296  PEE-CAMBRIAN   ROCKS   OF    NORTH    AMERICA.  [buli-86. 
1 
LITERATURE   OF  THE   AQUI   MOUNTAINS. 
Emmons,  (S.  F.),6  in  1877,  describes  at  Bonneville  peak  a  body  of  white 
quartzite  not  less  than  6,000  feet  in  thickness  dipping  to  the  westward. 
In  this  quartzite  arebeds  of  conglomerate  strata,  the  pebbles  of  which  are 
flattened  and  of  argillaceous  rock,  containing  mica  and  becoming  imper- 
fect mica-schists  like  those  east  of  Farmington.  This  series  is  regarded 
as  equivalent  to  the  Cambrian  of  the  Wasatch  on  lithological  grounds, 
because  it  rests  below  a  great  limestone  formation  and  because  it  is 
thicker  than  any  of  the  higher  quartzite  series  of  the  Wasatch.  On 
Grantville  peak  a  similar  series  is  found. 
King,7  in  1878,  describes  in  the  ridge  east  of  Egan  canyon  as  occur- 
ring directly  over  the  granite  several  thousand  feet  of  quartzitic  schists, 
capped  by  about  50  feet  of  highly  laminated  fissile  argillites,  which  are 
quite  similar  to  the  quartzitic  schists  of  the  Wasatch 
LITERATURE   OF   THE    RAFT   RIVER   RANGE. 
Hague,6  in  1877,  describes  in  the  Raft  river  range  a  considerable 
body  of  structureless  medium  grained  granite,  forming  the  central  mass. 
LITERATURE    OF    SOUTHERN   UTAH   AND   SOUTHEASTERN  NEVADA. 
Gilbert,36  in  1875,  states  that  the  ridges  of  the  Basin  range  system 
are  in  part  composed  of  granitic  and  cognate  rocks.  The  granite  occu- 
pies various  positions.  Often  it  is  the  nucleus  of  the  range  against 
which  inclined  strata  rest.  Elsewhere  it  appears  in  dikes,  traversing 
either  the  sedimentary  rocks  or  other  granites.  In  a  few  instances  it 
was  observed  to  overlie  the  sedimentary  rocks,  while  in  a  number  of 
localities  the  evidence  of  its  eruptive  character  is  unequivocal;  in 
others  it  is  plainly  metamorphic,  and  in  by  far  the  majority  of  cases  it 
appears  to  have  assumed  its  relation  to  the  undoubted  sedimentary 
rocks  before  the  upheaval  of  the  combination.  In  the  Granite  mining 
district  the  section  shows  a  white  crystalline  marble  overlain  by  gran- 
ite, which  appears  to  extend  from  the  summit  of  the  range  to  the  oppo- 
site base.  The  axis  of  the  Snake  river  range  consists  of  quartzite  and 
limestone,  with  a  limited  amount  of  crystalline  schists  and  granite. 
Metamorphic  sedimentary  rocks  of  undetermined  age  were  seen  at  a 
number  of  points  and  have  been  regarded  pro  vision  ally  in  mapping  as 
Archean,  with  which  have  been  grouped  the  granitoid  rocks. 
Mahvine,37  in  1875,  states  that  crystalline  rocks  are  found  on  the 
Salt  lake  road  in  the  Virgin  mountains. 
Howell,31  in  1875,  states  that  Granite  rock  is  an  island  of  granite 
in  the  desert,  which  shows  traces  of  bedding,  with  a  high  dip  to  the 
west.  The  nucleus  of  Snake  range  is  granite,  exposed  at  many  places, 
and  overlain  by  quartzite,  shale,  and  limestone. 
