90  CONTRIBUTIONS   TO   ECONOMIC    GEOLOGY,   1907,   PART   II. 
The  sample  from  Joe  Creek,  in  sec.  1,  T.  6  N.,  R.  16  E.,  was  cut  in 
the  face  of  the  drift  about  12  feet  from  the  surface  and  includes  the 
whole  bed,  which  is  28  inches  thick.  There  are  10  inches  of  solid 
coal,  separated  into  two  benches  by  18  inches  of  crushed  and  dirty 
coal.  It  is  probable  that  the  greater  portion  of  the  high  percentage 
of  ash  shown  in  the  analysis  is  contained  in  this  crushed  portion  of 
the  bed.  If  this  part  is  omitted  there  is  not  enough  good  coal  to  pay 
for  digging.  The  same  bed  was  sampled  by  cleaning  the  outcrop  on 
the  south  bank  of  Holcomb  Creek,  in  sec.  13,  T.  6  N.,  R.  16  E.,  where 
for  a  few  rods  it  has  a  thickness  of  30  inches.  The  excessive  moisture 
in  this  analysis  is  due  to  the  fact  that  the  coal  was  taken  from  the  out- 
crop. Aside  from  the  bed  being  too  thin  for  working,  the  percentage 
of  ash  is  objectionably  high. 
The  third  sample  is  from  a  prospect  in  the  Eagle  sandstone  at  Big 
Elk.  It  represents  the  lower  14-inch  bench  of  a  bed  which  is  too 
small  to  mine.  The  high  percentage  of  moisture  and  ash  may  be 
explained  in  part  by  the  fact  that  the  sample  was  taken  very  near  the 
outcrop. 
At  the  head  of  Sixteenmile  Creek  a  sample  was  obtained  by  cutting 
a  groove  across  the  17-inch  upper  bench  of  solid  coal  and  the  26  inches 
of  crushed  and  dirty  coal.  The  high  percentage  of  ash  shown  by  the 
analysis  is  probably  contained  in  this  lower  part.  The  exclusion  of 
this  lower  bench  leaves  less  than  \\  feet  of  coal,  which,  although  it 
may  be  of  fair  grade,  is  too  thin  for  exploitation. 
The  coal-bin  sample  was  intended  to  represent  the  character  of  the 
coal  at  the  southeast  corner  of  sec.  36,  T.  5  N.,  R.  8  E.  Drying  for 
several  months  under  cover  has  reduced  the  percentage  of  moisture, 
and  it  is  possible  that  there  is  less  ash  than  would  have  been  found  in 
a  sample  cut  from  the  entire  thickness  of  the  bed.  Although  the 
analysis  shows  a  coal  of  fair  quality,  the  bed  is  too  thin  to  mine  with 
profit. 
CONCLUSIONS. 
The  outcrop  of  the  Eagle  sandstone  shown  on  the  accompanying 
map  (PL  V),  if  compared  with  the  geologic  maps  of  the  area  in  Folio 
56,  will  be  seen  to  resemble  the  outcrop  of  the  Laramie  formation. 
The  discrepancy  in  age  determination  is  due  probably  to  a  lack  of 
fossil  evidence  on  the  part  of  the  author  of  the  folio,  and  the  difference 
in  mapping  to  the  difference  in  the  degree  of  refinement  in  the  field 
work.  Weed  was  mapping  the  complex  igneous  and  sedimentary 
geology  of  a  very  large  area  with  one  assistant,  whereas  the  writer 
was  studying  the  Cretaceous  of  only  1,000  square  miles  with  three 
assistants.  Furthermore,  the  writer  had  the  benefit  in  the  field  of 
the  cooperation  of  T.  W.  Stanton,  F.  H.  Knowlton,  and  A.  C.  Peale  in 
determining  the  formation  limits,  and  of  Stanton,  Knowlton,  and 
