320  CONTRIBUTIONS    TO   ECONOMIC    GEOLOGY,  190(3,  PART    I. 
white  clay   is  now   mined  by  the  American    Phosphorus  Company. 
The  data  obtainable  indicate  that  the  beds  on  the  north  face  of  the 
mountain  are  not  thick  enough  to  be  mined  profitably  on  a  large  scal< 
The  most  extensive  and  valuable  clay  deposits  occur  in  the  vallej 
of  Mountain  Creek.     This  valley  is  a  syncline  inclosing  Shenandoal 
limestone,  nearly  all  of  which  has  been  removed  by  erosion,  or  is  a 
deeply    weathered    that    its   outcrops   are   concealed.     It    has   bed 
observed  at  only  a  few  places  in  the  valley.     The  clay  occurs  along  tin 
margins  of  the  limestone  trough  next  to  the  quartzite  of  the  mountain. 
The  same  clay  belt   extends  over  the  divide  into  the  small  vallej 
draining  eastward,  where  a  mine  is  in  operation-.     Elsewhere  alone 
the  slopes  of  the  mountain,  farther  east ,  t  here  are  scattered  prospects, 
bu1  only  those  associated  with  the  abandoned  iron  pits  south  of  Boifl 
ing  Springs  were  visited  by  the  writer. 
CLAY   MINES   IN    OPERATION. 
The  operating  clay  mines  are  all  located  in  the  valley  of  Mountain 
Creek  and  its  extension  over  the  low  divide  to  the  east.  As  stated 
above,  numerous  undeveloped  prospects  and  abandoned  cla\  pits 
occur  along  the  mountain  front  in  the  vicinity  of  Mounl  Holly  Springs] 
and  a  small  amount  of  (day  is  mined  at  the  sand  pits  in  the  town. 
Cumberland  Clay  Company.-  The  eastern  end  of  Mountain  Creek 
valley  easl  of  Upper  Mill  has  been  extensively  prospected  by  the  Cum- 
berland (day  Company,  J.  L.  Musser,  manager,  which  has  opened  a 
mine  on  the  north  side  of  the  valley.  A  test  shaft  L50  I'^'t  deep  was 
Mink  in  a  prospect  near  the  sandstone  outcrop,  all  hut  23  feet  of  which 
was  reported  to  he  in  white  (day.  About  70  feet  below  this  opening 
a  tunnel  run-  northward  into  the  mountain.  This  had  been  driven 
in  about  225  feet  at  the  time  of  the  writer's  visit,  hut  according  to 
reports  is  now  in  about  350  feet,  and  at  its  end  a  branch  drift  has  been 
run  about  17")  feet  eastward  in  the  clay.  Some  of  the  (day,  possibly 
a  considerable  portion,  is  white  and  of  good  grade".  The  shaft  above 
will  soon  he  connected  with  this  tunnel  as  an  air  shaft  and  means  of 
escape.  It  is  reported  that  the  sandstone  wall  in  the  west  branch  of 
the  tunnel  was  pierced  and  found  to  be  but  2§  feet  thick,  and  that 
gray  and  white  (day  again  occur  hack  of  it.  The  sandstone  is  probably 
a  thin  bed  in  the  slate  overlying  the  main  sandstone. 
The  main  working  tunnel,  which  is  fitted  with  a  gravity  tram- 
road,  is  156  feet  lower.  This  was  650  feet  long  when  visited,  but  is 
now  reported  to  be  864  feet  long  and  to  terminate  in  the  white  clay. 
About  800  tons  of  crude  (day  have  been  mined  and  shipped  recently 
from  this  property  and  about  500  tons  more  are  ready  for  shipment. 
Some  of  the  clay  is  hard  and  compact  and  shows  slaty  cleavage,  but 
is  nevertheless  of  high  grade. 
The  gravity  tram  conveys  the  clay  to  the  plant,  which  was  in  pro- 
cess of  construction   when  visited.     The  building,  six  large  cement 
