COAL   ON   SOUTHWEST   SIDE    OF   BIGHORN    BASIN,    WYO.  205 
at  the  top  of  the  massive  sandstones.  Above  the  boundary  line  the 
shale  members  are  gray  and  contain  thin  coal  beds  and  lignitic  layers. 
The  formation  contains  no  workable  coal  beds.  Carbonaceous 
shale  and  coal  beds  are  exposed  in  many  of  the  outcrops,  and  near  the 
west  end  of  the  Grass  Creek  basin  the  lower  sandy  member  of  the  for- 
mation contains  a  bed  of  coal  18  inches  thick.  The  undifferentiated 
Montana,  however,  contains  no  coal  of  commercial  importance. 
LARAMIE  (?)   FORMATION. 
Overlying  the  Montana  group  is  a  series  of  sandstones  and  shales 
containing  beds  of  coal  and  lignite.  This  formation,  which  is  2,630 
feet  thick  where  it  is  exposed  on  Shoshone  River,  is  composed  of  two 
parts.  The  lower  part  consists  of  980  feet  of  dark  and  light  gray 
sandy  shales,  with  a  few  rust-colored  layers  and  numerous  beds  of 
coal  and  lignite.  The  carbonaceous  beds  are  so  numerous  that  they 
give  a  distinctly  banded  appearance  to  the  shale.  The  upper  part 
consists  of  dull  green  sandy  shale  with  local  brown  leaf-bearing  beds 
and  gray  or  dull  green  massive  sandstone. 
Fossils  collected  from  these  beds  were  examined  by  T.  W.  Stanton, 
who  reports  that  the  species  found  belong  to  a  fauna  characteristic  of 
the  "  Ceratops  beds."  As  the  stratigraphic  position  of  these  beds  is 
not  definitely  determined,  the  name  Laramie  is  applied,  because  the 
Laramie  formation  occupies  a  position  in  the  geologic  column  between 
the  Montana  and  Fort  Union.  Furthermore,  it  is  thought  best  not  to 
introduce  a  new  name  for  these  beds  because  they  are  a  part  of  the 
series  which  is  known  in  the  literature  of  the  region  as  the  Laramie 
formation.  The  name,  however,  should  not  be  considered  as  indica- 
tive of  a  positive  correlation  with  beds  of  Laramie  age  to  the  south. 
Lenticular  coal  beds  are  exposed  in  this  formation  at  various  places 
throughout  the  field. 
FORT    UNION    FORMATION. 
The  upper  coal-bearing  formation  consists  mainly  of  soft  shale  and 
massive  sandstone  with  conglomeratic  beds  in  the  lower  part.  Where 
it  is  typically  exposed  along  Shoshone  River  northeast  of  Cody  it  con- 
sists of  three  members.  At  the  base  there  are  about  1,000  feet  of  gray 
massive  sandstone  and  green  shale  with  coaly  layers  and  numerous 
beds  of  conglomerate  throughout.  This  member  is  overlain  by  1,700 
feet  of  soft  sandstone  and  somber-colored  shale  in  alternating  layers, 
some  of  which  contain  coal  beds.  At  the  top  of  the  formation  there 
are  400  feet  of  gray  sandy  shale  with  local  beds  of  sandstone 
Fossils  collected  at  various  horizons  in  this  formation  have  been 
examined  by  T.  W.  Stanton  and  F.  H.  Knowlton,  who  report  them 
to  be  characteristic  of  the  Fort  Union.  A  few  fossil  plants  were 
found  in  a  sandstone  immediately  below  the  conglomerate  beds  and 
