23 MODERN RAVINES. [CHAP. XXI. 



Another most singular phenomenon in the environs of Milledge- 

 ville is the depth to which the gneiss and mica schist have de 

 composed iii situ. Some very instructive sections of the disinte 

 grated rocks have been laid open in the precipices of recently 

 formed ravines. Were it not that the original intersecting veins 

 of white quartz remain unaltered to show that the layers of sand, 

 clay, and loam are mere laminae of gneiss and mica schist, re 

 solved into their elements, a geologist would suppose that they 

 were ordinary alternations of sandy arid clayey beds with occa 

 sional cross stratification, the whole just in the state in which 

 they were first deposited. Now and then, as if to confirm the 

 deception, a large crystal of felspar, eight or ten inches long, is 

 seen to retain its angles, although converted into kaolin. Simi 

 lar crystals, almost as perfect, may be seen washed into the ter 

 tiary strata south of the granitic region, where white porcelain 

 clays, quartzose gravel, sand, and micaceous loam are found, evi 

 dently derived from the waste of decomposed crystalline rocks. I 

 am not surprised, therefore, that some geologists should have con 

 founded the ancient gneiss of this district, thus decomposed in 

 situ, with the tertiary deposits. Their close resemblance con 

 firms me in the opinion, that the arrangement of the gneiss and 

 mica schist in beds with subordinate layers, both horizontal and 

 oblique, was originally determined, in most cases at least, by 

 aqueous deposition, although often modified by subsequent crys 

 talline action. 



The surprising depth of some of the modem ravines, in the 

 neighborhood of Milledgeville, suggests matter of curious specula 

 tion. At the distance of three miles and a half due west of the 

 town, on the direct road to Macon, on the farm of Pomona, is 

 the ravine represented in the annexed wood-cut (p. 29). Twenty 

 years ago it had no existence ; but when the trees of the forest 

 were cut down, cracks three feet deep were caused by the sun s 

 heat in the clay ; and, during the rains, a sudden rush of water 

 through these cracks, caused them to deepen at their lower ex 

 tremities, from whence the excavating power worked backward, 

 till, in the course of twenty years, a chasm, measuring no less 

 than 55 feet in depth, 300 yards in length, and varying in width 



