H284, 285] marls of jackson — bankin.. 171 



which contain the perfect shells, and are exposed under the bridge 

 on Pearl River, raid on Dry Creek near its mouth, ar A generally 

 indy, and comparatively poor in lime, that their use for 

 agricultural purposes would generally be too expensive, unless 

 they were very near at hand, and it were desired, at the same time, 

 to remedy extreme heaviness of the sod by the admixture of sand. 

 The character of this bed, however, is itself somewhat variable, so 

 that for instance, at its outcrop on the bank of the River near the 

 end of i he road embankment, in Rankin, it. is so much le-s sandy, 

 and richer in lime and greensand, as to form an eligible manure, 

 similar in its aspect to the marl of Vicksburg. I have not, however, 

 as yet analyzed it. 



28 4. With the marls of N. Rankin, and Scott, I am not person- 

 ally acquainted, except through a specimen furnished by Rev. E. JB. 

 Sims, from a locality near Morton, which resembles that but just 

 mentioned ; and so probably does the marl on Colfeebogue Creek, 

 mentioned by Prof. Wailes. The marl struck in R. R. cuts on the 

 upper Potoc-Chitto, in Newton county, has been mentioned above 

 (1F2"7). Marls similar to those of Madison and N. Hinds are 

 probably, however, the most prevalent ; at least, we find them of 

 precisely the same character on the headwaters of Leaf and Strong 

 Rivers, in S. Scott and N. E. Smith — so much so, that all that has 

 been said regarding the yellow and white marls of Madison and 

 N. Hinds, will apply equally to those of the region just mentioned. 



The yellow calcareous clay in which the large (Zeuglodon) bones occur, in 

 Mrs. Nichols' field, and neighborhood (l[207), is identical in almost every 

 particular with that occurring on the roadside 3 miles N. of Jackson, which 

 was found to contain l~}4 percent, of carbonate of lime, and some gypsum; 

 materials similar to the marl from Langley's field (see above) occur there also, 

 and may be distinguished by the same criterion from the clays comparatively 

 poor in lime. It is probable that greensand marls resembling the lower beds at 

 Jackson, likewise occur. They should be sought for in the lowest situations 

 (beds of creeks, etc.), underlying the yellow clay marls. 



2X5. The marls occurring near Brandon (belonging to the 

 Vicksburg Group — 11218,224. ff.) resemble somewhat, at first sight, 

 the yellow clay marls just described. But wdiile they coincide with 

 them in the absence of greensand grains, and consequent poverty 

 in Potash, they differ essentially in this, that the amount of inert 

 matter they contain is either very small, or when present consists 

 of sand instead of clay ; besides which, gypsum is entirely absent 

 from them. 



The yellowish-white marls of the neighborhood of Brandon contain much 

 less sand than from their grittiness to the touch, one would be led to suppose; 

 the latter circumstance being the effect of the crystalline nature of the calcare- 

 ixticles. Thus, the rough, yellowish-white, often somewhat indurate marl 

 occurring at the bluffs in Dr. I. M. Quin's field, 4 miles S. of Brandon, shows 

 the following composition : 



