126  PRE-CAMBRIAN    ROCKS    OF    NORTH    AMERICA.  [bull. 
oid  hematite  is  a  sedimentary  rock  and  not  an  eruptive  as  has  been  su 
posed  by  Wadsworth.    The  rock  was  not,  however,  deposited  in  i 
present  condition.     The  beds  have  been  upturned,  folded,  crushed,  ar  j 
affected  by  intense  chemical  action.     The  ore  is  regarded  as  a  result  « 
chemical  or  metasomatic  change.     The  general  succession  from  abo^ 
downward  is  as  follows:  (1)  gabbro;  (2)  diabase  dolerite.    These  re; 
unconformably  upon   the  lower    members.      (3)  Eeddish   gneiss  an 
syenite,  Avhich  includes  the  Misquah  hills,  White  Iron  lake,  and  tt 
Giant's  range  (Mesabi  heights).     This  is  a  case  of  a  fusion  of  sedimei 
tary  beds  in  situ,  although  it  is  not  generally  complete.     (4)  Graywack< 
sericite-schist,  argillite,  quartzite,  and  jaspilite,  which  occur  about  Ye: 
milion  lake.     (5)  Mica-schist,  hornblende-schist,  and  diorite.     The  Vei 
milion  group.     (6)  Mica-schist  and  granite  veined  with  syenite  am 
granulite.     (7)  Lower  syenites  and  gneisses,  generally  regarded  as  Lai 
rentian.     Nos.  3  to  7  are  conformable,  and  Nos.  4  to  7  graduate  int 
each  other. 
There  is  reason  for  believing  that  the  Animikie  rocks  overlie  th 
greenstone  No.  2  and  underlie  the  gabbro,  No.  1,  of  the  above  succes 
sion. 
Winchbll  (N.  H.),174  in  1888,  finds  the  Upper  Huronian  quartzite 
to  be  so  similar  to  those  of  Pipestone,  Cottonwood,  and  other  countie 
in  Minnesota  that  the  former  are  regarded,  with  the  latter,  as  Huronian 
The  Animikie  on  Gunflint  lake,  while  not  found  in  exact  superposition 
on  the  Keewatin,  bears  such  relations  as  to  render  it  probable  that  th 
two  formations  are  discordant.  A  short  distance  north  of  the  AnimikL 
the  Keewatin  rocks  are  found  with  a  dip  of  80°,  and  these  a  little  far 
ther  to  the  north  grade  conformably  into  the  crystalline  schists  of  tin 
Vermilion  group,  and  these  still  farther  to  the  north  by  transition  pass 
into  the  gneisses  and  syenites  of  the  Laurentian.  The  Animikie  rocks 
are  found  resting  unconformably  on  the  gneiss  west  of  Gunflint  lake 
The  gabbro  is  observed  overlying  the  Animikie  at  many  places,  tin 
Pewabic  quartzite,  the  Keewatin  rocks  north  of  Gunflint  lake,  and  th( 
syenite-gneiss  north  of  Flying  Cloud  lake. 
In  passing  from  Gunflint  lake  the  Animikie  is  found  to  Tiave  a  (Tip  as 
high  as  30°.  Near  Gobbemichigomog  lake  there  is  a  gradation  from  the 
flat-lying  Animikie  to  rocks  in  a  broken  and  tilted  condition,  and  fron 
these  into  the  Ogishki  Manissi  conglomerate,  with  which  they  are  inter 
stratified.  There  is  also  extending  from  Stuntz  island  in  Vermilion  lak( 
past  Ely  to  near  Ogishki  Manissi  lake  an  older  schistose  eruptive-looking 
conglomerate  associated  with  the  Keewatin.  schists,  and  therefore  oldei 
than  the  Ogishki  conglomerate.  The  beds  on  the  north  side  of  Gun 
flint  lake  resemble  those  on  the  south  side  of  the  Giant's  range  and  be 
long  in  the  same  stratigrapkical  position  near  the  beds  of  the  Animikie 
The  gneiss  is  regarded  as  a  metamorphosed  sediment,  because  of  tin 
gradation  of  the  Keewatin  beds  into  it,  and  because  it  cuts  through 
and    is    interstratified  with  the   Keewatin.     The    Keewatin   schists 
