580  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1904.         r bull.  260. 
Analysis  of  common  salt  from  El  Paso  County,  Tc.r. 
Silica 0.6 
Alumina 0.  G 
Iron   , Trace. 
Magnesia    Trace. 
Lime Trace. 
Potash    None. 
Sodium    sulphate 1.  4 
Sodium    chloride 97.  3 
Total 99.  9 
The  ground-water  level  here  is  very  near  the  surface.  The  test 
hole  above  referred  to  rapidly  filled  with  water  which  contained  con- 
siderable gas,  apparently  hydrogen  sulphide.  An  analysis  of  this 
water,  by  Mr.  S.  H.  Worrell,  shows  it  to  contain  9,990  parts  of  solids 
per  100,000,  consisting  chiefly  of  sodium  chloride. 
When  the  surface  layer  of  salt  is  removed  its  place  is  taken  by  this 
brine,  which  evaporates  and  deposits  salt,  so  that  within  a  few  weeks 
after  stripping  an  area  a  new  deposit  of  salt  replaces  that  which  was 
removed.     The  supply  is  popularly  believed  to  be  inexhaustible. 
These  facts  imply  that  the  salt  is  derived  from  an  underground 
source,  either  from  disseminated  salt  or  from  a  concentrated  deposit 
with  which  the  ground  waters  come  in  contact.  The  depth  below  the 
surface  and  the  extent  of  such  deposits  are  unknown. 
This  salt  is  extensively  used  by  ranchmen,  some  of  whom  come  from 
Fort  Davis,  a  distance  of  over  100  miles.  Considerable  salt  from  the 
"  lake  "  is  also  freighted  to  the  pan  amalgamation  works  at  Shaffer, 
150  miles  distant.  The  salt  is  sold  by  the  load.  A  two-horse  load! 
costs  $1  and  a  six-horse  load  $8.  No  careful  records  are  kept  of  the 
amount  hauled  away,  but  certainly  immense  quantities  have  been 
used,  and  apparently  there  is  as  much  in  sight  as  there  was  forty 
years  ago. 
PETROLEUM. 
The  presence  of  petroleum  in  commercial  quantities  in  parts  ol 
trans-Pecos  Texas — in  Pecos,  Reeves,  and  eastern  El  Paso  counties- 
has  been  suspected  for  several  years."  Indications  are  numerous. 
Bituminous  limestones,  sandstones,  and  shales  that  give  a  strong  odoi 
on  being  struck  with  a  hammer  outcrop  in  many  places.  The  occur- 
rence of  globules  of  oil  in  water  from  various  wells,  of  a  few  oil  seeps 
and  especially  of  small  quantities  of  petroleum  in  oil  prospects,  tends 
"  Phillips,  W.  B.,  Texas  petroleum  :  Bull.  No.  1,  University  of  Texas  Mineral  Survej 
1901. 
Phillips,  W.  B.,  Sulphur,  oil,  and  cjuieksilver  in  trans-Pecos  Texas  :  Bull.  No.  2,  TTni 
versity  of  Texas  Mineral  Survey,  1902. 
Hill,  R.  T.,  the  Beaumont  oil  field  and  notes  on  other  oil  fields  of  the  Texas  region 
Jour.  Franklin  Institute,  vol.  154,  p.  22G,  1902. 
