﻿368 
  Hay 
  — 
  Ages 
  of 
  Pleistocene 
  Deposits. 
  

  

  species 
  which 
  give 
  us 
  help. 
  Horse 
  remains, 
  however, 
  

   were 
  found 
  long 
  ago 
  in 
  the 
  Navesink 
  Hills 
  and 
  again 
  at 
  

   Swedesboro 
  ; 
  but 
  too 
  little 
  is 
  known 
  about 
  the 
  condition 
  

   under 
  which 
  they 
  were 
  discovered. 
  Fortunately 
  the 
  con- 
  

   ditions 
  are 
  better 
  understood 
  at 
  Fish 
  House, 
  just 
  above 
  

   Camden. 
  The 
  clays 
  at 
  this 
  place 
  had 
  long 
  been 
  regarded 
  

   as 
  belonging 
  to 
  the 
  Cretaceous 
  ; 
  but 
  in 
  1869 
  7 
  Cope 
  

   announced 
  that 
  he 
  had 
  found 
  at 
  the 
  bottom 
  of 
  the 
  clays 
  

   a 
  skull 
  of 
  a 
  horse, 
  and 
  he 
  referred 
  the 
  deposit 
  to 
  the 
  

   Pliocene. 
  In 
  1897 
  8 
  Woolman 
  described 
  other 
  horse 
  

   remains, 
  teeth, 
  from 
  the 
  same 
  clays 
  ; 
  and 
  he 
  referred 
  the 
  

   beds 
  to 
  the 
  Pensauken 
  formation. 
  Salisbury 
  and 
  Knapp 
  9 
  

   recorded 
  their 
  final 
  opinion 
  that 
  these 
  beds 
  belong 
  to 
  the 
  

   Pensauken. 
  On 
  page 
  78 
  of 
  the 
  volume 
  just 
  cited 
  these 
  

   geologists 
  suggest 
  that 
  this 
  formation 
  was, 
  in 
  part 
  at 
  

   least, 
  older 
  than 
  the 
  Kansan 
  drift. 
  

  

  Immediately 
  below 
  the 
  horse-bearing 
  layer 
  are 
  found 
  

   many 
  shells 
  which 
  have 
  been 
  referred 
  to 
  the 
  genera 
  Unio 
  

   and 
  Anodonta. 
  Twelve 
  species 
  were 
  described 
  during 
  the 
  

   time 
  that 
  the 
  beds 
  were 
  regarded 
  as 
  Cretaceous 
  ; 
  but 
  a 
  

   close 
  relationship 
  with 
  existing 
  species 
  was 
  recognized. 
  

   They 
  are 
  quite 
  certainly 
  to 
  be 
  identified 
  with 
  species 
  now 
  

   existing 
  in 
  rivers 
  of 
  North 
  America 
  ; 
  but 
  at 
  present 
  only 
  

   one-half 
  or 
  fewer 
  of 
  them 
  live 
  in 
  that 
  region. 
  The 
  others 
  

   are 
  now 
  found 
  in 
  the 
  St. 
  Lawrence 
  drainage 
  system 
  or 
  

   still 
  further 
  away. 
  One 
  is 
  confined 
  to 
  the 
  Ohio, 
  Cumber- 
  

   land, 
  and 
  Tennessee 
  rivers. 
  Another 
  occupies 
  the 
  Mis- 
  

   sissippi 
  and 
  Gulf 
  drainage 
  regions; 
  while 
  one 
  of 
  the 
  

   species 
  of 
  Anodonta 
  is 
  found 
  only 
  in 
  the 
  upper 
  Missouri 
  

   river 
  region. 
  We 
  have 
  then 
  these 
  reasons 
  for 
  believing 
  

   that 
  the 
  clays 
  at 
  Fish 
  House 
  are 
  of 
  early 
  Pleistocene 
  age 
  : 
  

  

  (1) 
  Competent 
  geologists 
  have 
  referred 
  them 
  to 
  Pen- 
  

   sauken. 
  (2) 
  They 
  contain 
  remains 
  of 
  Equws, 
  no 
  native 
  

   species 
  of 
  which 
  is 
  known 
  to 
  have 
  lived 
  during 
  or 
  after 
  

   the 
  Wisconsin 
  glacial 
  stage. 
  (3) 
  The 
  clays 
  enclose 
  

   many 
  species 
  of 
  Unionidae, 
  the 
  majority 
  of 
  which 
  now 
  

   live 
  only 
  in 
  far 
  distant 
  regions. 
  

  

  There 
  are 
  those 
  who 
  believe 
  that 
  the 
  Fish 
  House 
  clays 
  

   belong 
  to 
  the 
  Cape 
  May 
  formation, 
  which 
  was 
  laid 
  down, 
  

   as 
  Salisbury 
  and 
  Knapp 
  inform 
  us, 
  during 
  Wisconsin 
  

   times. 
  These 
  people 
  ought 
  to 
  explain 
  what 
  has 
  caused 
  

  

  7 
  Trans. 
  Amer. 
  Phil. 
  Soc, 
  vol. 
  14, 
  p. 
  249, 
  fig. 
  55. 
  

   •N. 
  J. 
  Surv. 
  Rep. 
  for 
  1896, 
  p. 
  201. 
  

   Geol. 
  Surv. 
  N. 
  J., 
  vol. 
  8, 
  p. 
  104, 
  1912. 
  

  

  