HAYES 
KEN 
nbdy D ] DETAILED SECTIONS. 43 
national and Great Northern Railroad. In this portion of the State 
these sandstones occupy a somewhat restricted area and have an 
estimated thickness of 350 feet. 
The Frio clays overtying these Fayette sands have in this area a 
thickness of 75 to 100 feet and rest more or less unconformable upon 
the eroded surface of the Fayette beds. The Frio clays here comprise 
a series of blue, yellow, and sometimes red clays, with concretions or 
nodules of lime carbonate interstratified with occasional beds of gv&y 
calcareous sands and thin-bedded, coarse-grained, soft, calcareous 
sandstones. The clays are mostly massive (although occasionally 
shaly or thin-bedded deposits occur) and show a tendencj^ to break 
up into cuboidal blocks. The colors also tend to intergrade, although 
at most localities there is a strongly defined line of color demarcation, 
but no sign of any change in the character or texture of the clays. 
In other words, changes of color do not indicate an3 r change of bed- 
ding. The lime nodules vary from 2 to 4 inches in diameter and 
show different degrees of hardness. When exposed to the air they 
slake or crumble to a fine powder. The geological survey of Texas a 
gives two sections showing the character of these Frio beds. One is 
as follows: 
Section of Frio beds between Brazos and Trinity rivers. 
Feet. 
1. Brown sand 3 
2. Grayish sandy clay with concretions or nodnles of lime . _ 8 
3. Thin stratum of sandstone \ 
4. Blnish-gray sand with nodnles of lime and clay . . 2 
In the second section, near Courtne} 7 , the beds are shown to be blue 
clays, changing to red, and in places white, containing numerous 
nodules or concretions of lime. 
This series occupies a comparatively narrow strip, probably not 
more than 15 or 20 miles in width. The base of the series is seen 
in the Christian well, near Courtney, Grimes County, and is found in 
wells at Howth station, in Waller County, and exposed in Lime Creek, 
4 miles south of Hempstead. These clays can be traced in a general 
northeastern direction to Longstreet, Montgomery County. From 
Longstreet to Dodge, on the International and Great Northern Rail- 
road, they rarely come to the surface, being for the greater distance 
completely overlapped by the mottled sands and clays of the succeed- 
ing deposits. At Point Blank post-office, in the northern end of San 
Jacinto County, these calcareous clays are seen in the following 
section: 
Section at Point Blank post-office, San Jacinto County, Tex. 
Feet. 
1 . Brown sandy clay . _ 8 
2. Calcareous clays with lime in nodnles or concretions +5 
Succeeding the Frio clays, and in many places completely obscuring 
them, is a series of red and brown (days and sands, with occasional indu- 
« Fourth Ann. Rept. Geol. Surv. Texas, p. 11. 
