EF. W. Hilgard—Later Tertiary of the Gulf of Mexico. 59 
‘The latter is found directly capping, almost everywhere, the 
claystones and sandstones that characterize the highest part of 
the Grand Gulf group. Clearly, the Grand Gulf rocks alone 
assy clays. In these, at a certain level, there occurs a stra- 
tum copiously traversed by calcareous seams; and smaller 
altogether exceptional and local, a few square miles of black 
prairie (Anacoco Prairie) in western Louisiana being its only 
striking manifestation east of the Sabine, it seems to become 
almost predominant in middle and southern Texas. The black 
calcareous prairies of that portion of Texas lie in bands sensibly 
parallel to the coast, each band differing somewhat in character 
from the rest, on account of its soils being more or less directly 
derived from the materials of the underlying formations. These 
are successively, counting from the coast landward: the Port 
Hudson (Champlain), Grand Gulf, Vicksburg, Jackson (Ter- 
tiary), and finally the Upper Cretaceous beds. is state o 
facts, my knowledge of which was until lately based only on 
scattered data gathered here and there, has received detailed 
confirmation from the observations made by Dr. R. H. Lough- 
ridge in 1879, on a reconnoissance of the State made in con- 
nection with the agricultural investigations of the Census. 
It is thus placed beyond doubt that the Grand Gulf rocks 
form a continuous belt, from the Perdido River on the western 
