vanhise.]  LAKE    SUPERIOR    REGION.  93 
quartzite  of  Eepublic  mountain,  near  its  base,  is  a  conglomerate  con 
taining  large  and  small  fragments  of  flaggy  ore.    At  the  New  England 
mine  between  the  ore  and  the  quartzite  is  a  mass  of  specular  conglom- 
erate similar  to  that  at  Eepublic  mountain. 
The  iron-bearing  series  is  unconformably  above  the  older  Laurentian 
rocks.  The  contact  is  observed  in  Plumbago  brook,  where  a  talcy  red 
rock,  unmistakably  belonging  to  the  Huronian,  dipping  at  a  low  angle 
to  the  northwest,  is  in  contact  with  the  Laurentian  chloritic  gneiss 
which  dips  at  an  angle  of  about  35°  SSW.  The  same  phenomena  can 
be  seen  near  Eepublic  mountain,  where  the  Huronian  schists  strike 
nearly  at  right  angles  to  the  Laurentian  gneiss  only  50  feet  distant; 
both  series  dipping  at  high  angles,  the  Laurentian  east  of  north,  and 
the  Huronian  about  45  degrees  west  of  north.  The  non-conformability 
is  further  shown  by  the  fact  that  the  Laurentian  generally  abounds  in 
dikes  of  granite  and  diorite,  which  are  almost  entirely  absent  from  the 
Huronian. 
Many  details  are  given  as  to  the  Menominee  and  Felch  Mountain 
districts.  The  rocks  of  these  ranges  are  parallel  with  those  in  the 
Marquette  district.  At  many  places  the  Silurian  rocks  unconformably 
cap  the  iron-bearing  rocks. 
The  lake  Gogebic  and  Montreal  river  iron  range  is  regarded  as  an 
eastern  prolongation  of  the  Penokee  range  of  Wisconsin.  The  northern 
geological  boundary  is  the  south  copper  range,  consisting  cf  massive 
and  amygdaloidal  copper-bearing  traps,  the  bedding  of  which  is  exceed- 
ingly obscure,  with  occasional  beds  of  sandstone  and  imperfect  con- 
glomerates. The  strike  of  these  rocks  is  east  and  west,  with  a  dip  to 
the  north  at  a  high  angle,  thus  conforming  with  the  Huronian  rocks 
underneath.  On  the  south  of  the  iron-bearing  rocks  is  a  series  of 
granites,  gneisses,  and  obscure  schists,  which  are  unmistakably  Lau- 
rentian in  their  lithological  character,  and  they  are  unconformably 
overlain  by  the  Huronian  rocks.  The  horizontal  Lower  Silurian  sand- 
stones occupy  a  broad  belt  of  country  north  of  the  copper  range.  Their 
actual  contact  with  the  highly  tilted  copper  rocks  was  not  seen,  but 
they  show  not  the  slightest  evidence  of  disturbance  within  a  few  miles 
of  these  steeply  inclined  rocks,  and  are  regarded  as  unconformably  above 
them. 
Pumpelly,102  in  1873,  gives  a  systematic  account  of  the  copper- 
bearing  rocks.  These  on  Keweenaw  point  consist  of  an  immense  devel- 
opment of  alternating  trappean  rocks  and  conglomerates  dipping  to  the 
northwest  at  an  angle  running  from  60°  to  23°.  The  red  sandstone  and 
shales  of  lake  Superior  are  everywhere  nearly  horizontal  on  the  south 
shore  of  lake  Superior  between  the  Sault  Ste.  Marie  and  Bete  <  I  rise  bay. 
At  the  western  edgeof  this  belt  its  nearly  horizontal  strata  abut  against 
the  steep  face  of  a  wall  formed  by  the  upturned  edges  of  beds  of  1 1n1 
cupriferous  series  of  melaphyre  and  conglomerate,  which  dip  away  from 
the  sandstone  at  angles  of  from  40°  to  00°.     This  sharp  line  has  been 
