van  HTSE.l  LAKE    SUPERIOR    REGION.  163 
even  yet  to  see  clearly  all  the  results  which  legitimately  follow  from  the 
work  d  one.  The  crude  notion  that  the  sandstones,  traps  Jaspers,  guei  sses, 
granites,  and  all  other  rocks  of  lake  Superior  represent  one  great  form- 
ation, the  crystalline  phases  being  more  metamorphosed  materials,  as 
maintained  by  some  of  the  earlier  geologists,  would  now  hardly  be  held 
by  any  one.  Also  it  is  doubtful  if  any  would  deny  that  the  rocks  below 
the  Keweenaw  series  are  divisible  on  a  structural  basis,  if  the  Animikie 
series  is  here  included.  The  successions  deduced  by  the  geologists  who 
have  made  the  most  extended  study  of  the  lake  Superior  region  arc  as 
follows : 
Logan  makes  the  Keweenawan  a  downward  extension  of  the  lake 
Superior  sandstone.  Below  the  Keweenaw  series,  as  before  defined, 
s  a  set  of  slates  (the  Animikie)  of  very  considerable  thickness,  which 
ire,  however,  a  part  of  the  Upj)er  Copper-bearing  group,  and  therefore 
superior  to  the  Original  Huronian  or  Lower  Copper-bearing  group.  The 
c\nimikic  rests  unconformably  itpon  the  Huronian.  As  to  the  relations 
)f  the  Huronian  and  Laurentian  about  lake  Superior  little  is  said,  ex- 
cept that  at  one  place  they  appear  to  be  conformable  and  grade  into 
ach  other.  We  thus  have  Logan's  succession,  lake  Superior  sand- 
tone;  Keweenawan;  Animikie;  unconformity;  Huronian;  Laurentian. 
The  Animikie,  as  well  as  the  Keweenawan,  is  regarded  as  a  part  of  the 
Jambrian  series. 
Selwyn's  succession  differs  from  Logan's  only  in  that  he  maintains 
hat  all  of  the  rocks  underlying  the  Animikie  in  Canada  constitute1  one 
general  conformable  succession,  but  divisible  into  two  systems  upon 
ithological  grounds  and  the  superior  position  of  the  second.  These 
ire  the  Laurentian  and  Huronian.  This  order  is  also  that  of  Bell. 
iVith  these  authors  the  Laurentian  is  granitoid  and  gneissic,  while 
he  Huronian  is  quartzose,  hornblendic,  schistose  and  slaty. 
Foster  and  Whitney's  succession  is  Keweenawan,  which  includes  the 
dke  Superior  sandstone;  unconformity;  Azoic — the  latter  said  to  be 
ndivisible  except  on  the  north  shore,  and  the  granites  are  intrusive 
ocks  later  than  the  Azoic  slates.  On  the  north  shore  the  Animikie 
eposes  upon  the  granite.  Until  recently  Wadsworth  has  held  to  the 
anic  succession  as  Foster  and  Whitney.  In  his  last  paper,  however, 
e  states  it  is  probable  that  in  the  Marquette  Azoic  there  are  three  dis- 
inct  geological  formations  or  ages  to  which  he  applies,  beginning  at 
he  base,  the  terms  Cascade,  Republic,  and  Holyoke  formations.  'The 
tst  two  are  unconformable  with  each  other. 
Macfarlane  recognizes  a  Huronian  and  a  Laurentian,  but  regards 
otli  series  as  wholly  of  igneous  origin  and  the  distinction  between  (lie 
wo  a  lithological  one,  the  basic  green  schists  referred  to  the  Huronian 
eing  newer  than  the  granite  and  gneiss,  and  the  pseudo-conglomerates 
)und  in  the  Huronian  a  consequence  of  the  intrusion  of  the  latter,  in 
hich  process  fragments  of  granite  and  gneiss  were  caught.  The 
keweenawan  is  full  of  debris  from  the  Huronian. 
