin  Bay. 
The  83  ncline  which  adjoins  this  anticline  on  the  west  is  a  much  nar- 
rower and  simpler  fold.  It  is  characterized  by  a  steeper  dip  on  the 
western  than  on  the  eastern  flank.  It  appears  to  die  out  toward  the 
northeast  and  was  not  recognized  on  Chinitua  Bay. 
West  of  this  syncline  is  an  anticline  in  which  the  rocks  are  badly 
crumpled  and  faulted.  The  crystalline  rocks  are  exposed  on  its  west- 
ern side  and  at  places  within  it.  The  contact  of  the  westernmost  out- 
crops of  the  shales  with  the  crystalline  rocks  appears  to  be  along  the 
line  of  a  great  fault.  The  amount  of  pitch  of  the  axes  of  these  folds 
is  not  known. 
OCCURRENCE  OF  PETROLEUM. 
Surface  indications. — The  surface  indications  of  petroleum  in  this 
region  consist  of  seepages  or  oil  springs,  and  the  so-called  gas  springs. 
In  the  first,  the  petroleum  may  be  seen  oozing  from  the  cracks  in  the 
rock  or  coming  out  of  the  soil.  On  the  east  shore  of  Enochkin  Bay  a 
good  seepage  was  seen  about  1,000  feet  below  the  lower  cabin,  although 
the  spring  is  covered  at  high  tide.  The  flow  is  often  so  strong  that 
the  petroleum  collects  in  large  blotches  on  the  pool,  or  even  covers  its 
entire  surface.  At  one  point  it  issues  from  a  crevice  in  the  rock,  which 
is  Jurassic  shale. 
In  the  vicinity  of  the  cabin  at  Oil  Bay  are  a  number  of  large 
springs.  From  the  bottom  of  one  the  petroleum  is  almost  continually 
rising,  the  flow  varying,  however,  from  time  to  time,  now  almost 
ceasing,  now  becoming  very  strong.  It  is  frequently  possible  to  skim 
several  quarts  of  petroleum  from  the  surface  of  the  pool. 
About  2  miles  west  of  the  beach  at  Dry  Bay  is  a  so-called  gas  spring, 
gas  of  unknown  composition  rising  in  a  continuous  stream  of  bubbles 
to  the  surface  of  the  water.  From  the  north  shore  of  Chinitua  Bay 
both  oil  and  gas  springs  have  been  reported,  but  they  were  not  seen 
by  the  writer. 
The  geologic  structure  of  this  region  has  already  been  outlined.  It 
consists  of  a  long  anticline,  parallel  to  the  coast,  with  an  axis  having  a 
N.  80°  E.  trend.  The  dip  on  each  flank  is  regular  and  comparatively 
moderate,  seldom  exceeding  20°.  Although  in  the  axial  region  of  the 
fold  the  strata  are  faintly  undulating,  the  crown  of  the  arch  is  almost 
flat.  Other  things  being  equal,  the  fold  is  such,  indeed,  as  should 
yield  a  good  flow  over  a  considerable  area,  granting  the  existence  below 
