GREAT   DIVIDE   BASIN    COAL   FIELD,    WYOMING. 
233 
UNDIFFERENTIATED  TERTIARY  ROCKS.a 
The  coal-bearing  beds  of  the  undifferentiated  Tertiary  are  sepa- 
rated from  the  Laramie  formation  by  an  unconformity,  above  which 
is  a  noncoal-bearing  series  of  soft  shale  and  brown  conglomeratic 
sandstones  probably  constituting  the  bottom  part  of  the  Tertiary. 
In  the  southern  part  of  the  field  this  formation  is  coal  bearing  in 
both  the  lower  and  upper  portions. 
The  lower  member  is  abundantly  coal  bearing  near  the  railroad 
and  becomes  less  so  to  the  north.  In  T.  27  N.,  R.  90  W.,  this  is  the 
only  part  of  the  formation  not  covered  by  Wasatch  beds,  and  it  is 
apparently  not  coal  bearing. 
The  upper  member  contains  numerous  coal  beds  of  workable  thick- 
ness between  Riner  and  Fillmore,  on  the  Union  Pacific  Railroad.  To 
the  northeast  it  disappears  under  Separation  Flats  and  is  concealed 
by  Quaternary  gravel  and  the  overlapping  Wasatch  conglomerate. 
The  highest  dip  is  7°,  and  within  a  short  distance  to  the  northwest 
the  beds  probably  are  horizontal.  At  Cherokee  siding,  in  sec.  10, 
T.  20  N.,  R.  91  W.,  a  prospect  slope  has  been  driven  down  a  dip  of 
7°  to  a  distance  of  75  feet.  At  the  old  Fillmore  station,  in  sec.  31, 
T.  21  N.,  R.  90  W.,  in  an  artesian  well  drilled  by  the  Union  Pacific 
Railroad  Company,  a  20-foot  bed  of  coal  was  reported  at  a  depth  of 
220  feet,  a  10-foot  bed  at  270  feet,  and  a  15-foot  bed  at  320  feet. 
At  Wamsutter,  in  sec.  34,  T.  20  N.,  R.  94* W.,  in  an  artesian  well  put 
down  by  the  same  company,  two  5-foot  coal  beds  were  found  at 
depths  of  150  and  220  feet.  These  beds  probably  belong  to  the 
upper  member  of  the  undifferentiated  Tertiary. 
The  following  sections  show  the  general  character  and  thickness  of 
the  coal  beds  of  this  formation.  Nos.  43  to  49  occur  in  the  lower 
member,  and  the  remainder  in  the  upper. 
Sections  of  coal  beds  in  the  undifferentiated  Tertiary  deposits. 
No.  on 
PI. 
XII. 
Location. 
Section  of  coal  bed. 
Remarks. 
Sec. 
T. 
R. 
43 
NW.'NW.i 
25 
21 
89 
Ft.  in. 
Coal,  impure 2 
Shale 2    6 
Coal,  impure 3    ('» 
Coal,  good 44- 
Abandoned  mine. 
12+ 
44 
SW.  |  S\V.  \. 
24 
21 
89 
Sandstone 2    5 
Coal,  impure <i 
Coal,  good 54- 
7  114- 
Abandoned  mine. 
a  Since  this  paper  was  written  fossil  plants  have  been  collected  from  several  horizons  in  these  beds 
near  liiner.    The  fossils  have  not  been  studied  in  detail,  but  are  believed  to  be  of  Fort  Union  age. 
