﻿Crosby 
  — 
  Geology 
  of 
  Newport 
  Neck 
  and 
  Conanicut 
  Is. 
  235 
  

  

  having 
  extended 
  so 
  far 
  with 
  approximately 
  uniform 
  intensity, 
  

   should 
  then 
  die 
  out 
  or 
  show 
  a 
  very 
  marked 
  diminution 
  within 
  

   a 
  few 
  feet 
  or 
  yards. 
  A 
  rapid 
  change 
  near 
  the 
  grauite 
  and 
  a 
  

   slow 
  change 
  at 
  a 
  distance 
  would 
  appear 
  to 
  be 
  a 
  better 
  expres- 
  

   sion 
  of 
  the 
  general 
  law 
  in 
  such 
  cases. 
  

  

  Considered 
  by 
  itself, 
  this 
  evidence 
  is, 
  perhaps, 
  inconclusive, 
  

   since 
  to 
  the 
  northward 
  there 
  are 
  no 
  outcrops 
  for 
  a 
  long 
  dis- 
  

   tance. 
  But 
  it 
  is 
  important 
  here 
  to 
  take 
  note 
  of 
  the 
  bed 
  of 
  

   arkose 
  (called 
  grit 
  by 
  Pirsson 
  and 
  quartz 
  and 
  clay 
  aggregate 
  by 
  

   Dale) 
  which 
  Dale, 
  Pirsson 
  and 
  Collie 
  have 
  mapped 
  on 
  the 
  east 
  

   shore 
  of 
  Mackerel 
  Cove, 
  between 
  the 
  granite 
  and 
  shales 
  (figure 
  

   2). 
  Each 
  of 
  the 
  maps 
  referred 
  to 
  shows 
  the 
  arkose, 
  which 
  has 
  

   a 
  breadth 
  on 
  the 
  shore 
  of 
  at 
  least 
  400 
  feet, 
  as 
  extending 
  in 
  a 
  

   northeasterly 
  or 
  diagonal 
  direction 
  toward 
  the 
  eastern 
  shore 
  of 
  

   the 
  island, 
  and 
  ending 
  abruptly 
  with 
  a 
  greatly 
  increased 
  

   breadth 
  when 
  less 
  than 
  half 
  way 
  across 
  the 
  island. 
  After 
  

   examining 
  the 
  outcrops 
  of 
  arkose 
  on 
  the 
  shore 
  of 
  Mackerel 
  

   Cove, 
  Mr. 
  Watson 
  and 
  I 
  were 
  searching 
  along 
  the 
  road 
  north 
  

   of 
  Mr. 
  Green's 
  barn 
  for 
  outcrops, 
  hoping 
  to 
  find 
  something 
  

   that 
  might 
  assist 
  in 
  the 
  interpretation 
  of 
  the 
  outcrop 
  upon 
  

   which 
  Pirsson's 
  argument 
  so 
  largely 
  rests, 
  when 
  our 
  attention 
  

   was 
  attracted 
  by 
  the 
  abundance 
  of 
  arkose, 
  identical 
  in 
  character 
  

   with 
  that 
  on 
  the 
  shore, 
  in 
  the 
  stone 
  walls 
  and 
  scattered 
  in 
  angu- 
  

   lar 
  masses 
  up 
  to 
  three 
  feet 
  in 
  diameter 
  over 
  the 
  adjoining 
  fields. 
  

   Following 
  up 
  this 
  clue, 
  we 
  found 
  that 
  the 
  arkose 
  debris 
  is 
  

   abundant 
  over 
  the 
  entire 
  slope 
  from 
  the 
  road 
  to 
  the 
  east 
  shore 
  

   for 
  a 
  breadth 
  of 
  400 
  to 
  500 
  feet 
  north 
  of 
  the 
  last 
  outcrops 
  of 
  the 
  

   flinty 
  slate 
  ; 
  and 
  on 
  the 
  shore, 
  from 
  the 
  flinty 
  slate 
  on 
  the 
  

   south 
  to 
  the 
  green 
  and 
  fissile 
  shales 
  on 
  the 
  north, 
  an 
  estimated 
  

   distance 
  of 
  four 
  hundred 
  feet, 
  there 
  are 
  many 
  angular 
  masses 
  

   of 
  the 
  same 
  coarse, 
  dark 
  arkose. 
  In 
  the 
  light 
  of 
  these 
  facts 
  it 
  

   cannot 
  be 
  doubted 
  that 
  the 
  arkose 
  extends 
  entirely 
  across 
  the 
  

   island 
  in 
  a 
  belt 
  of 
  approximately 
  uniform 
  breadth 
  (four 
  hun- 
  

   dred 
  feet 
  more 
  or 
  less) 
  between 
  the 
  unaltered 
  green 
  shales 
  on 
  

   the 
  north 
  and 
  the 
  flinty 
  slate 
  and 
  granite 
  on 
  the 
  south 
  (fig. 
  1). 
  

   Its 
  unconformable 
  relations 
  to 
  these 
  older 
  rocks 
  is 
  indicated 
  by 
  

   its 
  passing 
  obliquely 
  from 
  the 
  one 
  to 
  the 
  other. 
  

  

  This 
  continuous 
  belt 
  of 
  arkose 
  separating 
  the 
  flinty 
  slate 
  

   from 
  the 
  unaltered 
  green 
  shales 
  seems 
  to 
  materially 
  strengthen 
  

   the 
  conclusion 
  stated 
  above 
  with 
  regard 
  to 
  the 
  significance 
  of 
  

   the 
  ledge 
  south 
  of 
  Mr. 
  Green's 
  barn. 
  The 
  idea 
  of 
  an 
  import- 
  

   ant 
  or 
  significant 
  gradation 
  is 
  ruled 
  out 
  for 
  the 
  simple 
  reason 
  

   that 
  there 
  is 
  nothing 
  for 
  the 
  flinty 
  slate 
  to 
  grade 
  into. 
  The 
  

   arkose 
  is 
  quite 
  out 
  of 
  the 
  question 
  in 
  this 
  connection, 
  if 
  for 
  no 
  

   other 
  reason, 
  because 
  it 
  is 
  so 
  clearly 
  newer 
  than 
  the 
  granite 
  of 
  

   the 
  debris 
  of 
  which 
  it 
  is 
  chiefly 
  composed, 
  and, 
  therefore, 
  

   newer 
  than 
  the 
  metamorphism 
  of 
  the 
  flinty 
  slate 
  which 
  the 
  

   granite 
  intersects. 
  That 
  the 
  arkose 
  is 
  not 
  a 
  fault-breccia, 
  but 
  a 
  

  

  