IM GEOLOGICAL REPORT. [1277, 278 



extent, of the clayey materials of these strata, but also in the high 

 hills bordering the Big Black on the south, where it crops out both 

 on hillsidi ECirkwood's Ferry, and in the bluffs of streams — 



always ci ntaining more or less of the gnensand grains (and 

 impressions of sea-shells— both of which serve to distinguish this 

 material from the common red sand and brown sandstone of the 

 hilltops), which ar nes washed out and accumulated by the 



ins in their sand-bars, forming a very eligible manure — as may 

 be observed on Zilfa and Ponkta Creeks. 



I have not, as yet, specially examined the deposits of Attala, nor am I aware 

 how far they extend west ward of Shonga'.o--as they probably do ; they may 

 generally be looked for wherever the " red hill" soil prevails. N. E. of Shon- 

 galo, in S. W. Choctaw, tlr nd deposits seem to exist likewise ; since 



it is said thai, brown sandstone with sea-shells occurs there, and these, so far as 

 1 h ive seen, are always associated with greensand. The purple tinton the map, 

 in this region, indicates the probable extent of territory in which these deposits 

 may be looked fur ; it is quite likely that they may extend through E. Attala 

 into S. W. Winston, N. E. Leake, and Neshoba. 



277. Culccwous mark qf the TtYtiary. — These may be looked 

 for, more or less, in the whole of the territory, covered on the 

 map by the various shades of blue. 



Among the great variet} r of materials of this kind, forming all degrees of 

 transitions imaginable, from the one to the other, we may nevertheless distinguish 

 two chief classes, in an agricultural point of view ; to-wit : 



1st. The white marls, which consist mainly of carbonate of lime mixed, 

 mostly with clay, but often also with sand, and containing but small quantities of 

 other nutritive ingredients of plants ; 2d. the greensand marls, in which the 

 carbonate of lime is accompanied by more or less greensand grains, and more 

 usually by sand than by clay. The former are to be regarded rather more in 

 the light of stimulants, the latter, as true, nutritive manures. [See Agricultural 

 Report, General Part.] Both classes of marls appear in each of the three prin- 

 cipal stages of the marine calcareous Tertiary, and it would seem that one and the 

 same stratum is sometimes developed in one character, at others, in the other ; or 

 portions of one and the same stratum, in one and the same locality, may contain 

 thesj different marls in its several layers. It may be said in general, neverthe- 

 less, that greensand marls arc more abundant in the Jackson Group, than in 

 either of the others. On account of the great general similarity of these 

 materials in the several stages, I shall not, however, attempt to describe those 

 of each separately.' 



278. Ot the character of the marls of the Jackson Group in its territory 

 between the Bluff and Big Black River, I have no knowledge thus far, not having 

 visited the localities or seen any specimens. It seems likely, however, from 

 what I have heard of the character of the country, that they a re similar to those 

 of Madison and N. Hinds. 



At Vicksburg (1220) we find strata of bluish or greenish green- 

 sand marl between the ledges of limestone which are quarried in 

 the N. part of the city : and sometimes, we find the same stratum 

 composed of soft marl in one locality, and of . >ther. 



The uppermost shell stratum, which appears in the washed gullies near the 

 summit of the hill S of the creek, is very sandy, though overlaid by a heavy 

 yellow loam of a "prairie" character ; lower down, however, as in the "gully by 

 the roadside close to the bridge, the blue marl appears rather clayey, its shells 

 being somewhat less numerous than in the upper stratum. An analysis of a 

 specimen from this spot, which seemed to be about an average of the Vicksburg 

 marl, gave the following result : 



