- 
tas 
E. W. Hilgard— Geological Reconnoissance of Louisiana. 335 
however, have early suggested the probable equivalence of these 
beds with the detrital deposits of the southern Atlantic States, 
and the universality, in North America at least, of the cause 
which produced them. No one as yet, has taken up the sub- 
ject in those States ; much as we hear of the Northern Drift, 
the very existence of the Southern Drift has thus’ far been 
studiously ignored in all text-books. Yet it determines the 
character of the surface, not only of the greater part of five 
States, above mentioned, and of an important belt along the 
Atlantic coast, but I have now traced it in its characteristic 
development, across the Sabine river into Texas, and from scat- 
tered observations partly contained in United States and Texas 
geological reports, partly communicated verbally, I am satisfied 
that it forms an important feature of the geology of Texas, at 
least as far south as the Colorado river, and from the escarp- 
ments of the Llano Estacado to the Gulf of Mexico. How 
Calcasieu bored wells, that in one of them, e 
not been passed through at 450 feet below tide level, “rie 
transportation a considerable velocity of current. The some- 
What startling, but inevitable conclusion is, that if the sea 
€vel was the same then as now, the Gulf coast has in late 
uaternary times suffered a depression to the extent of at least 
mne hundred feet (perhaps more), and during the hag thes 
epoch, a contrary motion to the extent of about 
amount. 
