120, '^1! PEBBLE BEDS OF OKANGE SAND. 13 



siliceous ; hard aluminous sandstone, or siliceous claystone, is occasionally found, 

 1 mt by far the prevalent material is the several kinds of amorphous quartz — Chert, 

 Hornstone, and -Jasper, with numerous varieties of the rarer rocks of the same 

 class — Agate, Chalcedony, Cornelian, Sardonyx, Lydian Stone, etc., of which 

 very beautiful specimens have been obtained in the State. Gray and yellowish 

 Siliceous Sandstone is very common ; and pebbles of Hock Crystal, as well as of 

 white, crystalline quartz rock or Quartzite, are common in some localities, and 

 occasionally found throughout the pebble deposit. Porphyry, and trappean 

 rocks, are of rare occurrence, though not entirely absent. There is a marked 

 difference of character, however, between the pebbles of the eastern, and of the 

 western pebble region. In the former (at least in the valley of the upper Tom- 

 bigbec,) Chert and Bornstene, with siliceous and aluminous sandstone, and some 

 quartzite, are almost exclusively present ; while in the western belt, along the 

 Mississippi, a great variety of rocks, as above mentioned, is generally found. In 

 both regions, however, fossils of the ancient, paleozoic formations are of frequent 

 occurrence in the pebbles themselves. (See below IT 29 & ff-) 



20. The size and form of these pebbles, as may be supposed, are extremely 

 variable, from small gravel to the coarsest shingle, and from the perfect egg- 

 shape, ellipsoid and disc, to irregular fragments with rounded angles only. The 

 quartzite, rock crystal, lydite, jasper and trappean pebbles are almost always 

 much worn and of regular shapes, and usually small, while those of the fossili- 

 ferous chert, hornstone and sandstone are often large, very irregular, and 

 comparatively little worm. I have found a Cyathophyllum forming a pebble 

 by itself, in which projecting radii were still extant, though somewhat rounded ; 

 and on the blocks of crinoidai columns, the characteristic figures may sometimes 

 be seen almost unharmed. 



21. The average size of the pebbles might be stated as being between that of 

 a, pigeons and a large hens, or turkeys egg. But the maximum size found is very 

 considerable, and somewhat puzzling to account for, on the supposition of 

 transportation by water alone. Besides, angular blocks of considerable 

 size, have been known to occur, one of which, a white, perfectly rough block of 

 quartzite weighing about 150 pounds, (found in N. Lafayette county, in a hickory 

 valley on S. 24, T. 7, B. 3, W., by A. H. Pegues, Esq.,) is now in the collection 

 at Oxford. Bounded blocks of ferruginous quartz, a hundred pounds and more 

 in weight, have been found on the bluffs bordering on the lower Yazoo, (Harper.) 

 I myself have found, in Tippah county, T. 5, B. 1, E., (where pebbles are not 

 otherwise prevalent,) perfectly rounded pebbles of white quartzite, weighing up 

 to twelve pounds, at least ; and similar pebbles, even of larger size, are said to be 

 common in that region. 



In Claiborne county, at Bocky Springs, I found a rounded block of yellowish 

 siliceous sandstone of great hardness, weighing 64 pounds, and containing two 

 links of a calamite ; the rock differs decidedly from any sandstone known to me 

 in Mississippi. Scratches have not, however, in any instance been found on 

 their surface. 



