162 Geological Observations upon 
Arr. XXI.—Geological Observations upon Alabama, Georgia and 
Florida; by Cuartes U. Sueparp. 
In ascending the Alabama River, during the month of January 
last, occasional opportunities were presented me for observing the 
geological features of the country bordering on that river; although 
they were limited to such stoppages as were made by the boat in 
wooding, or in discharging freight. Since my return to the north, I 
find I have been preceded, in part, in the nature of my researches ;* 
but, as I am able to indicate certain localities, and to particularize a 
few fossils, the notices I had anticipated may not appear wholly su- 
perfluous. : 
The result of my observations upon the formations of this district 
lead me, for the present, to regard them as of earlier date than those 
of the Ferruginous Sand Formation of New Jersey and Maryland, 
and as belonging to the Plastic Clay of the Tertiary; a more ex- 
tended series of observations, however, may establish the opinion 
respecting them entertained by Dr. Morton. 
My first observations were made at Prairie Bluff, a place fifty 
miles above Claiborne, upon the west side of the river. The river 
passes directly under the side of the bluff, which is sixty or seventy 
feet high and six or eight hundred feet long, exposing a perpendicu- 
lar section of a white, slightly cohering sandstone, which is imper- 
fectly stratified, and in many places fast crumbling down into sand. 
The grains composing this rock are scarcely larger than a pin’s head ; 
and are white and transparent.. The principal cement, or cause of 
its integrity, appeared to be the shells it embraced, and an occasional 
admixture of white clay. Amongst the ruins of this rock, I gather- 
ed very distinct specimens of Exogyra costata, a large species of 
Gryphea, (mutabilis?), Ostrea falcata, (intermediate between the com- 
mon New Jersey variety and the variety nasuta, figured by Dr. Mor- 
ton, the shell extremely thin and fragile,) a species of Cyrena, casts 
of a Natica, a very thin shelled Terebratula? Turbinolia and Ver- 
micularia. 
Five miles above, at Campbell’s Landing, which is upon the same 
side of the river, I visited another bluff of smaller extent, in which 
* Vid. this Journal, Vol. XXII, p. 94, and Vol. XXIII, p. 228. 
