﻿42 
  Washington 
  — 
  Igneous 
  Rocks 
  from 
  Smyrna, 
  etc. 
  

  

  the 
  andesite 
  is 
  overlaid 
  by 
  masses 
  of 
  detritus 
  containing 
  numer- 
  

   ous 
  shells, 
  and 
  here 
  and 
  there 
  accumulations 
  of 
  shells 
  are 
  

   found, 
  principally 
  of 
  oysters 
  and 
  scallops 
  (murex) 
  ; 
  snail 
  shells 
  

   also 
  abound, 
  which 
  closely 
  resemble 
  the 
  numerous 
  land 
  snails 
  

   of 
  Greece, 
  so 
  far 
  as 
  I 
  was 
  able 
  to 
  judge. 
  Fragments 
  of 
  pot- 
  

   tery, 
  mortar 
  and 
  charcoal 
  are 
  also 
  found 
  in 
  the 
  detritus, 
  and 
  

   these 
  deposits 
  seemed 
  both 
  to 
  Mr. 
  Diller 
  and 
  myself 
  to 
  be 
  in 
  

   reality 
  " 
  kitchen-middens 
  " 
  rather 
  than 
  deposits 
  from 
  water 
  or 
  

   old 
  beaches. 
  Mr. 
  Diller's 
  notes, 
  however, 
  show 
  that 
  along 
  the 
  

   Meles 
  Eiver 
  the 
  andesite 
  is 
  overlaid 
  by 
  soft 
  travertine-like 
  lime- 
  

   stone, 
  apparently 
  a 
  lacustrine 
  deposit. 
  In 
  places 
  also 
  andesitic 
  

   conglomerates 
  were 
  observed. 
  

  

  The 
  general 
  mass, 
  however, 
  is 
  very 
  compact 
  and 
  shows, 
  espe- 
  

   cially 
  toward 
  the 
  west, 
  a 
  beautifully 
  banded 
  structure, 
  the 
  

   bands 
  being 
  red 
  and 
  black. 
  The 
  greater 
  part 
  of 
  the 
  mass 
  

   visible 
  is 
  reddish, 
  the 
  color 
  being 
  due, 
  as 
  we 
  shall 
  see, 
  to 
  

   decomposition. 
  The 
  freshest 
  rock 
  has 
  a 
  dark 
  gray 
  ground 
  mass, 
  

   carrying 
  numerous 
  phenocrysts 
  of 
  feldspar 
  and 
  augite 
  and 
  

   fewer 
  of 
  biotite. 
  Its 
  texture 
  is 
  harsh 
  and 
  in 
  cavities 
  are 
  found 
  

   small 
  crystals 
  of 
  biotite 
  and 
  acicular 
  hornblende, 
  with 
  globular 
  

   masses 
  of 
  a 
  zeolite 
  which 
  vom 
  Rath 
  regards 
  as 
  a 
  natrolite. 
  

   Fine 
  mammillary 
  hyalite 
  is 
  also 
  abundant. 
  The 
  specific 
  gravity 
  

   of 
  a 
  fresh 
  gray 
  piece 
  was 
  found 
  to 
  be 
  2'640 
  at 
  17° 
  C. 
  

  

  Under 
  the 
  microscope 
  the 
  rock 
  is 
  seen 
  to 
  be 
  composed 
  of 
  

   plagioclase, 
  diopside 
  and 
  biotite, 
  with 
  accessory 
  magnetite, 
  

   apatite 
  and 
  zircon, 
  lying 
  in 
  a 
  glass 
  base. 
  Neither 
  hypersthene, 
  

   hornblende, 
  olivine 
  nor 
  quartz 
  was 
  seen 
  in 
  any 
  of 
  the 
  speci- 
  

   mens. 
  The 
  structure 
  is 
  eminently 
  the 
  vitrophyric 
  of 
  Kosen- 
  

   busch 
  and 
  is 
  well 
  shown 
  in 
  fig. 
  4 
  of 
  Tafel 
  v 
  of 
  his 
  Mikro- 
  

   scopische 
  Physiographic, 
  vol. 
  ii. 
  

  

  The 
  plagioclase 
  phenocrysts 
  are 
  often 
  well 
  shaped, 
  but 
  in 
  

   many 
  cases 
  fragmentary. 
  They 
  are 
  clear 
  and 
  carry 
  only 
  few 
  

   inclusions 
  of 
  glass, 
  apatite 
  and 
  zircon. 
  Zonal 
  structure 
  is 
  com- 
  

   mon, 
  the 
  interior 
  being, 
  as 
  usual, 
  the 
  more 
  basic. 
  Nearly 
  all 
  

   show 
  well-developed 
  twinning 
  lamellae 
  according 
  to 
  the 
  albite 
  

   law, 
  and 
  here 
  and 
  there 
  pericline 
  twinning 
  is 
  seen. 
  Examina- 
  

   tion 
  of 
  sections 
  on 
  £(010) 
  by 
  Michel 
  Levy's 
  method* 
  showed 
  

   extinction 
  angles 
  of 
  20° 
  and 
  25° 
  on 
  each 
  side 
  of 
  the 
  twinning 
  

   plane, 
  indicating 
  a 
  labradorite 
  of 
  the 
  composition 
  AbjAn^ 
  or 
  

   somewhat 
  more 
  basic. 
  The 
  few 
  feldspar 
  phenocrysts 
  that 
  

   showed 
  no 
  lamellae 
  could 
  not 
  be 
  identified 
  with 
  certainty 
  as 
  

   orthoclase. 
  The 
  diopside 
  phenocrysts 
  are 
  often 
  well-shaped, 
  

   though 
  fragments 
  occur. 
  They 
  are 
  almost 
  colorless 
  and 
  clear, 
  

   and 
  carry 
  only 
  few 
  inclusions 
  of 
  brown 
  glass 
  and 
  magnetite. 
  

   Some 
  twinning 
  parallel 
  to 
  a(W0) 
  is 
  seen, 
  but 
  zonal 
  structure 
  is 
  

   uncommon. 
  Biotite 
  phenocrysts, 
  in 
  stout 
  hexagonal 
  prisms, 
  

  

  * 
  Michel 
  Levy 
  : 
  Determination 
  des 
  Feldspaths, 
  Paris, 
  1894. 
  

  

  