NINEVEH    AND    GORDON    OIL    SANDS,    PENNSYLVANIA.        365 
Evidence  from  position  o/CatsJcill  red  beds. — The  accuracy  of  the  tracing  is  facilitated  by 
several  red  shales  and  other  beds  associated  with  the  sands.  The  mosl  important  of  these 
is  a  thin  red  bed  which  generally  lies  directly  below  the  Nineveh  sand.  Sometimes,  as  in 
the  Fonner  well,  the  Nineveh  sand  itself  is  red.  This  horizon  is  not  always  red,  but  the 
color  occurs  so  frequently  that  when  carefully  correlated  there  is  little  danger  of  making 
a  permanent  mistake  in  identifying  the  Nineveh  sand  over  any  considerable  area.  This 
horizon  is  regarded  as  the  top  of  a  series  of  red  beds  recognized  beneath  large  areas  in  western 
Pennsylvania,  and  known  to  geologists  as  the  Catskill  beds,  which  attain  a  maximum 
thickness  of  200  to  300  feet  in  eastern  Greene  and  Washington  counties,  but  die  out  toward 
the  west,  so  that  in  western  Greene  County  the  horizon  is  marked  only  by  the  bed  of  red 
shale  mentioned  above  and  occasionally  by  one  or  two  other  thin  red  beds.  The  western 
limit  of  the  Catskill  beds,  therefore,  can  be  said  to  correspond  approximately  with  the 
western  boundary  of  the  State  of  Pennsylvania. 
Evidence  from  position  of  Bedford  (?)  red  shale. — A  second  horizon  of  red  shale — not  one 
of  the  Catskill  beds,  but  one  which  assists  in  correlations — is  a  bed  which  lies  between  the 
Thirty-foot  and  Gantz  (or  Fifty-foot)  sands  and  which  occurs  rather  extensively  in  western 
Greene  and  Washington  counties  and  to  the  northwest.  Toward  the  east  it  dies  out. 
This  fact  was  recognized  by  John  F.  Carll  in  the  Seventh  Report  on  the  Oil  and  Gas  Fields 
of  Pennsylvania, «  and  he  published  a  map  showing  the  distribution  of  this  bed  and  tracing 
it  beneath  the  counties  of  Forest,  southern  Venango,  and  western  Butler  in  Pennsylvania, 
and  in  eastern  Ohio  as  far  west  as  its  outcrop  along  the  Cincinnati  anticline.  By  Carll 
the  bed  was  provisionally  correlated  with  one  of  the  Bedford  shales  of  Ohio.  Since  Carll's 
report  was  issued  considerable  drilling  has  been  done  in  Washington  and  Greene  counties, 
and  the  red  shale  is  here  found  to  be  present  considerably  outside  his  southeastern  boundary 
for  it.  In  western  Greene  County  this  bed  occurs  from  30  to  80  feet  above  the  top  of  the 
Fifty-foot  sand  and  helps  in  the  identification  of  this  sand. 
Evidence  from  the  persistency  of  the  Nineveh  sand. — In  Washington  and  Greene  counties 
several  sandstone  horizons  occur  within  the  limits  of  the  rocks  designated  as  Catskill. 
These  are  generally  not  persistent  over  wide  areas,  owing  to  the  fact  that  by  nature  they 
are  lentils  in  the  Catskill  formation,  dying  out  toward  the  east.  The  Gordon  Stray,  Gordon, 
and  Fourth  sands  are  such  beds,  and  do  not  seem  to  be  persistent.  The  next  lower  bed, 
or  Fifth  sand,  and  the  next  higher  sand,  the  Nineveh,  are  much  more  regular,  and  can  be 
traced  for  great  distances. 
Evidence  from  intervals. — As  explained  above,  the  interval  of  the  Nineveh  sand  from  the 
Pittsburg  coal  runs  from  1,997  to  2,121  feet,  and  the  distances  of  the  Gordon  sand  from 
the  coal  vary  between  2,023  feet  and  2,287  feet.  The  figures  for.  the  Nineveh  sand  and 
their  averages  are  given  by  townships  in  the  following  table: 
Intervals  from  Pittsburg  coal  to  Nineveh  sand  in  western  Greene  County  (in  feet). 
Township. 
Least 
interval. 
Greatest 
interval. 
Average 
interval. 
Number 
of  records 
averaged. 
Morris.                                                                    
2,028 
1,997 
2,005 
2, 024 
2,018 
2,033 
2, 065 
2,033 
2,110 
2,054 
2,120 
2,065 
2,098 
2,045 
2,113 
2,121 
2, 055 
2,036 
2,039 
2,044 
2,056 
2,039 
2, 089 
2,052 
6 
Richhill 
32 
Center 
8 
Jackson 
66 
Aleppo 
101 
Wayne 
2 
Gilmore.   .                                                    
2 
Springhi  11..                                                    
94 
2,051 
a  Second  Geol.  Survey  Pennsylvania,  Rept.  I,  1890,  pp.  95-96,  PI.  V. 
Bull.  285—06 24 
