414         CONTRIBUTIONS   TO   ECONOMIC   GEOLOGY,    1907,   PART   II. 
Trace,  Straight  Creek,  and  Gin  Creek,  and  is  regarded  by  operators 
as  one  of  the  most  valuable  coal  beds  in  the  district.  It  is  mined  at 
Darbyville  and  consequently  is  known  to  some  extent  as  the  Darby 
bed.  It  is  said  to  be  the  stratigraphic  equivalent  of  the  Taggart  coal 
of  the  Big  Stone  Gap  region. 
Bed  6. — About  275  feet  above  bed  5  is  bed  6,  which  at  the  head  of 
Straight  Creek,  at  the  Virginia  Iron,  Coal  and  Coke  Company's  mine, 
has  a  thickness  of  4  feet  4  inches,  with  a  ^-inch  parting  14  inches  above 
the  base.  It  is  overlain  by  shale  and  underlain  by  clay.  This  coal 
was  examined  at  the  head  of  Straight  Creek,  where  it  outcrops  at  an 
elevation  between  1,600  and  1,700  feet. 
Bed  7. — Between  beds  6  and  7  there  is  a  stratigraphic  interval  of 
325  feet.  Coal  bed  7  has  an  average  thickness  of  3^  feet,  and  is  sepa- 
rated near  the  middle  by  a  clay  parting.  It  has  a  shale  roof  and 
floor.  This  coal  outcrops  relatively  high  in  the  slope  of  Little  Black 
Mountain,  and  consequently  has  a  smaller  areal  distribution  than  any 
of  the  beds  described  above.  A  section  of  this  coal  bed,  measured 
in  an  opening  on  the  left  fork  of  Gin  Creek,  is  as  follows: 
Section  of  coal  bed  7  on  left  fork  of  Gin  Creek. 
Ft.  in. 
Shale,  exposed 5 
Coal 2      5 
Clay,  light  gray '. 7 
Coal 1      9 
Shale. 
Total  coal 4      2 
Bed  8. — About  200  feet  above  No.  7  occurs  bed  8,  which  has  a 
thickness  of  4  feet.  This  bed  was  not  examined.  It  occurs  some 
distance  up  the  slopes  of  Little  Black  Mountain,  and  consequently 
has  a  relatively  limited  distribution  in  the  district,  underlying  only 
the  higher  portions  of  the  mountain.  At  a  horizon  halfway  between 
Nos.  7  and  8  there  is  a  coal  bed  which  attains  workable  dimensions 
in  some  places,  but  the  bed  as  a  whole  contains  so  large  a  percentage 
of  shale  that  it  can  not  be  worked. 
Bed  9. — This  bed  occupies  a  position  about  100  feet  above  No.  8. 
It  has  a  thickness  of  nearly  5  feet  and  in  some  localities  it  contains  a 
thin  parting  in  the  lower  half.  It  has  been  opened  at  many  places 
along  the  southern  slope  of  Little  Black  Mountain,  but  is  reported 
not  to  have  been  mined  anywhere  within  the  district.  It  was  exam- 
ined by  the  writer  at  the  heads  of  Baley  Trace  and  Gin  Creek.  The 
sections  of  the  bed  at  these  two  openings,  which  are  about  1J  miles 
apart,  are  very  similar.  The  coal  is  overlain  and  underlain  by  shale. 
A  section  of  the  bed  at  the  opening  on  Baley  Trace  is  given  on  the 
next  page. 
