90 
TRANSACTIONS OF THE TEXAS ACADEMY OF SCIENCE. 
Gulf series : 
Webber? ille and Eagle Pass formations . 
Taylor and Anacacho formations. .... 
Austin chalk 
Eagle Ford shales 
Comanche series: 
Shoal Creek limestone 
Del Rio clay 
Fort Worth limestone 
Edwards limestone 
Comanche Peak limestone 
Walnut formation 
den Rose formation 
Travis Peak and allied formations 
Each of the above formations is described, and those of the Cretaceous 
with considerable detail — measured sections often-times accompanying 
the descriptions. The carefully executed work about Austin can not 
fail to be of great value to students of the Texas Cretaceous which af- 
fords in that locality a most inviting field for study. 
The igneous rocks of the Rio Grande Plain occur “along the interior 
margin.” They are basic. 
The Balcones fault zone forms the “abrupt southern terminus of the 
Edwards Plateau/' “The strata on the seaward side of the faults have 
been dropped down/ so that any particular stratum — the top of the Ed- 
wards limestone, for instance — lies 500 to 1000 feet lower on the coast- 
ward or downthrow side of the fracture than on the interior or upthrow 
side.” It should be borne in mind that “the fault zone really consists 
of many faults having subparallel directions, all concentrated within a 
narrow belt of country.” The displacement at Mt. Bonnel, on the 
Colorado above Austin, is such as to bring the Eagle Ford shales of the 
Gulf series in contact with the Glen Rose beds of the Comanche series. 
The proof of the water-hearing property of the Edwards limestones 
is supplied by the “great springs * * * bursting out of them at the 
headwaters of the Llano, Guadalupe, Frio, and Nueces rivers;” the arte- 
sian well records at Manor, San Marcos, and San Antonio; and the ordi- 
nary wells on the Edwards Plateau. 
In discussing underground waters, non-flowing wells, springs, and 
artesian wells often receive detailed treatment. Of the latter, logs are fre- 
| Washita division. 
| Fredericksburg division, 
i Trinity division. 
Montana division. 
Colorado division. 
