ashley.]  CUMBERLAND    GAP    COAL    FIELD,    KY.-TENN"  267 
extent  and  workability  of  many  of  the  coals  is  very  imperfect.  Of 
the  coals  found,  two  only  have  been  so  widely  exploited  as  to  show 
beyond  doubt  more  or  less  continuous  workability,  the  Neal  and  Harlan 
coals,  described  below.  Several  coal  horizons  were  widely  recognized 
which,  though  showing  workable  coal  in  places,  on  the  whole  were  not 
promising,  while  at  still  other  horizons  coals  of  good  workable  thick- 
ness were  found  in  a  few  localities,  but  extensive  facing  will  be  neces- 
sary to  show  whether  or  not  they  will  prove  workable  over  wide  areas. 
The  Neal  and  Harlan  coals  mark  two  rather  distinct  horizons  that 
divide  the  stratigraphic  column  into  three  divisions. 
Above  the  Neal  coal  are  about  900  feet  of  strata  to  the  tops  of  the 
mountains.  The  physiographic  conditions  almost  entirely  prevent 
natural  outcrops  of  the  coals,  so  that  while  coal  blooms  were  found 
suggesting  thick  coals,  almost  nothing  is  known  of  their  thickness  or 
workability.  Their  extent  in  all  cases  would  be  small.  Several  coals 
have  been  exposed  within  the  lowest  200  feet  of  the  uppermost  series 
of  rocks,  of  which  one  coal  reaches  a  thickness  of  from  3  to  nearly  4 
feet. 
About  320  feet  above  the  Neal  coal  is  the  top  of  a  sandstone  which 
in  a  wide  range  of  localities  yields  small  quartz  pebbles,  being  often  a 
coarse  grit.  As  such  pebbles  are  found  only  in  what  appears  to  be  a 
single  sandstone  within  a  vertical  range  of  50  to  60  feet,  that  sandstone 
becomes  a  valuable  rock  for  the  identification  of  the  coals.  About  100 
feet  below  its  top  and  at  180  feet  above  its  top  occur  two  cliff-making 
sandstones,  of  which  the  upper  especially  is  a  prominent  object  around 
many  of  the  mountain  summits.  It  makes  the  Hanging  Rock  at  the 
head  of  Saviors  Creek.  About  160  feet  beneath  the  Neal  coal  is  another 
sandstone  which  makes  prominent  cliffs  over  most  of  the  area.  These 
four  sandstones  and  the  Neal  coal,  which  is  the  thickest  coal  in  this 
field,  having  fairly  constant  intervals  between  them,  can  generally  be 
recognized  through  the  eastern  part  of  the  field  and  serve  to  show  the 
structure  of  the  upper  part  of  the  measures. 
Neal  coal. — This  coal,  to  which  frequent  reference  has  already  been 
made,  has  a  thickness  of  from  5  to  13  feet,  commonly  yielding  7  feet 
of  minable  coal.  Owing  to  its  elevation  in  the  mountains,  it  offers 
rather  limited  areas.  It  occurs  about  2,500  feet  above  sea  level.  On 
account  of  its  thickness  and  stratigraphic  value,  several  outcrops  of  the 
coal  were  faced  by  members  of  the  Survey.     Several  sections  follow: 
Section  of  Neal  coal  in  ridge  at  head  of  Forrester  Creek. 
Roof  shale.  Ft  In. 
Coal 5     10 
Coal,  bony 0      3 
Coal - 1       0 
Clay 0      7 
Coal 0      8 
Total 8      4 
