346  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1906,  PART    I. 
JOHNSTOWN    DISTRICT. 
Flint  clay. — So  far  as  known  flint  clay  occurs  persistently  at  only 
one  horizon  in  the  Johnstown  district.  This  horizon  lies  very  close 
to  the  top  of  the  Mahoning  sandstone,  and  in  the  immediate  vicinity 
of  the  city  is  50  to  80  feet  above  the  horizon  of  the  Coke  Yard  coal. 
Though  fairly  well  distributed  in  favorable  localities  for  easy  exploit- 
ation, this  clay  is,  so  far  as  known,  worked  only  by  the  Johns- 
town Pressed  Brick  Company  at  their  plant  on  a  hill  east  of  the 
city.  A  section  of  the  rocks  in  the  hill  will  show  the  position  of  this 
clay  and  its  relation  to  the  underlying  coal,  which  is  at  the  top  of  the 
Allegheny  formation. 
Section  <>/l<>ir,r  pari  <>/ tin  Conemaugh formation  hi  hill  east  of  ,/<>h>istown. 
Ft.      in. 
Concealed,  and  sandstone  from  top  of  hill 91  0 
Shales ]0  0 
Black  shales 5  0 
Brick-red  Bhales -10  0 
Concealed,  but  probably  shales 25  0 
Dull-olive  shales,  weathering  reddish a 25  0 
Olive  to  red  shales 5  0 
Dark  olive-green  shales,  slightly  gritty,  with  iron  oxide  and 
manganese  oxide  on  tli"  bedding  planes0 13-15  0 
Lamina i»d  sandstone 15  0 
Shales 30  0 
Concealed,  bul  with  a  sandstone  in  its  upper  pari 42  0 
Flint  clay" 
Shales... 8  0 
Ferruginous  -hales ]0  0 
Green  concretionary  shales L0  0 
[rregularly  bedded  shales 5  0 
Sandy  shales 8  0 
Massive  Bandstone  (Mahoning) 25  0 
Concealed 12  0 
ill„          ..                   j  3  6 
.,       >Upper  Freeporl  or  Coke  Yard  coal. 
•  > 
In  Dale  Borough,  east  of  Johnstown,  on  the  road  ascending  Shingle 
Run,  2  feet  of  Hint  clay  were  noted  at  this  horizon.  An  old  prospect 
hole  was  seen  on  this  flint  clay  on  the  county  road  leading  to  Grand- 
view  Cemetery.  On  the  road  to  Ferndale,  a  short  distance  north  of 
the  Citizens'  Coal  Company's  Eighth  Ward  mine,  an  abundance  of 
flinty  clay  debris  occurs  above  the  road  near  the  top  of  the  massive 
Mahoning  sandstone.  In  the  hill  above  the  Baltimore  and  Ohio  tun- 
nel, east  of  Island  Park,  some  flint  clay  was  observed  on  the  new 
county  road  about  40  feet  above  the  Upper  Freeport  coal  and  near 
a  Beds  worked  for  brick  material. 
