relating to the Vale of the Mississippi. 55 
for, perhaps, twelve hundred years; carrying ‘the earth by secret 
paths to a great distance, where it was either appropriated in forming 
what is now called second bottoms or bluff-flats ; or deposited at a 
point where it was; at some distant day, to be again removed - by a 
river that did not then exist, and it was destined to assist in laying 
the foundation of. the Mississippi Delta, or what we have called the 
Orleans basin, with its upper or northern boundary beginning at Ba- 
ton Rouge and not at Natchez, as supposed by Mr. Dunbar. 
SUBTERRANEAN CAVITIES AND CHANNELS. 
Our first stratum of clay, beneath the vegetable soil, contains a 
multitude of irregular cavities, tratersed by the same clay, and dis- 
posed like the reticular texture of bones. These cavities are pro- 
duced and perpetuated by rain water, which, as fast as it is com- 
pressed by superincumbent weight, passes readily through the soil 
and vegetable matter, and through this clay, into the next stratum, 
or it forms «small channels between the two. These cavities are 
lined with a very thin coat of lime or chalk, derived from the 
water, bringing from the surface the spoils of the snail shells which 
time creates, destroys and decomposes. In very dry 
lime, iron and alumina, give to this stratum of clay, a og ee and 
almost equal to that of lead. It dries so hastily in the 
sun, that it cannot be used by the brick-maker. The second stra- 
tum, which contains a superabundance of sand, requires more alumi- 
na and iron, to produce the weight and tenacity which are so very 
important in bricks. It may be doubted whether the levigated marl, 
mentioned by Mr. Dunbar, which “ assumes a compactness and so- 
lidity resembling pitch,” is very well ‘adapted to the use of the 
potter.” This earth of the Mississippi bottom is alumina, with a 
siderable quantity of vegetable and animal matter. We have 
noticed the effects of heat upon this earth, when united with sand 
and made into brick. While burning, it is extremely difficult to 
raise and continue the white heat, without producing fusion; the 
bricks are very light, friable, and remarkably brittle. 
To show the readiness with which land covered by cane received 
absorbed the rain water, we will cite as instances two tracts 
thickly set with a natural growth of cane; both of these tracts 
received the heaviest falls of rain, without showing the least sign of 
draining on the surface. The first field contains about eighty acres, 
and was well known to the writer before the cane was remo 
