284  CONTRIBUTIONS   TO    ECONOMIC   GEOLOGY,    1907,    PART   II. 
FIELD  WORK. 
Personnel. — The  members  of  the  field  party  engaged  in  geologic 
work  throughout  the  season  were  John  A.  Davis,  Charles  W.  Stoops, 
and  the  author.  T.  W.  Stanton  spent  about  three  weeks  with  the 
party  at  the  beginning  of  the  season,  for  the  purpose  of  collecting 
fossil  evidence  bearing  on  the  age  of  the  coal-bearing  beds.  W.  H. 
Beekly  and  J.  Sidney  Heil  rendered  valuable  assistance  in  the  manage- 
ment of  the  camp  and  in  the  field  work. 
Methods  and  conditions. — This  work  was  planned  for  the  purpose 
of  making  a  preliminary  examination  and  classification  of  the  public 
lands  upon  which  valuable  coal  was  supposed  to  exist,  but  about 
which  very  little  authoritative  information  was  available.  Much 
of  the  field  work  was  based  on  the  recently  established  lines  of  the 
township  resurveys  in  this  part  of  Colorado.  In  each  township 
or  part  of  a  township  that  contained  coal,  a  large  proportion  of  the 
section  lines  were  retraced  for  the  purpose  of  locating  the  coal. 
This  was  done  with  a  pocket  compass,  the  distances  being  measured 
by  pacing  and  checked  by  the  corners  that  were  found  along  the 
lines.  An  average  of  about  five  working  days  for  one  man  was 
devoted  to  each  township,  and  this  may  serve  as  a  rough  measure 
of  the  detail  that  could  be  obtained  in  such  a  review  of  the  area. 
In  addition  to  this  work  meanders  were  made  along  roads  and  trails 
or  in  gulches  and  canyons  for  the  purpose  of  examining  the  most 
favorably  exposed  geologic  sections  and  procuring  such  additional 
data  as  could  not  be  obtained  by  other  methods. 
In  territory  where  the  new  surveys  had  not  been  completed  it  was 
necessary  to  pursue  a  method  of  traverse,  for  which  both  plane  table 
and  compass  and  notebook  were  used.  In  the  absence  of  the  constant 
checks  on  well-established  land  corners  it  was  not  possible  to  obtain 
so  satisfactory  a  result  as  by  the  other  method. 
By  far  the  greater  part  of  the  valuable  coal  is  concealed  at  the 
surface,  and  its  presence  over  much  of  the  region  can  only  be  inferred 
from  a  study  of  the  sections  where  it  is  better  exposed.  Individual 
beds  can  not  be  traced  from  place  to  place  for  any  considerable 
distance  without  doing  a  great  amount  of  development  work  along 
the  outcrops,  and  indeed  it  is  extremely  doubtful  if  such  work  could 
ever  be  satisfactorily  done  in  much  of  the  field  until  all  or  most  of 
the  beds  are  actually  opened  in  mining  or  have  been  prospected  by 
the  drill.  More  and  more  detailed  examinations  will  doubtless 
become  necessary  from  time  to  time  as  the  development  of  the  field 
progresses  and  the  coal  lands  themselves  become  more  valuable. 
