STRUCTURAL    MATERIALS.  28 
siblo  that  those  low-grade  fuels  may  become  extremely  valuable  in  the  near  future  for  the 
production  of  power.  The  geologic  work  was  done  in  anticipation  of  a  greater  demand  for- 
tius class  of  fuel. 
Oil  and  gas. — Comparatively  little  work  was  done  during  the  year  1905  on  the  oil  fields 
of  the  country.  In  the  Appalachian  region  Mr.  Griswold  continued  his  close  structural 
studies,  making  very  accurate  and  detailed  maps  of  the  oil-bearing  sands  of  a  part  of  west- 
ern Pennsylvania.  In  California  Mr.  Arnold  has  taken  up  the  work  of  Mr.  Eldridge  and 
during  the  latter  part  of  the  year  has  been  engaged  in  an  attempt  to  determine  the  condi- 
tions which  control  the  accumulation  of  the  heavy  oil  of  California,  so  as  to  be  able,  if 
possible,  to  assist  the  driller  in  possible  extensions  of  the  old  fields  and  in  the  discovery  of 
new  fields  where  oil  is  at  present  unknown. 
Asphalts. — A  report  by  Mr.  Taff  on  the  important  ozokerite  deposits  of  Utah  is  included 
in  the  present  bulletin,  the  report  being  based  on  work  done  in  1905. 
STRUCTURAL    MATERIALS. 
Cement. — In  the  summer  of  1905  Mr.  R.  S.  Bassler  spent  several  months  in  western 
and  southwestern  Virginia  examining  and  sampling  the  various  limestone  and  shale  depos- 
its of  that  portion  of  the  State.  The  important  beds  of  shaly  limestone  ("cement  rock") 
which  form  the  basis  of  the  Portland  cement  industry  of  the  Lehigh  district  (Pennsylvania- 
New  Jersey)  were  found  to  occur  at  many  localities  in  the  Shenandoah  Valley,  and  these 
areas  were  carefully  mapped  and  sampled.  The  results  of  this  work  will  appear  later  as 
a  report  on  the  "Cement  Resources  of  the  Valley  of  Virginia." 
Later  in  the  season  Mr.  Eckel  examined  the  cement  prospects  in  the  vicinity  of  Cum- 
berland Gap  (Tennessee-Virginia-Kentucky),  where  heavy  beds  of  nonmagnesian  limestone 
and  shale  outcrop  in  close  proximity  to  the  important  Middlesborough  coal  field  and  where 
transportation  facilities  are  satisfactory.  His  conclusions  are  stated  in  a  brief  report,  in 
the  present  bulletin,  on  the  "Cement  Resources  of  the  Cumberland  Gap  District." 
Lime. — The  most  important  lime-producing  district  of  the  eastern  United  States  is  that 
located  in  Knox  County,  Me.,  including  the  two  well-known  lime-burning  localities,  Rock- 
land and  Rockport.  During  the  past  season  Mr.  E.  S.  Bastin  made  a  careful  geologic 
survey  of  this  district,  and  a  report  on  his  results  is  contained  in  the  present  bulletin. 
In  this  report  Mr.  Bastin  shows  the  close  relation  of  the  geologic  structure  of  the  region 
to  its  economic  importance.  Obviously,  hi  any  search  for  good  limestone  beds,  intelli- 
gent exploration  must  be  based  on  a  thorough  knowledge  of  the  geology  of  the  limestones. 
In  a  folio  now  in  preparation  these  facts  will  be  taken  up  in  more  detail.  Mr.  Bastin's 
report  is  the  first  paper — since  1840  or  thereabouts — which  presents  data  of  value  on  either 
the  geologic  or  the  technologic  features  of  the  Rockland  lime  industry. 
Magnesite. — In  the  fall  of  1905,  on  his  return  from  Alaska,  Mr.  Frank  Hess  was  enabled 
to  spend  a  short  time  in  the  examination  of  the  magnesite  deposits  of  California.  His 
report,  which  is  published  elsewhere  in  this  bulletin,  is  a  notably  clean-cut  piece  of  work, 
which  marks  a  distinct  advance  in  our  knowledge  of  not  only  the  geology  but  the  tech- 
nology of  magnesite.  The  California  magnesite  deposits  are,  so  far  as  now  known,  the  only 
workable  bodies  of  this  mineral  in  the  United  States.  High  freight  rates  prevent  their 
product  from  reaching  the  eastern  market,  so  that  the  magnesia-brick  plants  of  Penn- 
sylvania and  Ohio  employ  imported  (Grecian  and  Austrian)  magnesite  exclusively. 
The  technology  of  magnesite  is  so  imperfectly  understood,  even  by  the  manufacturers 
who  use  the  material,  that  investigations  are  now  being  carried  on  in  the  Survey  labora- 
tory to  determine  such  important  points  as  burning  temperatures,  relation  of  tempera- 
ture to  loss  of  carbon  dioxide,  relation  of  physical  character  to  burning  phenomena,  etc 
The  results  of  this  work  will  doubtless  be  of  value  to  those  interested  in  the  American 
magnesite  industry.  Such  investigations  can  rarely  be  carried  on  by  any  individual  manu- 
facturer, for  few  commercial  laboratories  possess  the  facilities  necessary  for  accurate  work 
at  high  temperatures. 
