'ARTon.]  COAL   OF   BLACK   HILLS,    WYOMING.  433 
•olored,  sandy  clay,  capped  b}'  a  thick  mass  of  smooth,  uniform 
sandstone,  which  forms  a  good  roof.  The  floor  is  a  very  hard  sand- 
tone,  as  in  the  other  adit.  Two  miles  southwest,  on  sec.  12,  T.  47,  R. 
»3,  near  the  north  line  of  the  northwest  quarter,  is  another  adit,  100 
bet  long.  The  same  bed  is  exposed  here,  where  it  is  about  5  feet  I 
nches  thick,  and  nearly  all  pure  coal  of  great  hardness.  The  roof 
it  this  place  is  sandstone,  without  the  intervening  shale.  West  of 
lolwell  Ranch,  on  the  west  side  of  Skull  Creek,  coal  has  been  exposed 
,t  one  or  two  points  at  the  base  of  the  sandstone  cliffs,  but  its  thick- 
Less  and  extent  have  not  been  ascertained,  although  apparently  the 
leposit  in  this  locality  is  of  diminished  thickness. 
On  the  ridge  west  of  Inyankara  Mountain  it  is  reported  that  the 
loal  deposit  near  the  base  of  the  Lakota  formation  has  a  thickness  of  9 
jet,  including  a  number  of  layers  of  shale  and  bone. 
West  of  Sundance  the  principal  coal  exposed  is  a  bed  somewhat 
ver  4  feet  in  thickness  and  of  excellent  quality.  One  tunnel  300  feet 
mg  is  in  the  center  of  sec.  13,  T.  51,  R.  04  W.  Another  tunnel  050 
get  long  is  in  the  SW  j  sec.  11,  T.  50,  R.  04  W.,  while  a  third  tunnel, 
ot  now  in  use,  100  feet  long,  is  in  sec.  10,  on  the  opposite  side  of  the 
inyon  from  the  last.  The  coal  from  these  has  been  mined  to  a  mod- 
"ate  extent,  for  use  in  Sundance  and  vicinity. 
Edgemont. — Along  the  southern  slope  of  the  Black  Hills  uplift  the 
(akota  formation  contains  local  coal  basins,  but  no  large  amount  of 
pal  has  been  found  in  any  of  them.     The  principal  openings  have 
en  made  on  the  north  bank  of  Cheyenne  River,  east  of  Edgemont, 
NW.  J  of  NE.  i  sec.  24,  T.  9  S.,  R.  3  E.,  where  there  are  two 
ijmnels  75  feet  or  more  in  length  about  30  feet  above  the  river,  from 
ihich  a  small  supply  of  coal  has  been  obtained.  The  bed  is  5  feet 
lick  for  some  distance,  but  it  averages  much  less.  It  thins  out  to 
|e  east  and  gives  place  to  sandstone,  as  may  be  plainly  seen  in  the 
■riffs  below  the  river,  and  it  grades  into  coaly  shale  to  the  north- 
[est.  The  mine  product  was,  in  part,  light-weight  bituminous  coal 
i  good  quality,  containing  thin,  bony  layers,  and  only  a  moderate 
mount  of  pyrite.  To  the  east  only  a  trace  of  coal  was  found  in  the 
Ijikota  formation,  but  to  the  north  occasional  thin  bodies  of  coal  and 
cjnsiderable  coaly  shale  are  exposed  in  the  river  gorge.  Tn  Craven 
(an}Ton  there  was  at  one  time  a  small  mine,  and  there  was  also  a 
sjiall  production  from  Coal  Canyon. 
Bull.  260—05  m 28 
