THE   CORDILLERAS.  867 
folded  with  the  crystalline  schists  to  the  east  that  only  detailed  work 
can  establish  their  real  structural  relations.  Near  Kettle  River  these 
rocks  are  overlain  by  younger,  possibly  Tertiary,  lavas. 
Along  Kettle  River  south  of  Cascade  City  is  exposed  granitic  gneiss 
associated  with  mica  schist,  quartz  schist,  and  highly  metamorphosed 
crystalline  limestone.  These  rocks  extend  westward  almost  to  the 
northward-flowing  stretch  of  the  Kettle  River  between  Curlew  and 
Nelson.  On  lithological  grounds  they  are  supposed  to  be  pre- 
Cambrian. 
West  of  Nelson  and  Curlew  for  a  distance  of  30  miles  the  prevailing 
rocks  are  volcanics  of  unknown  age,  resembling  somewhat  those  be- 
tween Columbia  and  Kettle  rivers.  There  are  probably  at  least  two 
series  present — older,  compressed,  and  somewhat  metamorphosed  rocks 
being  overlain  by  what  may  be  a  Tertiary  andesitic  series.  Within 
this  area,  however,  is  an  island-like  mass  of  gneiss,  mica  schists,  and 
crystalline  schistose  limestone,  which  is  about  7  miles  wide  between 
Curlew  and  Midway,  and  extends  as  a  narrowing  band  southward, 
passing  a  few  miles  west  of  Republic.  On  lithological  grounds  the 
gneiss  and  schistose  rocks  may  be  assigned  with  some  probability  to 
the  pre-Cambrian. 
About  5  miles  west  of  Chesaw,  or  10  miles  east  of  Lake  Osoyoos, 
there  is  a  change  from  much-fissured  argillites,  slaty  green  tuffs,  fine- 
grained epidotized  eruptives  and  lenses  of  limestone  to  crystalline 
schists  and  granitic  gneisses.  The  gneiss  widens  greatly  to  the  south 
and  becomes  the  dominant  rock  between  Republic  and  Okanogan 
River.  It  possibly  connects  with  the  body  of  gneiss  which  crosses 
Kettle  River  between  Curlew  and  Midway.  It  is  provisionally  re- 
garded as  pre-Cambrian,  though  detailed  work  is  required  to  estab- 
lish its  relation  to  the  rocks  about  its  borders. 
OREGON. 
Lindqren,158  in  1901,  describes  and  maps  the  geology  of  the  gold 
belt  of  the  Blue  Mountains  of  Oregon.  Gneiss  referred  to  the  Arch- 
ean  occurs  northwest  of  Sumpter,  above  La  Belleview  mine. 
For  description  of  the  schists  in  the  Klamath  Mountains  of  Oregon, 
which  are  related  to  the  supposedly  Algonkian  of  California,  see 
page  874. 
CALIFORNIA,   WITH    ADJACENT   PARTS   OF    NEVADA    AND   ARIZONA. 
Dana,159  in  1849,  describes  various  crystalline  rocks  in  the  Umpqua 
and  Shasty  ranges.  These  include  granite,  syenite,  porphyry,  talcose 
rocks,  and  serpentine.  The  hornblendic  and  talcose  rocks  are  rarely 
schistose.  Associated  with  the  former  rocks  are  conglomerates  and 
sandstones. 
