WHITE   CLAYS    OF    SOUTH    MOUNTAIN,  PENNSYLVANIA.  327 
settling  tanks,  and  two  water  tanks  were  already  constructed.  It  is 
planned  to  handle  the  clay  from  washers  through  flotation  troughs 
into  the  settling  tanks  by  gravity.  The  capacity  is  to  be  100  tons 
a  day.  The  refined  clay  will  have  to  be  hauled  by  wagon  nearly 
one-half  mile  to  the  railroad  siding. 
Hopkins  reports  that  clay  was  mined  at  the  old  Medlar  ore  bank, 
just  south  of  upper  mill,  by  the  Mount  Holly  Brick  and  Clay  Com- 
pany during  1898  and  1899,  but  that  work  there  was  abandoned 
probably  because  the  supply  was  exhausted. 
Fig.  12. — Map  of  South  Mountain  in  the  vicinity  of  Mount  Holly  Springs,  showing  the  clay  mines  and 
the  rock  formations.  VR,  pre-Carnbrian  volcanic  rocks:  SS,  Cambrian  sandstone  and  shale;  LS, 
Cambrian  limestone. 
Philadelphia  Clay  Company. — The  main  body  of  clay  thus  far  dis- 
covered in  the  region  occurs  along  the  north  side  of  Mountain  Creek 
from  the  gap  westward  to  Henry  Clay.  The  Philadelphia  Clay  Com- 
pany, located  at  the  old  Crane  ore  bank,  is  the  most  important  mine 
in  the  area,  and  its  property  extends  from  the  Mount  Holly  Paper 
Company's  land  at  the  gap  to  the  York  Clay  mine,  11  miles  west. 
Mr.  S.  R.  Still,  the  manager,  courteously  showed  the  writer  the  mine 
and  works  and  gave  all  information  desired. 
The  clay  was  originally  prospected  along  outcrops  in  the  old  mine 
pits  on  the  upper  slopes  and  by  a  tunnel  100  feet  above  the  present 
opening.     The  mill  is  located  about  60  feet  above  the  creek  and  is 
