18 RIO GRANDE COAL FIELDS OF TEXAS. [bull. 164. 
BUDA LIMESTONES 
Above the Del Rio clays occurs a limestone, which both in its 
stratigraphic position and its lithologic characters corresponds to the 
Buda limestone of the Colorado River section at Austin. Macro- 
scopically this limestone is hard, and whitish or yellowish in color 
when freshly fractured. The fracture is conchoidal or splintery. It 
is frequently traversed by minute veins of calcite. Upon weathering 
it becomes yellowish or pinkish; occasionally, on account of the great 
amount of iron contained, weathered specimens may be incrusted by 
henfatite. Numerous small red or pink blotches characterize the lime- 
stone. Microscopically it consists of minute veins and patches of 
transparent calcite, between which are patches of minutely crystalline 
granular calcite of dark-gray or brownish color, in which angular 
transparent pieces of calcite are embedded. The calcite veins are 
sometimes clouded in appearance, but are lighter in color than the 
bulk of the rock. No well-preserved Foraminifera were observed, 
but there are grayish masses of minutely crystalline calcite that show 
the structure of Foraminifera of the Globigerina type. 
Outcrops of this limestone are to be seen northeast, east, and south- 
east of Del Rio, where it occurs above the Del Rio clays. It is also 
exposed at numerous places on the road from Brackett to Del Rio, 
between Sycamore Creek and the latter place. 
Measurements of the thickness of the limestone at Del Rio were not 
obtained, but near Brackett it is about 100 feet thick — a little more 
than twice the thickness at Austin. 
UPPER CRETACEOUS. 
DAKOTA DIVISION. 
(Absent.) 
EAGLE FORD FORMATION. 
The Buda limestone is overlain by a series of flaggy, argillaceous lime- 
stones, between the beds of which calcareous shaly layers are frequently 
found. These beds occupy precisely the same stratigraphic position 
with reference to the Buda limestone below and the Austin chalk 
above as do the Eagle Ford shales in central and northeastern Texas. 
The stratigraphic continuity of the beds has been traced from Del Rio, 
by way of San Antonio and Austin, to Red River, east of Sherman. 2 
As has been shown, these beds thin from Waco southward toward 
the Rio Grande; the more unctuous and darker-colored shales of the 
lower portion of the north Texas section disappear, and only the 
1 In accordance with a suggestion of Mr. R. T. Hill, the name Shoal Creek limestone is here changed 
to Buda limestone, as the former name is preoccupied. 
2 Robt. T. Hill : Am. Jour. Sci., Vol. XXXIV, Oct., 1887, pp. 291 et seq.; Bull. No. 4, Geol. Survey of 
Texas, Austin, 1889, p. xxvii; Artesian and other underground waters in Texas, New Mexico, and 
Indian Territory, Final Rept. of the artesian and underflow investigation of the U. S. Dept. Agricul- 
ture, 1892, p. 124. 
