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  Crosby 
  — 
  Geology 
  of 
  Newport 
  Neck 
  and 
  Conanicut 
  Is. 
  

  

  flinty 
  or 
  metamorphic 
  character 
  to 
  the 
  influence 
  of 
  the 
  granite 
  

   is 
  obvious, 
  and 
  it 
  undoubtedly 
  shows 
  some 
  gradation 
  in 
  the 
  

   degree 
  of 
  metamorphism 
  as 
  we 
  recede 
  from 
  the 
  border 
  of 
  the 
  

   granite. 
  But 
  that 
  it 
  grades 
  into 
  the 
  highly 
  fissile 
  Carbonifer- 
  

   ous 
  shales, 
  as 
  held 
  by 
  Pirsson, 
  cannot 
  be 
  admitted. 
  This 
  is 
  the 
  

   most 
  critical 
  and 
  at 
  the 
  present 
  time 
  the 
  most 
  distinctly 
  con- 
  

   troverted 
  point 
  in 
  the 
  geology 
  of 
  the 
  region. 
  According 
  to 
  

   Jackson 
  and 
  Pirsson 
  this 
  gradation 
  exists 
  ; 
  the 
  flinty 
  slate 
  is 
  

   simply 
  a 
  more 
  altered 
  part 
  of 
  the 
  Carboniferous 
  shales, 
  and 
  

   the 
  granite 
  is 
  post-Carboniferous 
  ; 
  while 
  according 
  to 
  Dale 
  

   and 
  Collie 
  the 
  flinty 
  slate 
  is 
  distinctly 
  older 
  than 
  the 
  Carbon- 
  

   iferous 
  series, 
  Dale's 
  view 
  differing 
  from 
  that 
  of 
  Collie 
  and 
  

   the 
  present 
  writer 
  only 
  as 
  regards 
  the 
  relations 
  of 
  this 
  older 
  

   flinty 
  slate 
  to 
  the 
  granite. 
  

  

  On 
  Newport 
  Neck 
  the 
  flinty 
  slates 
  and 
  the 
  Carboniferous 
  

   shales 
  are 
  certainly 
  very 
  strongly 
  contrasted, 
  both 
  lithologically 
  

   and 
  stratigraphically. 
  The 
  former 
  are 
  exceedingly 
  massive 
  

   gray 
  rocks 
  of 
  almost 
  flinty 
  hardness, 
  rarely 
  exhibiting 
  any- 
  

   thing 
  approaching 
  a 
  thin-bedded 
  or 
  shaly 
  structure 
  and 
  with 
  a 
  

   prevailing 
  east-west 
  strike 
  and 
  approximately 
  vertical 
  dip. 
  The 
  

   latter 
  are 
  soft, 
  fissile, 
  greenish, 
  greenish-gray 
  or 
  purplish 
  shales 
  

   with 
  a 
  prevailing 
  north-south 
  strike 
  and 
  moderate 
  easterly 
  dip. 
  

   Each 
  series 
  holds 
  its 
  characters 
  perfectly 
  up 
  to 
  the 
  common 
  

   boundary, 
  which 
  is 
  a 
  very 
  obvious 
  fault 
  line. 
  From 
  the 
  

   granite 
  westward 
  to 
  this 
  line 
  the 
  metamorphic 
  character 
  of 
  the 
  

   flinty 
  slate 
  diminishes 
  so 
  slightly 
  as 
  to 
  suggest 
  that 
  the 
  granite 
  

   may 
  underlie 
  the 
  entire 
  area 
  at 
  no 
  great 
  depth. 
  The 
  flinty 
  

   slates, 
  owing 
  to 
  their 
  superior 
  hardness, 
  form, 
  like 
  the 
  granite, 
  

   a 
  broken 
  and 
  ledgy 
  tract, 
  which 
  rises 
  boldly 
  above 
  the 
  low 
  and 
  

   swampy 
  ground 
  underlain 
  by 
  the 
  shales. 
  The 
  stratigraphic 
  

   discordance 
  is 
  perfect, 
  and 
  indications 
  of 
  a 
  lithological 
  grada- 
  

   tion 
  are 
  wholly 
  wanting, 
  although 
  it 
  might 
  be 
  claimed, 
  since 
  

   the 
  nearest 
  outcrops 
  are 
  thirty 
  feet 
  apart, 
  that 
  a 
  very 
  abrupt 
  

   gradation 
  is 
  still 
  a 
  possibility. 
  The 
  Carboniferous 
  age 
  of 
  the 
  

   shales 
  is 
  unquestioned, 
  while 
  it 
  may 
  safely 
  be 
  asserted 
  that 
  the 
  

   flinty 
  slate 
  resembles 
  no 
  other 
  formation 
  in 
  New 
  England 
  so 
  

   closely 
  as 
  the 
  Middle 
  Cambrian 
  slates 
  of 
  the 
  Boston 
  basin, 
  

   many 
  of 
  the 
  ledges 
  being 
  indistinguishable 
  from 
  the 
  more 
  

   characteristic 
  outcrops 
  of 
  the 
  Blue 
  Hills. 
  

  

  These 
  phenomena 
  are 
  repeated 
  in 
  all 
  essential 
  features 
  at 
  the 
  

   south 
  end 
  of 
  the 
  Cliffs, 
  between 
  Sheep 
  Point 
  and 
  Bailey's 
  

   Beach. 
  In 
  going 
  south 
  along 
  the 
  east 
  shore 
  we 
  pass 
  abruptly, 
  

   near 
  Sheep 
  Point, 
  from 
  Carboniferous 
  shales 
  that 
  are 
  in 
  part 
  

   greenish 
  gray 
  and 
  in 
  part 
  black 
  and 
  highly 
  carbonaceous, 
  

   affording 
  an 
  abundant 
  Carboniferous 
  flora, 
  to 
  a 
  compact 
  green- 
  

   ish 
  to 
  grayish 
  tough 
  rock, 
  with 
  occasional 
  bedding 
  lines 
  and 
  

   streaks 
  of 
  conglomerate, 
  which 
  is 
  undoubtedly 
  equivalent 
  to 
  

   the 
  flinty 
  slate 
  of 
  Newport 
  Neck. 
  About 
  half 
  way 
  from 
  

  

  