10 GEOLOGICAL REPORT. [1"12, 14, 15 



13. This ferruginous sandrock is very commonly designated as 

 ' ; iron ore ; ' among the people. It contains, however, much less 

 iron than the aspect and weight of the material generally lead us 

 to expect ; average specimens yield from 60 to 80 per cent, of 

 white sand. Iron ore of good quality, in the form of brown 

 hematite, is occasionally found, partly in the form of small 

 variously shaped nodules, statactitic in the interior (as in the S. 

 "W. corner of Tippah county), partly in thin sheets of pure fibrous 

 ore, interstratified with sand, (as in Tishomingo county, and other 

 localities near the Alabama line). I have nowhere, however, found 

 it in quantities sufficient to justify the erection of a furnace, and 

 where its occurrence in large masses has been reported, a dense 

 variety of the ferruginons sandstone has commonly been mistaken 

 for workable ore. 



14. It is an interesting fact, that the formation of similar sand- 

 stones is still in progress, in numerous localities. In depressions, 

 or in the heads of hollows, where iorest leaves or other vegetable 

 matter decays in contact with the ferruginous sand, the 

 iron is dissolved as proto-carbonate, giving rise to chalybeate 

 waters, which at times may be observed in almost every 

 rill of Orange Sand formation. Such waters in percolating 

 through the sand, deposit in it their iron ; especially where they meet 

 an impervious seam, of clay or other material. Thus the whole mass 

 gradually indurates, and hard ledges are formed within it, producing 

 precisely such shapes as we now find in the deposits on the hilltops. 

 The cementation of the sand of the latter into ferruginous sand- 

 stone, also took place, most probably, long after the deposition of 

 the stratum ; and here too we find the ledges underlaid, generally, 

 by an impervious layer of clay or clayey sand. As a general thing, 

 the sands of the formation are less ferruginous, and ferruginous 

 sandstone is less common, in the southern portion of the State, 

 than in the northern : the sand also is generally finer, and more 

 frequen tly micaceous. This is more especially true of the central 

 belt, N. and S.; while as we approach the channels of the Mississippi 

 and Tombigbee Rivers, this diiference is less perceptible, and the 

 materials quite coarse, down to a low latitude. 



15. It has been mentioned, that white sands are occasionally 

 found in the Orange Sand strata. Similarly, white, siliceous 

 sandstone occasionally occupies the place of the ferruginous sand- 



