﻿202 
  H. 
  E. 
  Gregory 
  — 
  Geologic 
  Sketch 
  of 
  

  

  southeast 
  trend 
  of 
  the 
  ridges 
  is 
  characteristic. 
  At 
  Challa 
  the 
  

   strike 
  is 
  N. 
  60° 
  ; 
  at 
  Ahyjadero 
  (Pucara) 
  the 
  strike 
  is 
  "N. 
  55°-60° 
  

   W. 
  ; 
  and 
  measures 
  between 
  N. 
  40° 
  W. 
  and 
  N. 
  60° 
  W. 
  were 
  taken 
  

   at 
  several 
  localities. 
  For 
  Yampnpata 
  the 
  figures 
  are 
  the 
  same. 
  

   Near 
  South 
  Yumani 
  where 
  the 
  strata 
  are 
  faulted, 
  1ST. 
  25° 
  W. 
  and 
  

   N. 
  20° 
  W. 
  were 
  measured, 
  and 
  at 
  a 
  few 
  places, 
  as 
  on 
  the 
  ridge 
  of 
  

   Kuru-pata 
  where 
  a 
  strike 
  of 
  ~N. 
  20° 
  W. 
  becomes 
  in 
  half 
  a 
  mile 
  

   N. 
  40° 
  E., 
  the 
  presence 
  of 
  minor 
  horizontal 
  and 
  vertical 
  folding 
  

   is 
  demonstrated. 
  In 
  addition 
  to 
  the 
  faults 
  traced 
  by 
  K. 
  C. 
  

   Heald 
  and 
  the 
  writer 
  and 
  indicated 
  on 
  the 
  map 
  (fig. 
  8), 
  there 
  

   are 
  many 
  minor 
  dislocations 
  which 
  are 
  of 
  economic 
  importance, 
  

   but 
  only 
  one 
  so 
  far 
  observed 
  has 
  interrupted 
  the 
  stratigraphic 
  

   succession 
  to 
  any 
  considerable 
  degree. 
  The 
  Ahyjadero-Kona 
  

   fault 
  has 
  offset 
  the 
  strata 
  for 
  nearly 
  one-half 
  mile. 
  

  

  Economic. 
  

  

  The 
  presence 
  of 
  coal 
  at 
  Yampupata 
  and 
  on 
  Titicaca 
  Island 
  

   is 
  mentioned 
  by 
  Forbes 
  (1861) 
  but 
  was 
  doubtless 
  recognized 
  at 
  a 
  

   much 
  earlier 
  date, 
  since 
  the 
  absence 
  of 
  fuel 
  other 
  than 
  llama 
  

   dung 
  for 
  domestic 
  purposes, 
  as 
  well 
  as 
  for 
  smelting 
  and 
  for 
  

   making 
  steam, 
  encouraged 
  a 
  search 
  for 
  mineral 
  fuels. 
  Agassiz 
  

   (1875) 
  found 
  the 
  mine 
  at 
  Yampupata 
  producing 
  "30 
  tons 
  of 
  

   coal 
  per 
  day," 
  "of 
  fair 
  quality." 
  More 
  recent 
  studies 
  of 
  these 
  

   deposits 
  were 
  made 
  by 
  engineers 
  in 
  the 
  employ 
  of 
  the 
  Peruvian 
  

   corporation 
  and 
  by 
  Dereims, 
  who. 
  reported 
  a 
  narrow 
  band 
  of 
  

   coal 
  running 
  the 
  length 
  of 
  the 
  island. 
  

  

  The 
  principal 
  coal-bearing 
  shales 
  and 
  sandstones 
  traverse 
  the 
  

   island 
  from 
  South 
  Yumani 
  to 
  Taana 
  Bay 
  as 
  a 
  belt 
  ten 
  to 
  fifty 
  

   feet 
  in 
  width, 
  a 
  limited 
  proportion 
  of 
  which 
  is 
  of 
  commercial 
  

   value. 
  The 
  coal 
  occurs 
  in 
  lenses 
  and 
  overlapping 
  layers 
  inter- 
  

   leaved 
  with 
  argillaceous 
  and 
  sandy 
  shales. 
  Bands 
  of 
  true 
  coal 
  

   from 
  a 
  few 
  inches 
  to 
  more 
  than 
  two 
  feet 
  in 
  thickness 
  were 
  ob- 
  

   served 
  at 
  South 
  Yumani 
  and 
  northwest 
  of 
  Challa. 
  The 
  con- 
  

   ditions 
  of 
  original 
  deposition 
  as 
  well 
  as 
  field 
  observation 
  

   indicate 
  that 
  the 
  maximum 
  thickness 
  of 
  a 
  given 
  stratum 
  of 
  

   true 
  coal 
  will 
  probably 
  not 
  exceed 
  three 
  feet 
  and 
  that 
  such 
  

   beds 
  will 
  vary 
  greatly 
  in 
  linear 
  extent. 
  It 
  is 
  improbable 
  that 
  

   workable 
  beds 
  over 
  three 
  feet 
  in 
  thickness, 
  continuous 
  for 
  

   more 
  than 
  300 
  or 
  400 
  feet, 
  will 
  be 
  found 
  on 
  the 
  island. 
  In 
  

   several 
  places 
  examined, 
  the 
  coal 
  lenses 
  have 
  much 
  smaller 
  

   dimensions. 
  

  

  Three 
  exposures 
  bordering 
  South 
  Yumani 
  Bay 
  show 
  re- 
  

   spectively 
  : 
  (1) 
  14 
  feet 
  of 
  carbonaceous 
  shale 
  with 
  abundant 
  

   thin 
  streaks 
  of 
  impure 
  coal 
  of 
  no 
  value. 
  (2) 
  At 
  a 
  prospect 
  

   hole, 
  10 
  feet 
  more 
  or 
  less 
  of 
  carbonaceous 
  shale 
  contains 
  beds 
  

   of 
  coal 
  three 
  inches 
  to 
  three 
  feet 
  thick, 
  exceedingly 
  variable 
  in 
  

  

  