OF THE SOUTHERN ATLANTIC STATES. 105 



ponds with the analysis given above of the limestone from Jones 

 county, North Carolina. The silica is the least injurious ingre- 

 dient, its principal effect being, unless the rock is burned at too 

 intense a heat, merely to render less sand necessary in tempering 

 it for mortar, while the magnesia is not only of small quantity 

 but doubtful tendency, and the oxide of iron is generally in too 

 minute proportion to seriously injure the lime by giving it a very 

 dark color. 



Besides the lime that will hereafter add to the mineral wealth 

 of this region, there is near Pocataligo, on navigable tide water, 

 a deposite of the purest quality of quartz sand, suitable for the 

 manufacture of glass. The pebbles of which it consists are small, 

 sharp, angular fragments of perfectly pure quartz, without any 

 foreign mixture. It may be obtained in any quantity, and would 

 probably pay for transportation as ballast under the cotton loads, 

 either to the northern glass-houses or across the ocean. The 

 locality is just half way between Charleston and Savannah, by 

 the turnpike, on Mi\ Spike's plantation. 



There is one more locality of the secondary limestone I visited, 

 which is near the Savannah river, in Georgia, at a place called 

 Jacksonboro'. The perfect similarity of the rock with that in 

 Jones county, North Carohna, and on the Santee and Edisto in 

 South Carolina, admits of no doubt that it is the same with them, 

 and continuous through this wide extent of country. Even to 

 the straw color of the rock, the brooks flowing out at its base, the 

 lukewEirm water, and the little shells that inhabit it, they are all 

 nearly alilte. This has been partially quarried, and the limestone 

 burned. On opening the bed it is found to be about twelve feet 

 thick, and within from the surface, the stone is of a much whiter 

 color, closely resembling challv, and appearing as if it had already 

 been burned. The heap of rock, in a hot southern sun, presents 

 so dazzling an appearance that one's eyes and head seriously 

 suffer from closely examining the pieces. They contain a great 

 variety of fossil shells, affording most beautiful specimens ; but I 

 have not succeeded in obtaining those I collected. A rude Idln 

 has been constructed of the coarse sandstone belonging to the 

 same formation, and a considerable quantity of lime made. It 

 8 



