vanhise.]  LAKE    SUPERIOR    REGION.  133 
out;  at  other  times  it  is  in  oval  forms,  the  greater  lengths  being  par- 
allel with  the  schistose  structure.  Again,  the  jaspilite  is  in  great  frag- 
ments within  the  green  or  massive  diabasic  schists,  the  masses  having 
sometimes  such  relations  with  each  other  as  to  show  that  they  are  a 
broken  continuous  layer.  The  branches  from  the  large  bodies  of  jas- 
pilite are  supposed  to  be  caused  by  the  crumpling,  breaking,  and  squeez- 
ing of  the  entire  rock  structure  by  which  the  thinner  sheets  have  been 
buckled  out  and  thrust  laterally  among  the  inclosing  schists.  The  ore 
always  occurs  associated  with  the  jaspilite,  the  forms  of  the  deposits 
being  exceedingly  irregular.  The  ore  and  jasper  are  regarded  as  a  di- 
rect chemical  deep-sea  precipitate,  accompanied  and  interrupted  by  re- 
peated ejections  ot  basic  volcanic  rocks  from  which  the  iron  for  the  ore 
is  extracted. 
The  rocks  of  the  Animikie  equivalent  to  the  Huronian  and  included 
in  the  Taconic  consist  chiefly  of  carbonaceous  and  argillaceous  slates 
with  siliceous  slates,  fine-grained  quartzites,  and  gray  limestones.  At 
the  bottom  of  the  series  is  a  fragmental  quartz  sandstone  300  feet  in 
thickness,  which  is  named  the  Pewabic  quartzite.  The  slates,  conglom- 
erates, and  quartzites  are  profoundly  affected  and  intermingled  with 
eruptive  material  which  is  similar  to  that  found  so  abundantly  in  the 
Keewatin.  These  beds  have  the  appearance  of  consolidated  beds  of 
basic  lava  or  of  porous  tuff,  but  where  this  prevails  there  is  a  sensible 
gradation  from  the  dark  trap-looking  beds  to  thin  beds  of  slate.  At 
Ogishki  lake  there  is  a  slate  conglomerate  similar  to  that  on  the  north 
shore  of  lake  Huron.  This  conglomerate  is  not  the  same  as  the  ag- 
glomerates of  the  Keewatin  such  as  that  on  Stuntz  island,  at  Vermilion 
lake  and  Ely.  The  Keewatin  is  always  nearly  vertical  while  the  dip 
of  the  Taconic  rarely  exceeds  15°.  The  iron-ore  beds  of  the  Taconic 
are  the  quartzose,  hornblendic,  magnetitic  group  of  the  Pewabic  quartz- 
ite; an  impure  jaspilite,  hematite,  and  limonite  group;  a  carbonated 
iron  group;  and  a  gabbro  titanic  iron  group.  The  jaspilitic  hematite 
igrouphasthe  same  lithological  peculiarities  as  the  jaspilite  beds  of 
the  Vermilion  rai^e.  The  gabbro  in  which  the  titanic  iron  occurs  con- 
stitutes the  MesaC^range.  This  has  been  before  regarded  as  the  base 
of  the  Keweenawan,  into  which  it  fades  upwardly,  but  it  has  been 
found  that  this  great  gabbro  flow  was  outpoured  at  an  earlier  date, 
and  it  is  placed  at  or  near  the  bottom  of  the  Animikie. 
Winchell  (H.  V.)189,  in  1891,  states  that  the  syenite  of  Saganaga 
lake  is  conglomeratic  in  places  and  contains  pebbles  which  are  similar 
to  each  other,  being  mostly  composed  of  lamellar  augite,  with  or  with- 
out grains  of  feldspar,  but  there  are  no  pebbles  of  syenite  or  jasper  such 
as  occur  in  the  Keewatin  conglomerates.  In  the  Saganaga  granite,  at 
the  end  of  the  portage  on  Granite  river,  is  a  band  of  silica  1J  inches  in 
diameter  and  3  feet  in  length.  IsTorth  of  Saganaga  lake  the  syenite 
grades  into  chloritic  syenite-gneiss,  and  this  into  thick  bedded  to  mas- 
sive Keewatin  rocks.  From  these  facts  it  is  concluded  that  the  syenite 
is  simply  a  result  of  locally  intense  metamorphism. 
