234  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,    1903.  [btjll.225. 
show  the  depth  of  the  ore  and  the  extent  to  which  it  occurs  in  covered 
areas  and  especially  beneath  the  limestone.  The  underground  work 
has  been  done  largely  to  meet  assessment  requirements,  and  up  to  the 
present  time  there  has  been  no  systematic  underground  exploration  of 
the  deposits  on  a  large  scale.  A  shaft  has  been  sunk  to  a  depth  of 
130  feet  in  ore  in  the  Pinto  group,  and  many  pits  and  drifts  in  this 
area  have  penetrated  a  short  distance  into  the  ore.  On  Desert  Mound 
also  a  large  number  of  pits  have  uncovered  red  earthy  hematite,  but 
have  not  penetrated  far  into  it.  It  might  be  suggested  that  where  the 
ore  seems  to  follow  the  contact  of  andesite  and  limestone  the  depth  of 
the  limestone  ma}^  measure  the  depth  of  the  ore. 
Mining. — It  seems,  then,  that  there  is  a  considerable  quantit}T  of 
high-grade  iron  ore  present  in  this  district  which  can  be  mined  under 
favorable  circumstances  and  undoubtedly  must  be  mined  in  the  future, 
but  it  remains  to  be  seen  whether  or  not  the  conditions  are  such  that 
profit  may  be  derived  from  mining  these  ores  at  the  present  time. 
The  nearest  railway,  the  San  Pedro,  Los  Angeles  and  Salt  Lake  Rail- 
way, running  south  from  Salt  Lake,  passes  about  22  miles  west  of  the 
iron  range.  Parties  interested  in  the  ores  are  now  discussing  the 
feasibilit3T  of  erecting  blast  furnaces  and  steel  plant  at  Utah  Lake  or 
on  Green  River.  Recent  coking  experiments  are  said  to  have  shown 
the  existence  of  coal  suitable  for  coking  within  a  reasonable  distance 
of  these  points.  If  this  be  true,  the  principal  difficulty  to  be  overcome 
is  the  securing  of  a  market  for  the  iron  and  steel  products — a  problem 
in  which  transportation  is  an  important  element. 
Origin  of  the  ores.— Until  the  ore  deposits  are  further  exploited 
and  studied  in  detail,  any^  discussion  of  their  origin  must  be  tentative 
and  perhaps  ought  not  be  attempted.  Yet  certain  features  of  the 
Utah  deposits  seem  to  be  significant  of  the  manner  of  origin,  and  a 
discussion  of  these  features  in  their  relations  to  origin  may  afford  a 
better  understanding  of  the  nature  of  the  deposits. 
The  contrast  between  the  Utah  and  the  Lake  Superior  ores  in 
relation  to  origin  is  striking.  The  Lake  Superior  ores  are  secondary 
enrichments  in  limited  areas  within  extensive  bedded,  sedimentary 
iron  formations.  That  the  Utah  ore  in  its  present  form  is  not  an 
original  sediment  nor  the  alteration  product  of  an  original  sedimentary 
rock  is  taken  to  appear  from  the  following  facts: 
(a)  No  traces  of  an  original  sedimentaiy  formation  are  to  be  observed. 
In  the  much  more  metamorphosed  iron  districts  of  the  Lake  Superior 
region,  where  the  ores  have  resulted  from  the  alteration  of  an  original 
sedimentary  iron  formation,  traces  of  the  original  bedded  iron  forma- 
tion are  always  to  be  found  in  protected  areas.  The  contact  of  the 
ore  with  the  overlying  limestone  shows  no  rock  other  than  ore  and 
limestone,  as  it  would  probably  show  were  a  sedimentary  iron  formation 
originally  present,  judging  from   analogy  with    the   Lake   Superior 
