North American Eastern Tertiary — Meyer. cjr 
said that they are Grand Gulf. For the question is made more 
complicated by the difficulty of determining what are Grand 
Gulf strata. Mr. Aldrich and myself met cross-bedded lignitic 
strata without fossils, south of Terry, Miss., which we considered 
as Grand Gulf. In beds near Brandon, Miss., which look very 
much alike and which are overlaid by orbitoidic limestone, we 
found imj)ressions of marine shells. In the typical locality, the- 
bluff near the town of Grand Gulf, I found impressions of sev- 
eral species of Unio. Therefore if the Grand Gulf formation- 
is entirely a fresh water formation, the lignitic sands near Bran- 
don do not belong to it, but it seems arbitrary to consider the 
sands near Terry as Grand Gulf. In the Grand Gulf bluff I 
did not notice such lignitic sands. If the synclinal form of the 
Tertiary should be proved, these lignitic strata may be consid- 
ered identifiable with the more northern lignitic beds in Mississ- 
ippi. 
The only rock that may with some certainty be regarded as- 
Grand Gulf is the characteristic white sandstone, which occurs 
in Grand Gulf itself and in many other places, and which is not 
known in the marine Tertiary. In looking out for a contact of 
marine Tertiary and Grand Gulf therefore we ought to search 
for a point where the white sandstone is in juxtaposition with 
the marine Tertiary. Such a contact might be looked for with 
some expectation of success in Louisiana at the Washita river, 
Hilgard says, Am. Jour. Sc, Nov. 1S69, p. 339: "According 
to the observations of my comjDanion, Dr. Walker, who de- 
termined the line between this [the Vicksburg group] and the 
Grand Gulf group on the Washita, lumps of Orbitoides lime- 
stone at the foot of Grand Gulf sandstone ridges are the first 
evidence of the change of the formation." 
From the foregoing it appears that one of the foundations of 
southern geology, the relation of Tertiary and Grand Gulf,, 
must be considered as yet undecided and in connection with it 
the succession of most of the Tertiary strata remains to be 
cleared up. Some European geologists seem to understand that 
I consider the former succession of strata as proved to be reversed, 
but I think this point undecided, although indeeed it seems tO' 
me more probable that the Grand Gulf will prove to be older 
than the Tertiary. Against this supposition the following ob- 
