30  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1904.         [bull.  260. 
groat  extent,  promises  to  be  of  considerable  importance  as  a  source 
of  gas  coal  for  the  Northwest  coast. 
The  accurate  determination  of  underground  structure,  on  which 
the  accumulation  of  oil  and  gas  so  largely  depends,  has  been  continued 
m  connection  with  the  work  in  Pennsylvania,  particularly  by  Mr. 
Griswold,  in  Washington  and  Allegheny  counties.  This  work  has] 
now  been  carried  far  enough  and  has  been  subjected  to  sufficiently 
searching  tests  by  actual  drilling  to  prove  its  great  value  in  the 
economical  development  of  an  oil  or  gas  field. 
The  Avork  in  the  oil  and  gas  field  of  Kansas  has  been  continued  by] 
the  survey,  by  Messrs.  Schrader  and  Haworth,  of  the  Independence 
quadrangle,  which  includes  the  southwestward  extension  of  the  Iola 
field.  The  report  upon  the  latter  by  Adams  and  Haworth  is  now  in 
press. 
The  active  development  in  the  Texas-Louisiana  Coastal  Plain  oil 
fields  since  their  examination  in  1901  made  a  reexamination  desirable.. 
This  work  has  been  carried  out  during  the  past  year  by  Mr.  Fenneman, 
who  is  now  preparing  a  full  report  and  who  contributes  a  summary 
of  his  conclusions  to  this  volume.  The  conclusions  of  the  formers 
work  are  in  the  main  sustained,  while  much  more  definite  statements 
concerning  the  geologic  conditions  under  which,  the  oil  occurs  are 
warranted  by  the  fuller  information  now  available  through  the 
extensive  drilling  which  has  been  in  progress  during  the  past  three 
years. 
BUILDING  MATERIALS 
The  cement  industry  formed  the  subject  of  an  extensive  investiga- 
tion by  Mr.  Eckel  in  1903.  This  was  continued  during  the  past  year, 
and  the  full  report  will  soon  be  published  as  Bulletin  243.  Important 
supplementary  examinations  Avere  carried  on  in  various  districts 
under  Mr.  Eckel's  supervision.  Mr.  Bassler  made  a  thorough  exami- 
nation of  the  Lehigh  district  in  Pennsylvania  and  New  Jersey.  By 
means  of  the  contained  fossils  he  was  able  to  separate  and  map  the 
upper  limestone  or  "  cement  rock  "  from  the  lower  beds,  which  conJ 
tain  too  large  a  proportion  of  magnesium  carbonate  for  use  in  the 
manufacture  of  cement.  Mr.  Bassler  also  differentiated  and  mapped 
the  cement  materials  in  a  considerable  area  in  Augusta  and  Rock- 
bridge counties.  Ya.  The  results  of  the  latter  Avork  are  summarized 
in  this  ATolume. 
The  investigation  of  the  cement  resources  in  the  region  tributary 
to  the  Gulf  of  Mexico  has  been  continued  during  1904  by  MessrS 
Eckel  and  Crider.     The  calcareous  formations  previously  studied  in 
Alabama   have   been   carefully  traced   across  Mississippi,  and  their 
suitability  for  the  manufacture  of  Portland  cement  has  been  thor- 
