martin]  PETROLEUM    FIELDS    OF    ALASKA.  371 
proportion  of  the  more  volatile  compounds  and  a  paraffin  base,  and  in 
containing  almost  no  sulphur. 
The  proportions  of  the  several  constituents  given  in  the  table  above 
do  not  necessarily  represent  the  full  amounts  that  could  be  obtained 
in  practice  by  different  treatment. 
CAPE  YAKTAG  PETROLEUM   FIELD. 
Cape  Yaktag  is  situated  about  75  miles  east  of  Controller  Bay.  The 
shore  line  is  here  straight  and  there  is  no  harbor  which  affords  shelter 
for  any  kind  of  boat.  A  strip  of  land  from  5  to  10  miles  in  width  lies 
between  the  coast  and  Bering  Glacier.  The  ice  front  is  marked  by  a 
line  of  hills  which  are  parallel  to  the  coast  and  from  which  a  steep 
slope  descends  to  the  sea.  This  slope  is  drained  by  many  short  par- 
allel streams,  some  of  which  head  in  the  ice.  The  Cape  Yaktag  oil 
field  extends  eastward  for  about  25  miles  from  the  mouth  of  Yaktag 
River,  which  is  the  easternmost  of  the  longer  streams  reaching  the 
ocean  near  Cape  Yaktag. 
GEOLOGY. 
The  writer  was  not  able  to  visit  this  region,  so  that  the  following 
observations  are  based  upon  the  statement  of  others.  The  structure,  it 
Is  said,  is  anticlinal,  with  the  axis  parallel  to  and  very  near  the  shore  line. 
The  dip  on  the  southern  flank  of  the  fold  is  very  steep,  the  rocks 
standing  vertically  along  the  beach.  The  dip  on  the  northern  side  is 
much  gentler,  seldom  exceeding  20°.  The  rocks  consist  of  shales  with 
interbedded  sandstone  and  limestone,  the  whole  resembling  very  closely 
in  lithologic  character  the  rocks  of  the  Controller  Bay  oil  field.  The 
northward  dip  continues  inland  as  far  as  the  region  has  been  explored. 
The  structure  is  very  uniform,  no  marked  variations  from  the  strike 
and  dip  recorded  above  having  been  noticed. 
BERING  RIVER  COAL  FIELD. 
Bering  River  coal  field  is  situated  from  12  to  25  miles  inland  from 
Controller  Bay.  The  coal  area,  as  far  as  known,  is  restricted  to  the 
region  north  of  Bering  Lake  and  upper  Bering  River.  Its  southern 
boundary  appears  to  coincide  approximately  with  the  position  of  the 
lake  and  with  Bering  River  above  the  lake.  The  western  boundary, 
although  not  definitely  known,  is  assumed  to  lie  along  a  north-south 
line  extending  through  the  north  arm  of  Bering  Lake  parallel  to  its 
western  shore.  The  northern  and  eastern  boundaries  are  also  uncer- 
tain, but  are  probably  at  a  considerable  distance  beyond  the  region  as 
now  known.  The  coal  area  as  at  present  recognized  includes  about  85 
square  miles. 
