(OAT,  ON   NORTHEAST  SIDE   OF  BIGHORN   BASIN,   WYO.  183 
SILVERTIP  COAL   FIELD. 
On  the  State  line  between  Montana  and  Wyoming  is  an  anticline 
which  exposes  the  Eagle  coal  horizon.  This  fold  may  be  known  as 
the  Silvertip  anticline,  from  the  name  of  the  principal  mine  at  that 
place,  and  the  same  name  will  be  used  in  this  report  for  the  coal 
field.  The  field  lies  about  12  miles  west  of  the  line  of  the  Chicago, 
Burlington  and  Quincy  Railroad.  It  is  about  20  miles  northwest  of 
Garland,  Wyo.,  which  is  situated  on  the  Cody  branch  of  the  Burling- 
ton Railroad,  21  miles  south  of  Bridger,  Mont.,  at  the  end  of  a  branch 
of  the  Northern  Pacific  Railway;  and  12  miles  southwest  of  Belfry, 
Mont.,  on  the  Yellowstone  Park  Railroad,  which  connects  at  Bridger 
with  the  Northern  Pacific.  The  coal  is  most  accessible  from  Belfry, 
as  the  valley  of  Silvertip  Creek  would  furnish  a  practicable  route 
for  a  railroad  between  Silvertip  and  that  town. 
The  Silvertip  coal  field  is  a  broad  ellipse  about  8  miles  long  and 
4  miles  wide.  On  the  west  side  of  this  ellipse  the  dips  are  south- 
westward  at  angles  of  15°  to  20°.  On  the  east  side  the  dips  are 
slightly  steeper,  ranging  from  22°  to  45°  NE.  The  continuity  of  the 
coal  bed  is  broken  by  a  great  many  normal  faults  which  trend  north- 
east and  southwest  across  the  axis  of  the  anticline.  These  faults  will 
probably  interfere  seriously  with  the  mining  of  the  coal  on  the  east 
side  of  the  anticline,  but  on  the  west  side  they  are  less  numerous 
and  will  give  little  trouble.  The  throw  of  the  faults  ranges  from 
10  to  250  feet. 
In  the  greater  part  of  the  Silvertip  field,  lying  north  of  the  State 
line,  there  are  two  workable  coal  beds,  but  most  of  the  part  of  the 
field  lying  in  Wyoming  contains  only  one  workable  bed,  though  in 
places  two  beds  may  be  found  to  be  thick  enough  to  mine. 
Three  coal  beds  are  recognizable  in  the  Silvertip  field.  These 
probably  correspond  to  the  three  beds  near  Bridger  and  Fromberg, 
Mont.  The  lower  bed  is  not  workable  at  any  place  in  this  field. 
The  workability  of  the  two  upper  beds  depends  largely  on  the  amount 
and  strength  of  the  material  separating  them.  In  most  places  this 
material  is  so  thick  that  both  coal  beds  can  not  be  mined  together, 
and  in  some  places  it  is  not  thick  enough  nor  strong  enough  to  make 
it  possible  to  mine  the  two  beds  separately.  On  the  west  side  of 
the  field  the  purling  consists  of  only  2  to  8  feet  of  sandy  shale,  bul  <>n 
the  cast  side  it  consists  of  4  to  10  feet  of  sandy  shale  and  sandstone, 
which  is  usually  si i  dicient  to  permit  both  beds  to  be  mined  separately. 
Typical  sections  of  the  three  beds  as  exposed  on  the  west  side  of  the 
field  are  shown  on  the  following  page. 
