lvi REPORT OF THE STATE GEOLOGIST. 



the outer edges of these belts, and were all formed previous to the fold- 

 ing of this system and are affected by it. 



The question of the manner of the formation of these lower gneisses 

 is still unsettled. If they were originally deposited as sedimentary 

 rocks, and altered to their present condition by subsequent action of 

 the combined forces of heat and pressure, the change has been so com- 

 plete as to leave few signs of their sedimentation ; but of their eruptive 

 origin there is even greater doubt. 



That many of the accompanying granites and other rocks were erupt- 

 ive is clearly proven, and the time of 'their eruption is frequently de- 

 terminable. In the eruptions which occurred while this was a part of 

 the only land area, we find, in the shape and character of crystals 

 which resulted, unmistakable evidences that the molten materials 

 cooled under considerable pressure. The great quartz beds are of this 

 age, as are also the graphic granite or pegmatite, and certain binary 

 granites which have very little mica. It may be, also, that the schists 

 of the Long Mountain Series are of eruptive origin, although this is 

 uncertain. 



FERNANDAN SYSTEM. 



After the folding and the arrangement of the rocks of the Burnetan 

 System in their present condition they formed an island, or more proba- 

 bly a great headland, in an ocean that spread around them on the north, 

 west, and south, in whose waters were deposited the rocks of the suc- 

 ceeding system, which is called the Fernandan. 



The evidence supporting the theory of this headland is found in the 

 character of the sediments of which the succeeding rocks are composed. 

 In Llano County they stretch in broad belts in several parallel folds, 

 but their original extent has been greatly diminished by denudation. 

 The indications are that the greater part of this system has, like the 

 Burnetan, always been a dry land area since its first elevation from the 

 Fernandan Sea. 



The general strike of the rocks of this system is approximately north- 

 west. The rocks composing it are a series of tough hornblendic schists, 

 less crystalline and containing more quartz, and of more slaty structure 

 than the similar rock of the underlying Long Mountain Series, which, 

 with the Bodeville schists, formed the shore line of the ocean, and fur- 

 nished the materials for the formation of these rocks and of the over- 

 lying mica schists, which together form the Yalley Spring Series. 



