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, 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 marginal stra- 

 tum which gives to it so unpleasant a smell. 



If we are correct in the conclusion, that this is the marginal stra- 

 tunj, 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 places, and thus raising and 

 extending the vallies. 



SOUKCES OF FKESH 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 he higher than the water level. 

 In proof, it may be stated that no water can be obtained in these 

 beds; they are also without the pebbles which invariably 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 remembered 

 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 eardiquakes. 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 

 the occasional appearance of blue .clay, from five to thirty feet in 

 depth, and formed by the gradual interpolation of land upon ponds, 



