52 
Transactions Texas Academy of Science. — 1907. 
mens is shown in Figure 2. I have observed the latter marks in a num- 
ber of localities in West Texas. They are quite frequent in some 
localities in the Eagle Ford shales, having been noted in Ochinaga, 
Mexico; at Terlingua, in Brewster county, Texas; and also in Kinney 
county. 
The evidence of contemporaneous erosion in connection with these 
sandy layers and the occurrence of these indications of the presence of 
ice, shows that shallow-water conditions prevailed during the making 
of the Del Rio clay. This is also indicated by the behavior of the forma- 
tion on a large scale, for it is quite changeable in thickness. To the 
northwest of Del Rio it thins out, and in the uplands on either side of 
Devil’s river, about thirty miles north of this town, it runs out entirely 
for some distance. 
