Tertiary Formations of the United States, 309 



Oliva Alabamiensis. Corbula nasuta. 



Calyptreea trochiformis. 

 Dentalium alternans. 

 Venericardia planicosta. 

 Cytherea Poulsoni. 

 perovata 



Nucula magnifica. 

 Crassatella praetexta. 

 Ostrea sellaeformis. 

 Alabamiensis. 



The same shelly, white, calcareous beds, overlaid by red clay and loam, 

 are exhibited at London Bluff, nine miles below Shell Bluff, and a ho- 

 rizontal bed of the large oysters is exposed in a cliff two miles farther 

 down the river. At Stony Bluff, on the borders of Scriven county, the 

 calcareous deposit is no longer visible, the cliff being composed of 

 siliceous beds of the burr-stone and millstone series, resting upon 

 brick-red and vermilion-coloured loam. This section, Mr. Lyell states, 

 is of great importance, as it concurs in proving that the millstone of 

 this region, with its eocene fossils, is an integral part of the great red 

 loam and sand formation usually devoid of organic remains. The 

 burr-rock of Stony Bluff abounds with cavities and geodes partially 

 filled with crystals of quartz and agates. In the fragments scattered 

 over the adjacent fields Mr. Lyell observed casts of univalves. At 

 Millhaven, eight miles from Stony Bluff and five from the Savannah 

 river, these siliceous beds again crop out and afford casts of the genera 

 Pecten, Eulima or Bonellia, and a Cidaris. It had been pierced 

 through to the depth of twenty-six feet, and was associated with red 

 loam, white sand and kaolin, affording further evidence of these de- 

 posits belonging to one formation. 



One mile west of Jacksonborough, in the ford of Briar and Beaver 

 Dam Creeks, is a limestone passing upwards into white marl which 

 appears to have been deeply denudated, and is overlaid by sand that 

 belongs to a formation of sand, loam, and ferruginous sand-rock, re- 

 ferred by Mr. Lyell to the red loam and burr-stone series. The 

 limestone and marl, although rarely exposed in sections, are consi- 

 dered to constitute very generally the fundamental strata of the re- 

 gion on account of the not unfrequent occurrence of lime-sinks or 

 circular depressions, formed in the beds of loam and sand by subter- 

 ranean drainage. The fossils procured from the limestone of Jack- 

 sonborough by Mr. Lyell, as well as those presented to him by Col. 

 Jones of Millhaven, were for the greater part well-defined casts, and 

 were specifically new to American palaeontologists ; nevertheless he 

 has no hesitation, from their general aspect, to regard them as belong- 

 ing to the eocene period. The genera enumerated in the paper 

 are, Conus, Oliva, Bulla, Voluta, Buccinum, Fusus, Cerithium ?, 

 Trochus, Calyptrsea, Dentalium, Crassatella, Chama, Cardium, Cy- 

 therea, Lithodomus, Lucina, Pecten, and Ostrea. The Trochus is 

 considered identical with the T. agglutinans which occurs in the Paris 

 basin ; and the Lithodomus to be undistinguishable from the L. dac- 

 tylus of the West Indies, one of the few eocene Parisian fossils iden- 

 tified by Deshayes. 



All the Bluffs examined by Mr. Lyell on the Savannah river below 

 Briar Creek belong to the beds above the limestone, and are refer- 

 able chiefly, if not entirely, to the burr-stone formation. In white 

 clays exposed a few hundred yards below Tiger Leap in Hudson's 



