K3KEL.] TEXAS. 309 
kian and Austin the formation is approximately 600 feet thick, and is 
generally uniform in texture and composition. From Austin south- 
eastward the chalk probably increases in thickness, but it is broken 
|nd in part concealed by faulting. 
The chalk has clay marls in contact both above and below. It 
rrades upward into chalk marl, which in turn is followed by limy 
lay, bringing into close relations all of the elements essential to the 
production of Portland cement. 
The Austin chalk is structurally well situated for quarrying. East 
If Sherman it is inclined southward and south of Sherman southeast- 
pi I'd at approximately 40 feet per mile. 
GOODLANl) LIMESTONE. 
The Goodland limestone is near the middle of the Comanche (Lower 
Cretaceous) series in Texas and southern Indian Territory. It is situ- 
ited west of and generally parallel with the outcrop of the Austin 
jhalk. It crops out in southern Indian Territory east of Ardmore. 
jsear Ardmore the outcrop turns southward, crossing into Texas in 
Cooke County. It occurs in large areas in Wise, Parker, Hood, Erath, 
Bosque, Hamilton, Coryell, Lampasas, Burnet, Blanco, Kendall, Comal, 
nd Bexar counties. Still larger areas are exposed in the Edwards 
Plateau west of San Antonio. 
In Indian Territory and in Texas north of the Brazos River Valley 
lie formation is a massive, semicrystalline white limestone 30 to 50 feet 
pick. From Brazos River Valley southward it gradually increases 
n thickness, reaching 300 feet on Colorado River. In this central 
fexas region the formation divides into two parts. The lower part 
pnsists of a massive white chalky limestone nearly 100 feet thick. 
fhis member has been described in Texas and United States Geologi- 
lal Survey reports as the Comanche Peak limestone. The upper 
ticmber, which has been described as the Edwards limestone, consists 
f thick beds of nearly pure chalky and siliceous limestone beds alter- 
ately stratified. They contain quantities of nodular and almost pure 
ints. The flints occur in both classes of rock, but are rather more 
bundant in the pure limestones. Near Austin and elsewhere in the 
entral part of the State these purer limestones are manufactured into 
high grade of white lime. 
The Goodland limestone and its southern equivalents are found cap- 
ing escarpments overlooking the timbered lands of the Trinit}^ sands 
i northern Texas and Indian Territory. In central Texas these lime- 
ones occur in a region of strongly incised diainage channels, and 
ap local table lands in the western part of their area of outcrop and 
ccur in escarpments, bluffs, and low lands in the eastern part. 
Like the Austin chalk, the Goodland limestone lies almost flat, being 
iclined at low angles toward the south in Indian Territory and 
^ward the east and southeast in Texas. 
