﻿108 
  J. 
  D. 
  Dana 
  — 
  Features 
  of 
  non-volcanic 
  Igneous 
  Ejections. 
  

  

  Mill 
  Rock 
  ends 
  to 
  the 
  eastward 
  in 
  a 
  south-southwest 
  fissure, 
  

   transverse 
  to 
  its 
  main 
  course 
  which 
  is 
  apparently 
  parallel 
  to 
  

   the 
  adjoining 
  part 
  of 
  the 
  East 
  Rock 
  trap. 
  East 
  Rock 
  com- 
  

   mences 
  with 
  a 
  nearly 
  north-and-south 
  course, 
  but 
  bends 
  around 
  

   to 
  east-southeast 
  Mill 
  Rock 
  and 
  Pine 
  Rock 
  are 
  not 
  neces- 
  

   sarily 
  synchronous 
  in 
  eruption 
  with 
  East 
  Rock 
  or 
  West 
  Rock, 
  

   but 
  they 
  belong 
  to 
  one 
  epoch 
  of 
  disturbance. 
  

  

  The 
  origin 
  of 
  these 
  courses 
  is 
  not 
  fully 
  ascertained. 
  I 
  have 
  

   long 
  explained 
  the 
  north-by-east 
  trend 
  of 
  West 
  Rock, 
  and 
  of 
  

   the 
  other 
  ridges 
  of 
  like 
  direction 
  to 
  the 
  north, 
  on 
  the 
  general 
  

   principle 
  that 
  the 
  mountain-making 
  forces 
  of 
  Eastern 
  America 
  

   operated 
  over 
  any 
  part 
  of 
  the 
  area, 
  as 
  a 
  general 
  thing 
  in 
  the 
  

   same 
  direction 
  from 
  Archaean 
  time 
  onward, 
  examples 
  occurring 
  

   in 
  the 
  Taconic 
  and 
  Jura-Trias 
  elevations 
  of 
  the 
  western 
  half 
  of 
  

   New 
  England. 
  In 
  accordance 
  with 
  this 
  view 
  the 
  strike 
  of 
  the 
  

   Jura-Trias 
  should 
  be 
  that 
  of 
  the 
  underlying 
  crystalline 
  rocks. 
  

   It 
  does 
  not 
  follow 
  that 
  a 
  like 
  dip 
  prevails 
  in 
  the 
  schists 
  be- 
  

   neath. 
  It 
  is 
  true 
  however 
  that 
  the 
  predominant 
  dip 
  in 
  them, 
  

   and 
  in 
  the 
  Jura-Trias 
  fissures 
  and 
  bedding, 
  is 
  eastward. 
  This 
  

   last 
  fact 
  seems 
  to 
  favor 
  the 
  suggestion 
  of 
  Professor 
  Davis 
  

   that 
  the 
  foliation 
  of 
  the 
  underlying 
  schists 
  has 
  determined 
  

   the 
  courses 
  of 
  fissures 
  in 
  the 
  Jura-Trias 
  area. 
  This 
  sug- 
  

   gestion 
  would 
  have 
  support 
  in 
  the 
  fact, 
  were 
  it 
  not 
  that 
  in 
  

   New 
  Jersey, 
  where 
  the 
  same 
  is 
  true 
  as 
  to 
  the 
  dip 
  of 
  the 
  

   underlying 
  schists, 
  the 
  Jura-Trias 
  fissures 
  and 
  bedding 
  dip 
  

   westward. 
  

  

  In 
  the 
  New 
  Haven 
  region, 
  the 
  idea 
  of 
  an 
  accordance 
  between 
  

   direction 
  of 
  foliation 
  in 
  the 
  schists 
  and 
  of 
  fissures 
  in 
  the 
  Jura- 
  

   Trias 
  finds 
  no 
  support. 
  The 
  West 
  Rock 
  ridge 
  crosses 
  the 
  line 
  

   of 
  strike 
  of 
  the 
  metamorphic 
  schists 
  two 
  miles 
  west 
  of 
  it 
  at 
  an 
  

   angle 
  of 
  20°. 
  East 
  Rock 
  has 
  an 
  east- 
  of 
  -north 
  course 
  only 
  in 
  

   its 
  northern 
  extremity, 
  and 
  curves 
  around 
  through 
  nearly 
  half 
  a 
  

   circle. 
  Pine 
  Rock 
  and 
  Mill 
  Rock 
  cut 
  across 
  any 
  probable 
  

   course 
  of 
  foliation 
  in 
  underlying 
  schists 
  and 
  do 
  it 
  on 
  lines 
  that 
  

   differ 
  50° 
  in 
  trend. 
  

  

  The 
  origin 
  of 
  the 
  east-and-west 
  courses, 
  which 
  commence 
  in 
  

   the 
  extremity 
  of 
  West 
  Rock 
  and 
  continue 
  to 
  Whitney 
  Peak, 
  

   four 
  miles, 
  may 
  have 
  its 
  explanation 
  suggested 
  by 
  the 
  remark 
  

   on 
  page 
  80. 
  Or, 
  it 
  may 
  be 
  a 
  consequence 
  of 
  the 
  movement 
  

   attending 
  the 
  production 
  of 
  the 
  north-and-south 
  fissures, 
  and 
  

   local 
  to 
  the 
  New 
  Haven 
  region. 
  The 
  subject 
  at 
  present 
  is 
  

   one 
  of 
  conjectures. 
  

  

  On 
  account 
  of 
  the 
  interest 
  of 
  the 
  dynamical 
  question 
  here 
  

   brought 
  into 
  view, 
  I 
  introduce 
  another 
  illustration 
  of 
  the 
  facts 
  

   from 
  a 
  transverse 
  ridge 
  only 
  six 
  miles 
  north 
  of 
  Whitney 
  Peak 
  

   and 
  Mill 
  Rock. 
  It 
  is 
  called 
  Mt. 
  Carmel. 
  The 
  ridge 
  is 
  only 
  

   one 
  and 
  a 
  half 
  miles 
  long. 
  It 
  is 
  higher 
  than 
  those 
  already 
  

  

  