rANHisE.]  THE    CORDILLERAS.  305 
the  granites  which  we  conceive  to  have  been  of  metamorphic  origin,  no 
natter  how  simple  the  mineralogical  composition,  have  always  a  pecu- 
liar variability  of  arrangement;  and  even  in  the  absence  of  any  pro- 
nounced parallelism,  they  show  the  effect  of  interior  compression  and 
rregular  mechanical  influences.  On  the  one  hand,  in  the  eruptive 
granites  there  seems  to  have  been  a  steady  expansive  force,  doubtless 
iue  to  the  heat  and  elastic  fluids,  which  gave  to  all  the  particles  a  cer- 
tain independent  polarity,  while  in  the  metamorphic  granites  they  seem 
X)  have  been  crowded  into  constantly  conflicting  positions.  As  the 
^esnlt  of  this,  the  crystalline  particles  of  the  metamorphic  granites  are 
nucli  less  apt  to  have  completed  their  crystallization,  or,  if  it  was  com- 
pleted, they  have  been  crushed  and  torn  asunder  and  their  particles 
scattered,  while  in  the  case  of  the  eruptive  granites  crystallization 
seems  to  have  been  more  i>erfected.  The  result  of  this  is  to  give  to  the 
eruptive  granites  something  of  the  uniformity  of  texture  of  a  volcanic 
X)ck,  while  all  the  metamorphic  granitoid  rocks,  when  once  the  gneis- 
joid  parallelism  of  minerals  is  broken  up,  have  a  crushed,  irregular, 
ind  confused  mode  of  arrangement. 
The  metamorphic  rocks  of  the  Humboldt  mountains,  Franklin  buttes 
md  the  Kinsley  district  are  provisionally  correlated  with  the  Huronian 
>f  Canada. 
The  foregoing  ranges  are  referred  to  the  Archean  simply  on  petrologi- 
al  evidence.  This  mode  of  correlation  is  dangerous,  but  a  general 
tudy  of  the  whole  region  has  strengthened  the  belief  that  in  the  Pa- 
eozoic  series  as  a  whole  there  are  none  of  those  results  of  extreme 
letamorphism  which  in  the  x^ppalachian  system  are  described  by  some 
eologists  as  closely  approximating  to  Archean  forms. 
Besides  mentioning  localities  given  by  Hague  in  which  Cambrian  is 
3und,  it  is  said  that  an  excellent  exposure  of  Cambrian  schists  and 
uartzites  is  found  underlying  the  Pogonip  limestone,  in  the  range  of 
I  ills  including  the  Eureka  Mining  district  and  connecting  the  Diamond 
nd  Pihon  ranges. 
Hague,39  in  1883,  describes  the  Eureka  district  as  a  mountain  block 
sanding  between  the  Piiion  and  Diamond  ranges.     At  the  base  of  the 
>ries  is  the  Prospect  mountain  quartzite,  1,500  feet  thick,  over  which 
a  shale  100  feet  in  thickness  bearing  the  Olenellus  fauna.     One  small 
rea  of  granite  is  found.     The  Prospect  mountain  quartzite  lies  in  con- 
tct  with  and  dips  away  from  it  in  irregular  broken  masses. 
Walcott,33  in  188G,  describes  the  Eureka  series  of  Nevada  as  mid- 
e  Cambrian  and  finds  at  the  top  of  the  Prospect  mountain  quartzite 
le  Olenellus  fauna.     In  the  adjacent  Highland  range  a  more  abundant 
,una  is  found  in  the  lower  1,500  feet  of  quartzite. 
Walcott,35  in  1889,  places  the  lower  quartzite  of  the  Eureka  and 
ighland  sections  as  basal  Cambrian. 
Bull.  86 20 
