CLAYS    AND    SHALES    IN    CAMBRIA    COUNTY,   PA.  353 
The  percentage  of  fluxing  materials,  principally  iron  oxide,  indicated 
n  this  analysis,  is  so  high  as  to  prohibit  its  practical  use.  A  lower  flint 
play,  lying  a  few  feet  below  what  may  prove  to  be  the  Upper  Freeport 
boal,  was  seen  at  a  few  places  in  the  valley  of  Mardis  Run,  near  the 
northwestern  edge  of  the  area.  This  clay  may  correspond  with  the 
Bolivar  clay  of  the  region  to  the  southwest.  Two  feet  of  clay  were  seen 
at  one  point  on  the  outcrop  and  the  bed  may  possibly  be  thicker.  This 
play  is  rather  remote  from  transportation. 
Plastic  clay. — The  coal  that  is  being  extensively  worked  in  the 
galley  of  Blacklick  Creek  is  regarded  as  the  equivalent  of  the  Lower 
jKittanning,  Miller,  or  "B"  seam  of  the  Johnstown  and  South  Fork 
districts.  In  the  Blacklick  Creek  district,  as  well  as  along  Cone- 
maugh  River,  this  coal  is  underlain  by  a  promising  clay  bed.  This 
play  is  not  exploited  at  present,  and  no  certain  measurement  of  its 
thickness  was  obtained.  At  many  of  the  mines  2  feet  or  more  of  prom- 
ising clay  were  seen,  comparable,  in  appearance  at  least,  with  tha£  in 
jthe  Johnstown  district. 
MISCELLANEOUS    OCCURRENCES    OF   CLAY. 
Along  the  western  flank  of  Laurel  Ridge,  near  the  line  of  the  Penn- 
sylvania Railroad,  the  Miller  coal  seam  has  been  opened  at  a  few 
places  and  the  clay  underlying  it  shows  in  workable  thickness.  At 
the  coal  mine  of  the  Johnstown  Coal  Company  more  than  2  feet  of 
clay  were  seen,  and  near  Seward,  beyond  the  western  limits  of  this 
area,  12  feet  of  clay  occur  in  this  same  position,  6  of  which  are  worked 
by  the  Seward  Brick  Company. a 
Along  the  southern  edge  of  this  area,  at  Scalp  Level  and  Windber, 
where  the  Miller  coal  seam  is  worked  on  a  large  scale  by  the  Berwind- 
White  Coal  Mining  Company,  sandy  clay  was  observed  below  the 
Miller  coal  seam  at  Eureka  mine  No.  37. 
PRODUCTION. 
The  firms  named  below  are  engaged  in  the  brick  and  clay  industry 
in  this  area.  In  addition,  coal  companies  mining  the  Miller  coal  seam 
about  Johnstown  and  South  Fork  may  produce  small  quantities  of  the 
underlying  clay  for  use  in  the  local  brick  plants. 
Clay  miners. 
Page-Reigard  Mining  Company,  flint  clay,  Mineral  Point. 
W.  J.  Williams,  plastic  clay,  Kernville. 
Citizens'  Coal  Company,  plastic  clay,  Green  Hill  mine,  Johnstown. 
Robertson  &  Griffith,  plastic  clay,  St.  Clairs  Run,  Morrellville. 
a  For  an  analysis  of  the  clay  underlying  the  coal  mined  at  Seward,  see  p.  348. 
