i 3) oe cia aa a te el 
ee Pee Pe AN aes re 
of Mississippi and Alabama. 39 
garding this point are given, but from the great breadth of coun- 
try upon which outcrops of one and the same group of the Ter- 
tiary occurin Alabama, the fact is apparent enough as concerns 
the latter. Whether the same is true of any part of the Creta- 
ceous, is doubtful; unless the great north and south width of the 
Ripley group, as exhibited on Chunnenugga ridge in Macon and 
Barbour counties (according to Tuomey’s and Thornton’s obser- 
vations combined), oa thus find its explanation. It seems 
doubtful, in fact, whether the true Rotten Limestone (if it exist 
there) comes to the oe at all. This is the more remarkable 
from the near proximity on the primary and metamorphic rocks 
of that portion of the state, whose original upthrusting would 
thus be proved to ante- ewes greatly the general Allegheny up- 
heaval. 
The Grand Gulf group.—I have considered the older sa well- 
efined eocene Tertiary apart from the two other gro de- 
scribed in my Report, whose age is doubtful and whose sslndians 
to the former is not well recognize glance at the map 
nevertheless shows that so far as extent is concerned, the Grand 
Gulf group is perhaps the most important 6f the formations of 
the state of Mississippi, and that, judging by the trend of its out- 
lines on = OTH —— it must e still more so in Lo ouis- 
attention that I find but two at fa who , passim, advert to 
anything resembling this formation as it exists in Mississippi. 
Conrad (this Jour., (2), vol. ii, 210) states that the bluffs of 
Vicksburg, Grand Gul f, Rodney and Natchez, have a similar 
geological origin; that their lower portion is of marine origin, 
of the Eocene 
Tam Snalle to refer to a prior areata: mentioned by Con- 
rad, for the data upon which this determination is based, so far 
as shee bluffs below Vicksburg are concerned. I have made de- 
Adams, at the extreme limits of the formation in Mississippi, 
and I may say, of all the reruaetiee outcrops in the interior; but 
thus far, have failed to find even a trace of a marine fossil, and 
in fact, but si single specimen—a bone fragment as I take it— 
likely to ve of zoogene origin. Vestiges of vegetation are 
common, of only’ in one instance, so far, have I found any speci 
posit on the co ge ad already referred to, which exhibits 
the trunks, peste roots of an ancient forest, inhabited, 
be that in proximity = siteala lignite beds 
of this Foote: better success might , bee ise 
case in the Lower Lignitic, In the sand- we claystones 
