relating to the Vale of the Mississippi. 53 
the snail shells are very abundant. Should we not attribute this stra- 
tum to the washing down of the land, the pushing out the sea, and 
the forming, i in this manner, of marshes and pools of stagnant water, 
_which series of events was followed by a luxuriant vegetable growth; 
It is evidently the vegetable and animal matter of this marginals stra- 
tum which gives to it so unpleasant a smell. 
If we are correct in the conclusion, that this is the marginal svar 
tum, which girded the sea in this quarter, the question may be asked, 
has the sea subsided ?>—We have made no calculations of the height 
of this stratum-above the sea, but incline to the opinion that it is 
more than one hundred feet above the gulf stream. Much attention 
has-been given by the writer to the appearance of bluffs, and many 
inquiries have been made of persons employed in the sinking of wells 
for water, to ascertain if there were any reasons to admit a heaving 
of the land. But it appeared, upon inquiry, that nothing of the kind 
has occurred, and that the land of the above named district has 
been gradually formed by the slow and uniform action of the rains, 
in bringing down: the earth from higher pe! and thus eens and 
ae. the Bae terres sce 
SOURCES OF FRESH WATER. 
It is worthy of remark, that, in some instances, wells have been 
sunk and the sand reached without observing the blue clay; but 
water was not obtained until they descended to the sand containing 
pebbles, whose depth is sometimes ten or twelve feet. This sand 
must be composed of such beds as are usually observed to be of un- 
equal height, such as form the downs of the sea shore, being thrown 
up by the wind, and consequently they lie higher than the water level. 
In proof, it maybe stated that no water can be obtained in these 
beds; they-are also without the pebbles which peared occur on 
the face of sand as the water runs over it, whether from the base of 
the bluffs, or across the bottom of wells. It should be re: 
that the appearance of sand, near the surface, on hills, or - other situ- 
ations, should not be-confounded with the downs above alluded to. 
This occasional and rare occurrence of sand, would seem to have 
been caused by earthquakes. Such deposits of sand are generally 
narrow and short. It is also worthy of remark, that the blue clay, 
or marginal stratum referred to above, should not be confounded with 
occasional appearance of blue clay, from five to thirty feet in 
: — and formed by the gradual iomcoclage of land upon ponds, 
