268 E. W. Hilgard—Geology of the Southwest. 
living in the Gulf or elsewhere, conveys a hint that when these 
“delta” deposits were made, the present state of things had not 
come to pass. From the somewhat arbitrary standpoint of some 
paleontologists, the strata in question would even have to come 
under the head of marine Pliocene! 
confess, also, to a violent distrust of the chemical method of 
identifying formations, as applied by my friend to deposits so 
exceedingly variable in their nature, and over such extensive 
areas. Had he gone to New Orleans instead of Arkansas, he 
might have found in the “drove wells” of that city about as 
eat a variety of waters, as the two extremes he refers to as 
characterizing the Port Hudson and river deposit waters, 
“in eae That ‘‘at various points between Baton Rouge 
and Arkansas, the alluvium is over a hundred feet in depth, 
I have not the slightest doubt; for the same is true of the 
the proof intended to be conveyed, that such is the least 
average depth of the alluvium. All direct stratigraphical 
observations heretofore made have led the observers to a con- 
ess coarse sand, but modified somewhat, in accordance with the 
nature of the underlying strata,+ in Louisiana as well as else- 
where. ‘This is the case even where it is in situ; but where, % 
in the case mentioned by him as occurring on Sicily Island &. 
177), it is merely a talus, commingled with the other materials 
furnished by the degradation of the hills, it of course will 
‘changed according to the nature and amount of the admixture. 
I doubt that there is any Yellow Loam to be found én situ oP 
ee Island. : 
The fine, more or less indurated silts, forming perpendicular 
walls when eroded, to which Prof. Hopkins refers, are clearly an- 
terior in time, and distinct from the Yellow Loam proper ; aS may 
be seen at Port Hudson itself, and at numerous points eo 
the edge of the Loess region in Mississippi, where a na 
transition into the Loess proper is frequently observable. It 1s 
* See Humphrey's and Abbot’s Report on the Mississippi river; this Journal, 
December, 1871, p. 402; Proceed. Am. Assoc. Adv. Sci., 1871, p. 252. 
+ Miss. Rep. 1870, p. 197, et al. 
¢ Miss. Rep. 1860, pp. 319-20, and 198, $334. 
