HARMONY,    COLOB,   AND    KANAB   COAL  FIELDS,    UTAH. 
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GEOLOGY. 
GENERAL  OUTLINE. 
A  large  part  of  the  High  Plateaus  of  Utah  is  composed  of  an  igneous 
complex  consisting  of  lava  sheets,  beds  of  tuff  and  volcanic  conglom- 
erate, and  intrusive  masses  of  various  types.  These  rocks  in  general 
overlie  an  eroded  surface  of  Eocene  strata  which  outcrop  at  lower  ele- 
vations around  the  igneous  uplands.  Beneath  the  Tertiary  rocks 
there  are  several  thousand  feet  of  practically  horizontal  Mesozoic  and 
Paleozoic  strata  which  outcrop  at  successive  lower  elevations  in  a 
series  of  benches  that  extend  southward  from  the  High  Plateaus  to 
the  platform  in  which  Colorado  River  has  cut  the  Grand  Canyon. 
The  Markagunt  and  Paunsagunt  plateaus  are  underlain  by  Eocene 
beds,  the  southernmost  extent  of  which  is  marked  by  their  outcrop 
in  the  Pink  Cliffs.  The  next  succeeding  bench  is  underlain  by  Cre- 
taceous strata;  rocks  of  Jurassic  age  underlie  the  Colob  Plateau;  and 
older  rocks  down  to  the  Carboniferous  are  exposed  along  the  western 
base  of  the  plateau.  Coal  occurs  in  the  lower  part  of  the  Cretaceous 
system  and  is  of  Colorado  age. 
STRATIGRAPHY. 
In  the  southern  Utah  coal  region  the  rocks  are  chiefly  sedimen- 
tary, ranging  in  age  from  Carboniferous  to  Eocene.  There  are  also 
local  intrusive  masses  and  lava  flows.  As  is  general  throughout  the 
Rocky  Mountain  province,  the  coal-bearing  rocks  are  of  Cretaceous 
age,  and  in  the  present  preliminary  report  it  will  suffice  to  limit  the 
description  to  the  coal  measures  and  to  the  immediately  overlying 
and  underlying  formations,  which  are  outlined  in  the  following  table: 
Outline  of  coal-bearing  and  associated  rocks  in  the  southern  Utah  coal  region. 
System. 
Scries. 
Formation. 
Thick- 
Character,                  ness  in 
feet. 
Tertiary 
Eocene 
Wasatch 
Varicolored     shale,     lime- 
stone,    sandstone,     and 
conglomerate. 
Hull'   sandstone  and  drab 
shale. 
Buff  sandstone   and   drab 
shale,  including  workable 
beds  of  coal  in  the  lower 
part. 
Varicolored  shale  and  sand- 
stone, with  lenses  of  lime- 
stone and  gypsum  over- 
lying    massive     marine 
limestone. 
500+ 
Upper  Cretaceous . . 
Unconfonnit  v. 
[Montana  (?) 
500 
Cretaceous.. . 
2,500 
Jurassic 
Unconformity. 
800-*- 
The  coal-bearing  strata  are  underlain  by  about  800  feet  of  gener- 
ally soft  rocks,  which  outcrop  in  a  lowland  belt  below  the  Cretaceous 
platform.  These  lower  rocks  are  composed  of  reddish  and  varicol- 
ored shale  and  thin-bedded  sandstone,  with  intercalated  beds  and 
