BOCK    SPRINGS    COAL   FIELD,    WYOMING. 
263 
atecl  for  a  short  time,  and  then  abandoned,  as   the  coal  is  inferior 
to  the  Rock  Springs  coal. 
The  following  sections,  which  are  a  few  of  the  numerous  measure- 
ments made  of  these  beds,  will  show  their  character  and  thickness: 
Sections  of  coal  beds  in  the  Almond  coal  group. 
Locution. 
Section  of  coal  bed. 
Location. 
Section  of  coal  bed. 
Sec. 
T. 
R. 
Sec. 
T. 
R. 
NW-iNE.  ',. 
32 
21 
101 
Ft.    in. 
Sand  stone 
and  shale. 
Coal 4 
Shale 1 
Sandstone..    2  • 
7      2+ 
NE.JNE.  ',. 
6 
22 
103 
Ft.     in. 
Sandstone...    1-+- 
Coal .') 
Sandstone...     1  + 
7+ 
NW.  i  NW.  \. 
24 
Shale 2+ 
Coal G 
Sandstone...    1+ 
9+ 
BE.  J  NE.  \. 
3 
21 
104 
Shale 1      2 
Coal :■> 
Sandstone..    2 
fi     2 
22 
104 
NW.  |  SE.  \. 
20 
22 
104 
Sandstone...     1+ 
Coal 2    G 
Sandstone...     1-f- 
3 
21 
104 
Sandstone..    3 
Coal 7 
S  ;i  n  d  stone 
and  shale. 
10 
NE.  I  SE.J. 
4    6+ 
NE.  INK.  ',. 
35 
22 
104 
Shale   and 
sandstone.    6 
Coal 6 
Sandstone...    2 
14 
NE.iSE.J. 
1G 
21 
104 
Sh  ale  and 
sandstone 
Coal 7 
Sandstone..    2+ 
9+ 
POST-MONTANA. 
Overlying  the  Lewis  shale  occur  two  groups  of  coal  beds,  separated 
from  each  other  by  an  unconformity  of  considerable  magnitude.  For 
convenience  in  the  following  discussion  the  lower  will  be  called  the 
Black  Buttes  coal  group  and  the  upper  the  Black  Rock  coal  group. 
The  unconformity  between  these  two  groups  may  in  places  readily 
escape  observation. 
Black  Buttes  coal  group. — Along  the  east  side  of  the  dome  the  Black 
Buttes  coal  group  lies  conformably  upon  marine  Lewis  shale,  which 
weathers  readily  and  produces  regions  of  low  relief.  The  basal  mem- 
ber of  the  Black  Buttes  coal  group  consists  of  a  massive  bed  of  yellow- 
ish-white sandstone,  in  places  over  100  feet  thick  and  not  known  to 
be  coal  bearing.  This  member,  resting  upon  the  soft,  friable  Lewis 
shale,  forms  steep  hills  and  cliffs  along  the  contact.  The  rocks  above 
this  sandstone  consist  of  a  series  of  variable  sandstone,  clay,  and  coal 
beds  that  lie  exposed  in  the  low  hills  and  ridges  east  of  the  main 
scarp.  On  the  west  side  of  the  dome  this  group  is  absent  and  the 
Black  Rock  group  rests  unconformably  upon  the  Almond  coal  group, 
and  all  traces  of  the  Black  Buttes  group  and  Lewis  shale  are  con- 
cealed by  overlap.  Considerable  prospecting  has  been  done  at  vari- 
ous places  along  this  coal  zone,  and  good  beds  of  coal  exposed. 
