DABTON.]  COAL    OF    BLACK    HILLS,    WYOMING.  431 
A  eoal  bed  averaging  6  feet  in  thickness  contains  about  3,000,000 
tons  of  coal  per  square  mile,  but  there  is  considerable  loss  in  working. 
There  are  now  in  the  Cambria  coal  field  about  10  square  miles  under- 
lain by  coal  that  would  average  5  feel  or  more  in  thickness,  so  situ- 
ated that  it  is  available  for  working.  It  is  estimated  that  this  area 
would  yield  a  total  of  30,000,000  tons. 
Aladdin. — The  deposits  of  coal  in  the  lower  portion  of  the  Lakota 
formation  are  developed  to  a  considerable  extent  at  Aladdin,  on  the 
north  slope  of  the  Black  Hills  uplift.  A  branch  railroad  extends 
from  the  mines  down  Hay  Creek  to  connect  with  the  Northwestern 
system  near  Belle  Fourche.  The  shipments  in  1902  amounted  to  about 
10,000  long  tons,  and  the  product  i^  a  good  soft  bituminous  coal,  suit- 
able for  locomotives  and  domestic  use.  The  principal  basin  lies 
to  the  north  of  I  lay  Creek.  It  contains  coal  beds  of  considerable 
thickness,  but  these  become  thinner  and  merge  into  more  impure  beds 
laterally.  Two  principal  beds  are  worked,  an  upper  one  3  to  5  feet 
thick  and  a  lower  one  -1  feet  thick,  separated  by  about  10  to  1^  feet  of 
sandy  shale.  The  deposits  are  broken  by  a  number  of  small  faults, 
which  add  greatly  to  the  difficulties  of  mining. 
The  mines  comprise  four  openings  in  the  lower  slope  of  the  ridge 
on  the  north  side  of  the  Hay  Creek  Valley  at  Aladdin.  They  begin 
at  the  coal  outcrop  under  a  steep  cliff  of  Lakota  sandstone,  and  two  of 
them  extend  nearly  a  quarter  of  a  mile  north  along  the  coal  beds, 
which  dip  vwy  gently  to  the  northeast.  One  small  opening  is  on  the 
lower  coal  bed,  which  is  about  *2\  feet  thick,  and  the  others  are  on  the 
upper  bed,  which  averages  about  4J  feet  thick  in  the  mines.  The  coal 
basin  appears  to  extend  over  an  area  of  considerable  size  about  Hay 
Creek,  and  numerous  prospect  holes  show  beds  of  pure  coal,  which  in 
most  portions  of  the  area  are  a  foot  or  less  in  thickness.  It  is  pos- 
sible that  other  basins  may  be  found  in  the  region,  for  the  coal 
horizon,  which  is  at  the  base  of  the  Lakota  sandstone,  is  above  ground 
all  along  both  sides  of  the  Bearlodge  Mountains  north  of  the  head  of 
Redwater  Creek,  in  the  basin  of  Pine,  Oak,  Deep.  Hay.  and  North 
Redwater  creeks,  and  the  slopes  on  the  south  side  of  Medicine  Creek; 
little  prospecting,  however,  has  been  done  outside  the  valley  of  Hay 
Creek.  The  coal  horizon  is  usually  hidden  by  talus  from  the  sand- 
stone cliffs  above,  and  when  coal  is  present  in  the  lower  Lakota  beds  it 
often  crumbles  or  burns  away  at  the  outcrop,  and  the  overlying  sand- 
stone sinks  down  into  its  place  for  some  distance.  At  a  number  of 
localities  in  the  outcrop  area  of  basal  Lakota  beds,  as  above  men- 
tioned, there  are  exposures  of  an  apparently  complete  succession  of 
the  beds  down  to  the  underlying  Morrison  shale,  showing  little  or  no 
trace  of  coal,  probably  indicating  that  if  coal  beds  are  present  west 
and  north  of  the  Hay  Creek  basin  they  are  of  limited  extent. 
