302  PRE-CA-MBRIAN    ROCKS    OF    NORTH    AMERICA.  [bull.  86. 
but  the  direct  contact  of  the  overlying  limestones  was  not  observed. 
Overlying  the  granite  of  thePogonip  mountains,  apparently  unconforma- 
ble 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  Pogonip  fossiliferous  limestone  the  higher 
beds  of  which  are  referred  to  the  Quebec  group.  In  the  Piiion  range, 
below  the  heavy  Silurian  limestone  there  occurs  a  heavy  bed  of  red  and 
brown  quartzite  underlain  by  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  arexeferred  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 
Wah-weah  range,  surrounding  the  granite,  occurs  a  heavy  bed  of 
quartzite,  which  is  referred  to  the  Ogden  Devonian,  although  but  little 
examined. 
In  the  Ombe,  G-osi-Ute,  Peoquob,  Little  Cedar,  Toyano,  Fountain 
Head,  Cortez,  Eiver,  Northern  Cortez,  and  Battle  ranges  the  rock over- 
*  lying  the  granite  is  a  nonfossiliferous  quartzite  referred  to  the  Weber. 
These  quartzites  are  generally  of  a  bluish  gray  color,  contain  flint  and 
elicit  fragments,  often  angular,  and  jasper  pebbles,  sometimes  have  thin 
seams  of  carbonaceous  material,  are  often  ferruginous,  and  not  infre- 
quently con glomeratic.  At  these  ranges  the  Weber  is  overlaid  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,  and  the  series  resembles  the  Cam- 
brian of  Bonneville  peak,  Aqui  mountains.  In  the  Seetoya  and  Sho- 
shone ranges  the  quartzites  referred  to  the  Weber  are  between  heavy 
beds  of  limestones,  and  in  Two  Cubits  it  conformably  overlies  an 
enormous  development  of  Wasatch  limestone. 
The  stratified  rocks  overlying  the  Havallah,  Pah-Ute,  West  Hum- 
boldt, and  Truckee  granites  are  referred  totheTriassic;  that  overlying 
the  granites  of  the  Pah-supp  range  is  referred  to  the  Jurassic $  while 
the  gray  slates  resting  un conformably  above  the  Sah- wave  are  referred 
to  the  Miocene.  These  references  are  mostly  made  on  lithological 
grounds,  because  no  Paleozoic  strata  have  been  recognized  west  of  the 
Battle  mountains,  although  in  certain  cases  paleontological  evidence  is 
found. 
It  is  remarked  that  throughout  Nevada  are  large  bodies  of  quartzites 
without  any  clue  to  their  stratigraphical  relations  with  an  underlying 
or  overlying  limestone,  the  adjacent  rocks  being  either  granites  or  Ter- 
tiary volcanic  outflows.  It  is  then  exceeding  difficult,  if  not  impossi- 
ble, definitely  to  determine  their  true  geological  horizons.     In  many 
