GREAT   DIVIDE   BASIN    COAL  FIELD,    WYOMING.  239 
Kawlins,  on  the  same  coals,  show  heating  values  ranging  from  8,339 
to  10,849  British  thermal  units  on  samples  as  received,  and  from 
8,806  to  11,567  British  thermal  units  on  air-dried  samples.  From 
these  two  sets  of  figures  it  is  evident  that  samples  taken  from  surface 
openings  and  prospects  do  not  represent  the  true  value  of  the  coals. 
It  is  probable  that  more  extensive  development  of  the  Mesaverde 
coals  near  Rawlins  will  prove  them  to  be  bituminous  coals  comparing 
favorably  with  the  best  of  those  at  Rock  Springs. 
LARAMIE    COAL. 
The  Laramie  coals  of  this  field  are  somewhat  inferior  to  the  Mesa- 
verde coals.  The  percentage  of  ash  is  somewhat  smaller,  but  the 
moisture  content  is  greater,  and  in  three  of  the  samples  much  greater, 
than  in  the  Mesaverde  coals.  No.  5816  was  taken  about  15  feet 
down  the  dip  from  a  prospect  which  had  been  filled  with  mud  and 
water  for  nearly  ten  years.  No.  6826  was  taken  from  an  abandoned 
drift  only  a  few  feet  above  the  dry  course  of  Lost  Soldier  Creek.  The 
drift  has  probably  been  subjected  to  flooding  in  the  spring  for  sev- 
eral years  past.  Nos.  3790  and  3548  were  taken  by  A.  C.  Veatcha 
from  better  openings  in  central  Carbon  County,  and  probably  repre- 
sent more  nearly  the  true  value  of  the  coal. 
UNDIFFERENTIATED  TERTIARY  COAL. 
The  coals  of  the  undifferentiated  Tertiary  have  been  developed 
very  little  in  this  field.  The  only  entry  or  drift  of  any  considerable 
size  was  driven  several  years  ago  in  a  nearly  horizontal  bed  in  the 
upper  part  of  the  formation  near  Cherokee  Siding.  This  coal  occurs 
in  about  the  same  part  of  the  formation  as  that  mined  at  Hanna,  in 
central  Carbon  County.  Analyses  Nos.  3610  and  3605,  representing 
samples  from  Hanna,  according  to  Veatch,a  show  a  fairly  good  low- 
grade  bituminous  coal.  It  is  not  improbable  that  the  coal  of  the 
same  ago  in  this  field,  if  developed  beyond  the  zone  of  surface  altera- 
tion, would  be  of  similar  quality.  Sample  No.  5815  was  taken  from 
lens-shaped  masses  of  brittle,  shiny  coal  found  in  one  of  the  beds  of 
the  lower  part  of  the  formation,  and  probably  represents  local  pecu- 
liarities in  the  coal. 
WASATCB    COAL. 
No  prospects  of  any  great  depth  have  been  opened  from  which  rep- 
resentative samples  of  the  Wasatch  coals  could  be  obtained.  Sn  tu- 
ple No.  5949  was  taken  from  a  shallow  surface  prospect  and  was  very 
badly  weathered.  The  effect  of  weathering  on  the  coals  of  this 
formation  may  be  readily  seen  by  comparing  samples  Xos.  5930  and 
5374  with  Nos.  5375  and  5367. b     In  the  first  two  samples,  which 
oBull.  U.  S.  Geol.  Survey  No.  316,  1907,  pp.  253  258, 
!)  Stv  report  by  A.  R,  Schulfz,  pp.  256-282 Ol  tWfl  volume. 
