NORTH    DAKOTA-MONTANA    LIGNITE    AREA.  317 
ointed  shales  of  this  formation  arc  brought  to  the  surface  by  an  anticline  along  Yellow- 
tone  River  12  miles  above  Glendive,  Mont.,  at  the  mouth  of  Cedar  Creek.  The  Laramie 
Leds  on  the  south  side  of  the  creek  have  a  dip  of  25°  SW.,  while  on  the  north  side  of  the 
ireek  valley  occurs  the  Pierre  shale  with  many  characteristic  fossils.  There  are  here  200 
eet  of  dark  shale  overlain  by  150  to  200  feet  of  light-buff  shale.  Scattered  through  these 
beds  arc  abundant  siliceous  and  ferruginous  nodules  of  lime  carbonate,  often  rich  in  fossils. 
fhe  fossil-bearing  nodules  are  most  numerous  toward  the  top  of  the  dark  shale,  in  a  horizon 
IpO  to  300  feet  above  the  river.  The  Pierre  strata  are  seen  outcropping  in  the  bluffs  of 
ihe  Yellowstone  for  a  distance  of  at  least  5  or  6  miles.  Shale  similar  in  appearance  and 
Ivith  many  of  the  same  Pierre  fossils  occupies  an  area  of  considerable  size  in  western  Bow- 
Irian  County,  N.  Dak.,  and  extends  across  the  line  into  Montana.  This  belt  stretches. 
Inany  miles  north  and  south  on  either  side  of  the  boundary  line  and  has  a  width  of  from  3 
lo  10  miles  or  more.  It  is  not  unlikely  that  the  Pierre  outcrops  at  other  points  within  the 
lignite  area,  but  the  above  were  the  only  localities  found  during  the  past  season. 
J  Fox  Hills  sandstone. — At  some  localities  the  Fox  Hills  sandstone  lies  between  the  Pierre 
md  Laramie  formations,  but  generally  it  is  absent  in  this  field.  Outcrops  of  this  forma- 
tion are  extremely  rare,  the  only  one  known  being  in  Morton  County,  N.  Dak.,  on  Cannon 
Ball  River.  About  8  miles  above  the  confluence  of  this  river  with  the  Missouri  a  brown, 
ferruginous,  friable  sandstone  occurs  containing  Tancredia  americana  M.  &  H.  and  Callista 
pp.,  possibly  Callista  nebrascensis  M.  &  H.  These  fossils  were  identified  by  T.  W.  Stanton, 
and  doubtless  are  of  Fox  Hills  age. 
Laramie  formation.  —-The  lignite  occurs  in  the  Laramie  beds,  which  show  remarkable 
uniformity  in  character  over  the  entire  region.  They  are  composed  of  semiconsolidated 
bands  and  clays,  the  sand  being  in  some  places  cemented  into  a  more  of  less  firm  sandstone. 
In  certain  localities  sandy  strata  predominate;  in  others  clay  and  sandy  clay  constitute 
the  hulk  of  the  formation.  The  character  of  the  Laramie  formation  is  shown  by  the  fol- 
lowing sections: 
Section  in  the  bluffs  of  the  Little  Missouri  at  Medora,  N.  Dak.a 
Ft.  in. 
40.  Shaly  sandstone,  gray,  weathering  to  yellow,  finer  grained  than  No.  39; 
contains  cherty  layer 15 
39.  Sandstone,  dark  gray,  rather  soft,  coarse  grained,  massive;  forms 
vertical  escarpment  near  top  of  bluff 45 
38.  Lignite  seam  and  coaly  shale 1-4 
37.  Clay  shale,  gray  and  yellow •. 9 
36.  Lignite  seam 3-4 
35.  Clay  shale 6 
34.  Gray,  fine-grained,  shaly  sandstone 6 
33.  Yellow  clay  shale 1        0 
32.  Lignite  seam G 
31.  Gray  clay  shale ' 1 
30.  Gray  sandy  shale G 
29.  Gray  clay  shale 1       G 
28.  Chocolate-brown  clay  shale,  with  thin  lignite  seam 1 
27.  Gray  clay  shale 4 
2G.  Soft  shaly  sandstone,  gray  and  bluff,  laminated,  fine  grained;  in  places 
forms  hard  sandstone  ledge  projecting  beyond  the  softer  shales  above 
and  below > 15 
25.  Gray  and  yellow  clay  shales,  with  some  sandy  layers 5 
24    Chocolate-brown  clay  shale,  with  plant  impressions 4 
23.  Lignite  seam 1        G 
22.  Clay  shale,  gray  and  yellow,  with  some  sandy  layers  and  a  thin  streak 
of  lignite 30 
21    Sandy  shale,  passing  above  into  a  compact,  hard,  fine-grained  gray 
sandstone;  this  rock  forms  a  projecting  ledge 3-4 
20.  Gray  and  yellow  clay  shale 5        G 
19.  Fine-grained  sandstone,  forming  projecting  ledge 2 
"Third  Bienn.  Kept.  Geol.  Survey  North  Dakota,  pp.  161-162. 
Bull.  285—06 21 
