100 GEOLOGICAL REPORT. [HU6, 147, 147 l 



insufficient for practical purposes. Otherwise. I have not found it 

 at any great distance from Ripley, except to the westward. 



14(5. The white or gray calcareous sand mentioned (""135), may 

 in many cases serve as a marl, when it is not too sandy — it would 

 generally, no doubt, improve greatly the "beeswax hommocks."' 

 That found at Tocahish church, and near Redland (T13- : >) : is scarcely 

 more sandy than the limestone it overlies. But its character in 

 this respect is so variable, that each one must be left to judge for 

 himself in his particular locality. 



The gray calcareous clay which frequently overlies the limestone 

 and calcareous sand in Pontotoc and Chickasaw, (1137), I have not 

 yet examined as to its fertilizing qualities ; but judging from the 

 rich growth of timber where it mingles with the sandy ridge toils, 

 it possesses other useful ingredients besides the lime, to render it a 

 serviceable manure. Outcrops of this material arc mentioned in 

 the passage just quoted. 



147. Limestone. — None is found within the territory either of 

 the Eutaw, or of the Tombigbce Sand Group. The most calca- 

 reous rocks of the latter only deserve the name of calcareous 

 sandstones. 



Rotten Limestone Group. — In numerous localities, the rock of 

 this group is well suited to the manufacture of lime of good quality, 

 and is so used quite extensively in the prairie region. Notwith- 

 standing its uniformity of aspect, however, there is considerable 

 variation in this rock as regards its suitability for lime-burning. 

 These variations often occur without any striking indication of a 

 change by the stratification, color, or otherwise : and a few direc- 

 tions concerning the selection of this rock for lime-burning, will 

 not, therefore, come amiss. 



The hardist varieties in one; and the same bed are usually the 

 purest (unless they be sandy), and should be selected in preference 

 to the soft. 



Those which arc chalky, and exhibit the least gloss on cut sur- 

 faces arc preferable to those showing a smooth shining cut. 



Another good distinctive mark is the degree of plasticity which 

 the rock attains when crushed and kneaded up with water. The 

 less it works like clay, and the more like prepared chalk ; and the 

 less, in moistening, the clay odor is perceived, the purer is the 

 rock — also, the more vividly it effervesces ("boils") with (one and 

 the same) strong vinegar, muriatic, or sulphuric acid. 



147 1 The difficulty in the manufacture of lime from the Rotten Limestone, is 

 not so much caused by the amount of foreign (usually clayey) matter it contains, 

 as by the extremely fine .state of division in which the carbonate of lime and 

 clay are mixed together, which renders the rock liable to overburning, unless 

 great care is had in the management of the fire. Experience must determine 

 in each locality the proper amount of burning to be given ; it ought to b 

 in all cases than would be employed in burning pure, hard limestone, and the 

 neat ought to be equalized as much as possible. It is not easy to regulate thesc v 

 :ircumstances in an ordinary kill 



