﻿Crosby 
  — 
  Geology 
  of 
  Newport 
  Neck 
  and 
  Conanicut 
  Is. 
  .231 
  

  

  rocks, 
  but 
  have 
  only 
  recently 
  had 
  an 
  opportunity 
  to 
  do 
  so.* 
  

   That 
  the 
  granite 
  is, 
  in 
  part 
  at 
  least, 
  intrusive 
  in 
  the 
  flinty 
  slate 
  

   appears 
  to 
  me 
  unquestionable. 
  Pirsson 
  has 
  clearly 
  set 
  forth 
  

   the 
  evidence 
  for 
  Conanicut 
  Island, 
  showing 
  conclusively 
  that 
  

   the 
  finer 
  grain 
  of 
  the 
  granite 
  near 
  the 
  contact, 
  the 
  fact 
  that 
  it 
  

   is 
  at 
  all 
  points 
  firmly 
  welded 
  to 
  the 
  flinty 
  slate, 
  and 
  above 
  all 
  

   the 
  fact 
  that 
  it 
  forms 
  beautifully 
  clear 
  apophyses 
  and 
  dikes 
  in 
  

   the 
  latter, 
  admit 
  of 
  no 
  other 
  explanation. 
  Dale 
  appears 
  to 
  

   have 
  overlooked 
  the 
  fact 
  that 
  the 
  evidence 
  is 
  similar 
  and 
  

   equally 
  conclusive 
  on 
  Newj)ort 
  Neck. 
  Dale's 
  map 
  of 
  the 
  

  

  1 
  P 
  .if 
  

  

  / 
  Shales, 
  etc. 
  

  

  , 
  Arkose. 
  

  

  Flinty 
  slate. 
  

  

  + 
  Granite. 
  

  

  Dikes. 
  

  

  Seile 
  

   Fig. 
  1. 
  — 
  Map 
  of 
  Newport 
  Neck 
  and 
  Conanicut 
  Island, 
  modified 
  from 
  Dale. 
  

  

  Neck, 
  reproduced 
  here 
  (fig. 
  1), 
  is 
  substantially 
  accurate. 
  Along 
  

   the 
  north-south 
  contact 
  of 
  the 
  granite 
  and 
  flinty 
  slate 
  the 
  fine- 
  

   grained 
  border 
  of 
  the 
  granite 
  is 
  firmly 
  welded 
  to 
  the 
  slate 
  and 
  

   clear 
  dikes 
  of 
  similar 
  granite 
  traverse 
  the 
  slate 
  in 
  the 
  vicinity 
  

   of 
  the 
  contact. 
  The 
  fine-grained, 
  reddish, 
  aplitic 
  granite, 
  

   whose 
  igneous 
  relations 
  to 
  the 
  flinty 
  slate 
  are 
  so 
  unequivocal, 
  

   is 
  but 
  the 
  marginal 
  portion 
  or 
  contact 
  zone 
  of 
  a 
  large 
  body 
  or 
  

   massif 
  of 
  normal, 
  coarse-grained, 
  gray 
  granite. 
  Prof. 
  Barton 
  

   and 
  I 
  found, 
  however, 
  some 
  evidence 
  of 
  the 
  existence 
  in 
  this 
  

   region 
  of 
  granitic 
  rocks 
  older 
  than 
  the 
  flinty 
  slate. 
  This 
  evi- 
  

   dence 
  consists 
  in 
  the 
  occurrence 
  in 
  the 
  flinty 
  slate, 
  on 
  the 
  

   north 
  shore 
  of 
  the 
  neck, 
  of 
  several 
  layers 
  of 
  conglomerate 
  

   containing 
  gray 
  granite 
  pebbles. 
  That 
  the 
  flinty 
  slate 
  owes 
  its 
  

  

  * 
  In 
  this 
  later 
  study 
  I 
  was 
  assisted 
  by 
  Mr. 
  T. 
  A. 
  Watson. 
  

  

  