martin.]  PETROLEUM    FIELDS    OP    ALASKA.  369 
Encouraged  by  such  success,  another  company  in  the  spring  of  1903 
began  work  on  a  well  about  4,000  feet  south  of  the  first  one.  In  July 
this  well  was  abandoned  at  a  depth  of  1,700  feet,  that  being  as  far  as 
it  was  possible  to  drill  with  the  light  rig  which  was  used.  No  flow  of 
oil  was  encountered  in  this  well,  but  a  little  was  brought  up  in  the 
bailer  from  time  to  time. 
It  should  be  noted,  in  comparing  the  results  obtained  in  these  two 
wells,  that  the  location  of  the  second  with  reference  to  the  first  is  in 
the  direction  of  the  dip.  The  dip  is  very  steep  in. the  interval  of 
4,000  feet  between  the  wells,  and  while  the  exact  amount  is  undeter- 
mined, it  is  surely  enough  to  carry  the  oil  sand  which  was  tapped  in 
the  first  well  to  a  depth  considerably  exceeding  3,000  feet  at  the  loca- 
tion of  the  second. 
A  third  company  began  drilling  in  Jul}7,  1903,  on  one  of  the  islands 
of  Bering  River,  about  7  miles  above  the  mouth.  In  September  they 
had  reached  a  depth  of  over  500  feet,  with  no  indication  of  oil. 
Another  well,  also  begun  during  July,  1903,  is  on  the  north  bank  of 
Katalla  River,  about  2  miles  above  the  town  of  Katalla.  No  infor- 
mation has  since  been  obtained  concerning  it.  At  the  time  the  writer 
left  Alaska,  in  September,  a  number  of  other  wells  were  about  to  be 
drilled,  but  no  account  of  their  progress  has  been  received. 
Structural  relations  of  the  petroleum. — The  conditions  believed  by 
the  majority  of  observers  to  be  necessary  to  the  occurrence  of  petroleum 
in  commercial  quantities  are,  first,  the  presence,  originally,  of  a  large 
amount  of  organic  matter  in  the  sediments  from  which  the  oil  was 
derived;  second,  the  existence  of  a  porous  rock,  in  the  aggregate  very 
considerable,  in  which  the  oil  could  accumulate;  and,  third,  the  protec- 
tion of  this  rock  in  such  a  manner  that  the  oil  can  not  escape.  The 
condition  generally  regarded  as  affording  the  most  efficient  protection 
is  the  presence  of  an  overlying  stratum  of  fine,  compact  rock,  which 
the  oil  can  not  penetrate,  and  the  flexure  of  the  strata  into  a  gentle  anti- 
cline, so  that  escape  of  the  oil  is  cut  off,  both  in  an  upward  direction  and 
laterally,  in  the  latter  case,  it  may  be,  by  the  body  of  water  behind 
it.  Other  conditions  which  govern  the  accumulation  and  distribution 
of  oil  are  changes  in  the  porosity  of  the  containing  bed,  either  from 
variation  in  the  coarseness  of  sediment,  or  from  the  filling  of  the 
interstices  with  mineral  deposits;  for  example,  carbonate  of  lime. 
Underground  water,  also,  doubtless  plays  a  part  in  the  accumulation 
and  distribution  of  oil. 
From  the  size  and  distribution  of  the  seepages  it  may  be  reasonably 
inferred  that  a  vast  amount  of  organic  matter  which  was  subsequently 
converted  into  petroleum  was  incorporated  with  the  sediments  now 
constituting  the  oil-bearing  shales  of  the  Controller  Bay  region.  The 
appearance  of  the  rocks  is  evidence  that  there  are  numerous  horizons 
in  the  series  sufficiently  porous  to  afford  reservoirs  for  the  accumula- 
Bull.  225—04 24 
