﻿Washington 
  — 
  Igneous 
  Rocks 
  from 
  Smyrna, 
  etc. 
  49 
  

  

  l 
  2 
  

  

  Si0 
  2 
  _.. 
  63-17 
  61-93 
  

  

  A1 
  2 
  3 
  _ 
  17*15 
  16-45 
  

  

  Fe 
  3 
  2-84 
  4-66 
  

  

  FeO 
  1-31 
  0-40 
  

  

  MgO 
  2-17 
  2-94 
  

  

  CaO 
  4-17 
  4-40 
  

  

  Na 
  2 
  3-08 
  4-03 
  

  

  K 
  2 
  G 
  4-19 
  2-20 
  

  

  H 
  2 
  2-51 
  2-50 
  

  

  100-59 
  99-51 
  

  

  Sp.gr 
  2-525 
  2-539 
  

  

  17° 
  C. 
  15° 
  C. 
  

  

  The 
  analyses 
  resemble 
  in 
  general 
  those 
  of 
  the 
  Smyrna 
  rocks, 
  

   especially 
  that 
  of 
  the 
  Kara 
  Tash 
  specimens. 
  Silica 
  is, 
  how- 
  

   ever, 
  considerably 
  higher 
  — 
  so 
  high, 
  indeed, 
  that 
  the 
  name 
  

   dacite 
  is 
  justified, 
  though 
  no 
  quartz 
  has 
  crystallized 
  out.* 
  Iron 
  

   oxides, 
  magnesia 
  and 
  lime 
  are 
  all 
  lower 
  than 
  at 
  Smyrna. 
  There 
  

   is 
  a 
  discrepancy 
  in 
  the 
  quantities 
  of 
  the 
  two 
  oxides 
  of 
  iron 
  in 
  

   the 
  two 
  analyses, 
  but 
  their 
  total 
  amount 
  is 
  about 
  the 
  same. 
  

   There 
  is 
  also 
  a 
  discrepancy 
  in 
  the 
  alkali 
  determinations, 
  though 
  

   here 
  again 
  their 
  total 
  amount 
  is 
  about 
  the 
  same. 
  Lepsius' 
  

   differ 
  from 
  the 
  others 
  in 
  showing 
  higher 
  soda 
  than 
  potash, 
  

   which 
  is 
  rather 
  surprising 
  when 
  the 
  abundance 
  of 
  biotite 
  and 
  

   the 
  presence 
  of 
  orthoclase 
  are 
  considered. 
  The 
  high 
  H 
  2 
  is 
  

   largely 
  to 
  be 
  referred 
  to 
  the 
  abundant 
  glass 
  base, 
  though 
  some 
  

   of 
  it 
  belongs 
  to 
  the 
  biotite 
  molecule. 
  

  

  General 
  remarks. 
  — 
  It 
  would 
  be 
  of 
  much 
  interest 
  to 
  compare 
  

   the 
  rocks 
  just 
  described 
  with 
  the 
  other 
  volcanic 
  rocks 
  of 
  

   western 
  Asia 
  Minor. 
  At 
  the 
  present 
  time, 
  however, 
  we 
  are 
  

   confronted 
  at 
  the 
  outset 
  of 
  any 
  such 
  inquiry 
  by 
  the 
  insur- 
  

   mountable 
  obstacle 
  of 
  almost 
  total 
  lack 
  of 
  data, 
  i. 
  e. 
  of 
  modern 
  

   petrographical 
  and 
  chemical 
  descriptions. 
  An 
  examination 
  of 
  

   the 
  geological 
  map 
  of 
  Tahihatcheft 
  shows 
  that 
  a 
  line 
  of 
  vol- 
  

   canic 
  centers 
  extends 
  along 
  the 
  west 
  coast 
  from 
  Smyrna 
  north- 
  

   ward, 
  including 
  the 
  areas 
  of 
  Smyrna, 
  Sipylos, 
  Phocgea, 
  Yund 
  

   Dagh, 
  Pergamon, 
  Dalanlar 
  (Kiepert, 
  Doghanlar), 
  the 
  extensive 
  

   district 
  of 
  the 
  Troad, 
  and 
  Kapoudagh 
  on 
  the 
  Sea 
  of 
  Marmora. 
  

   As 
  we 
  have 
  already 
  seen 
  in 
  the 
  case 
  of 
  the 
  Assos 
  rocks 
  (page 
  

   41), 
  and 
  as 
  may 
  be 
  inferred 
  from 
  the 
  brief 
  descriptions 
  of 
  

   Tchihatcheff 
  and 
  Dillerf 
  the 
  andesitic 
  rocks 
  of 
  these 
  centers 
  

   much 
  resemble 
  each 
  other. 
  According 
  to 
  Diller, 
  in 
  the 
  Troad 
  

   some 
  of 
  them 
  carry 
  hypersthene, 
  and 
  they 
  are 
  associated 
  with 
  

  

  *Cf. 
  Kiich: 
  Yulk. 
  Gest. 
  Republ. 
  Colombia, 
  Berlin, 
  1892, 
  19; 
  also 
  H. 
  S. 
  

   Washington: 
  Jour, 
  of 
  Geology, 
  iii, 
  21, 
  1895. 
  

  

  f 
  Diller: 
  Quart. 
  Jour 
  Geol. 
  Soc, 
  xxxix, 
  632, 
  1883. 
  

  

  Am. 
  Jour. 
  Scl— 
  Fourth 
  Series, 
  Yol. 
  Ill, 
  No. 
  13.— 
  January, 
  1897. 
  

   4 
  

  

  