REPORT OF THE STATE GEOLOGIST. lvii 



Above this is found the Iron Mountain Series, consisting of a fine- 

 grained quartz rock with scales of mica, which underlies the great bed 

 oi magnetic iron of which so much has been written ; and this is over- 

 laid by the Carbonaceous schists, graphitic at the base and carbona- 

 ceous and shaly at the top, which gradually blend into the slaty chlo- 

 ritic schists overlying them ; and thirdly, the beds of dolomitic marble 

 of the Click Series, whose present state of metamorphism marks the 

 great change that has taken place since their original deposition as 

 limestones. This system also had its characteristic irruptions of gran- 

 ites and granulites and quartz, and the final movement gave it its 

 present general trend of northwest and southeast. 



In the Trans-Pecos Eegion the granites of the Quitman and Franklin 

 mountains seem to be referable, in part at least, to this period. Their 

 lithologic character and general trend, as well as their relations to strata 

 of later date, seem sufficient warrant for such determination, but the 

 complications arising from the masking of these relations by the great 

 deposits of Quaternary age which surround them have always been a 

 cause of trouble in the determination. 



EPARCELEAN GROUP. 



TEXAN SYSTEM. 

 The next great system which was deposited around and upon the 

 Fernandan is called the Texan. As the Fernandan was in a great 

 measure derived from material provided by the denudation of the Bur- 

 netan, so this system had its origin in great part in sediments derived 

 from both these earlier systems. The present areal distribution of its 

 exposures in the Central District is in three principal belts running 

 north and south through Mason and Llano counties and west of the 

 Colorado River, which seems to have been somewhere near the old 

 shore line of these seas. The first or eastern of these areas is south of 

 Long Mountain, and covers the region west of the river to Packsaddle 

 Mountain. The second is west of Riley Mountains ; and the third, 

 about ten miles in width, stretches still further west to Katemcy and 

 Mason, and the rocks included in this system show no effects of any 

 uplift prior to that north and south, although they are. badly broken 

 and faulted by later ones. The rocks are principally siliceous, begin- 

 ning in the Mason Series by sandy shales and schists with mica, pass- 

 ing into quartzites and sandstones in the Llano Series, and shaly beds 

 marble in the Packsaddle Series. To this system (Texan) we may 



