PHOSPHATE    DEPOSITS    IN    NORTHERN    ARKANSAS.  467 
The  St.  Clair  limestone. — The  St.  Clair  limestone  lies  above  the 
Cason  shale.  In  the  vicinity  of  the  developed  deposits  it  is  from  8 
to  18  feet  thick.  It  is  a  compact  crystalline  limestone,  pinkish  in 
color,  and  is  composed  largely  of  small  fragments  of  crinoids  and  other 
fossils.  The  fossil  fragments  stand  out  on  weathering,  producing 
very  rough  surfaces.  The  St.  Clair  limestone  is  thought  to  be  the 
only  representative  of  the  Silurian  in  the  region. 
The  St.  Joe  marble  and  Boone  chert. — Upon  the  St.  Clair  limestone 
rest  rocks  of  Carboniferous  age,  known  as  the  St.  Joe  marble  and  the 
Boone  chert.  The  former  is  the  older  of  the  two,  and  is  only  locally 
present  in  the  eastern  part  of  the  phosphate  region.  Where  typically 
developed  the  St.  Joe  limestone  occurs  in  layers  from  a  few  inches  to 
2  feet  or  more  in  thickness.  Elsewhere  it  is  usually  a  somewhat  coarse- 
textured  rock,  and  is  gray  at  the  lower  and  upper  parts,  while  the  mid- 
dle portion  is  often  red,  but  the  rocks  that  occupy  the  stratigraphic 
position  of  the  St.  Joe  in  the  locality  under  discussion  are  usually 
gray  to  dove-colored,  compact,  and  contain  large  numbers  of  calcite 
seams.  These  beds  maybe  the  representatives  of  the  St.  Joe  marble, 
and  may  therefore  belong  to  an  older  Carboniferous  formation. 
The  Boone  chert  is  a  heavy  deposit  of  limestone,  contains  a  large 
amount  of  chert,  and  is  of  wide  extent  over  the  southern  part  of  the 
Ozarks.  Where  the  St.  Joe  is  absent  in  the  region  under  discussion 
the  Boone  chert  rests  on  the  St.  Clair  limestone  if  this  is  present;  if 
not  it  rests  on  the  Cason  shale,  the  chert  lying  immediately  over  the 
phosphatic  deposits. 
THE  DEVELOPED   DEPOSITS. 
Location. — The  developed  phosphate  deposits  of  northern  Arkansas 
are  confined  to  sees.  14  and  15,  T.  14  N.,  R.  8  W.,  situated  on  LafTerty 
Creek,  near  the  junction  of  East  LafTerty  and  West  LafTerty  creeks, 
about  4  miles  a  little  south  of  west  of  the  town  of  Cushman,  in  Inde- 
pendence County.  They  are  about  12  miles  northwest  of  Batesville, 
the  county  seat,  and  from  a  half  mile  to  1^  miles  from  White  River 
and  the  White  River  branch  of  the  Missouri  Pacific  Railway. 
History  of  the  operating  company. — The  following  history  was  fur- 
nished by  Mr.  F.  S.  Williams,  secretary  and  manager  of  the  company 
operating  the  mines: 
In  June,  1900,  a  company  was  organized  under  the  name  of  the 
Arkansas  Phosphate  Company,  for  the  purpose  of  developing  the 
phosphate  beds  along  LafTerty  Creek,  Independence  County,  Ark. 
After  several  months  of  prospect  work  it  was  found  that  the  phos- 
phates exist  in  sufficient  quantities  to  justify  extensive  mining  opera- 
tions. A  mining  and  milling  plant  was  erected,  several  miles  of  rail- 
way spur  were  laid,  and  mining  was  begun.  After  only  a  few  months 
of  active  operation  the  plant  was  destroyed  by  fire,  which  stopped 
