﻿Hatcher 
  — 
  Sedimentary 
  Rocks 
  of 
  Southern 
  Patagonia. 
  91 
  

  

  Upper 
  Conglomerates. 
  — 
  The 
  Belgrano 
  beds 
  in 
  the 
  canon 
  of 
  

   Rio 
  Tarde 
  are 
  conformably 
  overlaid 
  by 
  330 
  feet 
  of 
  hard 
  fine- 
  

   grained 
  red 
  and 
  variegated 
  sandstone 
  with 
  occasional 
  layers 
  of 
  

   clay 
  ending 
  above 
  in 
  a 
  series 
  of 
  very 
  hard 
  fine 
  conglomerates. 
  

   ISTo 
  characteristic 
  fossils 
  were 
  found 
  in 
  these 
  beds, 
  which 
  may 
  

   be 
  called 
  the 
  Upper 
  Conglomerates 
  as 
  distinguishing 
  them 
  

   from 
  the 
  Zoiver 
  Conglomerates 
  near 
  the 
  base 
  of 
  the 
  series. 
  A 
  

   somewhat 
  careful 
  search 
  for 
  fossils 
  was 
  rewarded 
  only 
  by 
  the 
  

   discovery 
  of 
  a 
  few 
  imperfect 
  plant 
  remains 
  and 
  one 
  or 
  two 
  

   casts 
  of 
  bivalve 
  mollusca. 
  

  

  Thus 
  far 
  all 
  the 
  rocks 
  of 
  the 
  entire 
  series 
  of 
  strata 
  through 
  

   which 
  we 
  have 
  passed 
  in 
  ascending 
  the 
  lower 
  one 
  and 
  a 
  half 
  

   miles 
  of 
  the 
  course 
  of 
  the 
  canon 
  are 
  conformable 
  and 
  evidently 
  

   of 
  marine 
  origin. 
  Taken 
  together 
  they 
  constitute 
  the 
  Pueyr- 
  

   redon 
  Series, 
  with 
  an 
  aggregate 
  thickness 
  of 
  from 
  750 
  to 
  800 
  

   feet. 
  

  

  The 
  present 
  surface 
  distribution 
  of 
  rocks 
  belonging 
  to 
  the 
  

   Pueyrredon 
  Series, 
  known 
  to 
  the 
  writer 
  from 
  personal 
  observa- 
  

   tions, 
  is 
  of 
  very 
  limited 
  extent 
  and 
  is 
  confined 
  to 
  the 
  lowermost 
  

   800 
  feet 
  of 
  strata 
  exhibited 
  in 
  the 
  lower 
  course 
  of 
  the 
  caflon 
  of 
  

   Rio 
  Tarde 
  and 
  to 
  other 
  very 
  limited 
  exposures 
  to 
  be 
  seen 
  

   -about 
  eight 
  miles 
  to 
  the 
  eastward, 
  in 
  a 
  small 
  canon 
  cut 
  in 
  the 
  

   surface 
  of 
  the 
  first 
  bench, 
  which 
  at 
  this 
  point 
  has- 
  an 
  altitude 
  of 
  

   some 
  200 
  feet 
  above 
  the 
  bottom 
  of 
  the 
  valley 
  of 
  Gio 
  basin 
  

   which 
  extends 
  eastward 
  from 
  Lake 
  Pueyrredon. 
  In 
  this 
  vicin- 
  

   ity 
  the 
  bottom 
  of 
  the 
  valley 
  of 
  Gio 
  basin 
  is 
  occupied 
  by 
  a 
  lake 
  

   shown 
  on 
  the 
  map 
  as 
  White 
  Lake, 
  and 
  the 
  exposures 
  in 
  ques- 
  

   tion 
  will 
  be 
  found 
  at 
  a 
  distance 
  of 
  about 
  two 
  miles 
  south 
  of 
  

   the 
  western 
  border 
  of 
  this 
  lake. 
  They 
  are 
  neither 
  conspicuous 
  

   nor 
  extensive, 
  but 
  are 
  exceedingly 
  rich 
  'in 
  well-preserved 
  fossil 
  

   remains. 
  From 
  verbal 
  descriptions 
  by 
  Dr. 
  F. 
  P. 
  Moreno, 
  I 
  

   infer 
  that 
  outcrops 
  of 
  the 
  same 
  series 
  of 
  beds 
  may 
  be 
  seen 
  in 
  

   the 
  region 
  between 
  Lakes 
  Argentino 
  and 
  Viedma 
  and 
  lying 
  west 
  

   of 
  the 
  Rio 
  Leon. 
  Certain 
  beds 
  discovered 
  by 
  Dr. 
  Rodolfo 
  

   Hauthal 
  in 
  the 
  vicinity 
  of 
  Last 
  Hope 
  Inlet, 
  appear 
  also 
  to 
  

   belong 
  to 
  this 
  series. 
  

  

  Dr. 
  Ameghino 
  has 
  on 
  several 
  occasions 
  in 
  his 
  published 
  

   papers 
  referred 
  to 
  certain 
  beds 
  containing 
  Cephalopod 
  remains, 
  

   in 
  each 
  instance 
  almost 
  invariably 
  applying 
  to 
  them 
  a 
  different 
  

   name 
  and 
  assigning 
  them 
  to 
  the 
  Jurassic 
  without 
  giving 
  any 
  

   reasons 
  whatever 
  for 
  so 
  doing. 
  Since 
  Dr. 
  Ameghino 
  gives 
  no 
  

   localities 
  where 
  his 
  so-called 
  Jurassic 
  beds 
  may 
  be 
  found 
  and 
  

   nowhere 
  characterizes 
  them, 
  either 
  by 
  giving 
  adequate 
  descrip- 
  

   tions 
  of 
  their 
  lithological 
  characters 
  or 
  specific 
  and 
  generic 
  

   lists 
  of 
  the 
  fossils 
  contained 
  in 
  them, 
  I 
  have 
  been 
  unable 
  to 
  

   identify 
  any 
  of 
  his 
  Jurassic? 
  horizons 
  except 
  the 
  one 
  referred 
  

   to 
  above 
  in 
  speaking 
  of 
  the 
  small 
  teeth 
  collected 
  by 
  myself 
  

  

  