148  PRE-CAMBRTAN    GEOLOGY    OF    NORTH    AMERICA. 
basal  conglomerate,  and  in  other  places  reposes  directly  on  the 
Cascade  formation. 
The  quartzite  in  the  Menominee  district,  running  from  Sturgeon 
River  along  Pine  River  to  Metropolitan,  is  thought  to  belong  to  the 
base  of  the  Republic  formation,  since  it  is  found  at  various  places 
close  to  the  gneiss  and  granite,  dipping  away  from  them,  and  is  cut 
by  dikes  of  granite  in  sec.  12,  T.  41  N.,  R.  30  W.  The  dolomite  oc- 
cupies a  low  horizon,  either  interbedded  with  the  quartzite  or  occupy- 
ing its  place.  The  fundamental  ore  and  jaspilite  appear  to  belong, 
stratigraphically,  to  the  Republic  formation.  Most  of  the  jaspilite 
of  the  format  ion  is  of  detrital  origin,  being  originally  conglomerates, 
breccias,  sands,  and  muds,  which  have  been  subsequently  chemically 
acted  upon  by  percolating  waters,  since  in  the  Cascade  range  the 
jaspilite  and  ore  form  layers  which  are  frequently  interlaminated 
with  quartzite.  The  jaspilite  of  Negaunee  and  Ishpeming  has  failed 
to  reveal  any  evidence  that  it  is  sedimentary,  although  the  associated 
argillite  and  schist  arc,  in  part  at  least,  clearly  sedimentary.  The 
argillite  and  schists  are  directly  associated  with  the  jaspilite  and  iron 
ore.  In  places  they  grade  up  into  the  fragmental  jaspilite,  and  in 
other  places  are  interbedded  with  it.  They  also  succeed  the  latter 
rocks  and  overlie  them.  These  argillites  and  schists  are  older  than 
the  diorites  of  the  district,  and  are  cut  by  them. 
The  Holyoke  formal  ion  has  the  following  succession,  as  far  as 
known,  commencing  with  the  base:  Conglomerate-breccia  and  con- 
glomerate schist;  quartzite;  dolomite;  argillite;  graywacke  and 
schist;  granite  and  f elsite ;  diabase,  diorite,  and  porodite;  peridotite, 
serpentine,  and  dolomite ;  melaphyre  or  picrite ;  diabase  and  melaphyre. 
The  conglomerate  at  the  base  of  the  Holyoke  contains  granitic  ma- 
terial, as  well  as  fragments  from  the  jaspilite.  In  many  places  the 
unconformity  between  the  Republic  and  Hotyoke  formations  is  most 
marked,  being  seen  at  many  of  the  mines.  In  many  places,  also, 
the  Holyoke  formation  overlaps  the  Republic  and  is  in  contact  with 
the  granite  and  gneiss  of  the  Cascade.  Associated  with  the  Holyoke 
conglomerate  is  a  quartzite  which  includes  the  Mount  Mesnard  and 
Teal  Lake  quartzites.  In  sec.  20,  T.  47  N.,  R.  26  W.,  and  sees.  8  and 
19,  T.  49  N.,  R.  28  W.,  near  Silver  Lake  and  in  other  places,  sedi- 
ments of  the  Holyoke  formation  have  sifted  down  into  the  fissures  and 
joints  of  the  preexisting  rocks,  when  they  have  a  dikelike  character. 
For  such  formations  the  term  "  clasolite  "  is  proposed.  The  dolomite 
of  Mount  Mesnard 'and  thence  to  Goose  Lake,  while  lithologically  like 
that  placed  in  the  Republic  formation,  is  doubtfully  referred  to  the 
Holyoke.  Argillite,  graywacke,  and  mica  schist  occur  extensively  in 
the  Hqlyoke,  constituting  the  upper  horizon.  It  is  doubtful  whether 
any  granite  or  f elsite  of  Holyoke  age  exists  in  the  Marquette  district. 
Diabase,  diorite,  porodite,  and  peridotite  occur  abundantly,  belong- 
ing to  both  the  Republic  and  the  Holyoke  formations.     According  to 
