264  PRE-CAMBRIAN    GEOLOGY    OF    NORTH    AMERICA. 
Bell,241  in  1878,  gives  observations  on  the  geology  of  the  east  shore 
of  Lake  Superior  from  Batchawana  Bay  to  Michipicoten  River.  The 
Upper  Copper-bearing  series  of  Mamainse  is  calculated  to  have  a 
thickness  of  22,400  feet.  It  consists  of  a  great  variety  of  amygdaloids] 
volcanic  tuffs,  felsites,  cherts,  crystalline  diorites,  sandstones,  and 
coarse  conglomerates,  the  latter  forming  one  of  the  most  striking 
features  in  the  series  as  it  passes  into  a  bowlder  conglomerate.  The 
bowlders  are  sometimes  crowded  in  a  sandy  matrix,  the  largest  run- 
ning as  high  as  3  feet  8  inches  in  diameter,  but  the  majority  are  under 
1  foot.  Far  the  greater  number  consist  of  granite  and  crystalline 
schists  like  those  of  the  Huronian  series,  but  there  are  also  found 
white  quartz,  amygdaloid,  and  gneiss.  Granites,  gneisses,  and  schists, 
as  well  as  basaltic  dikes,  are  found  at  many  points.  Cape  Choyye  is 
composed  of  Huronian  rocks,  which  consist  of  mica  schists  and  horn- 
blende schists,  slaty  quart  zite,  and  massive  diorite.  The  rocks  of 
Gros  Cap  are  mostly  slaty  diorite,  interstratined  with  siliceous  rock, 
in  which  occur  exposures  of  purplish  red  hematite.  A  dioritic  slate 
west  of  Gros  Cap  holds  layers  and  lenticular  patches  of  felsite  and 
also  rounded  pebbles  of  granite,  the  largest  of  which  are  9  inches  in 
diameter. 
Macfarlane,242  in  1879,  in  discussing  Selwyn's  paper  on  the  Que- 
bec group,  maintains  that  there  are  frequently  found  between  the 
water  and  the  Laurentian  or  Huronian  hills  narrow  strips  or  patches 
of  rocks  of  the  Upper  Copper-bearing  group.  Such  localities  are 
Gros  Gap,  south  shore  of  Batchawana  Bay,  and  Cape  Gargantua. 
The  conglomerates  are  full  of  Huronian  debris,  and  in  Batchawana 
Bay  may  be  observed  bowlders  of  red  jasper  conglomerate,  the  char- 
acteristic rock  of  the  typical  Huronian.  On  Michipicoten  Island  the 
igneous  and  sedimentary  strata  of  the  Upper  Copper-bearing  rocks 
have  a  dip  of  25°  SE.,  while  the  nearest  Huronian  rocks  dip  34°  to 
55°  N. 
Bell,243  in  1883,  gives  a  further  account  of  the  distribution  of  the 
rocks  of  the  Lake  of  the  Woods  and  adjacent  country.  They  are  not 
different  from  those  mentioned  in  his  previous  report  for  1872-73. 
The  line  between  the  Laurentian  and  Huronian  systems  crosses  Win- 
nipeg River  at  Rat  Portage,  keeps  near  the  railway  to  a  point  between 
Lake  Lulu  and  Keewatin  Mills,  where  it  crosses  it  diagonally  and  con- 
tinues in  a  westerly  direction  on  the  south  side  of  the  track. 
Selwyn,244  in  1883,  as  a  result  of  an  examination  of  the  north 
shore  of  Lake  Superior  from  Thunder  Bay  to  Sault  Ste.  Marie, 
and  thence  eastward  to  Echo  Lake,  fails  to  find  evidence  of  the  sup- 
posed unconformity  of  the  Huronian  and  Laurentian.  The  author 
can  give  no  better  reason  for  supposing  that  certain  sets  of  beds 
belong  to  the  so-called  Laurentian  and  others  to  the  Huronian  sys- 
tem  than   a   considerable   difference   in   the   litholojncal   characters. 
