292  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1905. 
composition  as  well  as  thickness.     In  the  Wasatch  Plateau  it  is  80  feet  or  more  thick  am  , 
generally  a  massive  magnesian  sandstone.     In  the  Book  Cliffs  it  is  thinner  and  more  shall 
It  is  always  present,  however,  and  is  exposed  in  steep  bluffs  and  often  impassable  cliffs 
This  bed  invariably  overlies  the  marly  shale  formation  of  Castle  Valley.     Above  the  lowe 
sandstone  is  a  series  of  shale  and  sandstone  beds.     The  sandstone  rarely  reaches  a  thicknes; 
of  20  feet,  and  the  whole  aggregates  60  to  100  feet.     These  beds  are  often  talus  covered  i; 
Where  exposed  they  make  rather  steep  terraced  slopes,  and  the  sandstone  ledges  project  ii  ii 
benches  or  low  bluffs.     Beneath  the  lowest  productive  coal  bed  in  the  Book  Cliffs  field  then 
is  a  continuous  sandstone  80  to  100  feet  thick.     It  is  light  yellow  or  drab  in  color  exeepl  i 
the  upper  10  to  20  feet,  which  is  usually  white.     In  the  eastern  and  southern  slopes  of  the  < 
Book  Cliffs  and  Wasatch  escarpments  the  sandstone  stands  out  in  steep  bluffs  and  ofter 
impassible  cliffs.     In  the  northern  and  western  slopes  of  the  canyons  entering  the  escarp- 
ments it  is  often  broken  down,  but  is  rarely  concealed  by  talus.     This  sandstone  bed  is  ai 
most  valuable  guide  in  searching  for  coal  in  this  region,  as  it  occurs  just  below  the  lowest 
workable  coal  in  the  Book  Cliffs  field.     It  can  not  only  be  traced  readily  from  point  to  point 
of  the  cliffs,  but  can  be  recognized  at  a  range  of  several  miles  by  its  characteristic  features 
and  position. 
2.  The  coal-bearing  rocks  consist  of  nearly  equal  portions  of  sandstone  and  shale,  with 
several  beds  of  coal.  With  the  exception  of  some  heavy  beds  in  the  lower  part,  the  series 
consists  of  relatively  thin  strata  that  are  usually  more  or  less  concealed  by  talus.  The  low- 
est coal  bed  where  it  has  been  seen  fully  exposed  in  mines  and  prospects  varies  between  3 
and  20  feet  in  thickness.  It  rests  often  directly  upon  the  massive  sandstone  at  the  top  of  the 
series  below  the  coal.  In  the  localities  of  its  thinner  occurrence  blue  to  black  shales,  usually 
containing  thin  coals,  occur  above  it.  Where  the  coal  bed  is  thickest  it  commonly  has  a 
sandstone  roof. 
Pinkish  to  yellow  sandstone,  associated  with  shale,  overlies  the  lowest  coal.  These 
deposits,  30  to  50  feet  thick,  usually  make  steep  slopes  between  cliffs  of  sandstone  in  the 
escarpments  and  canyons  that  face  toward  the  south  and  cast.  In  sec.  16,  T.  13  S.,  R.  10  E., 
north  of  Price,  they  are  succeeded  by  a  second  coal  bed  8  feet  6  inches  thick. 
A  massive  sandstone  overlies  this  second  coal  bed.  It  is  yellow  to  pink  in  color,  except 
the  upper  15  to  20  feet,  which  is  almost  white.  This  sandstone,  like  that  underlying  the 
lowest  coal,  extends  throughout  the  Book  Cliffs  field.  Its  thickness  is  rarely  below  50 
feel  and  sometimes  approaches  nearly  100  feet. 
A  third  coal  horizon  occurs  immediately  above  this  sandstone  in  sec.  16,  T.  13  S.,  R. 
10  E.,  where  the  rocks  are  naturally  displayed  for  inspection.  Fifteen  feet  of  coal  were 
exposed.  In  Coal  Canyon,  in  T.  13  S.,  R.  11  E.,  a  coal  in  this  position  is  8  feet  thick. 
A  coal  having  approximately  the  same  stratigraphic  position  in  Huntington  Canyon,  in 
see.  2  1,  T.  16  S.,  R.  7  E.,  is  8  feet  thick.  Above  this  third  coal  horizon  there  is  a  uniform 
succession  of  sandstone,  shale,  and  coal,  upward  for  600  to  800  feet  to  the  top  of  what  is 
now  recognized  as  the  coal-bearing  series.  It  is  not  usual  that  the  individual  sandstone 
beds  exceed  10  feet  in  thickness.  Shales  and  sandy  shales  are  usually  concealed  by  talus. 
It  is  estimated  that  the  aggregate  thickness  of  the  shaly  beds  is  nearly  equal  to  that  of 
the  sandstones.  Several  coal  beds,  some  of  workable  thickness,  occur  in  this  series  of 
sandstones  and  shales.  In  the  Book  Cliffs  north  of  Price,  between  Bull  and  Helper  can- 
yons, one  bed  occurs  50  feet  and  another  150  feet  above  the  third  coal  horizon.  In  Coal 
Canyon  six  coal  beds  have  been  exposed  in  a  section  of  rock  360  feet  thick.  The  upper- 
most one,  4  feet  11  inches  thick  and  of  excellent  quality,  appears  to  be  above  the  third 
coal  horizon.  In  Huntington  Canyon  and  in  other  places  in  the  Wasatch  Plateau  coals 
of  workable  thickness  are  known  to  occur  in  the  upper  part  of  the  coal-bearing  series, 
but  little  attention  has  been  paid  to  them  where  coals  4  to  20  feet  thick  occur  lower  in  the 
section  and  are  more  accessible. 
3.  The  coal-bearing  series  of  shale,  sandstone,  and  coal  is  succeeded  by  a  formation  of 
light-yellow  sandstone  that  continues  upward  to  the  base  of  the  Tertiary  deposits  in  the 
crest  of  the  Book  Cliffs  Plateau.     Thin  coal  seams  have  been  seen  at  a  few  places  in  the 
