﻿AND 
  AVES 
  OF 
  NORTH 
  AMERICA. 
  249 
  

  

  by 
  Cook 
  in 
  the 
  Geological 
  Survey 
  of 
  New 
  Jersey 
  as 
  the 
  Chocolate 
  stratum. 
  This 
  bed 
  

   differs 
  from 
  the 
  pure 
  green-sand 
  above 
  it, 
  in 
  its 
  containing 
  a 
  much 
  larger 
  proportion 
  of 
  

   clay 
  and 
  sand, 
  indications 
  of 
  shallower 
  water. 
  Near 
  its 
  middle 
  is 
  the 
  great 
  bed 
  of 
  Ostrea 
  

   vesicularis, 
  also 
  an 
  indication 
  of 
  estuary 
  enclosure. 
  While 
  bones 
  are 
  abundant 
  through- 
  

   out, 
  they 
  are 
  especially 
  so 
  near 
  its 
  upper 
  surface. 
  I 
  suppose 
  it, 
  therefore, 
  to 
  have 
  been 
  

   the 
  slowly 
  subsiding 
  bottom 
  of 
  an 
  area 
  not 
  far 
  removed 
  from 
  shore. 
  The 
  termination 
  of 
  

   the 
  Chocolate 
  bed, 
  and 
  commencement 
  of 
  the 
  stratum 
  of 
  pure 
  green-sand, 
  indicates 
  per- 
  

   haps 
  a 
  more 
  rapid 
  or 
  sudden 
  submergence 
  to 
  the 
  greater 
  depth, 
  appropriate 
  to 
  the 
  life 
  of 
  

   the 
  Globigerinae, 
  in 
  whose 
  empty 
  shells 
  the 
  green-sand 
  grains 
  are 
  supposed 
  to 
  have 
  been 
  

   formed. 
  That 
  towards 
  the 
  close 
  of 
  this 
  period 
  of 
  deposit 
  shallower 
  water 
  may 
  have 
  cov- 
  

   ered 
  the 
  area, 
  is 
  suggested 
  by 
  the 
  great 
  bed 
  of 
  Ostrea 
  vesicularis 
  at 
  that 
  horizon. 
  Between 
  

   it 
  and 
  the 
  chocolate, 
  the 
  remains 
  of 
  Reptilia 
  are 
  comparatively 
  rare. 
  

  

  From 
  the 
  above, 
  I 
  am 
  much 
  disposed 
  to 
  conclude 
  that 
  the 
  clay 
  and 
  mixed 
  green-sand 
  

   marls 
  of 
  our 
  upper 
  Cretaceous 
  were 
  deposited 
  in 
  a 
  series 
  of 
  estuaries, 
  whose 
  direction 
  fol- 
  

   lowed 
  the 
  lines 
  of 
  the 
  Appalachian 
  axis, 
  i. 
  e., 
  northeast 
  and 
  southwest, 
  and 
  which 
  were 
  

   protected 
  by 
  shore 
  lines 
  to 
  the 
  seaward. 
  Such 
  a 
  shore 
  line 
  formed 
  of 
  an 
  anticlinal 
  of 
  

   Eozoic 
  rocks, 
  separated 
  an 
  estuary 
  from 
  the 
  Miocene 
  ocean 
  in 
  North 
  Carolina. 
  Its 
  crest 
  

   can 
  be 
  seen 
  where 
  exposed 
  by 
  the 
  denuding 
  action 
  of 
  the 
  Tar, 
  Cape 
  Fear 
  and 
  other 
  rivers 
  

   and 
  streams. 
  

  

  II 
  The 
  Fresh-ivater 
  Clays 
  of 
  the 
  Pea 
  Shore. 
  

  

  This 
  deposit, 
  which 
  I 
  discovered 
  to 
  be 
  truly 
  fresh-water 
  in 
  its 
  origin, 
  by 
  the 
  observa- 
  

   tion 
  of 
  numerous 
  species 
  of 
  Unio 
  and 
  Anodonta 
  near 
  its 
  base, 
  has 
  been 
  regarded 
  by 
  

   Rogers 
  and 
  all 
  others 
  who 
  have 
  examined 
  it 
  up 
  to 
  the 
  present 
  time, 
  as 
  a 
  member 
  of 
  Meek 
  

   and 
  Hayden's 
  No. 
  1, 
  and 
  as 
  lying 
  conformably 
  beneath 
  the 
  upper 
  Cretaceous 
  strata 
  to 
  the 
  

   southward 
  and 
  eastward. 
  The 
  most 
  important 
  part 
  of 
  the 
  deposit 
  consists 
  of 
  a 
  heavy 
  

   black 
  clay 
  which 
  is 
  used 
  for 
  making 
  brick, 
  which 
  rests 
  on 
  a 
  bed 
  of 
  hard 
  laminated 
  clay, 
  

   with 
  a 
  thin 
  layer 
  of 
  iron-stone 
  between. 
  The 
  clay 
  bed 
  at 
  one 
  place 
  examined, 
  is 
  25 
  feet 
  

   in 
  thickness, 
  and 
  at 
  from 
  one 
  to 
  three 
  feet 
  from 
  its 
  bottom 
  occurs 
  a 
  bed 
  of 
  fresh-water 
  

   mussels. 
  These 
  are 
  Unios 
  and 
  Anodontas 
  of 
  six 
  species, 
  all 
  of 
  them 
  as 
  pointed 
  out 
  to 
  

   him 
  by 
  Dr. 
  Lea, 
  hitherto 
  undescribed. 
  The 
  beds 
  are 
  from 
  the 
  top 
  of 
  the 
  clay 
  down, 
  con- 
  

   formable, 
  and 
  have 
  a 
  dip 
  of 
  about 
  25° 
  to 
  the 
  southeast. 
  The 
  upper 
  surface 
  of 
  the 
  clay 
  is 
  

   worn 
  into 
  holes, 
  which 
  are 
  filled 
  by 
  the 
  material 
  of 
  a 
  bed 
  of 
  coarse 
  gravel 
  of 
  little 
  depth, 
  

   which 
  covers 
  the 
  whole. 
  Above 
  this 
  is 
  a 
  bed 
  of 
  fine 
  sand 
  varying 
  from 
  6 
  to 
  15 
  feet 
  in 
  

   thickness 
  to 
  the 
  soil. 
  

  

  AMERJ. 
  PHILOSO. 
  SOC 
  VOL. 
  XIV 
  63 
  

  

  