454  PRE-CAMBRIAN    ROCKS    OF    NORTH    AMERICA.  [bull.  86. 
with  the  ordinary  sediments  of  the  period,  as  rooks  of  similar  origin 
and  composition  certainly  were  in  the  Huronian  and  in  all  later  geologi- 
cal ages,  a  fact  which  has  been  singularly  overlooked  or  ignored  by 
most  writers  on  American  geology. 
At  present  we  have  in  Canada  no  evidence  which  would  warrant  us 
in  making  more  than  two  great  divisions  in  the  Archean  crystalline 
rocks.  In  many  parts,  especially  in  the  eastern  provinces,  it  has  been 
found  impossible  to  define  even  these  clearly.  Rocks  of  typical  Lauren- 
tian  character  are  there  so  intimately  associated  with  others  of  equally 
typical  Huronian  characters,  and  in  such  constant  alternations,  that  in 
mapping  them  they  could  not  be  separated,  and  are  therefore  all  classed 
as  Archean  or  pre-dimbrian. 
Whitney  and  Wadswobth,15  in  1884,  after  a  very  wide  but  dis- 
proportionate review  of  the  literature  of  the  pre-Potsdam  rocks,  conclude 
that  it  is  impossible  for  any  unprejudiced  worker  in  this  department  of 
science  to  peruse  with  care  the  pages  given  and  not  be  obliged  to  ad- 
mit that  the  geology  of  a  large  portion  of  this  country,  and  especially 
that  of  Canada  and  New  England,  is  in  an  almost  hopeless  state  of  con- 
fusion. The  belief  is  justified  that  our  chances  of  having  at  some  future 
time  a  clear  understanding  of  the  geological  structure  of  northeastern 
North  America  would  be  decidedly  improved  if  all  that  were  written 
about  it  were  at  once  struck  out  of  existence.  While  not  desiring  to 
conceal  the  fact  that  some  of  the  problems  presented  in  the  course  of 
the  study  of  the  older  rocks  are  extremely  difficult,  it  is  clearly  proved 
that  want  of  knowledge,  want  of  experience,  and  a  desire  to  produce 
sensational  theories,  have  brought  about  this  condition  of  confusion. 
In  reference  to  Azoic  rocks,  there  are  several  classes  to  which  this 
term  may  be  applied.  First,  it  may  be  applied  to  strata  once  fossilif- 
erous  in  which  the  evidences  of  life  have  disappeared.  Second,  rocks 
may  be  Azoic  even  if  laid  down  when  life  was  existing  on  the  globe, 
provided  the  local  conditions  were  not  favorable  to  its  development  at 
the  particular  locality  under  consideration.  Third,  rocks  must  neces- 
sarily be  Azoic  when  formed  or  originating  under  such  a  condition  as 
were  incompatible  with  the  existence  of  life.  Such  was  the  original 
crust  of  the  earth  and  the  volcanic  eruptive  rocks.  Fourth,  we  may 
have  rocks  formed  under  such  conditions  as  were  not  inimical  to  life, 
but  yet  Azoic,  because  life  had  not  begun  to  exist  on  the  globe  at  the 
time  of  their  deposition.  These,  according  to  our  view,  would  be  the 
rocks  properly  designated  by  the  term  "Azoic,"  and  the  body  of  rocks 
having  this  character  might  properly  be  called  the  "Azoic  System." 
And  we  think  that,  in  view  of  what  has  here  been  set  forth,  no  one 
will  deny  that  it  is  important  that,  if  there  are  such  rocks,  they  should 
have  a  special  designation,  and  that  the  term  "Azoic n  would  be  a 
proper  one  to  apply  to  them. 
This,  however,  is  exactly  what  was  done  by  Foster  and  Whitney  in 
1850,  when  they  gave  the  name  of  the  "Azoic  System  "  to  a  body  of 
