﻿GEOLOGY. 
  235 
  

  

  marl 
  is 
  very 
  obvious 
  in 
  that 
  of 
  the 
  eocene 
  beds 
  at 
  Vicks- 
  

   burg, 
  as 
  seen 
  in 
  i\\e 
  frosted 
  surface 
  of 
  the 
  detritus 
  form- 
  

   ing 
  the 
  talus 
  of 
  the 
  bluffs 
  above 
  the 
  city, 
  denoting 
  the 
  

   presence 
  of 
  copperas 
  or 
  vitriol. 
  

  

  These 
  may, 
  however, 
  be 
  neutralized 
  by 
  the 
  intermix- 
  

   ture, 
  in 
  the 
  compost 
  heap, 
  of 
  a 
  small 
  proportion, 
  about 
  

   one 
  per 
  cent., 
  of 
  newly 
  burnt 
  and 
  caustic 
  lime 
  thoroughly 
  

   disseminated 
  through 
  the 
  mass. 
  

  

  Those 
  who 
  desire 
  to 
  try 
  the 
  effects 
  of 
  marl 
  upon 
  their 
  

   lands, 
  and 
  have 
  had 
  no 
  experience 
  in 
  such 
  matters, 
  can- 
  

   not 
  do 
  better 
  than 
  to 
  consult 
  Ruffin's 
  Essay 
  on 
  Cal- 
  

   careous 
  Manures, 
  and 
  his 
  Report 
  on 
  the 
  Agriculture 
  of 
  

   South 
  Carolina. 
  His 
  great 
  experience, 
  his 
  extended 
  

   research, 
  and 
  witbal 
  his 
  long-continued 
  and 
  success- 
  

   fully 
  conducted 
  experiments 
  with 
  the 
  marls 
  of 
  Virginia, 
  

   have 
  caused 
  him 
  to 
  be 
  looked 
  upon 
  in 
  the 
  light 
  of 
  a 
  

   public 
  benefactor, 
  and 
  procured 
  for 
  him 
  recently 
  a 
  very 
  

   complimentary 
  election 
  as 
  an 
  honorary 
  member 
  of 
  the 
  

   United 
  States 
  Agricultural 
  Society, 
  in 
  consideration, 
  as 
  

   it 
  was 
  flatteringly 
  announced, 
  " 
  of 
  the 
  incalculable 
  bene- 
  

   fits 
  conferred 
  by 
  him 
  upon 
  the 
  whole 
  farming 
  interest 
  

   of 
  Virginia 
  by 
  his 
  genius 
  and 
  industry." 
  

  

  The 
  indurated 
  marl, 
  generally 
  known 
  as 
  the 
  rotten 
  

   limestone, 
  is 
  described 
  by 
  Dr. 
  Troost, 
  the 
  late 
  eminent 
  

   geologist 
  of 
  Tennessee, 
  as 
  " 
  having 
  an 
  earthy 
  appear- 
  

   ance, 
  interspersed 
  with 
  minute 
  particles 
  of 
  mica 
  and 
  

   grains 
  of 
  green-sand 
  sometimes 
  so 
  small 
  as 
  to 
  be 
  per- 
  

   ceptible 
  only 
  by 
  the 
  aid 
  of 
  the 
  magnifying 
  glass. 
  

  

  " 
  It 
  is 
  soft, 
  and, 
  when 
  exposed 
  to 
  atmospheric 
  influ- 
  

   ence, 
  disintegrates, 
  crumbles 
  to 
  dust, 
  and 
  forms 
  a 
  more 
  

   or 
  less 
  plastic 
  paste 
  with 
  water. 
  

  

  " 
  When 
  properly 
  mixed 
  with 
  soil, 
  it 
  is 
  very 
  beneficial 
  

   to 
  agriculture. 
  Of 
  this 
  fact, 
  the 
  farmers 
  of 
  Pennsylvania 
  

   are 
  well 
  convinced, 
  and 
  hundreds 
  of 
  loads 
  are 
  taken 
  

  

  