COAL  IN  NORTHWESTERN  COLORADO  AND  NORTHEASTERN  UTAH.       297 
and  has  to  be  shot,  as  it  can  not  be  picked  out  before  it  is  broken.  It 
is  reported  that  exposure  to  the  open  air  for  three  weeks  will  slack 
the  coal  completely.  When  first  lighted  it  emits  a  pale  blue  smoke 
resembling  that  given  off  by  dry  soft  wood,  but  this  color  soon  dis- 
appears, leaving  a  clear,  smokeless  flame. 
The  analysis  of  the  post-Laramie  coal  (No.  5514,  p.  314)  shows  it  to 
be  of  somewhat  lower  efficiency  than  the  average  Mesaverde  coals 
of  the  Yampa  field.  The  coal  would  probably  fall  in  the  class 
of  subbituminous  coals  formerly  described  as  black  lignite.  The 
amount  of  moisture  (12J  per  cent  on  air-dried  coal)  is  rather  too 
high  to  place  the  coal  in  the  bituminous  class,  although  the  fixed 
carbon  (50  per  cent)  compares  very  favorably  with  that  in  many  of 
the  high-grade  coals.  The  ash  (7i  per  cent)  is  a  fair  average  for 
commercial  coal.  The  appearance  of  this  coal  when  first  mined  is 
very  like  that  of  the  high-grade  bituminous  coals.  Its  principal  dis- 
advantageous feature  is  the  fact  that  it  slacks  readily  when  exposed 
to  the  air. 
Total  thickness  of  workable  beds. — All  the  coal  beds  of  this  group 
are  not  exposed  in  any  one  section,  and  hence  complete  measurements 
were  not  obtained  in  the  present  investigation.  A.  G.  Wallihan,  of 
Lay,  states  that  some  good  exposures  are  to  be  found  in  the  ridges 
west  of  Emerson's  ranch,  on  Lay  Creek,  where  he  claims  to  have 
opened  by  digging  twelve  different  coal  beds,  ranging  from  4  to  20 
feet  in  thickness  and  aggregating  a  total  of  more  than  100  feet  of 
workable  coal  as  measured  at  the  croppings. 
LOWER   WHITE   RIVER   FIELD. 
POSITION    AND    OUTLINE. 
West  of  the  Danforth  Hills  the  Mesaverde  strata  and  the  valuable 
coal  beds  which  they  contain  are  continuous  to  and  beyond  the  Utah 
line,  as  shown  by  PL  XVII.  This  field  occupies  in  part  the  divide 
between  White  and  Yampa  rivers,  but  by  far  the  greater  part  of 
it  lies  in  the  drainage  basin  of  White  River  in  Colorado.  As  White 
River  joins  Green  River  about  40  miles  west  of  the  Colorado-Utah 
line,  and  as  the  coals  are  mostly  confined  to  the  Colorado  portion 
of  that  drainage  basin,  it  has  seemed  most  appropriate  to  apply  the 
name  " lower  White  River"  to  the  Colorado  field. 
This  field  includes  a  continuous  outcrop  of  the  Mesaverde  rocks, 
extending  from  the  northwestern  part  of  the  Danforth  Hills,  describ- 
ing roughly  a  semicircle  around  the  north  end  of  Crooked  Wash,  or 
Coyote  Basin,  and  thence  passing  southward  along  Pinon  Ridge  to 
White  River  at  the  mouths  of  Wolf  and  Yellow  creeks.  From  this 
point  the  outcrops  of  the  coal-bearing  rocks  bend  abruptly  westward, 
forming  a  narrow  hogback  on  the  north  side  of  White  River.     In  the 
