stone.]  OIL    AND    GAS    FIELDS    OF    GREENE    COUNTY,   PA.  399 
Average  depth  of  top  of  sands  below  Pittsburg  coal. 
Sand. 
Number 
of 
wells. 
Depth. 
Feet. 
20 
765 
32 
932 
86 
1,228 
19 
1,795 
43 
1,916 
53 
1,  937 
58 
2,147 
43 
2,230 
63 
2,313 
62 
2,433 
Gas  sand 
Salt  sand 
Big  Injun  sand 
30-foot  sand . . . 
Gantz  sand  . . . 
50-foot  sand . . . 
Gordon  sand  . . 
4th  sand 
5th  sand 
Bayard  sand  . . 
It  should  be  understood  that  these  figures  are  averages,  and  may  not 
be  duplicated  by  exact  measurements  in  any  well.  They  should  be 
found  to  be  most  nearly  like  actual  conditions  along  the  Bellevernon 
anticline. 
GENERAL    SECTION    BELOW    PITTSBURG    COAL. 
Many  of  the  logs  of  wells  drilled  in  Greene  County  give  no  details 
of  stratigraphy  in  the  first  few  hundred  feet  below  the  Pittsburg  coal. 
It  is  known,  however,  from  an  occasional  well  and  from  the  general 
section  in  those  parts  of  the  State  where  these  rocks  are  exposed  at  the 
surface,  that  a  limestone  should  be  found  within  50  feet  of  the  coal, 
and  that  this  is  underlain  by  a  massive  sandstone  which  is  sometimes 
50  feet  thick.  Another  heavy  sandstone  is  met  with  at  a  distance  of 
from  150  to  300  feet,  and  is  often  underlain  by  a  considerable  thickness 
of  red  shales.  Whether  this  belt  of  red  shales  is  continuous  through- 
out the  county  can  not  be  asserted  as  a  fact,  because  the  logs  are  often 
incomplete  at  this  point.  Beginning  at  a  depth  of  425  feet  below  the 
Pittsburg  coal,  there  is  an  interval  of  over  150  feet  which  may  often  be 
largely  occupied  by  a  massive  sandstone.  This  is  the  sandstone  which 
produced  oil  in  the  Dunkard  Creek  field  in  1860,  and  is  generally 
known  as  the  Dunkard  sand. 
A  trace  of  the  Upper  Freeport  coal,  if  it  is  present  beneath  this 
county,  as  noted  in  a  very  few  wells,  should  be  found  about  600  feet 
below  the  Pittsburg  coal.  Succeeding  this,  and  in  an  interval  of  250 
feet,  there  may  be  traces  of  two  or  three  other  coal  seams. 
Gas  sand. — The  first  sand  rock,  which  is  commonly  recognized  by 
the  drillers  and  watched  for  in  order  to  determine  the  horizon,  is  what 
is  commonly  known  as  the  Gas  sand.  The  position  of  this  sand  varies 
considerably  according  to  the  different  drillers,  and  it  seems  probable 
