﻿Hatcher 
  — 
  Sedimentary 
  Rocks 
  of 
  Southern 
  Patagonia. 
  103 
  

  

  and 
  Shell 
  Gap, 
  which 
  according 
  to 
  Ameghino 
  should 
  be 
  Supra- 
  

   Patagonian 
  beds, 
  there 
  is 
  a 
  preponderance 
  of 
  species 
  given 
  by 
  

   him 
  as 
  characteristic 
  of 
  the 
  Piso 
  Juliense 
  at 
  the 
  base 
  of 
  the 
  

   Patagonian 
  beds. 
  

  

  From 
  a 
  consideration 
  of 
  these 
  facts 
  regarding 
  the 
  association 
  

   of 
  fossils, 
  it 
  is 
  clear 
  that 
  the 
  terms 
  Piso 
  Juliense 
  and 
  Piso 
  

   Leonense 
  cannot 
  be 
  accepted, 
  and 
  also 
  that 
  the 
  Patagonian 
  

   and 
  Supra- 
  Patagonian 
  heels 
  are 
  not 
  distinct 
  formations, 
  but 
  

   simply 
  represent 
  different 
  phases 
  of 
  one 
  and 
  the 
  same 
  forma- 
  

   tion. 
  The 
  Patagonian 
  phase 
  prevails 
  at 
  the 
  base 
  of 
  the 
  series 
  

   and 
  the 
  Snpra-Patagonian 
  at 
  the 
  top, 
  but 
  neither 
  is 
  limited 
  to 
  

   any 
  definite 
  horizon. 
  I 
  therefore 
  discard 
  the 
  term 
  Snpra- 
  

   Patagonian 
  beds, 
  and 
  shall 
  refer 
  to 
  strata 
  formerly 
  known 
  under 
  

   that 
  name 
  as 
  the 
  Supra-Patagonian 
  phase 
  of 
  the 
  Patagonian 
  

   beds. 
  

  

  Age 
  of 
  the 
  Patagonian 
  beds. 
  — 
  Concerning 
  the 
  age 
  of 
  the 
  

   Patagonian 
  beds, 
  there 
  has 
  been 
  much 
  difference 
  of 
  opinion. 
  

   This 
  difference 
  has 
  been 
  due 
  largely 
  to 
  careless 
  collecting 
  and 
  

   imperfect 
  observations 
  as 
  to 
  their 
  true 
  stratigraphic 
  position. 
  

   During 
  the 
  first 
  five 
  years 
  of 
  their 
  work 
  on 
  Patagonian 
  geol- 
  

   ogy 
  and 
  paleontology, 
  the 
  Ameghinos 
  considered 
  the 
  Pata- 
  

   gonian 
  beds 
  as 
  overlying 
  the 
  Santa 
  Cruz 
  beds. 
  They 
  then 
  

   placed 
  the 
  so-called 
  Supra-Patagonian 
  beds 
  not 
  only 
  beneath 
  

   the 
  Patagonian 
  beds, 
  but 
  separated 
  from 
  them 
  by 
  the 
  entire 
  

   series 
  of 
  strata 
  composing 
  the 
  Santa 
  Cruz 
  beds. 
  At 
  that 
  time 
  

   they 
  called 
  the 
  Supra-Patagonian 
  beds 
  the 
  Sub- 
  Patagonian 
  

   beds, 
  and 
  the 
  sequence 
  as 
  then 
  determined 
  by 
  the 
  Ameghinos 
  

   in 
  Patagonia 
  was 
  beginning 
  below 
  the 
  Sub- 
  Patagonian 
  beds, 
  

   the 
  Santa 
  Cruz 
  beds 
  and 
  the 
  Patagonian 
  beds. 
  In 
  1893, 
  

   Senor 
  Alcides 
  Mercerat 
  visited 
  Patagonia 
  and 
  determined 
  the 
  

   true 
  stratigraphic 
  relations 
  of 
  these 
  deposits, 
  which 
  he 
  found 
  

   to 
  be 
  identical 
  with 
  those 
  suggested 
  by 
  Darwin 
  a 
  half 
  century 
  

   earlier. 
  In 
  1894, 
  in 
  his 
  fifth 
  year 
  of 
  field 
  work 
  in 
  Patagonia, 
  

   Senor 
  Carlos 
  Ameghino, 
  following 
  Mercerat, 
  was 
  able 
  to 
  con- 
  

   firm 
  the 
  latter's 
  determinations 
  concerning 
  the 
  relative 
  posi- 
  

   tions 
  of 
  these 
  various 
  formations, 
  and 
  the 
  2,500 
  feet 
  of 
  strata 
  

   composing 
  them 
  were 
  forthwith 
  turned 
  upside 
  down, 
  so 
  to 
  

   speak, 
  by 
  Dr. 
  Ameghino, 
  the 
  Patagonian 
  beds 
  being 
  placed 
  at 
  

   the 
  base 
  of 
  the 
  series 
  instead 
  of 
  at 
  the 
  top 
  and 
  the 
  Supra- 
  

   Patagonian 
  beds 
  were 
  removed 
  from 
  the 
  bottom 
  to 
  the 
  middle 
  

   of 
  the 
  series 
  and 
  the 
  sequence 
  changed 
  to 
  Patagonian, 
  Supra- 
  

   JPatagonian 
  and 
  Santa 
  Cruz 
  beds, 
  passing 
  from 
  beneath 
  up- 
  

   wards. 
  This 
  remarkable 
  bit 
  of 
  stratigraphic 
  juggling 
  was 
  

   accomplished 
  in 
  such 
  a 
  skillful 
  manner 
  by 
  Dr. 
  Ameghino 
  that 
  

   it 
  became 
  unnecessary 
  for 
  him 
  to 
  make 
  any 
  considerable 
  

   changes 
  in 
  the 
  age 
  of 
  the 
  various 
  beds 
  to 
  accommodate 
  and 
  har- 
  

   monize 
  with 
  their 
  altered 
  and 
  true 
  stratigraphic 
  relations. 
  To 
  

  

  