186 
Transactions Texas Academy of Science. 
Kennedy, W. 
I hiave been led to the opinion that this peculiarity might be due to the 
origin of the materials forming these deposits, or that some clue to their 
source might be obtained by a study of this phenomenon.” 
Per cent, of potash and soda in clays of New Jersey, Ohio and Ken- 
tucky; in shales of Arkansas. Texas clays are sodic clays. Section of 
the underlying deposits of the Orettaceous age. Per cent, of potash and 
soda in these deposits. 
“Clays naturally partake of the nature of the rocks from which they 
may have been derived, and the proportionis of their constituents will in 
the same manner be in a ratio more or less in accordance with those of the 
parent rock, the variations being due to the solubility of the constituent 
and the number of changes to which it may have been subjected during the 
course of its transportatiion from the original locality to that in which we 
may find it. These changes are, however, sometimes extremely great, as, 
for instance, in the case of kaolin. Williams shows a kaolin in Arkansas, 
evidently derived from a syenite containing 5.48 potash and 5.96 soda, to 
have only 0.23 potash and 0.37 soda. 
“'Since, then, the Texas Tertiary clays appear to be sodic, where are we 
to look for their sources? Are they due to the destruction of the syenites 
of Arkansas or the basaltie outbreaks of which Pilot Knob is a representa- 
tive, or must they be traced to a still more remote source among the 
eruptive and intrusive rocks of western or Central Texas through the 
media of the Cretaceous, Carboniferous and other stages found in Texas?” 
The Tertiary deposits bear strong evidence of marine origin. Had this 
condition of deposition anything to do with the quantities of soda found in 
the beds? Discussion. 
Description of the five divisions of the Texas Tertiary recognized by the 
State (Survey: First, the basal beds or Will’s Point clays; second, the lig- 
nite beds; third, the marine beds; fourth, the Yegua beds; fifth, the Fay- 
ette sands. The Fleming beds or Frio clays. The Coastal clays. “In 
the Tertiary clays of TexaiS the proportions of soda exceed the potash as 
3.19 of soda to 1.18 of potash.” The per cent, of potash and .soda in the 
clays of the above formations. 
“The question of the origin of these clays involves the existence of an 
extensive land area of deposits in which the alkalies were strongly repre- 
sented, and, assuming the solubility of the two to be approximately similar 
(as a matter of fact the potash is slightly more soluble), one in which 
the soda was considerably more abundant than the potash. Again, through- 
out the deposits and interbedded with the clays we have heavy beds of 
sand, many of them almost pure quartz, and the greater portion of the 
clays^ themselves are highly siliceous., * * * 
“It appears to me that the most probable immediate sources of the mate- 
rials entering into the composition of these Tertiary deposits are the under- 
lying iCretaceous beds for the lowermost or basal Tertiary, and a partial 
reworking of the older Tertiary with the Cretaceous materials for the 
upper or newer deposits.” 
A comparison of analyses of Tertiary and Cretaceous marls, and clays. 
The per cent, of lime in the Tertiary beds. 
“It would thus appear that the structural conditions of the Basal beds 
