﻿GEOLOGY. 
  217 
  

  

  It 
  lias 
  been 
  found 
  a 
  convenient 
  material 
  for 
  the 
  

   foundations 
  of 
  houses 
  and 
  the 
  construction 
  of 
  chimneys, 
  

   and 
  in 
  early 
  times 
  it 
  was 
  frequently 
  used 
  in 
  the 
  neigh- 
  

   borhood 
  for 
  mill-stones. 
  The 
  abutments 
  of 
  the 
  new 
  

   bridge 
  at 
  Grindstone 
  Ford, 
  on 
  the 
  Bayou 
  Pierre, 
  are 
  built 
  

   of 
  it 
  quarried 
  on 
  the 
  sj^ot, 
  and 
  at 
  Grand 
  Gulf 
  it 
  has 
  been 
  

   freely 
  used 
  in 
  paving 
  the 
  streets 
  or 
  side-walks. 
  

  

  This 
  rock 
  presents 
  itself 
  in 
  mass 
  in 
  the 
  escarpment 
  of 
  

   the 
  bold 
  promontory 
  on 
  the 
  Mississippi, 
  about 
  a 
  mile 
  

   below 
  the 
  mouth 
  of 
  the 
  Big 
  Black 
  River, 
  and 
  immedi- 
  

   ately 
  above 
  the 
  town 
  of 
  Grand 
  Gulf, 
  against 
  which 
  the 
  

   current 
  of 
  the 
  river 
  sets 
  in 
  full 
  force, 
  and 
  by 
  which 
  it 
  is 
  

   deflected 
  by 
  its 
  effective 
  resistance 
  in 
  such 
  a 
  manner 
  as 
  

   to 
  create 
  the 
  extensive 
  and 
  formerly 
  dangerous 
  whirl- 
  

   pool 
  or 
  eddy 
  which 
  gave 
  name 
  to 
  the 
  place. 
  

  

  At 
  many 
  points 
  within 
  the 
  scope 
  I 
  have 
  mentioned, 
  

   this 
  rock 
  crops 
  out 
  in 
  the 
  beds 
  of 
  the 
  watercourses, 
  and 
  

   upon 
  the 
  sides 
  of 
  the 
  ridges, 
  exhibiting, 
  as 
  in 
  that 
  in 
  the 
  

   Mississippi 
  bluff, 
  such 
  an 
  identity 
  of 
  -character 
  as 
  to 
  in- 
  

   duce 
  me 
  to 
  characterize 
  it 
  wherever 
  met 
  with 
  as 
  the 
  

   Grand 
  Gulf 
  rock. 
  

  

  On 
  the 
  Tallahaly, 
  a 
  branch 
  of 
  the 
  Bayou 
  Pierre, 
  near 
  

   Colonel 
  Dabney's, 
  Township 
  4, 
  Eange 
  3 
  W., 
  in 
  Hinds 
  

   County, 
  it 
  is 
  abundant, 
  and 
  has 
  been 
  freely 
  used 
  for 
  the 
  

   foundations 
  and 
  chimneys 
  of 
  negro 
  quarters 
  in 
  that 
  

   neighborhood. 
  

  

  At 
  the 
  Mississippi 
  Springs, 
  the 
  attendant 
  clays, 
  or 
  

   decomposed 
  portions 
  of 
  the 
  imperfectly 
  formed 
  rock, 
  are 
  

   very 
  similar 
  to 
  those 
  of 
  the 
  Backbone 
  in 
  Franklin 
  County, 
  

   before 
  mentioned. 
  

  

  The 
  course 
  of 
  this 
  ledge 
  seems 
  arrested 
  at 
  this 
  point 
  

   by 
  the 
  limestone 
  intervening 
  between 
  it 
  and 
  Pearl 
  River, 
  

   and 
  which 
  seems 
  to 
  range 
  from 
  the 
  lime 
  quarry 
  of 
  Mr., 
  

  

  