L % C. Johnson — Grand-Gulf Formation of Gulf States. 215 



Wayne County, three miles southeast of Waynesboro, where 

 the Grand Gulf stands alone, with clean cuts of its peculiar 

 clays and quartzitic rocks, to a thickness of seventy feet. The 

 most southern three miles of these exposures are particularly 

 instructive. 



Beneath the surface actually visible at Brown's Bend lie two 

 beds of clay, very sandy, very compact, and of a greenish- 

 yellowish color, mottled with pink, on the whole of a cast seen 

 only in the Grand Gulf formation, and indescribable. They 

 are six to eight feet in thickness each, and have a layer of sand, 

 one foot deep, intercalated between them. Beneath this 

 double bed of clay, lies another layer of sandy material, about 

 two feet thick, containing lumps and fragments possibly of 

 organic origin but not recognizable. This much, unseen at 

 the Bend itself, crops out half a mile farther north ; and still a 

 little farther, all these layers, the double-bedded clay and 

 attendant sands, appear above water at a low stage, with 

 sufficient of the underlying strata fully to explain the nature 

 of the unstratified sand beneath the clays. 



The first that comes to the surface beneath the above 

 described clays and sands, is about four feet thick, and a very 

 compact sand made up as it were of fucoidal stems like tangled 

 roots. Beneath this lie four to six feet of a dark crumbling 

 sand filled with spines and fragments of Echinoderms and 

 decayed remains of Ostrea. One mile up the river from 

 Brown's Bend, at Trigg's Old Ferry, all these fossiliferous 

 layers may be seen well above water, together with the next 

 underlying, which at this point consists almost exclusively of 

 gigantic oyster shells. At Cochran's Ferry, a few hundred 

 yards still farther north, ten feet of this great Ostrea bed are 

 visible at low water, and other Vicksburg fossils are discover- 

 able scantily among the oyster shells. 



A general section may be made to show the structure from 

 Brown's Bend to Cochran's Ferry, one and a half miles, as 

 follows : 



OS. Stratified Orange Sand; 1, sandy soil with. 

 pine woods, old terrace. 10 ft. thick; 2, gray 

 sandy clay, 60 feet; 3, compact whitish sand, be- 

 coming sandstone in places, 20 ft.: 4, clays, 10 

 feet ; 5, clayey sands, no distinct fossils, 6 feet ; 

 6, fucoidal hard sands, 2 feet; 7, compact sands, 

 with fragments of Ostrea and other shells, 3 

 feet; 8, dark sands, with fragments of Echino- 

 derms, 5 feet; 9, bed of Ostrea gigantea and 0. 

 Vicksburgensis, etc., over 10 feet of it, probably 30 to 40 feet; two miles to the 

 north this mingles with the Vicksburg limestone of Hugging Bluff having Orbi- 

 ioides Mantelli and Pecten Poulsoni; a, line of calcareous Eocene; b. Trigg's Old 

 Ferry ; c, Cochran's Ferry ; d to e, line of very old erosion filled in again with 

 the so-called Orange Sand ; w I, water line. 



At Trigg's Old Ferry, by means of a small spring branch, 

 which comes pouring out of the sands a short distance to the 



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