GENERAL  ACCOUNT    OF    THE    PRE-CAMBRIAN    ROCKS.  57 
the  number  of  certainly  recognized  divisions  of  sedimentary  rocks  of 
pre-Cambrian  age  are  precisely  the  same  as  in  the  Lake  Superior 
region.  Willis  suggests  that  the  three  lower  groups,  which  he  places 
in  the  Wu-t'ai  series,  are  equivalent  to  the  Huronian  of  the  Lake 
Superior  region,  which  also  is  divisible  into  throe  unconformable 
parts.  This  would  leave  the  Hu-t'o  series  to  be  correlated  with  the 
Keweenawan.  It  would  not  be  Avell  to  emphasize  too  strongly  this 
close  correlation  suggested,  but  certainly  the  similarity  of  the  suc- 
cession is  astonishing  and  suggests  the  possibility  that  in  the  future 
we  may  be  able  to  correlate  the  unconformable  series  in  the  Algon- 
kian  in  provinces  separated  as  far  from  one  another  as  the  Lake 
Superior  region  and  northern  China.  The  similarity  of  the  succes- 
sion in  Finland  gives  additional  emphasis  to  this  suggestion. 
In  the  classification  of  the  Algonkian  presented  by  Willis  for 
China  he  introduces  into  the  nomenclature  of  the  pre-Cambrian  the 
words  neo-Proterozoic  and  eo-Proterozoic.  We  question  this  prac- 
tice, since  we  can  see  no  philosophical  basis  upon  which  such  a 
division  can  be  made,  nor  do  the  facts  as  they  occur  in  the  field  seem 
to  us  to  require  any  such  division. 
JAPAN. 
The  Imperial  Geological  Survey  of  Japan  outlines  the  geology  of 
Japan."  At  the  base  of  the  column  is  the  Archean  group  (in  the 
sense  of  pre-Paleozoic),  sedimentary  phases  of  which  occupy  3.4  per 
cent  of  the  total  area  of  Japan.  The  group  comprises  two  systems. 
The  lowest,  the  gneiss  system,  consists  of  gneiss,  schists,  and  am- 
phibolites,  with  intercalated  limestone  and  granulites.  It  is  de- 
scribed as  similar  in  lithological  character  to  the  Laurentian  of  North 
America  and  to  the  oldest  rocks  found  in  Korea,  China,  and  Siberia. 
The  succeeding  system,  called  the  crystalline  schists,  consists  of 
various  schists  of  a  phyllitic  aspect,  accompanied  by  serpentine  and 
gabbro  eruptives  but  not  by  granitic  eruptives.  The  junction  between 
the  crystalline  schist  system  and  the  gneiss  system  is  generally  in- 
dicated by  faults.  The  crystalline  schist  system,  according  to  the 
Japanese  geologists,  may  correspond  to  the  Algonkian  of  North 
America  or  to  the  phyllite  system  of  Europe,  but  nothing  can  be 
said  as  regards  the  correlation,  as  the  oldest  fossiliferous  series  of 
the  Paleozoic  group  has  not  yet  been  found  in  Japan. 
GENERAL. 
This  brief  and  imperfect  summary  of  the  pre-Cambrian  of  other 
countries  than  North  America  brings  out  the  significant   fact   thai 
"  Outlines  of  the  seolo.uy  of  Japan,  descriptive  text,  with  geological  map  of  Japan,  com- 
piled by  officials  of  the  Imperial   Geological  Survey  of  Japan,  Tokyo,    L902. 
