240 E. W. Hilgard— Geology of the Delta, 



from tlie same sources as tlie drift boulders of Missouri and 

 Illinois* 



In the bored wells of Calcasieu, these pebbles have been 

 found as much as 450 feet below tide level ; the inevitable 

 inference being (provided the sea level remained constant), tliat. 

 since the time of their transportation, the coast has suflPered a 

 depi-ession to at least that extent — in matter of fact, probably, 

 fully twice that amount f The thickness of the drift stratiiin 

 is about one hundred feet, the materials growing finer toward 

 the top; indicating, therefore, a diminished Velocit}- of tlie 

 depositing current. 



Overlying this sand and pebble drift, we find, as at Port 

 Hudson, alternating strata of more or less lignitiferous clay 

 and sand, 350 feet thick ; a 130-foot clay bed lying on top. 

 In its uppermost portion, this bed recalls to mind at once the 

 variously colored clays of the Cote Blanche profile, with their 

 calcareous cohcretions; but here, according to the concurrent 

 testimony of the inhabitants and the microscope, wianne shells 

 take the place of the fresh-water fauna observed at the tormer 

 locality. The sands which, on the whole, predominate in the 

 lower portion, are readily distinguished under the microscope 

 from those of the drift, by the predominant sharpness of t he 

 grains, and the occurrence of particles of lignitized wood: 

 but I have not thus far succeeded in finding in them any other 

 organisms. They resemble strikingly the materials obtained at 

 corresponding depths in the bored 'wells in the city of ^ew 

 Orleans. 



Few deep wells exist near the coast, in the inter^^al between 

 that city and the Calcasieu bores. In the only one of whicli i 

 possess definite data, viz., at Salt Point on Bayou Sale, a bea 

 of marine shells was found after passing through the first cia} 

 bed, at 60 feet. 



,n, May, 1866; and Nor. 1«66' 

 . 1869; Ibid. Nov.. 1869. 



,- 9 Prof. Newberry's interesting paper on "The Surface ( . 

 t ■' no deposits, corresponding to the drift of the northern and wes 

 ?t south of the Ohio river." (Ann. Lye. Nat. Hist, N. York, u, ^^^ 

 ■ This Journal, II, Nov., 1869, p. 335. 



