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Ch. XIX.] 



STRATA OF THE SOIL AT NEW ORLEANS. 



459 



Orleans to the depth of 630 feet, through strata containing 

 shells of recent species, without any signs of the foundations 

 of the modern deposit having been reached. The mineral 



fl 



character of the strata pierced through, as given in the report 

 of Messrs. Humphreys and Abbot, will be seen to consist 

 throughout of various coloured clays and sands, with much 

 vegetable matter. One bed of sand at the depth of 582 feet 

 is described as nearly stony, but the rest as unconsolidated. 

 At the depth of 66 feet, cypress roots (Taxodium distichum) 

 and waterworn pebbles are mentioned — again at 130 feet bark 



Hil 



& 



and at the depth of 153 feet a cedar log in a sound state. 

 All these remains are exactly of such a character as we 

 should expect to find in a formation accumulated in the sea 

 off the mouths of the great river. 



General Humphreys has had the kindness, at my request, 



to submit the 



shells which were brought 



up from various 



Hil 



the 



stratum 



Mississippi, and he informs 



Artesian boring, and which was composed exclusively of shells, 



determinable 



All of them are of species now living in the gulf, and of 

 which, with one or two exceptions, he has himself collected 

 specimens on the shores of Ship Island, near the mainland 

 (see map, fig. 32). They all belong to saltwater genera such 

 as Mactra, Area, Cardium, Lucina, Venus, Pandora, Astarte, 

 Donax, Teliina, Oliva, Marginella, Buccinum, !N T atica, &c. 

 Recent marine shells occurred at intervals as far down as 

 235 feet, but among the species obtained at that depth were 

 a Teliina and Cardium which Mr. Hilgard has not yet been 

 able to name ; he remarks, however, that they do not agree 

 with any of the American Miocene or Eocene species known 

 to him. From much greater depths and near the bottom of 

 the boring shells of living species were again identified, and 

 among them Venus- Paphia, Area transversa, A. ponder osa, 

 and Gnathodon cuneatus, the latter bivalve being one which 



delta, such as Lake Pont- 

 chartrain, in such numbers that the dead shells are used for 

 making roads. Professoi 



swarms in the lagoons of the 



Hilgard 



