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  Darton 
  and 
  Kemp 
  — 
  Newly 
  Discovered 
  Dike 
  at 
  

  

  Art. 
  XXXIX. 
  — 
  A 
  Newly 
  Discovered 
  Dike 
  at 
  De 
  Witt, 
  near 
  

   Syracuse, 
  New 
  York. 
  Geologic 
  notes 
  by 
  N. 
  H. 
  Darton, 
  

   U. 
  S. 
  Geological 
  Survey. 
  Petrographic 
  description 
  by 
  

   J. 
  F. 
  Kemp, 
  Columbia 
  College. 
  

  

  In 
  November, 
  1894, 
  1 
  received 
  intelligence 
  of 
  an 
  occurrence 
  

   of 
  intrusive 
  rock 
  penetrating 
  the 
  Salina 
  formation 
  near 
  Syra- 
  

   cuse, 
  and 
  soon 
  after 
  had 
  an 
  opportunity 
  to 
  visit 
  the 
  locality. 
  

   The 
  materials 
  obtained 
  were 
  submitted 
  to 
  Prof. 
  J. 
  F. 
  Kemp 
  

   for 
  microscopic 
  study, 
  and 
  an 
  analysis 
  of 
  the 
  rock 
  was 
  made 
  in 
  

   the 
  laboratory 
  of 
  the 
  U. 
  S. 
  Geological 
  Survey. 
  

  

  The 
  locality 
  is 
  at 
  the 
  new 
  reservoir 
  on 
  the 
  top 
  of 
  an 
  isolated 
  

   hill, 
  a 
  half 
  mile 
  south 
  of 
  Dewitt 
  Center 
  (De 
  Sono 
  station 
  on 
  

   the 
  West 
  Shore 
  railroad), 
  3 
  miles 
  east 
  of 
  Syracuse. 
  Mr. 
  Phil- 
  

   lip 
  F. 
  Schneider, 
  a 
  professor 
  in 
  the 
  High 
  School 
  at 
  Syracuse, 
  

   was 
  the 
  discoverer 
  of 
  the 
  dike, 
  and 
  to 
  him 
  also 
  we 
  are 
  indebted 
  

   for 
  information 
  regarding 
  its 
  relations. 
  The 
  dike 
  was 
  exposed 
  

   by 
  the 
  excavations 
  for 
  the 
  reservoir 
  and 
  does 
  not 
  appear 
  to 
  

   reach 
  the 
  natural 
  surface. 
  It 
  was 
  buried 
  under 
  a 
  mantle 
  of 
  

   glacial 
  drift, 
  and 
  in 
  part, 
  at 
  least, 
  was 
  covered 
  by 
  shales 
  and 
  

   limestones 
  of 
  the 
  Salina 
  formation. 
  Unfortunately 
  the 
  reser- 
  

   voir 
  was 
  practically 
  completed 
  and 
  filled 
  with 
  water 
  before 
  Mr. 
  

   Schneider 
  learned 
  of 
  the 
  dike, 
  so 
  that 
  he 
  was 
  unable 
  to 
  observe 
  

   the 
  relations. 
  According 
  to 
  the 
  statements 
  of 
  the 
  contractor, 
  

   the 
  rock 
  occurred 
  in 
  masses 
  imbedded 
  in 
  a 
  greenish-yellow 
  

   earth 
  which 
  underlaid 
  the 
  entire 
  area 
  of 
  the 
  excavation, 
  which 
  

   was 
  about 
  200 
  by 
  250 
  feet. 
  The 
  masses 
  varied 
  greatly 
  in 
  size. 
  

   Some 
  were 
  20 
  by 
  50 
  feet 
  and 
  afforded 
  an 
  adequate 
  supply 
  of 
  

   building 
  stone 
  for 
  the 
  walls 
  of 
  the 
  reservoir. 
  A 
  considerable 
  

   amount 
  of 
  the 
  excavated 
  materials 
  now 
  remains 
  on 
  the 
  banks 
  

   and 
  it 
  was 
  from 
  that 
  source 
  that 
  I 
  secured 
  specimens. 
  The 
  

   greenish-yellow 
  earth 
  in 
  which 
  the 
  rock 
  masses 
  occurred 
  is 
  

   undoubtedly 
  a 
  product 
  of 
  the 
  decomposition 
  of 
  the 
  intrusive 
  

   rock. 
  The 
  original 
  surfaces 
  of 
  all 
  the 
  rocks 
  are 
  more 
  or 
  less 
  

   deeply 
  decomposed 
  to 
  a 
  serpentinous 
  matter, 
  and 
  some 
  of 
  the 
  

   smaller 
  rocks 
  are 
  filled 
  with 
  calcite 
  veins 
  and 
  other 
  secondary 
  

   products. 
  Whether 
  the 
  mass 
  was 
  really 
  a 
  dike 
  or 
  mainly 
  an 
  

   intruded 
  sheet 
  was 
  not 
  determined. 
  No 
  traces 
  of 
  the 
  rock 
  

   have 
  been 
  found 
  on 
  the 
  surface 
  or 
  in 
  wells 
  in 
  the 
  vicinity. 
  

  

  The 
  dike 
  at 
  Dewitt 
  is 
  in 
  the 
  upper 
  portion 
  of 
  the 
  Salina 
  for- 
  

   mation 
  which 
  consists 
  of 
  shales 
  and 
  limestones. 
  A 
  short 
  dis- 
  

   tance 
  south, 
  rise 
  the 
  slopes 
  of 
  the 
  Helderberg 
  escarpment, 
  and 
  

   to 
  the 
  north 
  are 
  wide 
  plains 
  of 
  the 
  lower 
  Salina 
  beds. 
  The 
  dip 
  

   is 
  a 
  gentle 
  monocline 
  to 
  the 
  southward. 
  The 
  rocks 
  adjoining 
  

   the 
  intrusive 
  were 
  thrown 
  out 
  in 
  considerable 
  amount 
  in 
  the 
  

  

  