236         CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1906,  PART    1. 
Sulphuric  anhydride  (S03) 0.05 
.„    ,.  |Xa.,<) 33 
Alkalies  . . 
'K.O 09 
Water  at  100°  C 25 
Ignil  i<»n  loss 43.  65 
LOO.  47 
This  rock  contains  too  much  magnesia  to  be  used  for  the  manufao 
ture  of  Portland  cement . 
SHALE. 
Morrison  shale.  The  most  important  exposures  of  Morrison  shale] 
which  is  the  lowesl  Cretaceous  formation  here  and  is  150  feet  thick, 
cov<  r  considerable  portions  of  the  drainage  basin  of  Salt  Creek.  The 
shale  at  the  supposed  coal  prospect  on  the  east  hank  of  Salt  Creek  I 
miles  above  its  month  is  carbonaceous  and  slightly  plastic.  It  con- 
tain- a  little  iron  pyrite  in  nodules  and  few  if  any  sand  grains.  An 
average  sample  from  the  20-fool  face  exposed  here  was  analyzed  bj 
Mr.  P.  11.  Bates. 
Analysis  of  Morrison  sjmh  . 
Sili. -a    Si02 15.78 
Alumina     \1_,<  >3) L2  !»l' 
Ferric  oxide    Fe2<  >3) 3.96 
Manganese  oxide    MnO) '■'>'■'> 
I.ii  o(i 
Magnesia    M'_r<  >      .7:1 
Sulphuric  anhydride    S03)  .42 
Alkalies/*9*0- 64 
IK20 .50 
Water  al    L00°  C 8.26 
[gnitionloss i^<i.  :i2 
LOO.  42 
This  is  a  high-grade  normal  -hale,  in  which  the  ratio  of  silica  to 
combined  alumina  and  ferric  iron  is  practically  .'>  to  1—  an  ideal  ratio. 
The  magnesia  and  alkalies  are  very  low  ,  and  although  silica  is  low  t lie 
loss  by  ignition  (largely  carbonaceous  matter)  is  very  high.  This 
carbonaceous  matter  can  he  considered  as  so  much  fuel  added  to 
the  mixture,  and  it->  presence  will  considerably  decrease  the  cosl  of 
burning. 
Graneros  shah.  The  Graneros  shale  underlies  the  broad  valley 
south  of  Newcastle,  comprising  an  area  extending  from  the  1.  A  K 
ranch  northwestward  to  and  for  several  miles  along  the  Burlington 
and  Missouri  River  Railroad.  From  the  ranch  the  outcrop  of  the 
formation  swings  approximately  southward,  and  because  of  steeper 
dips  becomes  narrower.  It  consists  mainly  of  dark-gray  shale,  and 
in  the  vicinity  of  Newcastle  is  about  1,100  feet  thick.  Thin  veinlets 
of  gypsum  are  common  in  the  shale,  but  at  no  point  are  these  so 
abundant  as  to  make  it  unfit  for  use  as  Portland  cement  material. 
