﻿W. 
  Lindgren 
  — 
  Granitic 
  Mocks 
  of 
  California. 
  313 
  

  

  uralitized 
  pyroxene 
  occur 
  near 
  Round 
  Top 
  and 
  to 
  the 
  west 
  of 
  

   Slippery 
  Ford, 
  and 
  are 
  connected 
  with 
  the 
  diorites 
  by 
  abun- 
  

   dant 
  transitions. 
  

  

  Normal 
  syenites 
  have 
  not 
  been 
  recognized, 
  but 
  intermediate 
  

   rocks 
  of 
  the 
  composition 
  of 
  monzonites 
  may 
  occur 
  in 
  places 
  ; 
  

   it 
  does 
  not 
  appear 
  practicable, 
  however, 
  to 
  separate 
  them 
  from 
  

   the 
  diorites. 
  

  

  A 
  normal 
  diorite 
  from 
  the 
  western 
  slope 
  of 
  the 
  Pyramid 
  

   Peak 
  range 
  was 
  partially 
  analyzed 
  (YIII). 
  The 
  rock 
  is 
  gran- 
  

   ular, 
  dark 
  grayish 
  green, 
  the 
  grains, 
  averaging 
  two 
  millimeters 
  

   in 
  diameter, 
  consist 
  of 
  feldspar, 
  dark 
  green 
  hornblende 
  and 
  a 
  

   little 
  biotite. 
  The 
  plagioclase, 
  which 
  does 
  not 
  exceed 
  andesine 
  

   in 
  basicity, 
  occurs 
  in 
  imperfect 
  short 
  prisms, 
  occasionally 
  

   cemented 
  by 
  a 
  little 
  orthoclase. 
  There 
  is 
  no 
  quartz. 
  The 
  

   mica 
  is 
  in 
  well-defined 
  yellowish 
  brown 
  foils, 
  often 
  including 
  

   small 
  feldspar 
  prisms. 
  The 
  hornblende 
  occurs 
  in 
  irregular 
  

   grains, 
  but 
  is 
  sometime 
  roughly 
  idiomorphic. 
  Small 
  grains 
  of 
  

   titanite 
  are 
  present. 
  The 
  structure 
  is 
  typically 
  hypidiomor- 
  

   phic. 
  The 
  composition 
  is 
  that 
  of 
  a 
  normal 
  diorite, 
  indicated 
  

   by 
  the 
  high 
  percentage 
  of 
  lime 
  and 
  soda 
  and 
  small 
  amount 
  of 
  

   potash. 
  The 
  hornblende 
  must 
  contain 
  much 
  lime. 
  

  

  Analysis 
  IX 
  shows 
  the 
  composition 
  of 
  one 
  of 
  the 
  interme- 
  

   diate 
  rocks, 
  occurring 
  in 
  a 
  diorite 
  area 
  a 
  couple 
  of 
  miles 
  south 
  

   of 
  Taliac 
  Peak. 
  It 
  js 
  a 
  coarse-grained, 
  dark 
  rock 
  made 
  up 
  

   chiefly 
  of 
  hornblende, 
  a 
  little 
  biotite 
  and 
  feldspar. 
  It 
  carries 
  

   a 
  considerable 
  amount 
  of 
  orthoclase, 
  and 
  its 
  composition 
  corre- 
  

   sponds 
  nearly 
  exactly 
  to 
  the 
  monzonite 
  from 
  Mulatto, 
  analyzed 
  

   by 
  Lemberg.* 
  

  

  The 
  relation 
  and 
  succession 
  of 
  the 
  granitic 
  rocks. 
  — 
  The 
  

   contacts 
  of 
  the 
  granodiorite 
  with 
  the 
  granite 
  are 
  sometimes 
  

   sharp, 
  but 
  more 
  commonly 
  much 
  pegmatite, 
  diorite 
  and 
  gran- 
  

   ite-porphyry 
  occur 
  on 
  them, 
  making 
  them 
  indistinct. 
  In 
  other 
  

   places 
  transition 
  forms 
  may 
  be 
  observed, 
  such 
  as 
  at 
  the 
  north- 
  

   ern 
  end 
  of 
  Pyramid 
  Peak 
  granite 
  area. 
  Especially 
  interesting 
  

   are 
  the 
  exposures 
  along 
  the 
  Pyramid 
  Peak 
  range. 
  Wherever 
  

   branches 
  or 
  bays 
  of 
  granodiorite 
  reach 
  into 
  the 
  granite 
  a 
  great 
  

   variety 
  of 
  lighter 
  or 
  darker 
  clioritic 
  rocks 
  make 
  their 
  appear- 
  

   ance, 
  in 
  places 
  bordering 
  sharply 
  against 
  the 
  granodiorite, 
  at 
  

   other 
  times 
  forming 
  extremely 
  graded 
  transitions 
  into 
  it. 
  

   Near 
  the 
  contacts 
  of 
  the 
  schist 
  areas 
  it 
  is 
  quite 
  common 
  to 
  find 
  

   the 
  granodiorite 
  gradually 
  growing 
  darker 
  and 
  changing 
  to 
  

   diorites. 
  The 
  contacts 
  between 
  the 
  granite 
  and 
  the 
  diorite 
  are 
  

   usually 
  sharper, 
  and 
  south 
  of 
  the 
  south 
  fork 
  of 
  the 
  American 
  

   River 
  abundant 
  well-defined 
  dikes 
  of 
  granite 
  occur 
  in 
  the 
  

   diorite. 
  

  

  * 
  W. 
  C. 
  Brogger: 
  Die 
  Eruptionsfolge 
  der 
  triadischen 
  Eruptivgesteine 
  bei 
  Pre- 
  

   dazzo 
  in 
  Slid 
  Tyrol, 
  p. 
  62. 
  

  

  