794  PRE-CAMBRIAN   GEOLOGY   OF    NORTH   AMERICA. 
Archean  gneissic  rocks,  which  are  quite  unlike  any  other  observed 
rocks  in  western  Nevada.  The  Pea  Vine  Mountains  consist  of  quartz- 
ites  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  Pihon  ranges 
the  granite  is  overlain  by  Cambrian  strata.  In  the  Schell  Creek 
Mountains  are  limestones  bearing  Primordial  fossils  overlying  heavy 
bodies  of  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 
struct  lire.  A  portion  of  the  quartzite  shows  evidence  of  having  been 
subjected  to  great  pressure,  and  the  slate  at  times  gets  to  be  mica- 
ceous, and  even  becomes  a  normal  mica  schist.  This  series  doubtless 
represents  the  Cambrian,  but  the  direct  contact  of  the  overlying  lime- 
stones was  not  observed.  Overlying  the  granite  of  the  Pogonip  Moun- 
tains, apparently  unconformable  with  the  granite,  are  outcrops  of  mica 
slate  and  black  arenaceous  and  argillaceous  slates  and  shales,  in  turn 
overlain  by  an  undetermined  thickness  of  compact  vitreous  quartzite. 
Above  this  quartzite  (regarded  as  Cambrian  because  resembling  the 
Cambrian  quartzites  of  the  other  Nevada  localities)  occurs  the  Pogo- 
nip fossiliferous  limestone,  the  higher  beds  of  which  are  referred  to 
the  Quebec  group.  In  the  Pinon  Range,  beloAv  the  heavy  Silurian 
limestone,  occurs  a  heavy  bed  of  red  and  brown  quartzite  underlain 
b}7-  mica  schists  and  quartzitic  schists  5,000  feet  in  thickness,  which 
from  their  position  inferior  to  the  Silurian  and  their  similarity  to 
the  Wasatch  Cambrian  are  referred  to  the  Cambrian  age. 
In  the  East  Humboldt  Range,  overlying  the  granite  is  quartzite, 
which  is  referred  to  the  Ogden,  but  without  any  overlying  rock.  In 
the  Wahweah  Range  surrounding  the  granite  occurs  a  heavy  bed 
of  quartzite,  which  is  referred  to  the  Ogden  Devonian,  although  but 
little  examined. 
In  the  Ombe,  Gosiute,  Peoquob,  Little  Cedar,  Toyano,  Fountain 
Head,  Cortez  River,  Northern  Cortez,  and  Battle  ranges  the  rock 
overlying  the  granite  is  a  nonfossiliferous  quartzite  referred  to  the 
Weber.  These  quartzites  are  generally  of  a  bluish-gray  color,  con- 
tain flint  and  chert  fragments,  often  angular,  and  jasper  pebbles, 
sometimes  have  thin  seams  of  carbonaceous  material,  are  often  fer- 
ruginous, and  not  infrequently  conglomeratic.  At  these  ranges  the 
Weber  is  overlain  by  heavy  bodies  of  limestone  referred  to  the  Upper 
Coal  Measures,  generally  carrying  fossils  to  the  contact  with  the 
quartzite.  At  most  of  these  ranges  the  quartzite  is  several  thousand 
feet  thick,  sometimes  as  much' as  6,000  or  7,000.  At  Pilot  Peak  of 
the  Ombe  Range,  interstratified  with  the  quartzites  are  mica  schists, 
