380  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,   1903.  [bull.  225. 
COLD   BAY   PETROLEUM   FIELD. 
GEOGRAPHY. 
Cold  Bay  is  situated  on  the  south  shore  of  the  Alaska  Peninsula  at 
the  southwest  (Mid  of  Shelikof  Strait  and  opposite  the  west  end  of 
Kodiak  Island.  It  may  be  reached  by  steamer  from  Seattle  either 
director  by  transfer  at  Valdes  or  Kodiak,  or  from  Dutch  Harbor. 
From  Seattle  the  time  is  about  fifteen  days;  from  Valdes,  four.  It 
may  also  be  reached  from  Bristol  Bay  by  a  canoe  and  portage  across 
the  peninsula. 
The  southern  shore  of  the  Alaska  Peninsula  is  very  sinuous,  with 
deep  indentations  and  long,  rugged  forelands.  Cold  Bay  is  one  of  the 
best  of  the  harbors.  It  is  roughly  triangular  in  shape,  about  10  miles 
long  by  7  wide  at  the  mouth,  and  contains  a  very  large  area  of  deep 
water. 
The  surrounding  country  consists  of  an  elevated  upland  with  gently 
rounded  or  flat-topped  hills  rising  above  it.  Its  general  level  is  about 
750  feet  above  tide.  Most  of  the  higher  peaks  rise  to  an  elevation  of 
about  1,500  feet,  while  farther  back  from  the  coast,  in  the  central 
part  of  the  peninsula,  are  mountains  5,000  feet  or  more  in  height. 
The  streams  emptying  into  Cold  Bay  and  into  the  other  bays  in  the 
vicinity  are  short  and  swift,  but  carry  a  large  amount  of  water.  The 
northern  slope  of  the  peninsula,  on  the  other  hand,  is  drained  by 
a  comparatively  small  number  of  fairly  large  rivers  which  empty 
either  into  shallow  bays  or  directly  into  the  sea.  All  of  these  rivers 
have  lakes  either  at  their  headwaters  or  along  their  courses.  Lake 
Becharof,  the  head  of  which  is  situated  about  15  miles  from  the  land- 
ing at  Cold  Bay,  is  one  of  the  largest. 
Timber  is  almost  entirely  lacking  in  this  region,  the  only  trees  being 
a  few  small  cottonwoods,  willows,  and  scrub  alders  along  the  banks  of 
the  streams.  This  is  characteristic  of  the  greater  part  of  the  Alaska 
Peninsula. 
GEOLOGY. 
The  rocks  observed  in  the  vicinity  of  Cold  Bay  consist  of  a  few  thin 
limestones  and  dark  shales  which  break  on  the  weathered  surface  with  a 
conchoidal  fracture.  These  alternate  irregularly.  Their  age  is  Meso- 
zoic,  corresponding  closely  to  that  of  the  rocks  of  the  Cook  Inlet 
oil  fields.  They  carry  Jurassic  fossils  everywhere  except  at  the 
promontory  on  the  east  side  of  the  bay,  where  Triassic  forms  have 
been  reported. 
Structure. — The  rocks  either  lie  horizontal  or  with  a  dip  that  is 
very  gentle,  though  somewhat  irregular,  both  in  amount  and  direction. 
In  the  forelands  the  general  dip  is  northwestward.  Several  miles  back 
this  dies  out  and  the  rocks  lie  horizontal  or  dip  slightly  toward  the 
