366 
CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1905. 
The  figures  representing  the  interval  of  the  Gordon  sand  below  the  coal  are  .somewhat 
more  variable  in  their  extremes  than  these.     They  run  in  general  as  follows: 
Intervals  from  Pittsburg  coal  to  Gordon  sand  in  western  Greene  County  {in  feet). 
Township. 
Morris 
RichhilL. 
Center 
Jackson . . 
Aleppo . . . 
Wayne... 
Gilmore.. 
Springhill 
Least 
interval. 
2,100 
2,094 
2,083 
2, 070 
2,110 
2, 133 
2, 177 
2,130 
General  average. 
( ireatest 
inter's  al. 
2,141 
2,155 
2,170 
2,175 
2,183 
2,287 
2,189 
2,205 
Average 
interval. 
Number 
of  7-ecords 
a  sera  god. 
2,133 
2, 136 
2,127 
2,111 
2,157 
2,213 
2,181 
2,  L66 
2, 153 
From  a  comparison  of  the  figures  iu  the  foregoing  tables  it  will  be  seen  that,  while  the 
('.onion  sand  in  its  averages  for  the  various  townships  in  this  part  of  the  county  varies 
between  2,111  and  2,213  feet,  amounting  to  a  difference  of  102  feet,  the  Nineveh  sand,  on 
the  other  hand,  differs  in  its  averages  by  only  ">.'->  feet.  It  will  be  noticed  thai  none  of  the 
averages  given  in  the  table  for  the  Gordon  sand  approach  within  20  Feet  of  the  highest 
figures  given  in  the  Nineveh  table,  and  the  general  averages  of  each  table  differ  by  over  100 
feet.  The  overlapping  of  several  of  the  figures  in  the  maxima  and  minima  columns  is  due 
to  local  variations  or  to  inaccuracies  in  the  drillers'  measurements. 
From  the  foregoing  discussion  it  can  be  seen  thai  there  is  little  danger  of  confusing  these 
two  sands  when  proper  care  is  taken  in  making  interpretations. 
