COPPER  IN  THE  RED  BEDS  OF  THE  COLORADO  PLATEAU 
REGION." 
By  S.  F.  Emmons. 
The  singular  frequency  and  world-wide  distribution  of  copper  ores 
n  the  "  Red  Beds "  of  the  rather  ill-defined  Permian  and  Triassic 
lorizons  has  long  been  a  subject  of  remark  among  geologists.  The 
nanner  of  occurrence  of  these  ores  is  generally  such  as  to  afford  no 
rery  decided  evidence  as  to  their  origin,  and  not  unnaturally  there 
las  been  a  very  wide  divergence  of  opinion  upon  this  subject  among 
hose  who  have  had  opportunity  to  study  them. 
I  have  taken  as  my  text  for  some  general  remarks  upon  this  class 
>f  deposits  certain  copper  ores  which  came  under  my  observation 
luring  the  past  summer  in  the  region  of  the  Grand  Canyon  of  Ari- 
ona.  These  ores  occur  in  the  stratified  rocks,  apparently  uncon- 
lected  with  any  igenous  intrusions,  and  their  genesis  seems  particul- 
arly obscure.     I  can  hardly  pretend,  in  view  of  the  very  limited  time 
was  able  to  devote  to  these  observations,  to  throw  any  new  or  very 
ecided  light  upon  the  moot  question  as  to  the  origin  of  this  class 
>f  deposits,  but  I  have  thought  that  it  might  be  useful  to  the  active 
vorkers  in  this  field  to  have  brought  to  their  attention  some  of  the 
xroblems  involved. 
I  have  called  the  Permian  and  Trias  rather  ill-defined  formations, 
>ecause,  in  this  country  especially,  paleontologists  often  find  it 
lifficult  to  draw  the  line  between  the  two.  As  is  often  the  case  in 
rur  geological  nomenclature,  the  respective  names  have  lost  their 
>riginal  meaning.  The  Permian  takes  its  name  from  the  Russian 
Province  in  which,  in  the  opinion  of  many  geologists,  it  is  not  typi- 
ally  developed,  and  consists,  in  part  at  least,  of  Triassic  sediments. 
The  Trias,  or  three-membered  formation,  consists,  in  middle  Ger- 
nany,  it  is  true,  of  three  prominent  members — a  lower  sandstone 
iBuntsandstein),  a  middle  marine  limestone  (Muschelkalk),  and  an 
ipper  sandstone  and  shale  (Keuper),  but  this  triple  lithological 
livision  rarely  obtains  outside  of  that  country. 
<*  Read  before  the  Geological  Society  of  Washington,  November  9,  1904. 
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