LOUISIANA. 



very fertile, though not easily worked. In 

 the territory {hey ocuupy they freciuoiuly 

 protrude through the thiclc cover of red, 

 jsaudy clay and drift, ishuid-like. coii- 

 spi;-uou.s through the broalc iu the vege- 

 tati;,ii. as well as through their liiholog- 

 ieal material, mostly iudurated yellow 

 uiarls gradating downward iuto calcare- 

 ous gray clays, especially exposed along 

 their uorthei'u boundary line. Kreiiuer.tly 

 while and yellow limestone bowldei-s are 

 srattered promiscuously over the outcrops, 

 more rarely limestone ledges a few feet 

 in thickness are found cai)ping the hills. 

 Zeuglodon boues have been found on the 

 edge of the parishes, the most character- 

 istic fossil of the Jackson of Mississippi. 

 The outcrops of the lower series are 

 fouud frequently on a level with the Jack- 

 son beds, on account of the deep erosion 

 they have sustained l)efore these strata 

 were deposited upon them. 



THE VIOKSBURG GROUP. 

 If it were not for the paleontological 

 evidence found in these strata, mark- 

 ing a different© geological horizon, 

 they hardly could be distinguished 

 from the underlying Jackson 



bods. Perfectly couformable. they rest 

 upon them, and no change iu the topog- 

 raphy of the territory they occupy, nor 

 ii\ the vegetation growing upon their line 

 of outcrops, marks a uew geological sub- 

 division. With the underlying beds they 

 have the bald prairies aaid the lithological 

 material iu common. They mostly consist 

 of "yellow calcareous fossiliferous marls." 

 are similar, if not identi'^al, in composi- 

 tion, with that of the Jackson group. The 

 waters found iu the region are like those 

 carried by the underlying formation, of 

 bad quality, and the soils possess the 

 same qualities, like those of the former 

 group. In a narrow band, their northern 

 boundary very irregular, though sub- 

 parallel to the northern boundary of the 

 Jackson beds, they cross the state from 

 west to east, with a south boundary co- 

 inciding with the boundary of the grand 

 gnlf rocks, beneath which formation they 

 disappear. Their outcrops are frequently 

 marked by the drift, appearing ruly iu 

 isolated spots in the sandy sheet. They 

 are of the sane economic importance as 

 the Jackson strata, 



THE GRAND GULF ROCKS. 

 This formation, though the poorest of 

 all described, is of the higliest econonuc 

 importance to Louisiana on account of the 

 immense territory it occupies and the in- 

 fluence it has on other regions of the 

 state.' Along the .south boundary Inu: of 

 the Vicksburg marls the sandstones and 

 claystones and massive clays of the 

 grand gulf group overlap them, and in a 

 line of hills and bluffs cross the state 

 from west to east, dipping southward, 

 but under a far steeper angle than the 

 underlying formations. Examining its 

 northern boundary line and advancing in 

 a southerly direction, we notice a rapid 

 tliickcning of the strata and soon lose all 

 sight of the contact of the underlying 

 formation, notwithstanding the hills and 

 bluffs are steep, not unfrequently rising 

 along this boundary line over 150 feet 

 above the country drainage. More than 

 any of the previous regions described, it 

 has the plain structure preserved, tliotigh 

 erosion has chiseled out dilferent forms. 

 Instead of tlie well rounded hills and 

 more gentle slopes of the ridges occupy- 

 ing tlie region uortli of its boundary, it 

 slopes from its deeply deutated and 



broken north line southward under a sleep 

 angle, rapidly towards tlie gulf, present- 

 ing a plateau in which the rivers liave 

 <'ift wide valleys with steeii walls, and 

 their tributaries; narrow gulleys with 

 broken and dentated embankments, sev- 

 eral over 100 feet in height. I'''re(iuently 

 the country roads wind along a narrow 

 ridge, falling steep to either side for 

 many miles through this section. The 

 features of erosion resemble somewhat 

 the country north of it, where tlie drift- 

 sands have accumulated, forming sections 

 almost equally steep. They lessen in 

 height in a southerly direction. The 

 landscape these rocks offer is very mo- 

 notonous. The open woods of the long- 

 leaf pine, as far as the eye can reach, 

 and the green turf, interrupted by bare 

 spots of the gray sands, derived from the 

 underlying sandstones, sometimes crop- 

 ping out in high knolls along the road, or 

 from the sands and gravels of the drift 

 which generally cover the rocks of this 

 formation in a thin sheet. The waters of 

 streams and creeks are swift, rich iu tish, 

 especially trout and perch, and almost of 

 crystalline clearness, unless they \vind 

 along a swampy bottom, and springs are 

 even more numerous than in the north- 

 ern )iart of the state. 



TUB RED SANDY CLAYS. 



The strata of this formation, deposited 

 at the close of the tertiary in Louisiana, 

 cover all the territory north of the Vicks- 

 burg, Shreveport and Facitic Raili'oad, 

 and can be traced, though frequently in- 

 terrupted by drift materia) and out- 

 crops of the underlying formation, al- 

 most to the north boundary of the grand 

 gulf rocks. They cover the eroded sur- 

 faces of the gray clays, the Jackson and 

 Vicksburg rocks, and sometimes even 

 mantle the outcrops of the laminated 

 clays and sands of the lower series of 

 tertiary rocks. To a large extent, the 

 soils of the region they occupy are di- 

 rectly derived from them, sometimes they 

 enter into their composition with the 

 drift tind, mixed with the clay of older 

 formations, they form the bottom soils 

 and the covering loam-sheet of the di- 

 luvial flats. There cau be but little doubt 

 as to the circumstances under which 

 they have been deposited. Throughout 

 their deposits they show the fluviated 

 structure. To judge from their geographi- 

 cal distribution in this state, it" seems 

 that the sandstones of the grand 

 gulf rocks formed their southern shore 

 and that the shallow basin deepened 

 towards the north, having a connection 

 with the gulf through the wide Missis- 

 sippi valley. Everywhere the formation 

 is largely denuded and their outcrops 

 can bo seen in great abundance in the 

 territory tliey occupy. They wnsist gen- 

 erally of highly ferruginous sandy clays, 

 mottled and streaked and sometimes 

 studded v.itli pebbles derived from the 

 underlying gray clays forming lines of 

 stratification. The irregularity of these 

 lines which show so clearly their process 

 of deposition have been mentioned before. 

 Ferruginous sandstones and claystones. 

 which frequently cap the hills north of 

 the Vick.sburg, Slireveport and Pa- 

 cific Railroad. are seldom found 

 south of that lino, and wiih 

 the exception of a few locali- 

 ties in the Dolct hills none won' 

 seen. The fossil wood, hov.ever, leinanis 

 to be a characteristic feature of this 

 formation, and like in the n<>rtli<'ni Icj- 



