LAKE    SUPERIOR   REGION.  173 
Seaman,80  in  11)02,  as  a  result  of  observations  made  through  a  long 
series  of  years,  concludes  that  the  Lower  Huronian  series  of  the  Mar- 
quette district  as  mapped  by  the  United  States  Geological  Survey 
really  consists  of  two  unconformable  series,  the  upper  one  including 
the  Negaunee  iron  formation,  the  Siamo  slate,  and  the  Ajibik  quartz- 
ite,  and  the  lower  one  including  the  Wewe  slate,  the  Kona  dolomite, 
and  the  Mesnard  quartzite.  The  unconformity  between  these  two 
series  is  believed  to  be  as  great  as  that  previously  described  between 
the  Upper  Huronian  and  the  rocks  underlying.  The  principal  evi- 
dences of  this  are  the  conglomerates  at  the  base  of  the  Ajibik  ob- 
served both  east  and  west  of  Teal  Lake,  on  Carp  River,  and  at  various 
localities  southwest  of  Goose  Lake,  and  the  fact  that  the  Ajibik 
quartzite  comes  in  contact  now  with  one  member  and  now  with  an- 
other of  the  underlying  series,  indicating  a  preceding  erosion  in- 
terval great  enough  to  allow  of  the  deep  truncation  of  the  under- 
lying series. 
Additional  evidence  of  faulting  is  noted  along  Carp  River,  in  the 
Palmer  area,  and  east  of  Teal  Lake.  The  extremely  complicated  re- 
lations in  the  Teal  Lake  area  seem  to  be  fully  explained  by  the  dis- 
covery of  the  unconformity  within  the  series,  together  with  the  fault- 
ing. The  faults  are  mainly  gravity  faults,  striking  parallel  to  the 
limbs  of  the  main  Marquette  syncline.- 
Hotchkiss,87  in  1903,  describes  and  maps  the  Palmer  area.  This 
is  far  more  detailed  work  than  anything  preceding.  One  and  per- 
haps more  east-wTest  faults  are  mapped. 
Van  Hise,  Bell,  Adams,  Miller,  Lane,  Hayes,  Seaman,  and 
Leith,S8  in  1904,  visited  the  Marquette  district  and  made  observa- 
tions confirming  the  conclusions  previously  reached  by  geologists  of 
the  United  States  Geological  Survey  and  by  A.  E.  Seaman.  Three 
distinct  sedimentary  series  intruded  by  basic  and  acidic  igneous  rocks 
and  separated  by  unconformities  were  noted.  These  lie  unconform- 
ably  upon  a  Basement  Complex  consisting  of  basic  and  acidic  igneous 
rocks  with  small  quantities  of  mechanical  sediments  and  of  iron  for- 
mation, as  previously  described.  The  three  sedimentary  series  are 
called  the  Upper,  Middle,  and  Lower  Marquette  series.  The  basic 
portion  of  the  Basement  Complex,  including  greenstone  schists  with 
associated  iron  formation  and  slate,  is  called  Keewatin,  and  the  gran- 
ites and  gneisses  intrusive  into  the  Keewatin  but  not  into  the  Hu- 
ronian are  called  Laurentian. 
The  same  authors  visited  the  Gogebic  district  and  particularly  the 
areas  in  the  vicinity  of  Ironwood,  Bessemer,  and  Presque  Isle  River. 
The  conclusions  of  Irving  and  Van  Hise  and  of  Seaman  were  con- 
firmed. Two  sedimentary  series,  called  respectively  the  Upper  and 
Lower  Huronian,  separated  by  unconformities,  were  observed  to  lie 
on  a  Basement  Complex  consisting  of  a  basic  division  previously 
