PORT HUDSON FORMATION. 47 
Doctor Hilgard and others regarded the clays and sands of the Yazoo delta as belonging to 
the Port Hudson formation; likewise deposits bordering on the Gulf coast. In correlating 
the outcrop at Port Hudson with the material of the Yazoo delta, he further adds: 
The stump stratum (No. 1), however, as appears from numerous data collected by myself or con- 
tained in Humphreys and Abbot's Report on the Mississippi River, exists at about the same level 
—that is, near that of tide water— not only over all the so-called delta plain of the Mississippi, but also 
higher up, perhaps as far as Memphis, and all along the Gulf coast, at least from Mobile on the east to 
the Sabine River. Wherever circumstances allow, the overlying clay stratum (No. 2) is also observed. 
In the report on the Coastal Plain of Alabama, page 40, Dr. E. A. Smith, in speaking of 
the eastward extension of the Port Hudson along the Gulf coast, says: 
Whether there is any real genetic difference between the loess and the Port Hudson other than the 
order of deposition, the lowest and therefore the oldest members of this section have received the latter 
designation and there is no good reason for discussing it here and seeking change. It is these members 
from 1 to 4, inclusive [of the Port Hudson sections of Hilgard], that we find spreading along the northern 
shore of Lake Pontchartrain and underlying the alluvium of Pearl River, modified and reappearing 
beyond, and underlying and constituting the terrane of all the region of the "Pine Meadows," together 
with a variable fringe to the northward, covered by washings from the sand hills, and an undefined por- 
tion of the territory covered by the coastal sands, above more definitely called "Biloxi." 
From Hilgard's sections there is little room for doubt regarding the order of deposition of 
the Port Hudson and the overlying loess. In both sections, made from two localities 1 
mile apart, there is practically the same order of strata, with the loess or hardpan above 
what he describes as Port Hudson proper. 
As will be seen from the above quotation, Smith has suggested the possibility that the 
entire section, as given by Hilgard, belongs to the loess and that the lower portion has re- 
ceived the name Port Hudson. 
The section as above given is clear enough as it stands and shows the relation of the Port 
Hudson to the loess; but the correlation of the so-called Port Hudson of the upper Mississippi 
or Yazoo delta offers some difficulties which have not at present been removed. This corre- 
lation has been made chiefly from the fact that there are logs and decayed vegetation found 
in the clays of the Yazoo delta, and likewise calcareous concretions. The decayed logs, or 
"stump stratum/' according to Hilgard, occur at about tide level throughout the Yazoo 
delta as well as farther south. At Port Hudson, Miss., the loess rests directly upon the Port 
Hudson formation, but farther north the loess caps the hills on the east rim of the Yazoo 
delta at 100 feet or more above the so-called Port Hudson. Finding the Port Hudson clays 
in the bottom and the loess on the east rim of the Yazoo delta 100 feet higher would, accord- 
ing to Hilgard's theory, necessarily imply that the entire Mississippi Valley contained at one 
time 100 feet more of Port Hudson than it does to-day. Succeeding this was a time of vig- 
orous degradation, carrying away the loess and 100 feet of Port Hudson, until the present 
level was reached. This would mean that the vast bottom land in northern Mississippi, 
northeastern Arkansas-, and Louisiana attained its present surface form by destructional 
rather than constructional agencies. 
The Yazoo delta and the corresponding areas on the west side of the Mississippi, previous 
to the deposition of the present materials, were scoured out 50 to 100 feet deeper than they 
are at present. This is clearly proved by finding old logs, bark, and river gravels at these 
depths. The loess, Port Hudson, Lafayette, and portions of the Tertiary were removed by 
degradation. Then began the deposition which has continued until the present level has 
been attained. 
A study of these later formations in northeastern Arkansas during the spring of 1905 has 
revealed the fact that the present levels of this vast plain have been reached by a construc- 
tional and not by a degradational agency. Much of the so-called Port Hudson of the low- 
lands appears to be the reworked products of the loess, which still caps the adjacent hills 
and Crowley Ridge. 
If the materials of the Yazoo delta are considered to be Port Hudson, then, from the order 
of the strata in the south, the Lafayette must underlie it. While gravels are found at vari- 
ous depths in the wells over the delta, they do not resemble the typical Lafayette pebbles on 
