

Ch. XV.] 



NEWLY-FORMED GULLEYS. 



345 



It occurs three miles 



Milledo-eville 



drawing which I made 

 and a half due west of 

 and is situated on the farm of Pomona, on the direct road to 



Macon."* 



Twenty years ago, before the land was cleared, 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 

 the principal crack deepened it at its lower extremity, from 

 whence the excavating power worked backwards, 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 from 

 20 to 180 feet, was the result. The high road has been 

 several times turned to avoid this cavity, the enlargement of 

 which is still proceeding, and the old line of road may be 

 seen to have held its course directly over what is now the 

 widest part of the ravine. In the perpendicular walls of this 

 great chasm appear beds of clay and sand, red, white, yellow, 

 and green, produced by the decomposition in situ of horn- 

 blendic gneiss, with layers and veins of quartz, which remain 

 entire to prove that the whole mass was once crystalline. 



The termination of the cavity on the right hand in the 

 foreground is the head or upper end of the ravine, and in 

 almost every case, such gulleys are lengthened by the streams 

 cutting their way backwards. The depth at the upper end 

 is often, as in this case, considerable, and there is usually at 

 this point, during floods, a small cascade. 



I infer, from the rapidity of the denudation which only 

 began here after the removal of the native wood, that this 

 spot, elevated about 600 feet above the sea, has been always 

 covered with a dense forest, from the remote time when it 

 first emerged from the sea. 



It is, however, probable that when the granite and gneiss 

 first rose above the waters, they consisted entirely of hard 

 rock which had not yet been exposed to superficial decom- 

 position and disintegration. Still we may conclude that the 

 forest has been continuous from the time when the upper 



* Ly ell's Second Visit to the United States, 1846, vol. ii. p. 25 



