﻿loo 
  Geological 
  Survey 
  of 
  Louisiana 
  [Sect. 
  

  

  report 
  in 
  the 
  12th 
  Annual 
  of 
  the 
  United 
  States 
  Geological 
  

   Survey. 
  

  

  Safford 
  referred 
  the 
  Orange 
  Sand 
  to 
  the 
  Cretaceous, 
  to 
  which 
  

   only 
  a 
  portion 
  of 
  his 
  deposits 
  belonged, 
  but 
  later 
  called 
  it 
  Ter- 
  

   tiary 
  and 
  proposed 
  a 
  new 
  iiame 
  the 
  " 
  Bluff 
  Gravel" 
  for 
  the 
  por- 
  

   tion 
  which 
  was 
  of 
  presumably 
  Quarternary 
  age*. 
  Hilgard 
  

   maintained 
  that 
  the 
  deposit 
  was 
  of 
  Quarternary 
  age 
  and 
  was 
  a 
  

   southern 
  equivalent 
  of 
  the 
  notthern 
  drift. 
  He 
  supposed 
  that 
  

   the 
  deposit 
  originated 
  in 
  the 
  great 
  floods 
  of 
  water 
  issuing 
  from 
  

   the 
  ice 
  front. 
  This 
  idea 
  has 
  given 
  rise 
  to 
  the 
  names 
  "Drift," 
  

   "southern 
  Drift" 
  and 
  "Stratified 
  Drift" 
  which 
  have 
  been 
  

   applied 
  to 
  this 
  formation. 
  

  

  The 
  uncertain 
  meaning 
  of 
  the 
  term 
  Orange 
  Sand 
  caused 
  the 
  

   adoption 
  in 
  1891 
  of 
  the 
  term 
  Lafayette 
  formation, 
  from 
  the 
  

   typical 
  locality 
  in 
  Lafayette 
  county, 
  Mississippi 
  where 
  Hilgard 
  

   first 
  studied 
  and 
  named 
  the 
  formation. 
  The 
  opinion 
  now 
  gener- 
  

   ally 
  held 
  is 
  that 
  the 
  Lafayette 
  is 
  a 
  littoral 
  or 
  coastal 
  deposit 
  of 
  

   late 
  Pliocene 
  age 
  and 
  hence 
  anterior 
  to 
  the 
  glacial 
  period. 
  It 
  

   has 
  no 
  connection 
  whatever 
  with 
  the 
  great 
  sheets 
  of 
  true 
  drift 
  

   or 
  till 
  brought 
  down 
  by 
  the 
  glaciers. 
  

  

  Features 
  of 
  the 
  Formation 
  in 
  Louisiana 
  

  

  Definitive 
  Features 
  of 
  the 
  Deposits 
  

  

  In 
  Louisiana 
  the 
  only 
  criterion 
  for 
  the 
  determination 
  of 
  the 
  

   beds 
  of 
  this 
  formation 
  seems 
  to 
  be 
  the 
  chert 
  and 
  quartz 
  pebbles, 
  

   often 
  with 
  casts 
  of 
  Paleozoic 
  fossils, 
  which 
  portions 
  of 
  the 
  

   beds 
  contain. 
  The 
  lithological 
  resemblance 
  of 
  the 
  sands 
  of 
  this 
  

   formation 
  to 
  the 
  weathered 
  sands 
  of 
  the 
  underl5dng 
  deposits 
  is 
  

   so 
  close 
  that 
  it 
  is 
  impossible 
  to 
  differentiate 
  them. 
  This 
  resem- 
  

   blance 
  has 
  led 
  to 
  manj^ 
  incorrect 
  references 
  of 
  red 
  sandy 
  mater- 
  

   ial 
  to 
  the 
  Lafayette. 
  Thus, 
  Hopkins 
  refers 
  the 
  iron 
  bearing 
  

   sandstone 
  common 
  around 
  Rocky 
  Mount 
  and 
  in 
  all 
  the 
  higher 
  

   hills 
  of 
  northern 
  Bossier, 
  Claiborne, 
  Jackson 
  and 
  Union 
  parishes 
  

   to 
  the 
  Drift. 
  Harris 
  has 
  collected 
  Lower 
  Claiborne 
  fossils 
  in 
  

   the 
  Rocky 
  Mount 
  material 
  and 
  is 
  inclined 
  to 
  regard 
  the 
  fossils 
  

   as 
  being, 
  z« 
  ^///^. 
  Veatch 
  has 
  obtained 
  a 
  series 
  of 
  ver}^ 
  perfect 
  

  

  * 
  Geol. 
  of 
  Tenn., 
  1869, 
  pp. 
  432-433. 
  

  

  