vVEBER    RIVER    COAL    FIELD,    UTAH.  287 
nearly  3,000  feet  northeast  of  the  Wasatch  mine.  It  crosses  the  township  line  near  the 
center  of  the  north  side  of  sec.  3,  T.  2  N.,  R.  5  E.  This  fault  has  limited  operations 
in  the  Wasatch  mine  toward  the  north.  Minor  faulting  and  belts  of  fractured  strata  are 
found  frequently  in  the  mines. 
In  Dexter  Hollow  and  at  the  Dexter  mine,  1  mile  southeast  of  Coalville,  the  rocks  dip 
16°  SE.  Between  Dexter  Hollow  and  Spring  Canyon,  1  and  2  miles,  respectively,  south- 
southeast  of  Coalville,  the  dips  are  eastward.  As  Spring  Canyon  is  ascended  eastward  2 
miles  from  Weber  River  Valley,  the  rocks  are  seen  to  dip  successively  northward  and  then 
northwestward.  These  observations  indicate  that  a  basin-like  fold  bears  eastward  from 
Weber  River  Valley  in  the  central  part  of  T.  2  N.,  R.  5  E.  Between  this  fold  and  the  north- 
westerly dipping  rocks  at  Coalville  the  structure  is  anticlinal  and  the  rocks  are  probably 
faulted.  Exposures  of  the  rocks  are  insufficient,  however,  to  reveal  the  character  of  the 
structure, 
COAL. 
There  are  certainly  three  and  probably  four  coal  beds  mined  or  prospected  in  the  region 
of  Coalville.  These  coals  will  be  considered  in  the  order  of  stratigraphic  succession  and,  as 
it  happens,  at  the  same  time  in  the  order  of  economic  importance. 
Wasatch  coal. — The  first  of  these  coals  may  be  called  the  Wasatch  coal,  from  the  Wasatch 
mine,  now  in  operation,  2  miles  northeast  of  Coalville,  The  coal  here  has  been  removed 
from  an  area  4,000  feet  on  the  strike  by  750  feet  in  the  direction  of  the  dip.  The  coal  is 
massive,  and  varies  in  thickness  between  9  and  14  feet.  A  sandstone  bed  40  feet  thick 
forms  the  roof.  The  floor  is  a  dense  clay,  and  is  underlain  by  a  bed  of  bony  coal,  the 
thickness  of  which  has  not  been  determined.  The  coal  mines  in  block,  is  moderately  hard, 
and  appears  to  be  a  fair  grade  of  the  bituminous  variety.  In  the  proximity  of  faults  and 
zones  of  shearing  that  are  of  common  occurrence  the  coal  has  suffered  considerable  crush- 
ing.    In  such  places  it  is  rendered  weak  and  considerable  slack  and  soft  coal  is  produced. 
The  same  coal  is  mined  on  Grass  Creek,  7  miles  northeast  of  Coalville,  in  sec  18,  T.  3  N., 
R.  G  E.  The  Grass  Creek  coal  is  the  same  bed  as  that  of  the  Wasatch  mine.  Massive 
sandstone  40  feet  thick  overlies  it.  The  coal  is  usually  8  feet  thick,  but  swells  locally  to 
12  feet.  In  this  mine,  as  in  the  Wasatch,  the  coal  is  much  jointed  and  broken  by  faults. 
Water  enters  the  mine  freely  through  the  joints  and  fault  fissures,  requiring  constant 
pumping.  Because  of  excessive  water  the  pillars  are  being  drawn  in  the  mine  preparatory 
to  moving  operations  one-fourth  mile  to  the  southwest. 
The  outcrop  of  the  same  coal  follows  Grass  Creek,  and  has  been  mined  at  a  number  of 
localities  down  the  valley,  from  sec  IS,  T.  3  N.,  R.  6  E.,  to  sec  27,  T.  3  N.,  R.  5  E.,  where 
it  is  interrupted  by  a  dip  fault  which  displaces  the  outcrop  of  the  coal  toward  the  south- 
east. The  coal  has  been  mined  at  seven  or  more  places  along  Grass  Valley  within  a  dis- 
tance of  4  miles  below  the  Grass  Valley  mine,  but  all  have  been  abandoned.  The  Union 
Pacific  Railroad  was  the  chief  operator,  but  it  is  reported  to  have  abandoned  the  work 
here  in  favor  of  better  property  in  the  Wyoming  field.  The  Wasatch  coal  was  mined  also 
in  the  town  of  Coalville  and  for  a  time  a  mile  northwest  of  town  near  the  strike  fault,  but 
these  operations  have  been  abandoned. 
Dexter  coal. — A  coal  bed  is  being  developed  by  the  Dexter  Brothers,  1  mile  southeast  of 
Coalville,  in  the  SE.  \  sec.  16,  T.  2  N.,  R.  5  E.  It  is  presumed  by  some  that  this  bed  is 
the  same  as  the  Wasatch  coal,  but  the  identity  of  the  two  beds  is  not  proved  by  surface 
indications.     The  section  at  the  Dexter  mine  seems  to  be  as  follows: 
Section  at  Dexter  mine,  1  mile  southeast  of  Coalville,  Utah. 
Feet. 
Sandstone,  full  thickness  not  determined. 
Shales,  roof  of  coal,  reported  to  contain  fossil  shells 4 
Coal,  upper  bed 7 
Shale 4 
Coal,  lower  bed 7 
Clay  shale 4 
