﻿206 
  H. 
  E. 
  Gregory— 
  Geologic 
  Sketch 
  of 
  

  

  from 
  Titicaca 
  Island 
  collected 
  by 
  K. 
  C. 
  Heald 
  and 
  the 
  writer 
  

   in 
  1912 
  are, 
  according 
  to 
  Schn 
  chert,* 
  of 
  characteristic 
  Pennsyl- 
  

   vanian 
  aspect. 
  

  

  The 
  Permian, 
  Triassic, 
  Jurassic, 
  Cretaceous, 
  and 
  Tertiary 
  

   from 
  the 
  Titicaca 
  area 
  have 
  as 
  yet 
  not 
  been 
  satisfactorily 
  dif- 
  

   ferentiated. 
  Forbes 
  assigned 
  certain 
  strata 
  to 
  the 
  Permian 
  on 
  

   the 
  ground 
  of 
  lithologic 
  resemblance 
  to 
  the 
  Russian 
  Permian. 
  

   D'Orbigny 
  mapped 
  Triassic 
  which 
  Dereims 
  considers 
  Permo- 
  

   Carboniferons. 
  The 
  fossil 
  Ghemnitzid 
  potosensis, 
  relied 
  upon 
  

   by 
  both 
  these 
  writers, 
  seems 
  not 
  to 
  be 
  of 
  sufficiently 
  diagnostic 
  

  

  Fig. 
  9. 
  

  

  LAKE 
  LEVEL 
  

  

  Fig. 
  9. 
  Approximate 
  geologic 
  section 
  from 
  Kea-Kollu 
  to 
  South 
  Yumani 
  

   to 
  illustrate 
  section 
  A, 
  below. 
  

  

  value. 
  The 
  Puca 
  sandstone 
  at 
  Cora-cora 
  which 
  extends 
  north- 
  

   ward 
  into 
  Peru,f 
  and 
  which 
  is 
  believed 
  by 
  Steinmann 
  (1906) 
  

   to 
  be 
  Cretaceous, 
  is 
  assigned 
  by 
  Dereims 
  to 
  the 
  Permian 
  or 
  

   Permo-Carboniferous. 
  Fresh-water 
  Tertiary 
  may 
  be 
  present 
  

   in 
  certain 
  lake 
  deposits 
  of 
  the 
  ' 
  Andean 
  basin. 
  Pleistocene 
  

   deposits 
  of 
  considerable 
  thickness 
  are 
  represented, 
  but 
  the 
  

   glaciers 
  appear 
  not 
  to 
  have 
  extended 
  to 
  the 
  borders 
  of 
  the 
  lake. 
  

   Through 
  the 
  courtesy 
  of 
  the 
  Peruvian 
  Corporation, 
  the 
  

   writer 
  was 
  enabled 
  to 
  make 
  a 
  brief 
  examination 
  of 
  the 
  strati- 
  

   graphy 
  of 
  Titicaca 
  Island, 
  and 
  of 
  the 
  northern 
  extremity 
  of 
  

   Copacabana 
  peninsula. 
  The 
  strata 
  here 
  are 
  entirely 
  sedi- 
  

   mentary 
  and 
  of 
  Carboniferous 
  (Pennsylvanian) 
  age. 
  (See 
  fig. 
  

   8.) 
  The 
  following 
  sections 
  indicate- 
  the 
  relations 
  of 
  the 
  vari- 
  

   ous 
  beds. 
  Sections 
  A, 
  C, 
  and 
  D 
  were 
  measured 
  by 
  the 
  writer. 
  

   Sections 
  B 
  and 
  E 
  were 
  compiled 
  from 
  data 
  obtained 
  by 
  Mr. 
  

   K. 
  C. 
  Heald. 
  All 
  measures 
  recorded 
  are 
  approximate, 
  espe- 
  

   cially 
  for 
  the 
  thickest 
  beds. 
  

  

  Section 
  A. 
  

  

  Ahyjadero 
  Bay 
  (Pucara) 
  to 
  South 
  Yu?ncmi. 
  (Fig. 
  9.) 
  

  

  Distances 
  determined 
  by 
  pacing, 
  elevations 
  estimated 
  or 
  meas- 
  

   ured 
  by 
  hand 
  level. 
  

  

  *This 
  collection, 
  now 
  in 
  the 
  Yale 
  University 
  Museum, 
  will 
  be 
  discussed 
  by 
  

   Professor 
  Schuchert 
  at 
  a 
  later 
  date. 
  

  

  f 
  Adams, 
  G. 
  I., 
  Ann. 
  Report 
  of 
  the 
  Smithsonian 
  Institution 
  for 
  1908, 
  

   p. 
  404. 
  

  

  