374  PRE-CAMBRIAN   GEOLOGY   OF    NORTH   AMERICA. 
Keewatin,  though  for  the  most  part  it  corresponds  with  the  United 
States  Geological  Survey's  lower  Huronian.  His  Animikie  and 
Keweenawan  correspond  with  those  of  the  United  States  Geological 
Survey.  He  concludes  that  the  Sioux  quartzite,  Baraboo  quartzite, 
and  New  Ulm  quartzite  are  unconformable  above  the  Animikie  and 
below  the  Keweenawan.  For  this  no  evidence  is  presented.  He  con- 
cludes further  that  the  granites  and  gneisses  show  gradation  through 
schists  into  true  fragmental  rocks,  and  thus  have  been  derived  from 
the  metamorphism  of  the  sedimentary  rocks.  In  the  same  manner 
gabbro  has  been  derived  from  the  metamorphism  of  greenstones  with 
their  clastic  variations.  The  iron  formation  of  the  Animikie  of  Min- 
nesota, classed  as  sedimentary  by  all  other  writers,  is  held  by  Winchell 
to  be  of  volcanic  origin. 
Bailey  Willis  was  the  first  to  approximate  the  succession  in  the 
western  Vermilion  district,  though  his  evidence  was  incomplete  and 
his  succession  faulty.  His  succession  is,  from  the  base  up  :  (1)  Chlo- 
ride schist;  (2)  jasper  interstratified  with  layers  of  hard  blue  specular 
ore,  which  also  occurs  in  ore  bodies  of  considerable  extent  running 
across  the  bedding,  thickness  200  to  600  feet  or  more;  (3)  chloritic 
schist,  similar  to  1,  original  thickness  probably  about  150  feet;  (4) 
quartzite,  containing  grains  of  magnetite  which  make  it  a  readily 
recognized  magnetic  formation,  probable  thickness  200  feet;  (5) 
conglomerate,  consisting  of  sandstone  pebbles  and  traces  of  black 
slate  inclosed  in  siliceous  chloritic  schist;  (C)  compact  homogeneous 
rock,  which  may  be  an  eruptive  quartz  diorite,  but  is  considered  a 
metamorphosed  sedimentary  transition  bed  between  5  and  7;  (7) 
black  clay  slate. 
Smyth's  and  Findlay's  succession  for  the  western  part  of  the  Ver- 
milion range  is:  Fragmental  slate  formation,  overlain  by  the  iron- 
bearing  formation.  Both  are  intruded  by  basic  and  acidic  igneous 
rocks,  which  exceed  in  quantity  the  sedimentary  later  rocks.  This 
succession  is  directly  the  reverse  of  that  of  Willis  and  later  of  Van  Hise, 
Clements,  Bayley,  Merriam,  Leith,  and  others  for  the  United  States 
Geological  Survey.  Their  succession  is:  (1)  Keewatin  greenstone 
and  green  schist,  largely  basaltic,  with  ellipsoidal  and  other  surface 
structures,  interbedded  and  overlain  by  iron  formation  with  a  small 
amount  of  slate;  (2)  Laurentian  granites,  gneisses,  and  porphyries; 
(3)  lower  Huronian  conglomerates  (Ogishke  and  Stuntz  forma- 
tions), grading  up  into  graywackes  and  slates  (Knife  Lake  slate)  ; 
(4)  upper  Huronian  quartzite,  iron  formation,  and  slate,  restricted 
to  the  east  end  of  the  district.  The  great  conglomerates  at  the  base 
of  the  fragmental  series,  containing  fragments  of  iron  formation  and 
green  schists  of  the  basement  complex,  are  held  by  Smyth  and  Find- 
lay — on  evidence  which  we  believe  to  be  quite  insufficient — to  be 
breccias.     In  their  earlier  work  Irving  and  Van  Hise  placed  the  iron- 
