260  PRE-CAMBRIAN    GEOLOGY    OF    NORTH    AMERICA. 
each  other.  In  many  places  the  trap  lies  unconformably  upon  the  up- 
turned and  contorted  edges  of  the  sandstone. 
Along  the  coast  and  upon  many  islands  is  found  an  almost  hori- 
zontal red  sandstone,  which  is  supposed  to  be  a  continuation  of  the 
Sault  Ste.  Marie  sandstone.  Its  relations  to  the  Copper-bearing  rocks 
arc  not  clearly  made  out,  but  the  lowest  members  of  the  Mamainse 
series  are  unconformably  overlain  by  sandstones  which  may  be  the 
equivalent  of  the  horizontal  red  sandstones,  but  their  lithological 
character  is  different.  It  is  suggested,  on  lithological  grounds,  that 
this  red  sandstone  may  be  of  Permian  age. 
Macfaklane,229  in  1869,  describes  at  Thunder  Cape  a  series  of  in- 
terstratified  argillaceous  and  white  and  red  dolomitic  sandstones, 
which  had  been  disturbed  and  eroded  before  the  flow  appeared  which 
forms  the  summit  rock  of  the  cape. 
Bell,230  in  1870,  gives  an  account  of  the  geology  of  the  northwest 
coast  of  Lake  Superior  and  the  Nipigon  district.  The  Copper-bear- 
ing rocks  are  divided  into  a  lower  group  and  an  upper  group,  and 
each  of  these  groups  is  separated  into  several  divisions.  In  the  upper 
group  only  is  found  interbedded  trap.  Different  portions  of  this 
series  are  found  overlying  unconformably  in  certain  places  the  Lau- 
rentian  and  in  others  the  Huronian;  and  the  great  trap  overflow 
which  crowns  Thunder  Cape  rests  in  various  places  unconformably 
upon  different  members  of  both  the  upper  and  the  lower  groups  of 
the  Upper  Copper-bearing  series.  On  account  of  the  great  thick- 
ness of  this  series,  the  absence  of  fossils,  the  prevalence  of  marls  and 
sandstones  charged  with  red  oxide  of  iron,  and  of  basalts,  amygcla- 
loicls,  and  trap  rocks,  and  various  zeolites  and  native  copper,  this 
series  is  considered  as  probably  of  Permian  or  Triassic  age.  Be- 
tween the  margin  of  the  Upper  Copper-bearing  rocks  on  Thunder 
Bay  and  the  Laurentian  range  all  the  country  not  occupied  by  the 
syenitic  areas  appears  to  be  composed  of  rocks  of  the  Huronian  series, 
consisting  of  diorites,  dioritic  conglomerates,  hornblendic  and  fine- 
grained micaceous  slates,  Avith  some  quartzites. 
Bell,231  in  1872,  finds  in  the  country  north  of  Lake  Superior,  be- 
tween  Nipigon  and  Michipicoten  rivers,  both  Laurentian  and  Hu- 
ronian rocks.  The  former  includes  gneisses  and  granites,  and  the 
latter  includes  slates,  conglomerates,  massive  and  schistose  diorites, 
fine-grained  gneisses,  mica  schists,  micaceous,  hornblendic,  chloritic, 
feldspathic,  and  epidotic  schists,  slates,  granites,  and  iron  bre.  The 
Huronian  rocks  dip  in  various  directions.  At  White  River  horn- 
blendic schist  and  light-gray  gneiss  are  interstratified  with  massive 
granitic  gneiss,  and  similar  schists  appear  to  rest  conformably  upon 
massive  gneisses  for  a  long  way  north  of  the  river. 
Bell,232  in  1872,  finds  in  the  country  between  Lake  Superior  and 
Albany   River  areas  of  Laurentian  and  Huronian  rocks.     Between 
