LIGNITES  OF  THE  MIDDLE  AND  UPPER  MISSOURI  VALLEY. 
Bv  Ernest  F.  Burchard. 
LIGNITE  IN   NORTHEASTERN   NEBRASKA. 
In  the  middle  Missouri  Valley  many  unsuccessful  attempts  have 
been  made  either  to  find  coal  or  to  develop  a  fuel  supply  from  the 
lignites.  Of  the  States  in  the  western  interior  coal  field  Nebraska 
alone  shows  no  record  of  production,  and  a  liberal  bounty  for  the  dis- 
covery of  a  workable  bed  of  coal  within  its  borders  has  been  offered 
by  this  State.  Encouraged  by  this  bounty,  extensive  prospecting 
was  done  in  1902  in  Dakota  County,  and  the  writer  was  thus  afforded 
opportunity  to  make  detailed  investigations  into  the  geologic  relations, 
extent,  and  chemical  composition  of  the  lignite. 
This  paper  is  presented  for  the  purpose  of  explaining  the  con- 
ditions actually  existing  in  the  region  of  which  this  area  is  a  part,  in 
order  that  unprofitable  prospecting  may  be  avoided. 
Geologic  relations. — The  indurated  rocks  underlying  Dakota  County 
are  of  upper  Cretaceous  age.  The  oldest  formation  exposed  is  the 
Dakota,  which  comprises  sandstones,  clays,  and  shales,  with  inter- 
bedded  seams  of  lignite.  The  Dakota  is  overlain  by  the  basal  shales 
of  the  Benton  group,  which  also  contain  a  thin  seam  of  lignite,  and 
over  these  shales  is  a  limestone  member,  very  probably  corresponding 
to  the  Greenhorn  limestone  of  the  Benton  in  the  Colorado  section. 
Over  the  eroded  surface  of  these  sediments  lie  unconsolidated  Qua- 
ternary materials,  consisting  of  a  heavy  covering  of  loess,  with  thin 
deposits  of  glacial  till  and  sands  at  its  base. 
Throughout  its  trough  Missouri  River  has  removed  these  rocks  to 
a  depth  of  200  to  300  feet,  presenting  in  its  escarpment  several  expo- 
sures of  the  entire  sequence.  The  strata  lie  nearly  horizontal,  a  suc- 
cession of  broad  undulations  being  traceable  in  the  escarpment  section 
from  southeast  to  northwest  through  the  county. 
Prospecting  has  been  confined  to  the  upland  region  back  from  the 
escarpment,  experience  having  shown  that  in  its  flood  plain  Missouri 
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