EPAROHEAN GROUP. 561 



VALLEY SPRING SERIES. 



Certain schists in the northwest trend, having for the most part a granular 

 or friable texture, form the base of the Fernandian System. These are of 

 two varieties, one being green or black or dark gray in color and carrying 

 hornblende, the other resembling more nearly the earlier micaceous schists. 

 Some of the members of this series are slaty, but there are also thick beds of 

 more massive character. One of the best regions for studying the former is 

 near the head of the Little Llano, east of Babyhead Postoffice. The latter 

 set is well developed on Phillips and Johnson creeks, not far from Valley 

 Spring. 



IRON MOUNTAIN SERIES. 



The extensive outcrops of magnetite and hematite in Llano and Gillespie 

 counties in their original situations belong to the middle of the Fernandian 

 System. The ores are usually underlaid by fine-grained yellowish quartzites, 

 which shade off below into the earlier mica schists, and above into the mag- 

 netites. Overlying the iron ores there is a set of carbonaceous rocks com- 

 prising graphite schists and graphitic clay slate, and above these may some- 

 times be recognized a slaty chloritic schist. Special consideration of the iron 

 Mountain series will necessarily be given in the discussion of the economic 

 values and relations of the ore deposits. It is possible that graphite deposits 

 of some value may be found in this series. 



CLICK SERIES. 



The marbles of the Fernandian System must not be confounded with those 

 of the succeeding Texian period. The Click marbles are usually blue, weath- 

 ering almost black. They are prominent in the area of the iron ores, but are 

 less characteristic of the best mining tracts than of special districts where 

 those are largely unexposed. Near the town of Llano, east of Valley Spring 

 and between Packsaddle Mountain and Honey Creek Cave, there are out- 

 crops of several parallel bands in which the marbles are thoroughly crystal- 

 ized. 



II. EPARCHEAN GROUP. 



A group of strata of later origin than the Archean and unconformable 

 thereto, upon which the Cambrian terranes are not conformably placed, is re- 

 garded as Eparchean, because of its relation in general to the rocks which 

 have been so designated by members of the United States Geological Sur- 

 vey. Only one system is recognized in Central Texas. 



