60 E. W. Milgard—Later Tertiary of the Gulf of Mexico. 
line of Florida (where according to Dr. Smith the Vicksburg 
rocks reach the coast) to the Rio Grande; attaining a width of a 
little over a hundred miles in the axis of the Mississippi 
trough, southward of Vicksburg, and thence narrowing rapidly 
to an average width of forty miles in Texas, and crossing the 
Rio Grande with an approximate width of 150 miles. What 
becomes of it beyond the latter line, is a matter of conjecture. 
Of the sweep of about 900 miles thus outlined as the known 
extent of this formation, about 400 may be considered as hav- 
ing been examined sufficiently in detail to prove the absence 
of marine fossils from the formation; the portion so examined 
embracing, moreover, its widest part and fully two-thirds of 
the area of outcrop. 
I have heretofore (this Journal, Dec., 1871) remarked that 
such: absolute dearth of fossils in a formation whose materials 
are so well adapted to their preservation, staggers belief; and 
that I interpret the calcareous seams and concretions, found in 
some portions of the formation, as derived from the long-con- 
tinued maceration of an apparently copious fauna; as 1s 
exemplified in the Quaternary beds of Céte Blanche on the 
Louisiana coast, and notoriously in the limestones of the coral 
reefs. 
But even upon this basis two points confront us in the dis- 
cussion of the relations of the formation to the sea: the great 
rarity of the calcareous feature in the main body of the forma- 
tion; and the utterly “ unmarine” character of the materials 
generally, in the constant recurrence of the lignito-gypseous 
facies. 
The first objection disappears, as just stated, in the south 
‘exan portion of the area. Curiously enough, precisely the 
deposits, with fossils macerated to unrecognizability. 
‘To complement this statement of facts, while unable to find 
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