•       THE   CORDILLERAS.  865 
extended  to  include  also  the  Algonkian  quartzites  of  southwestern 
Colorado  and  of  the  Grand  Canyon. 
The  wide  extent,  thickness,  comparative  uniformity,  and  lack  of 
deformation  of  the  Belt  series  make  it  unique  among  the  pre-Cam- 
brian  series  of  North  America.  When  first  studied  it  was  supposed 
throughout  to  be  a  conformable  downward  gradation  from  the  Cam- 
brian. Subsequent  work  showed  that  in  Montana  at  least  there  was 
an  actual  structural  unconformity.  This  has  not  been  found  in  the 
Uintas,  the  Wasatch,  or  British  Columbia. 
Under  the  classification  here  used  the  Belt  series  is  late  Algon- 
kian; the  Cherry  Creek  group  is  probably  earlier  Algonkian;  the 
Archean  is  presumably  represented  by  a  part  of  the  old  granite- 
gneiss-schist  complex  of  southwestern  Montana,  but  it  has  not  yet 
been  proved  to  be  unconformable  below  the  Cherry  Creek  group. 
SECTION   10.     WASHINGTON,   OREGON,   AND    CALIFORNIA. 
SUMMARY    OF   LITERATURE. 
WASHINGTON. 
Gibbs,153  in  1855,  states  that  in  central  Washington,  in  the  valley 
of  the  Methow,  is  found  granite,  syenite,  and  gneiss,  well  character- 
ized and  blended  with  one  another.  The  syenite  is  often  divided  by 
joints  so  as  almost  to  appear  stratified  and  to  give  its  perpendicular 
walls  the  semblance  of  artificial  construction.  The  gneiss  is  found 
both  horizontal  and  displaced  by  the  intrusion  of  trap.  Along  Co- 
lumbia River  Avas  found  syenite,  granite,  gneiss,  quartzose  rocks,  tal- 
cose  slate,  and  greenstone. 
Russell,154  in  1900,  describes  the  schists  of  the  northern  Cascades 
and  states  that  they  are  lithologically  similar  to  xVrchean  schists  of 
the  eastern  portion  of  North  America.  Metamorphic  rocks  of  this 
type  on  the  Pacific  coast,  however,  are  known  to  be  of  Mesozoic  age, 
and  these  schists  of  the  Cascades  are  presumably  Paleozoic  or  post- 
Paleozoic. 
Landes,155  in  1002,  outlines  the  geology  of  Washington.  Meta- 
morphic rocks  of  unknown  age,  but  some  of  them  possibly  Archean, 
occupy  a  large  portion  of  the  State,  being  frequently  met  with 
throughout  the  Cascades,  from  Stampede  Pass  northward  to  the  Brit- 
ish  Columbia  boundary,  and  from  near  Puget  Sound  eastward  across 
the  Cascade  Mountains  and  the  Okanogan  highlands  to  the  Idaho 
line.  The  ordinary  varieties  of  metamorphic  locks  in  Washington 
are  gneiss,  schist,  marble,  slate,  and  quartzite. 
Smith  (G.  0.)>156  in  1903,  considers  the  East  on  schist  the  oldest 
rock  in  central  Washington,  and  describes  it  as  commonly  a  quartz 
mica  rock  extremely  crumpled  and  gashed  and  seamed  with  quartz. 
5r)T2L— Bull.  360—09 55 
