308 
CKMENT MATERIALS AND INDUSTRY. 
[BULL. 24| 
most densely populated portion of the State. The cities of Shermaj 
Dallas, Fort Worth, Waco, Austin, and San Antonio are located upon i\ 
Facilities of transportation are ample, for railroads extend from tl 
principal cities to other centers of population in the State and beyonj 
Two formations in the Cretaceous system contain limestone deposil 
of remarkable purity that are well adapted to the manufacture of 
Portland cement. These formations are the Austin chalk and Good{ 
land or Comanche limestone. 
AUSTIN CHALK. 
The Austin chalk is situated in the lower part of the Gulf seri 
(Upper Cretaceous). Its exposed area is shown in the sketch m 
(PL XIV). From a point on Red River near the northeast corner 
the State its outcrop bears westward, passing near Clarksville, Hone 
grove, and Paris, to Sherman. From Sherman its course bears sout 
westward beneath Dallas, Waco, Austin, and San Antonio. Besides 
these, numerous other but smaller cities are situated upon it, from 
San Antonio its course westward paralleling the Southern Pacifiqj 
Railway to the Rio Grande near Del Rio. 
The rock is a massive white friable limestone or chalk. Through 
several hundred feet from near the base to the top the rock varies 
from 70 per cent to 90 per cent carbonate of lime, as shown in tha 
table of analysis of Texas chalk. Massive beds of many feet in thick- 
ness are remarkably uniform in texture and composition. 
Analyse* of Texas chalk and marl. 
No. 
1 
2 
3 
4 
5 
6 
7 
8 
Silica, 
SiOo, and 
insoluble. 
5.77 
5.94 
10. 32 
11.31 
15. 98 
48.02 
60.82 
23. 55 
Ferric oxide 
and alumina, 
Fe«0 3 and 
A1 2 3 . 
Lime,CaO. 
Magnesia 
MgO. 
2.14 
1.72 
6.56 
7.50 
8.47 
20.95 
21. 30 
1.50 
50.45 
48.73 
45. 30 
42.61 
38. 86 
14. 26 
3.66 
39. 32 
0.28 
.28 
Carbonate 
of lime, 
CaCO,. 
Carbonate 
magnesi 
MgC0 3 . 
90.15 
86.57 
79. 75 
76.47 
70.60 
24.62 
6.51 
70.21 
1. Fresb rock from quarry, average material used in the manufacture of cement, Alamo Ceme 
Works, 3 miles north of Sari Antonio, Tex. 
2. Brushy Creek, Williams County, Tex., 100 feet above base of chalk. 
:>. Brushy Creek, Williams County, Tex., middle part of chalk. 
4. Brushy Creek, Williams County, Tex., upper part of chalk. 
5. San Gabriel River, Williams County, Tex., chalk marl at top of white chalk. 
6. Williams County, Tex., lower part of blue marl above the white chalk. 
7. Williams County, Tex., greensand marl, central part above blue marl. 
8. Average fresh rock from quarry, Texas Portland Cement Works, 3 miles west of Dallas, Te 
lower 20 feet of white chalk. 
Near Red River, east of Sherman, the chalk probably does not exceed 
400 feet in thickness and it is interbedded with chalk marls. He 
however, there are thick beds of nearly pure chalk. Between Sh 
