vanhise]  DISCUSSIONS    OF    PRINCIPLES.  507 
THE   QUARTZITE   MOUNTAINS. 
In  the  Quartzite  mountains  the  Algonkian  is  represented  by  a  series 
of  quartzites,  interstratined  with  slates  Several  thousand  feet  thick. 
The  series  had  suffered  powerful  dynamic  action,  being  turned  on  end 
and  deeply  truncated  before  Carboniferous  time.  The  relations  of  this 
series  to  the  Archean  are  not  certainly  knoAvn,  but  all  the  evidence 
points  toward  the  conclusion  that  the  Algonkian  is  of  later  age  and 
that  between  it  and  the  Archean  is  a  great  unconformity. 
GRAND  CANYON  OF  THE  COLORADO. 
The  Algonkian  in  the  Grand  canyon  region  is  represented  by  three 
series,  the  Chuar,  the  Grand  canyon,  and  the  Vishnu.  The  dinar 
series  consists  of  shales  and  limestones,  over  5,000  feet  thick.  It  con- 
tains a  fauna  of  a  pre-Cambrian  type,  including  at  least  five  distinct 
forms.  The  Grand  canyon  series  is  of  sandstones,  with  basic  lava  flows 
in  its  upper  part,  and  is  nearly  7,000  feet  thick.  The  Vishnu  series  con- 
sists of  bedded  quartzites  and  schists,  cut  by  intrusive  granite,  and  is 
known  to  be  at  least  1,000  feet  thick,  but  how  much  thicker  has  not- 
been  determined,  as  it  has  not  been  measured  to  its  base.  The  Chuar 
rests  upon  the  Grand  canyon  and  between  the  two  is  a  minor  uncon- 
formity. The  Grand  canyon  rests  upon  the  Vishnu  and  between  the 
two  is  another  unconformity.  The  Ohuar  and  Grand  canyon  sediments 
are  wholly  unmetamorphosed,  while  the  Vishnu  sediments  are*  indurated 
quartzites  and  semicrystalline  schists.  Between  these  series  as  a  whole 
and  the  underlying  Archean  complex  is  a  very  great  unconformity. 
Between  the  Ohuar  and  the  Tonto  sandstone  (Upper  Cambrian)  there 
is  another  unconformity  sufficient  to  have  caused  the  cutting  across  of 
at  least  10,000  feet  of  the  flexed  beds  of  the  Grand  canyon  and  Ohuar 
series.  In  this  region  is  the  fullest  known  succession  of  Algonkian 
rocks  in  the  United  States,  with  the  exception  of  the  lake  Superior  re- 
gion. The  statement  would  not  be  warranted  that  the  series  here  found 
stand  as  the  equivalent  of  like  series  in  the  latter  region,  but  there  is 
a  remarkable  lithological  likeness  both  in  the  detrital  and  eruptive  ma- 
terial of  the  Ohuar  and  Grand  canyon  to  the  Keweenawan.  Also  these 
series  occupy  a  position  of  unconformity  below  the  Upper  Cambrian,  as 
does  the  Keweenawan,  and  is  separated  by  an  unconformity  from  a 
series  of  quartzites  and  quartz- schists  which  are  analogous  to  the 
Huronian.  This  latter,  Vishnu  series,  is  not  well  known,  so  that  it  is 
unsafe  to  assert  whether  it  is  nearer  like  the  Lower  or  the  Upper 
Huronian  of  the  lake  Superior  region. 
BRITISH   COLUMBIA. 
The  recent  work  of  Dawson  appears  to  show  that  in  British  Colum- 
bia there  is  a  widespread  series  of  Algonkian  of  great  thickness.  It 
consists  of  argillites,  argillite -schists,  quartzites,  conglomerates,  and 
