﻿120 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  the 
  filled 
  fissure 
  is 
  scarcely 
  anywhere 
  over 
  2 
  feet, 
  but 
  the 
  lateral 
  

   offshoots 
  extend 
  many 
  feet 
  into 
  the 
  walls 
  of 
  Manlius 
  limestone. 
  

   These 
  offshoots 
  or 
  rootlets 
  of 
  the 
  dike 
  are 
  irregular, 
  commonly 
  nar- 
  

   row, 
  and 
  often 
  appear 
  as 
  isolated 
  quartz 
  masses 
  in 
  the 
  Manlius 
  or 
  

   the 
  waterlime 
  rock, 
  the 
  connection 
  with 
  the 
  main 
  dike 
  not 
  being 
  

   always 
  discernible. 
  Such 
  masses 
  of 
  quartz 
  sandstone 
  have 
  been 
  

   traced 
  for 
  more 
  than 
  30 
  feet 
  from 
  the 
  dike. 
  The 
  irregularity 
  of 
  the 
  

   walls 
  of 
  the 
  fissure 
  is 
  very 
  pronounced. 
  Angular 
  masses 
  of 
  lime- 
  

   stone 
  project 
  into 
  the 
  quartz 
  rock, 
  while 
  narrow 
  tongues 
  of 
  sand- 
  

   stone 
  everywhere 
  enter 
  the 
  limestone. 
  Extensive 
  brecciation 
  of 
  the 
  

   limestone 
  has 
  occurred 
  along 
  the 
  margin, 
  and 
  the 
  sandstone 
  there 
  

   is 
  filled 
  with 
  angular 
  fragments 
  of 
  the 
  limestone, 
  which 
  show 
  no 
  

   traces 
  of 
  solution 
  or 
  wear 
  by 
  running 
  water. 
  These 
  limestone 
  frag- 
  

   ments 
  are 
  themselves 
  frequently 
  injected 
  with 
  tongues 
  of 
  the 
  quartz 
  

   sand. 
  Microscopic 
  examination 
  shows 
  evidence 
  of 
  a 
  certain 
  amount 
  

   of 
  shearing 
  along 
  the 
  margin 
  of 
  the 
  dike, 
  accompanied 
  by 
  a 
  pul- 
  

   verizing 
  or 
  trituration 
  of 
  the 
  limestone, 
  and 
  followed 
  by 
  reconsoli- 
  

   dation. 
  These 
  and 
  other 
  features 
  point 
  to 
  a 
  cataclysmic 
  origin 
  of 
  

   the 
  fissure 
  which 
  contains 
  the 
  dike 
  and 
  a 
  more 
  or 
  less 
  violent 
  in- 
  

   jection 
  of 
  the 
  sand. 
  The 
  fissure 
  must 
  have 
  been 
  formed 
  and 
  filled 
  

   before 
  the 
  deposition 
  of 
  the 
  Onondaga 
  limestone 
  and 
  while 
  the 
  Man- 
  

   lius 
  limestone 
  was 
  covered 
  by 
  a 
  stratum 
  of 
  unconsolidated 
  sand. 
  

   The 
  formation 
  of 
  the 
  fissure 
  and 
  the 
  injection 
  of 
  the 
  sand 
  into 
  it 
  

   from 
  above 
  must 
  have 
  occurred 
  simultaneously; 
  for 
  this 
  appears 
  

   the 
  only 
  way 
  to 
  account 
  for 
  the 
  inclusion 
  of 
  large 
  fragments, 
  or 
  

   "' 
  horses 
  ", 
  of 
  the 
  wall 
  rock 
  in 
  the 
  loose 
  sand, 
  and 
  the 
  injection 
  of 
  

   the 
  sand 
  into 
  all 
  the 
  cracks 
  and 
  crevices. 
  It 
  seems 
  probable 
  that 
  

   the 
  fissure 
  records 
  an 
  earthquake 
  shock 
  during 
  the 
  period 
  interven- 
  

   ing 
  between 
  the 
  close 
  of 
  the 
  Siluric 
  age 
  and 
  the 
  deposition 
  of 
  the 
  

   Devonic 
  limestones. 
  This 
  is 
  borne 
  out 
  by 
  the 
  occurrence 
  of 
  numer- 
  

   ous 
  small 
  faults 
  or 
  displacements 
  in 
  the 
  underlying 
  strata 
  of 
  water- 
  

   lime. 
  

  

  Devonic 
  strata 
  

  

  The 
  Lower 
  Devonic 
  is 
  represented 
  in 
  the 
  Niagara 
  region 
  by 
  the 
  

   thin 
  beds 
  of 
  shale 
  and 
  sandstone 
  before 
  mentioned 
  as 
  occupying 
  

   erosion 
  hollows 
  in 
  the 
  Manlius 
  limestone. 
  These 
  are 
  perhaps 
  the 
  

  

  