﻿^•3G 
  Geological 
  Soviet 
  t/. 
  

  

  replaced 
  by 
  overthrusts. 
  Four 
  sections 
  from 
  east 
  to 
  west 
  show 
  the 
  

   increased 
  folding 
  and 
  overthrusting 
  towards 
  the 
  northern 
  part 
  of 
  

   the 
  area. 
  

  

  The 
  paper 
  concludes 
  with 
  a 
  reference 
  to 
  the 
  age 
  of 
  the 
  folding. 
  

  

  2. 
  ' 
  The 
  Lahat 
  " 
  Pipe 
  " 
  : 
  A 
  Description 
  of 
  a 
  Tiu-Ore 
  Deposit 
  in 
  

   Perak 
  (Federated 
  Malay 
  States).' 
  By 
  John 
  Brooke 
  Scriveuor, 
  M.A., 
  

   F.G.S. 
  (Geologist 
  to 
  the 
  Federated 
  Malay 
  States 
  Government). 
  

  

  Large 
  quantities 
  of 
  tin-ore 
  have 
  been 
  obtained 
  during 
  recent 
  

   years 
  in 
  the 
  Kinta 
  district 
  of 
  Perak, 
  principally 
  from 
  detrital 
  

   deposits, 
  but 
  also 
  in 
  some 
  cases 
  from 
  the 
  limestone 
  which 
  forms 
  the 
  

   floor 
  of 
  the 
  Kinta 
  Valley. 
  From 
  1903 
  rill 
  1907 
  the 
  Societe 
  des 
  

   Etains 
  de 
  Kinta 
  secured 
  over 
  1000 
  tons 
  of 
  dressed 
  tin-ore 
  from 
  

   a 
  peculiar 
  deposit 
  which 
  had 
  the 
  form 
  of 
  a 
  pipe 
  in 
  the 
  limestone, 
  

   measuring 
  only 
  7 
  feet 
  by 
  2 
  at 
  the 
  surface, 
  but 
  widening 
  when 
  

   followed 
  downwards. 
  It 
  was 
  worked 
  to 
  a 
  depth 
  of 
  314 
  feet. 
  The 
  

   veinstone 
  was 
  a 
  deep 
  red 
  mixture 
  of 
  calcite 
  and 
  iron-oxide 
  with 
  

   some 
  quartz, 
  chalyhite 
  and 
  chalcopyrite, 
  but 
  no 
  tourmaline 
  was 
  

   found 
  in 
  it. 
  In 
  this 
  the 
  cassiterite 
  occurred 
  in 
  irregular 
  pieces 
  and 
  

   broken 
  fragments, 
  some 
  of 
  which 
  consisted 
  of 
  radiating 
  needles. 
  

  

  In 
  Kinta 
  the 
  tin-ores 
  occur 
  in 
  the 
  limestone 
  in 
  two 
  different 
  

   ways 
  : 
  — 
  (1) 
  As 
  lodes 
  or 
  veins 
  with 
  fresh 
  sulphides 
  but 
  not 
  

   iron-oxides. 
  The 
  tin-oxide 
  crystals 
  have 
  a 
  definite 
  arrangement. 
  

   (2) 
  As 
  transformed 
  masses, 
  deposited 
  in 
  fissures. 
  The 
  cassiterite 
  is 
  in 
  

   rounded 
  grains, 
  and 
  quartz, 
  tourmaline, 
  and 
  other 
  minerals, 
  also 
  

   well 
  rounded, 
  accompany 
  it. 
  For 
  a 
  long 
  time, 
  it 
  has 
  been 
  doubtful 
  to 
  

   which 
  of 
  these 
  classes 
  the 
  Lahat 
  pipe 
  should 
  be 
  assigned, 
  as 
  it 
  

   presents 
  some 
  features 
  of 
  each 
  class. 
  Kecently, 
  however, 
  specimens 
  

   have 
  been 
  obtained 
  showing 
  veins 
  of 
  arsenopyrite 
  and 
  cassiterite 
  in 
  

   limestone, 
  and 
  from 
  these 
  the 
  author 
  concludes 
  that 
  the 
  Lahat 
  pipe 
  

   was 
  originally 
  a 
  vein 
  or 
  lode-deposit 
  in 
  the 
  limestone, 
  which 
  sub- 
  

   sequently 
  afforded 
  a 
  course 
  for 
  surface-waters 
  ; 
  these 
  dissolved 
  away 
  

   the 
  calcite 
  and 
  oxidized 
  the 
  sulphides, 
  caves 
  being 
  formed 
  'into 
  

   which 
  the 
  insoluble 
  ores 
  were 
  carried 
  by 
  the 
  water. 
  Finally, 
  the 
  

   brecciated 
  mass 
  was 
  recemented. 
  Some 
  foreign 
  material 
  has 
  been 
  

   introduced, 
  but 
  the 
  bulk 
  of 
  the 
  contents 
  of 
  the 
  pipe 
  is 
  of 
  local 
  

   origin 
  and 
  consequently 
  not 
  rounded 
  by 
  transport. 
  In 
  other 
  words, 
  

   the 
  Lahat 
  pipe 
  is 
  a 
  lode-deposit 
  which 
  has 
  been 
  converted 
  into 
  a 
  

   detrital 
  deposit 
  in 
  situ. 
  

  

  3. 
  ' 
  On 
  the 
  Sculptures 
  of 
  the 
  Chalk 
  Downs 
  in 
  Kent, 
  Surrey, 
  and 
  

   Sussex.' 
  By 
  George 
  Clinch, 
  F.G.S., 
  F.S.A. 
  Scot. 
  

  

  The 
  author 
  classifies 
  the 
  various 
  forms 
  of 
  sculpture 
  of 
  the 
  Chalk 
  

   Downs 
  under 
  three 
  heads, 
  namely, 
  (1) 
  dry 
  valleys 
  of 
  simple 
  form, 
  

   (2) 
  dry 
  valleys 
  of 
  complex 
  form, 
  and 
  (3) 
  wet 
  valleys. 
  He 
  draws 
  

   attention 
  to 
  the 
  relatively 
  small 
  catchment-areas 
  of 
  the 
  dry 
  valleys, 
  

   and 
  to 
  the 
  large 
  number 
  of 
  tributary 
  valleys 
  found 
  in 
  some 
  districts, 
  

   two 
  ])oints 
  which 
  he 
  considers 
  have 
  not 
  received 
  hitherto 
  entirely 
  

   satisfactory 
  explanation. 
  

  

  