THE  SHERIDAN  COAL  FIELD,  WYOMING. 
By  Joseph  A.  Taff. 
INTRODUCTION. 
This  report  is  a  brief  discussion  of  the  economic  geology  of  the  coal 
in  the  Sheridan  field,  Wyoming,  and  includes  in  addition  only  so 
much  of  the  stratigraphy,  topography,  structure,  and  culture  as  seem 
to  have  a  bearing  on  the  development  of  the  coal  field.  A  more  com- 
plete report  on  the  coal  fields  of  northeastern  Wyoming,  east  of  the 
Bighorn  Mountains,  is  contemplated,  to  be  prepared  when  geologic 
surveys  are  carried  farther  south  and  east. 
The  Sheridan  field  is  covered  by  public-land  surveys,  and  no  maps 
other  than  township  plats  were  available  for  field  use,  with  the  excep- 
tion that  a  small  part  of  the  coal  area  west  of  the  longitude  of  Sheridan 
is  within  the  Dayton  quadrangle  and  has  been  surveyed  topographic- 
ally. The  principal  object  in  the  survey  being  the  classification  of 
the  coal  land,  it  was  necessary  that  all  points  should  be  located  with 
reference  to  the  Land  Office  unit  of  subdivision — the  section.  Many 
of  the  section  corners  could  not  be  found,  even  in  the  larger  valleys 
where  settlements  have  been  made.  In  the  rougher  parts  of  the  field 
the  number  of  corners  that  could  be  found  was  still  less,  and  many  of 
those  that  were  located  contained  no  distinctive  markings.  Local 
county  and  other  surveyors  report  that  great  difficulty  has  been 
encountered  in  locating  settlers  upon  their  lands,  the  only  corners 
that  could  be  found  being  in  many  cases  several  miles  distant  from 
these  lands.  Moreover,  the  locations  of  stream  crossings  on  section 
lines  and  of  other  topographic  features  shown  on  the  township  plats 
were  found  to  be  so  erroneous  as  to  suggest  that  a  considerable  pari 
of  the  land  subdivisions  had  never  been  made. 
The  map  (PI.  VIII)  accompanying  this  paper  is  based  on  coin; 
surveys  tied  to  known  land  corners  and  to  each  other.  Distances 
were  measured  by  pacing  on  section  lines  or  from  section  corners.  In 
the  eastern  and  central  parts  of  the  field  but  few  sect  ion  corners  could 
be  found.  The  traverse  lines  between  known  section  corners  were 
long,  and  even  when  these  lines  are  adjusted  to  each  other  and  to  t In- 
known  corners  the  locations  of  many  points  are  only  approximately 
correct. 
