vanhise.]  THE    CORDILLERAS.  301 
and  the  fine  grained  mica-schists.  The  granite  of  the  Humboldt  is 
similar  to  the  Lauren tian  of  the  Appalachian,  while  the  unconformably 
overlying  series  closely  resembles  the  eastern  Hurooian.  In  the  South- 
ern Shoshone  range  an  original  Archean  island  is  wrapped  around  by 
fine  grained  micaceous  slate.  ^The  Archean  granite  of  E-avenswood 
peak  has  remarkably  regular  bedding  planes  apparently  conformable 
to  those  of  the  overlying  slates,  which  give  it  the  appearance  of  being 
a  stratified  granite,  although  it  at  the  same  time  traverses  the  slates 
in  dikes.  The  Ravenswood  peak  granite  to  the  east  is  essentially  dif- 
ferent from  the  Archean  granite  and  is  evidently  of  later  origin.  In 
the  West  Humboldt  range  the  granite  shows  structural  planes.  Along 
its  northern  and  western  edge  it  is  overlain  by  a  series  of  metamorphic 
schists  and  gneisses,  which  are  in  turn  overlain  by  fine,  white,  knotted 
schists.  The  strike  of  these  beds  is  N.  38°  E.,  and  they  stand  nearly 
vertical.  The  contact  of  the  granite  and  schist  shows  in  a  horizontal 
plane  irregular  angular  intrusions  of  the  former  into  the  latter,  masses 
of  schists  lying  in  the  granite  and  extending  as  promontories  from  the 
main  mass  for  400  or  500  feet.  The  line  of  demarcation  between  the 
two  bodies  is  easily  observed,  and  there  seems  to  be  no  tendency  for 
the  schists  to  pass  by  gradation  into  the  granite.  Dikes  penetrate 
both  the  granite  and  schists.  The  range  is  regarded  as  an  anticlinal 
fold.  In  the  Montezuma  range  are  slates  and  schists  which  rest  uncon- 
formably upon  the  granite.  The  Pah-tson  mountains  consist  almost 
entirely  of  granite  and  crystalline  schists,  which  are  cut  by  numerous 
dikes,  the  whole  being  regarded  as  Archean,  because  the  dikes  do  not 
cut  later  eruptive  granites,  which  are  found  in  considerable  quantity, 
and  differ  markedly  from  those  which  are  regarded  as  Archean.  In 
the  Truckee  range  are  found  quartzitic  schists  and  hornblendic  rocks 
with  both  older  and  later  types  of  granite.  The  metamorphic  schists 
cut  by  intrusive  granites  referred  to  the  Archean  occupy  but  a  small 
area,  the  later  granites  making  up  the  greater  part  of  the  range.  In 
the  Lake  range  are  granite  and  Archean  gneissic  rocks,  which  are 
quite  unlike  any  other  observed  rocks  in  western  Nevada.  The  Pea 
Vine  mountains  consist  of  quartzites  and  fine  grained  feldspathic  rocks, 
which  are  referred  to  the  Archean,  but  their  relation  to  the  other 
crystalline  rock  masses  has  not  been  made  out. 
In  Schell  creek,  Egan,  Pogonip  or  White  Pine,  and  Pinon  ranges  the 
granite  is  overlain  by  Cambrian  strata.  In  the  Schell  creek  mountains 
are  limestones  bearing  Primordial  fossils  overlying  heavy  bodies  oi 
Cambrian  quartzite.  In  the  Egan  range,  overlying  the  granite,  is  a 
series  several  thousand  feet  thick  of  quartzites  and  quartzitic  schists 
with  a  50-foot  bed  of  roofing  slate.  The  main  mass  of  quartzite  is 
thoroughly  vitrified,  showing  little  trace  of  granular  structure.  A  por- 
tion of  the  quartzites  show  evidence  of  having  been  submitted  to  great 
pressure,  and  the  slate  at  times  gets  to  be  micaceous,  and  even  becomes 
a  normal  mica-schist.    This  series  doubtless  represents  the  Cambrian, 
