stone]  OIL    AND    GAS    FIELDS    OF    GREENE    COUNTY,   PA.  405 
mean  sea  level  is  easily  determined.  It  is  believed  that  the  position 
of  the  Pittsburg  eoal  on  the  west  flank  of  the  anticline  down  to  the  400- 
foot  contour  line  will  vary  scarcety  more  than  10  feet  from  the  posi- 
tion indicated  on  the  sketch  map  (fig.  11). 
The  eastern  slope  of  the  Bellevernon  anticline  is  short  and  gentle 
in  the  region  of  the  greatest  development  of  the  Waynesburg  gas 
field.  From  the  crest  of  the  fold  near  the  mouth  of  Bradens  Run  on 
Tenmile  Creek  to  the  bottom  of  the  Whiteley  syncline  on  Muddy  Creek 
the  fall  is  scarcely  more  than  200  feet.  From  the  crest  at  the  same 
point  to  the  axis  of  the  Waynesburg  syncline  on  the  west  the  reference 
stratum  descends  fully  400  feet.  The  regularity  of  the  western  flank 
of  the  Bellevernon  anticline  is  shown  by  the  contour  lines  on  the 
sketch  map.  This  axis  is  commonly  known  in  Greene  County  as  the 
Waynesburg  anticline. 
Waynesburg  syncline. — The  structural  basin  which  lies  west  of  the 
Bellevernon  anticline  is  the  Waynesburg  syncline.  This  term  was 
used  by  Professor  Stevenson  in  1876,  but  he  described  the  axis  as  lying 
much  nearer  the  village  of  Waynesburg.  The  axis  crosses  the  Wash- 
ington-Greene county  line  about  a  mile  west  of  Castile,  crosses  Ruff 
Creek  near  the  mouth  of  Boyd  Run,  and  Browns  Fork  at  Rees  Mill  2 
miles  west  of  Wa3Tnesburg.  The  basin  deepens  gradually  to  the  south, 
and  it  is  possible  that  the  Pittsburg  coal  is  less  than  300  feet  above 
tide  where  it  crosses  Tenmile  Creek,  although  the  contour  line  was 
not  drawn. 
Amity  anticline. — The  structural  feature  which  shows  for  a  short 
distance  across  the  northwest  corner  of  the  sketch  map  is  a  low  anti- 
clinal fold  which  has  been  traced  northward  in  Washington  County  to 
the  village  of  Amity,  and  is  named  from  that  place.  The  crest  of  this 
fold  is  probably  not  more  than  100  feet  above  the  axis  of  the  Waynes- 
burg syncline,  where  it  enters  the  county  from  the  north,  but  it  rises 
in  Washington  County  and  becomes  a  more  pronounced  structural 
feature.  Stevenson  and  White  called  it  the  Pin-hook  anticline,  from 
a  locality  in  Amwell  Township,  Washington  County.  The  name  is 
taken  from  a  burlesque  appellation  of  a  little  village  known  as  Pleasant 
Valley  or  Lone  Pine,  and  is  not  suitable  for  geologic  nomenclature. 
ORIGIN   OF  OIL  AND   GAS. 
There  is  no  place  in  this  paper  for  a  discussion  of  the  theories  which 
have  been  advanced  to  explain  the  origin  of  petroleum.  It  is  sufficient 
to  state  briefly  that  all  of  the  theories  can  be  grouped  in  three  classes: 
(a)  Those  which  ascribe  the  origin  of  oil  to  inorganic  agencies,  (b) 
those  which  advocate  organic  origin,  and  (c)  those  which  argue  for  a 
combination  of  organic  and  inorganic  agencies. 
It  is  generally  conceded  that  petroleum  of  the  Penns}dvania  type  is 
