18  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1906,  PART    T. 
Mr.  Ransome's  accident  had  incapacitated  him  for  further  field  work 
this  season,  W.  PL  Emmons  was  sent  to  the  region  after  he  had  com- 
pleted his  field  work  in  Montana,  and  is  now  studying  the  geology  of 
the  region  at  and  near  Rhyolite.  As  soon  as  he  is  able  Mr.  Ransome 
will  resume  his  field  work  in  Nevada,  and,  it  is  hoped,  will  complete 
the  report  upon  this  region  before  the  opening  of  the  new  field  season. 
Under  the  circumstances  no  abstract  of  this  report  has  be 311  possible. 
OREGON. 
In  connection  with  area!  work  in  western  Oregon,  G.  K.  Kay  has 
made  a  new  examination  <>('  the  interesting  deposits  of  silicate  of  nickel 
near  Riddles,  an  account  of  which  appears  in  this  bulletin.  These 
deposits  have  heretofore  excited  considerable  interest  because  of  their 
close  mineralogical  and  geological  resemblance  to  the  famous  deposits 
of  New  Caledonia,  which,  up  to  comparatively  recent  times,  have  fur- 
nished a  large  proportion  of  the  world's  production  of  nickel. 
The  deposits  are  evidently  of  secondary  origin,  but  have  not  yet 
been  found  in  bodies  sufficiently  large  to  be  of  great  economic  value. 
There  seems  to  be,  however,  no  good  reason  why  exploration  may  not 
develop  ore  in  amounts  large  enough  to  constitute  a  profitable  soured 
of  the  metal,  but  such  discovery  is  rather  the  work  of  the  prospector 
than  of  the  geologist,  since  in  a  region  so  highly  altered  it  is  only  by 
actual  mine  openings  that  the  localities  of  ore  concentration  can  be 
detected. 
UTAH. 
During  the  last  summer  the  writer  was  engaged  for  a  few  weeks  in 
studying  the  geological  structure  of  the  western  Uinta  Mountains, 
especially  of  the  region  around  Duchesne  River,  on  the  southern  flanks 
of  the  range  an  area  that  once  formed  part  of  the  Indian  reserva- 
tion but  has  recently  been  thrown  open  to  occupation  as  mineral  land. 
Deposits  of  iron  ore  of  good  (jualityand  size,  as  well  as  small  amounts 
of  otlier  metals,  have  long  been  known  to  exist  in  this  region,  hut  no 
deposit  of  great  economic  value  has  yet  been  found.  The  range  is 
remarkable  for  the  entire  absence  of  igneous  rocks,  the  only  known 
occurrence  of  which  are  late  intrusive  sheets  in  the  Mesozoic  bed! 
along  the  Provo  Valley,  at  the  extreme  western  end  of  the  range.  All 
the  important  deposits  of  metals  except  the  lead  and  zinc  deposits  of 
the  Mississippi  Valley  are  found  in  regions  that  are  traversed  by  igne- 
ous rocks,  and  for  this  reason  the  Uinta  Mountains  can  hardly,  on 
theoretical  grounds,  be  considered  a  very  favorable  locality  for  the 
occurrence  of  these  or  the  more  valuable  metals.  The  result  of  the 
writer's  visit  was  negative,  since  he  found  no  evidence  of  any  con- 
siderable mineralization, 
