ashley.]  CUMBERLAND    (JAP    COAL    FIELD,    KY.-TENN.  273 
Section  of  Harlan  coal  on  Crummies  Creek. 
Ft.  In. 
Coal 0  6 
Clay 0  4 
Coal 3  3 
Total 4       1 
Section  of  Harlan  coal  in  Little  Black  Mountain. 
Shale  roof.                                                                                                     Ft.  In. 
Coal 4  0 
Clay  0  7 
Coal 1  0 
Total 5      7 
Section  of  Ha  da  1 1  coal  in  Big  Black  Mountain. 
Sandstone  roof.  Ft.    In. 
Coal 4      0 
On  account  of  the  narrowness  of  the  valleys  and  its  nearness  to 
drainage,  this  coal  will  probably  be  found  to  underlie  considerably 
more  than  half  the  total  area  of  this  part  of  the  basin,  not  including 
Pine  and  Cumberland  mountains.  It  characteristically  lies  between 
two  fairly  massive  sandstones  and  about  250  feet  above  the  sandstone 
that  makes  almost  continuous  cliffs  along  Clover  Fork  and  Martins 
Fork,  so  that  its  recognition  is  not  usually  difficult,  and  its  correlation 
in  the  various  parts  of  the  eastern  field  is  probably  correct. 
Durham  coal.—  Between  the  Harlan  coal  and  the  top  of  the  Lee 
conglomerate  is  an  interval  of  about  500  feet.  The  most  conspicuous 
member  of  this  interval  is  the  sandstone  last  mentioned,  which  it  was 
believed  was  traced  continuously  through  the  area  drained  by  the 
three  forks  of  Cumberland  River.  Considerable  effort  was  given 
to  tracing  it  westward  to  Yellow  Creek,  but  as  in  that  direction  it  is 
no.  more  conspicuous  than  several  other  sandstones  close  above  or 
below  it,  it  is  uncertain  whether  the  final  correlations  are  correct. 
Though  the  coals  between  the  Harlan  coal  and  the  Lee  formation  in 
places  are  of  workable  thickness,  on  the  whole  they  do  not  promise 
large  areas,  for  many  of  these  horizons  at  most  points  showed  coals 
less  than  3  feet  thick.  A  short  distance  above  the  sandstone  so 
prominent  on  Clover  Fork  occurs  a  coal  which  is  slightly  over  3  feet 
thick  at  several  points,  and  future  exploration  may  show  small  areas 
over  which  it  will  prove  workable;  especially  may  this  prove  true  in 
the  western  part  of  this  area,  near  Yellow  Creek.  Two  sections  will 
show  its  thickness  near  Yellow  Creek. 
Bull.  225—04 18 
