﻿Il8 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  of 
  Triassic 
  age 
  in 
  the 
  Connecticut 
  valley 
  1 
  (figure 
  10). 
  The 
  accompanying 
  

   photograph, 
  plate 
  17 
  of 
  the 
  walls 
  of 
  Stark's 
  knob 
  shows 
  the 
  general 
  

   structure. 
  

  

  The 
  fragment 
  shown 
  in 
  figure 
  9, 
  lying 
  south 
  of 
  the 
  fault, 
  is 
  more 
  massive 
  

   than 
  the 
  main 
  stock, 
  and 
  the 
  ground 
  mass 
  approaches 
  more 
  nearly 
  the 
  dense, 
  

   dark 
  basalt, 
  but 
  here 
  are 
  also 
  developed 
  amygdules. 
  

  

  A 
  hand 
  specimen 
  obtained 
  here 
  displayed 
  fairly 
  coarse 
  crystals 
  of 
  plagio- 
  

   clase, 
  indicative 
  of 
  an 
  intratelluric 
  origin, 
  such 
  as 
  are 
  common 
  in 
  the 
  diabase 
  

   of 
  many 
  dikes. 
  This 
  combination 
  of 
  the 
  characteristics 
  of 
  dike 
  rocks 
  and 
  of 
  

   effusive 
  explosive 
  products 
  makes 
  Stark's 
  knob 
  one 
  of 
  the 
  most 
  interesting 
  

   igneous 
  occurrences, 
  small 
  as 
  it 
  is, 
  within 
  the 
  limits 
  of 
  the 
  State. 
  

  

  Jointing 
  of 
  the 
  lava 
  crusts. 
  The 
  surfaces 
  of 
  the 
  lava 
  balls 
  are 
  beset 
  with 
  

   a 
  network 
  of 
  cracks 
  perpendicular 
  to 
  the 
  surface. 
  On 
  exposed 
  walls 
  the 
  lava 
  

   crusts 
  frequently 
  fall 
  to 
  pieces 
  in 
  short, 
  polygonal 
  joint 
  columns 
  similar 
  to 
  

   basaltic 
  columns. 
  

  

  Fig. 
  10. 
  Sketch 
  of 
  a 
  portion 
  of 
  the 
  western 
  wall 
  of 
  Stark's 
  Knob, 
  showing 
  

   the 
  gray, 
  scoriaceous 
  interior 
  of 
  the 
  lava 
  balls, 
  the 
  basaltic, 
  jointed 
  crust, 
  and 
  

   the 
  fissile, 
  devitrified, 
  volcanic 
  glass 
  surrounding 
  the 
  lava 
  balls 
  

  

  The 
  inclusions 
  of 
  limestone 
  point 
  to 
  an 
  irruption 
  through 
  the 
  lower 
  

   Paleozoic 
  limestones 
  which 
  must 
  occur 
  in 
  this 
  field 
  beneath 
  the 
  Hudson 
  

   terrane. 
  The 
  inclusions 
  may 
  be 
  appealed 
  to 
  as 
  evidence 
  that 
  the 
  trap 
  came 
  

   up 
  through 
  the 
  Silurian 
  and 
  subjacent 
  terrane, 
  as 
  held 
  in 
  this 
  paper, 
  and 
  that 
  

   the 
  rock 
  is 
  not 
  to 
  be 
  regarded 
  as 
  an 
  in-faulted 
  remnant 
  of 
  a 
  lava 
  flow 
  once 
  

   covering 
  the 
  Hudson 
  terrane 
  in 
  this 
  vicinity. 
  

  

  Since 
  Woodworth's 
  study 
  of 
  the 
  knob, 
  the 
  rock 
  has 
  been 
  utilized 
  

   for 
  various 
  purposes 
  and 
  largely 
  quarried 
  away. 
  We 
  visited 
  it 
  

   in 
  1 
  910, 
  in 
  191 
  1 
  and 
  in 
  1912. 
  In 
  19 
  10 
  active 
  quarrying 
  was 
  in 
  

   progress; 
  in 
  191 
  1 
  this 
  was 
  not 
  the 
  case 
  but 
  much 
  material 
  had 
  

  

  1 
  Emerson, 
  B. 
  K. 
  Diabase 
  Pitchstone 
  and 
  Mud 
  Enclosures 
  of 
  the 
  Tri- 
  

   assic 
  Trap 
  of 
  New 
  England. 
  Geol. 
  Soc. 
  Am. 
  Bui. 
  1897. 
  8:59-96. 
  For 
  an 
  

   illustration 
  of 
  the 
  ball 
  structure 
  at 
  Meriden, 
  Conn., 
  see 
  Davis, 
  W. 
  M., 
  The 
  

   Lost 
  Volcanoes 
  of 
  Connecticut. 
  Pop. 
  Sci. 
  Mo. 
  1891, 
  p. 
  221, 
  fig. 
  1 
  ; 
  U. 
  S. 
  Geol. 
  

   Sur. 
  18th 
  Rep't. 
  1898, 
  pt 
  2, 
  p. 
  65. 
  

  

  