382         CONTRIBUTIONS   TO   ECONOMIC   GEOLOGY,   1907,   PART   II. 
lenses  of  gray  limestone  and  white  gypsum,  and  about  400  feet  of 
massive  gray  limestone  at  the  base.  Marine  Jurassic  fossils  occur 
abundantly  in  the  lower  limestone,  but  no  remains  of  life  have  yet 
been  found  in  the  upper  strata.  The  lithology  and  stratigraphic 
relations  of  these  upper  rocks  suggest,  however,  their  equivalence  to 
the  fresh-water  Jurassic  beds  (Morrison)  that  are  well  developed  in 
other  parts  of  the  Rocky  Mountain  region.  These  rocks  are  delim- 
ited above  by  an  erosional  unconformity,  marked  by  the  varying 
thickness  of  the  Jurassic  and  by  a  basal  Cretaceous  conglomerate. 
Throughout  the  Plateau  Province  Lower  Cretaceous  time  is  unrep- 
resented by  rocks,  and  Upper  Cretaceous  strata  lie  directly  upon 
beds  of  Jurassic  age.  In  the  area  under  consideration  the  Upper 
Cretaceous  rocks  consist  of  about  3,000  feet  of  buff  sandstone  and 
drab  shale,  in  the  lower  part  of  which  coal  beds  of  workable  thick- 
ness occur.  No  Dakota  fossils  have  been  found  in  this  area,  although 
possibly  the  thin  bed  of  conglomerate  at  the  base  of  the  Cretaceous 
is  of  that  age.  The  greater  part  of  the  Cretaceous  rocks,  including 
the  coal,  are  assigned  to  the  Colorado,  but  the  upper  few  hundred 
feet  contains  fresh-water  shells  and  plants  of  undetermined  age, 
which  may  possibly  belong  to  the  Montana.  The  succession  of  Cre- 
taceous strata  in  the  southern  Utah  region  is  unlike  that  in  western 
Colorado  and  northeastern  Utah,  so  that  the  formation  names  used 
in  the  coal  fields  of  those  areas  can  not  be  applied  to  the  rocks  in  the 
area  under  consideration.  The  coal  in  southern  Utah  is  older  than 
that  in  the  Uinta  Basin  region,  which  includes  the  Book  Cliffs  field, 
the  largest  and  most  important  in  the  State.  The  southern  Utah 
coal  belongs  to  the  same  group  as  that  in  the  Weber  River  field. 
The  Cretaceous  rocks  are  unconformably  overlain  by  Eocene 
strata,  which,  as  already  stated,  outcrop  in  the  Pink  Cliffs  and  under- 
lie the  Markagunt  and  Paunsagunt  plateaus.  The  unconformity, 
marked  by  a  basal  conglomerate  containing  pebbles  of  the  underly- 
ing rocks,  is  emphasized  by  the  absence  of  the  upper  members  of  the 
Cretaceous  system,  which  are  well  developed  in  other  parts  of  the 
Plateau  province.  The  Eocene  rocks  consist  of  a  variable  succes- 
sion of  shale,  limestone,  sandstone,  and  conglomerate  that  are  char- 
acteristically varicolored.  Shades  of  red  and  white  predominate  and 
are  beautifully  developed  in  the  Pink  Cliffs.  Fossils  are  extremely 
rare  in  these  rocks,  and  only  a  few  fragments  of  Vivipara  and  TJnio 
have  been  obtained  in  this  area;  but  the  characteristic  peculiarities 
of  stratigraphy  and  coloring  of  the  rocks  leave  little  room  for  doubt 
that,  except  possibly  a  few  feet  of  basal  beds  containing  conglomer- 
ate of  doubtful  significance,  they  belong  to  the  Wasatch  formation 
of  the  Eocene  series,  which  is  so  largely  developed  in  the  High  Pla- 
teaus of  Utah  and  from  which  characteristic  fossils  have  been  obtained 
in  a  number  of  places. 
