REPORT OF THE STATE GEOLOGIST. ly 



AKCELEAN GKOUP. 



The great corner stone, around which the forces of nature, in their 

 work through former ages, have built up the grand empire we now 

 call Texas, is found in a plateau of granite and gneiss, which forms a 

 prominent feature in the topography of Llano and Burnet counties. 

 It has always been the bulwark of the land. It has withstood all 

 storms, the earthquake, and the subtle corrosion of the powers of the 

 air ; and although it may be greatly diminished in size since first it ap- 

 peared as dry land above the earliest seas, where it arose either as an 

 island or, as is most probable, as a part of a great mountain chain or 

 elevated plateau which stretched northward toward the Lake Superior 

 region and west toward the Pacific, it nevertheless does stand, as it has 

 always stood, a most enduring monument of the earliest dry land area 

 of which we have any knowledge. 



BURNETAN SYSTEM. 



These rocks, which we have called the Burnetan System, occupy an 

 oblong oval area, stretching from the western part of Burnet County 

 into the eastern part of Llano. It comprises a series of gneisses, gran- 

 ites, etc., the present outcrops of whj.ch occupy two broad elevated belts 

 running a little north of west (north 75 degrees west), with such outly- 

 ing peaks and ranges as Niggerhead, Babyhead, King Mountain, etc. 



Certain facts suggest the probability that the present shape of this 

 nucleal area is different now from that in which it was first uncovered, 

 and that, as has already been stated, it formed a part of a range or 

 plateau running toward the north, and after its emergence it was folded 

 by dynamic influence into its present trend. This system is divided into 

 three series, which are, beginning at the lowest or earliest, a series of 

 gneisses and granites and allied rocks, which are called the Lone Grove 

 Series, resting on which we find certain schistose rocks, consisting of 

 hornblende, pyroxene, etc.; others containing garnets, and in addition 

 to these the steatite or soapstone, actinolite, etc. These are well exposed 

 at Long Mountain and named therefor. Above these occur other schist- 

 ose rocks, composed of minerals containing much larger percentages of 

 silica (mica, chlorite, and talcose schists), with bands of quartzite, such 

 as are seen at Bodeville. 



These two latter series are found in the synclinal basin or trough be- 

 tween the belts of the Lone Grove granites and gneisses, as well as on 



