of Mississippi and Alabama. . 41 
tiary at its southern limits. Moreover, Bigelow (this Jour., ii, 419) 
describes a sandstone formation in Baldwin n county, Ala. ct 
. Re 
sand.” Bieelow states that in the lowest portion of this rock he 
has seen obscure impressions of shells; which, if my oon jelba 
be correct, might offer an opportunity of determining the age of 
the group. ‘The same rock is said to occur at eset: 
vit “blue clay bottom” of the Coast—‘‘Coast Pleiocen 
as regards the sane known black clay peti 
of the coast (Miss. Rep., p. 154, ff.), a rege eae of specimens 
of shells and borings obtained from the New Orleans artesian 
well,* in 1854, seems to show that = underlies the whole of the 
delta, perhaps as high up as Port n, whose subterranean 
ypress swamps, observed by anaes and by Lyell, may be- 
long to this formation. No Eocene fossils have been brought 
up by the augur, even from the lowest shell-bed found, at the 
depth of 6T0" feet, (the greatest depth was -_ while from 
among the shells of the first bed stru ck, at 41 feet, I have thus 
far determined eighteen marine species, all now living i in the Gulf. 
At 158 feet a trunk of cypress, with bark, was foun 56 
feet, some extinct, or if living, undescribed sholla seem to occur; 
and at 480 a Gnathodon bed. I hope to be able to determine 
by microscopic comparison mcr: or not the Grand Gulf group 
has been passed through or reached in this bore, which from 
as been observed in the former series. Should the chain 
of the Antilles, after the close of the Hocene epoch have for some 
time cut off the Gulf of Mexico from the Atlantic, it seems 
sible that the deposits of the former might have changed their 
character to the extent required by the facts observed. A strong 
influx of fresh water—perhaps that pertaining to the Great 
Lignite era—from the continent might for the time being have 
extinguished the Eocene marine fauna without replacing it by 
another sufficiently numerous to be readily detected in the de- 
posits of the period, which might thus correspond to the ae 
tic Miocene. Upon the subsequent irruption of the Gulf st 
through the Antilles chain, the formation of penne marine de 
posits along the margin of the Gulf would be resumed. 
a. of Mississippi, July 26, 1866. 
nana were furnished by Drs. Copes and S. 8. pee of New Or- 
sia to > Map Gen. A. A. Hu oa A aud by him referred to me for examination ; 
, however, is not yet c 
‘a Jour. Sc1.—SEeconpD Pt Vou. XLII, No. 127.—Jan., 1867. 
6 
