BOOK    CLIFFS    COAL    FIELD,    UTAH.  L>(.>1 
I  Sandstone  of  the  Red  Plateau. — Reddish,  yellow,  and  brown  sandstone  overlies  the  blue 
[hale  of  the  San  Rafael  Swell.  On  Muddy  Creek  southeast  of  Emery,  where  the  seel  ion  was 
[neasured,  the  formation  consists  of  sandstone,  shale,  and  coal,  in  the  following  order,  from 
[he  top  down: 
Section  on  Muddy  ( 'reek. 
Base  of  Castle  Valley  shale. 
1.  Brownish  and  yellow  sandstone,  with  some  shale  interstratified 25 
2.  Thin  seam  of  coal. 
3.  Shaly  sandstone 10 
4.  Shale 5 
5.  Coal 5 
6.  Shale  and  thin  coal J      1     r> 
Uo  2 
7.  Yellow,  brown,  and  pinkish  sandstone 125 
8.  Bony  coal,  separated  into  two  nearly  equal  benches  by  variable  bands  of  1      4    '.) 
bony  shale  4  to  14  inches  in  thickness \to  7    2 
9.  Yellowish  sandstone 15 
10.  Bituminous  shale  and  coal,  the  coal  occurring  in  two  bands  of  nearly 
equal  thickness 3 
11.  Yellow,  somewhat  friable  sandstone,  with  thin  carbonaceous  shale  in  the 
central  part 225 
This  sandstone  formation  makes  the  bold,  rugged  escarpment  and  the  Red  Plateau, 
bounding  the  San  Rafael  Swell  on  the  northwest  side  and  the  north  end,  respectively.  The 
escarpment  grows  higher  and  more  rugged  northward  from  Muddy  Creek,  and  for  this  reason 
it  is  believed  that  the  formation  becomes  thicker  in  the  same  direction.  The  coal,  which  is 
of  little  economic  importance,  is  known  to  occur  only  to  the  east  and  southeast  of  Emery. 
Shale  of  Castle  Valley. — A  blue-clay  shale  or  marl  1,000  to  1,500  feet  thick  overlies  the 
sandstone  of  the  Red  Plateau.  Castle  Valley  is  eroded  in  this  shale,  and  the  sandstone  lent  i  Is 
in  the  upper  part  produce  the  characteristic  topographic  features  from  which  the  valley 
derived  its  name.  The  lower  half  of  the  formation  lies  in  a  gently  undulating  desert  plain, 
and  the  rocks  usually  are  not  exposed.  In  the  coal  investigation  there  was  no  occasion  to 
examine  the  lower  part  of  the  formation.  The  upper  part,  except  the  sandstone  lentils,  is 
an  even-textured  blue  marl  that  is  highly  impregnated  with  alkaline  salts.  Even  on  rapidly 
weathering  surfaces  the  white  salts  exude  in  many  places.  In  poorly  drained  irrigated  dis- 
tricts, where  the  soil  is  thin,  alkaline  salts  are  so  abundant  as  to  destroy  vegetation.  The 
sandstone  lentils  that  occur  500  to  700  feet  below  the  top  are  made  up  of  beds  of  varying  purity 
and  thickness.  From  the  vicinity  of  Sunnyside  westward  to  Price  River  they  are  repre- 
sented by  thin  shaly  sandstone  that  is  scarcely  perceptible,  having  very  slight  effect  on  the 
topography.  Westward  from  Price  River  the  beds  increase  in  thickness,  aggregating  more 
than  100  feet  in  the  valley  of  Gordon  Creek.  Toward  the  south  the  beds  thin  out  to  mere 
bands  in  a  distance  of  13  miles.  Southward  from  Huntington  they  increase  again,  reaching 
nearly  200  feet  on  Quitchupah  and  Ivie  creeks,  at  the  south  end  of  the  coal  field.  The  sand 
stones  comprising  the  lentils  include  many  shaly  sandstone  and  shale  beds. 
The  Castle  Valley  shale  was  examined  by  T.  W.  Stanton  in  a  brief  reconnaissance  nip 
near  the  Rio  Grande  Western  Railway  about  50  miles  southeast  of  Cast  legate.  The  col- 
lections of  fossils  that  he  was  able  to  make  showed  that  the  upper  part  of  the  Castle  Valley 
shale  belongs  to  the  Montana  group  of  the  Cretaceous  and  that  the  parting  between  this  group 
and  the  succeeding  Laramie  coincides  approximately  with  the  boundary  between  this  shale; 
and  the  overlying  sandstone  of  the  Book  Cliffs. 
Laramie  formation. — The  Laramie  formation  consists  of  sandstone,  shale,  and  coal  in 
alternate  succession.  The  sandstones  occur  in  beds  ranging  from  a  few  feet  to  nearly  500 
feet  in  thickness.  For  convenience  of  description  the  Laramie  formation  may  be  separai  ed 
into  three  parts-  (1)  that  below  the  coal,  consisting  of  sandstone  and  shale  in  almost  equal 
proportions;  (2)  coal-bearing  series  of  sandstone,  shale,  and  coal  alternately  stratified;  (3) 
upper  beds,  consisting  almost  entirely  of  sandstone. 
1.  The  rocks  below  the  coal  consist  of  two  thick  yellowish  to  drab  and  light-gray  sand- 
stones separated  by  a  mass  of  shale  and  thin  sandstone.     The  lower  sandstone  varies  in 
