THE   CORDILLERAS.  879 
Lake  series  in  the  vicinity  of  Shuswap  Lake.  The  upper  limit  of 
the  Nisconlith  series  is  believed  to  be  somewhat  below  that  assigned 
on  lithological  grounds  to  the  Bow  Kiver  series.  The  Adams  Lake 
series  lie  above  the  Nisconlith.  The  Nisconlith  series,  resting  upon 
the  Shuswap  series,  consists  of  15,000  feet  of  dark-gray  or  blackish 
argillite  schists  or  phyllites,  usually  calcareous,  and  toward  the  base 
with  one  or  more  beds  of  nearly  pure  limestone  and  a  considerable 
thickness  of  gray  flaggy  quartzites.  These  beds  have  also  been 
recognized  in  the  southern  part  of  the  West  Kootenai  district  and 
in  the  western  portion  of  the  interior  plateau  of  British  Columbia. 
The  Adams  Lake  series  consists  chiefly  of  green  and  gray  chloritic, 
felspathic,  sericitic,  and  sometimes  nacreous  schists,  greenish  colors 
preponderating  in  the  lower  and  gray  in  the  upper  parts  of  the 
.section. 
McConnell,189  in  1902,  describes  the  granite  gneiss  of  the  upper 
part  of  the  Yukon  Valley,  extending  from  Nordenskiold  River  in  a 
northwesterly  direction  across  the  White  River  valley  to  the  Tanana 
and  down  this  stream  to  near  the  mouth  of  Delta  River,  a  total  dis- 
tance of  about  380  miles,  and  concludes  that  part  of  the  gneisses  at 
least  must  be  regarded  as  intrusive  through,  and  therefore  younger 
than,  the  clastic  schists  associated  with  them.tt  It  is  still  possible, 
however,  as  the  work  done  so  far  has  been  largely  of  an  exploratory 
character,  that  older  gneisses  may  be  present  in  the  district,  but  no 
evidence  of  this  was  obtained  in  the  course  of  the  investigation. 
McConnell,100  in  1902,  1903,  1904,  and  1905,  summarizes  the  results 
of  his  exploration  in  the  Yukon  territory  and  makes  frequent  refer- 
ence to  the  character  and  distribution  of  the  schists,  gneisses,  and 
granites  in  this  region,  but  expresses  no  opinion  as  to  whether  they 
are  of  pre-Cambrian  or  post-Cambrian  age.  The  general  tendency 
of  recent  work  has  been  to  throw  emphasis  upon  the  Cambrian  or 
post-Cambrian  age  of  such  rocks. 
Daly,191  in  1902,  1903,  1904,  and  1905,  reports  on  the  geology  of 
the  international  boundary  region.  West  of  Midway  is  a  great  group 
of  phyllites,  slates,  quartzites,  chloritic  slates,  and  amphibolites, 
with  highly  altered  limestone  and  true  volcanic  bands,  and  probably 
also  crystalline  limestone,  in  which  no  fossils  were  found.  Intrusive 
into  this  is  a  great  batholith  of  granite,  granodiorite,  and  quail/ 
diorite. 
The  southern  Selkirk  country,  between  Salmon  River  and  the 
western  boundary  crossing  of  Kootenai  River,  is  underlain  in  its 
eastern  part  by  a  great  series  of  crystalline  schists — biotite  schist. 
a  It  might  bo  added  that  Prindle's  Investigations  in  the  Yukon-Tanana  province  con- 
firm the  work  of  McConnell  in  indicating  the  intrusive  characteristics  of  the  granite 
forming  the  so-called  "  basal   complex."      (Unpublished   notes.) 
