542 GEOLOGY OF NORTHWESTERN TEXAS. 



county is bounded on the south by the Colorado River. The entire drainage 

 is from the northwest to the southeast. 



The topography of the county is varied. The hills along the larger streams 

 are high and often precipitous. There has been great erosion in this part of 

 the State, which has left in places high hills and bold escarpments. In places 

 the plateaus are broad and level and the creeks and river valleys are broad. 



The high escarpment of the Cretaceous on the eastern side of the county 

 stands out in bold relief. Here and there in the county are isolated buttes of 

 Cretaceous strata. 



GEOLOGY. 



Brown County belongs partly to the Carboniferous and partly to the Cre- 

 taceous formations, the greater part to the Carboniferous. 



The high hills along the eastern border of the county are Cretaceous, and 

 there is a belt of the Cretaceous between Pecan Bayou and the Colorado River 

 southeast of Brownwood and extending as far west as the upper road from 

 Brownwood to San Saba. The Carboniferous of the county is about the 

 middle portion of the formation in Texas. The limestone at the mouth of 

 Jim Ned Creek is the same bed that occurs at Rock Creek, in Jack County, 

 and the bed south of Brownwood is the same as that found at the mouth of 

 Keechi, in Jack County. Both of these beds of limestone are much thinner in 

 the southern counties than in the counties farther north. The sea was deeper 

 on the north during the Carboniferous times than along the south, and this 

 was to have been suspected from the fact that the sea shore in that time was 

 only a short distance farther to the south in Llano County. 



The sandstones in the southern part of the county are the same as found 

 above the coal at the Texas and Pacific mine, in Palo Pinto County. 



SOIL. 



The soils of Brown County are principally of three kinds, whose character 

 is determined by the strata from which they were derived. The Trinity 

 Sands of the Cretaceous has contributed largely in places to the soil making, 

 and where that is the case they are quite sandy. Yet there are no more fer- 

 tile soils in the county than these. The limestones and clay beds of the Car- 

 boniferous have made other soils, which are black and in places more or 

 less sandy, the sand coming from the disintegration of the Carboniferous 

 sandstones. Another class of soils are those made from material beyond the 

 limit of the county, that have been brought there during the period of erosion 

 or by the floods during overflows in the rivers and larger creeks. 



The native growths of plants and grasses show that the soil is fertile. The 



