T12J FERRUGINOUS SANDSTONE. 9 



denuding' action which has removed the rest of the stratum. 

 12. It is comparatively but rarely the case, however, that solid 

 ledges of any considerable thickness are found on these summits. 

 Solid ledges of 4 feet are not common, and but two cases arc known 

 to me in which their thickness amounts to ten or more feet. Most 

 usually they consist of connected masses of fantastical shape, 

 such as concretionary bodies are wont to assume ; the interstices 

 are filled with loose, or loosely cemented, sand. The latter, as 

 might be supposed, is washed out in course of time, where the 

 stratum is exposed to the weather ; and when the remaining harder 

 portions are broken asunder, it does not require a strong imagina- 

 tion to recognize in them the remnants of works of art ; and 

 nothing can convey a better idea of the prevalent forms, and 

 character of the material, than the popular likening of such spots 

 with the "ruins of a forge," or more properly, those of an iron- 

 foundry. There are angular plates, of several square feet, of plane 

 surface, straight edges (the latter often provided with a regular 

 rim,) and of uniform thickness; smaller plates, of a similar character, 

 joined together at various angles, like fragments of boxes ; others 

 channeled, and variously curved, so as to form gutters and very 

 frequently, tubes of considerable length and diameter, and? 

 remarkable regularity of shape. In some localities (as for instance, 

 in S. E. Tippah, near the heads of Hatchie,) complete assortments 

 of tubes may be seen strewn about on the hilltops — sometimes five 

 feet in length, and of various bores from I inch to four inches- 

 The rough sandy surface, and even the color of these concretionary 

 forms, renders them strikingly similar to newly made castings ; and 

 in districts where such forms are common, springs are not unfre- 

 quently provided with spouts and gutters from these natural 

 warehouses. Sometimes these tubes may be found in place, 

 ensconced in a mass of rock, so as to allow of blowing or even 

 seeing through the latter. When thus in place, I have generally 

 found them pointing in a N. E. and S. W. direction. Similar tubes 

 and concretions of various shapes and sizes, are in many localities 

 found isolated, in the interior of loose sandy strata ; the hollows 

 being, as in the case of those found on the hilltops, filled with 

 loose ferruginous sand, or sometimes with yellow ochre. Round 

 and oblong concretions of this kind, of small size, are very common 

 in the neighborhood of Oxford ; portions of them have been used 

 as drinking cups. 



