CHAPTEE   II. 
LAKE  SUPERIOR  REGION. 
SECTION  I.      WORK  OF  THE  OFFICIAL  GEOLOGISTS  OF  THE  CANADIAN 
SURVEY  AND   ASSOCIATES. 
Bigsby,1  in  1825,  describes  in  detail  the  roGks  at  many  points  along 
the  north  shore  of  lake  Superior,  between  the  falls  of  St.  Mary  and 
Grand  Portage,  an  interval  of  445  miles.  The  varieties  of  rocks  are 
few  in  number  when  compared  with  a  similar  extent  of  country  in 
Europe.  Of  mica-slate,  clay-slate,  etc.,  not  a  vestige  was  found,  not  even 
in  debris,  nor  of  any  secondary  deposits  above  the  Mountain  limestone. 
Sandstone,  under  various  modifications,  occupies  the  greatest  space; 
in  intimate  connection  with  the  next  prevailing  rocks,  the  amygdaloids, 
porphyries,  and  greenstone  trap.  The  alternating  granites  and  green- 
stones of  the  northeastern  and  eastern  coasts  are  nearly  equal  in  quan- 
tity to  these.  The  granites  and  syenites  are  not  stratified.  The  por- 
phyry, amygdaloid,  and  sandstone  are  considered  contemporaneous  and 
newer  than  the  granites,  although  not  much,  as  indicated  by  the  transi- 
tions and  alternations  occurring  about  Gargantua.  The  age  and  con- 
nections of  the  greenstone  trap  the  author  is  not  prepared  to  state. 
The  sandstone  is  most  probably  Old  Red,  a  conclusion  reached  from  the 
materials  composing  it,  and  its  direct  superposition  on  inclined  rocks  in 
this  and  other  great  lakes  of  the  St.  Lawrence  and  because  it  supports 
a  fossiliferous  limestone  full  of  products,  turbinolise,  caryophyllia', 
trilobites,  conularige,  encrinites,  and  orthoceratites,  etc.  The  granite 
and  syenite  seem  to  be  of  the  same  age  and  belong  to  the  transition  or 
to  the  youngest  of  the  x>rimitive. 
On  the  old  route  from  lake  Superior  to  the  lake  of  the  Woods  (for 
430  miles)  is  an  alternation  of  chloritic  greenstone  and  amphibolitic 
granite,  but  at  and  toward  the  lake  of  the  Woods  the  greenstone, 
passes  into  gneiss,  and  mica-slate,  traversed  in  many  ways  and  in  great 
quantities  by  graphic  granite. 
Bayfield,2  in  1829,  gives  an  outline  of  the  geology  of  lake  Superior. 
The  rocks  of  the  lake  are  divided  into  four  divisions :  First,  the  inferior 
order,  comprising  granites,  which  almost  always  contain  more  or  less 
hornblende.  In  this  division  neither  gneiss  nor  mica-slate  was  met 
with,  although  the  granite  by  the  abundance  of  its  mica  or  lamellar 
structure  may  for  a  short  distance  assume  the  appearance  of  either, 
Second,  the  submedial  order,  which  includes  greenstones,  common 
jaspery  variety  of  greenstone  slates,  flinty  chlorite,  talcose  slate,  and  in 
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