470  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,   1903.  [bull. 225. 
with  its  mouth  near  a  railroad,  and  offers  exceptional  facilities  for 
the  manufacture  of  clay  products.  Moreover,  mining  here  could  be 
carried  on  by  drifts  instead  of  shafts. 
As  to  mining  facilities,  Blockhouse  Run  ranks  with  Brady s  Run, 
but  Lower  Kittanning  clay  is  exposed  for  only  a  mile  east  of  New 
Brighton.  Nevertheless  Blockhouse  Run  has  been  the  site  of  clay- 
mining  operations  ever  since  the  infancy  of  the  industry. 
On  Raccoon  Creek  the  Lower  Kittanning  clay  bed  dips  under  the 
stream  just  beyond  the  mouth  of  Fishpot  Run,  about  2J  miles  from 
Ohio  River.  At  several  points,  however,  in  this  distance  the  clay  is 
covered  by  stream  gravels,  which  would  have  to  be  removed  in  min- 
ing. This  same  clay  bed  is  further  exposed  on  Mill  Run  and  Little 
Mill  Run,  near  Georgetown,  for  about  a  mile  from  the  river.  But 
here,  as  on  Raccoon  Creek,  transportation  facilities  are  lacking.  On 
the  opposite  side  of  the  river  the  Lower  Kittanning  clay  bed  extends 
several  miles  up  Little  Beaver  River  and  its  tributaries,  which  for  the 
most  part  lie  in  Ohio,  but  some  of  the  eastern  branches  head  in  Beaver 
County,  as  Island  Run  and  Little  Beaver  Creek.  So  far  as  known 
this  clay  has  not  been  mined  on  these  streams,  but  at  Darlington  it 
has  been  reported  as  10  feet  thick. a 
This  clay  bed  varies  in  thickness  from  5  to  11  feet,  the  lower  half 
being  usually  more  siliceous  than  the  upper  half.  Different  thick- 
nesses are  therefore  mined,  according  to  the  purpose  for  which  it  is  to 
be  used,  a  greater  thickness  being  removed  for  paving  brick  and  other 
crude  products  than  for  pottery. 
Thickness  of  Lower  Kittanning  clay  at  various  points. 
Feet. 
Spear  Clay  Company,  Vanport 11 
Van  port  Brick  Company,  Vanport 9  to  1 1 
Miller  Brick  Works,  Rochester 10 
American  Sewer  Pipe  Company,  New  Brighton 9 
Ingram  Fire  Brick  Company,  New  Brighton 10 
S.  Barnes  &  Co. ,  Rochester 7\  to    8 
Pennsylvania  Clay  Company,  Crow  Run 5 
Welch  Fire  Brick  Company,  Monaca 10 
Sherwood  Pottery,  New  Brighton 6 
Standard  Brick  Company,  Bradys  Run 8£ 
E.  Smith's  Brick  Works,  New  Brighton 5|  to    9 
Fallston  Fire  Brick  Company,  Fallston 10 
Enterprise  Pottery,  New  Brighton 7 
Park  Fire  Brick  Company,  Mahan« 10  to  12 
Dando  &  McLain,  Merrill  & 10 
"Second  Penn.  Geol.  Surv.,  Report  Q,p.  232. 
bProf.  Paper  U.  S.  Geol.  Survey  No.  11,  p.  225. 
