PALEOZOIC GROUP. 563 



PACKSADDLE SERIES. 



The best normal outcrops of the highest Texian series are in Llano County, 

 south of Packsaddle Mountain, and in a small area in Mason County, coinci- 

 dent with the earlier series. In other places, as west of Packsaddle Mountain, 

 in Llano County, and near Niggerhead Peak, in Burnet County, they are not 

 always lying in the position into which they were thrown by the uplift next 

 succeeding their deposition. The marbles and graphitic shales of this set 

 may be mistaken for the Fernandian strata of similar appearance, but close 

 inspection will enable one to distinguish each from the other. The Pack- 

 saddle marbles are clear white, usually weathering yellow, unlike the dark 

 weathering blue marbles of Fernandian (Click) time. The graphitic shales 

 of the Packsaddle series are plainly detrital, as far as we have observed them, 

 while the Fernandian (Iron Mountain) graphitic schists are crystalline and 

 more evidently foliated. In the majority of exposures the trend of the beds 

 is sufficient to determine the system without much further examination. 



None of the graphite of this series is liable to possess any important com- 

 mercial value, in my judgment, after the tests which have been made by my- 

 self and the chemists of the Survey. 



III. PALEOZOIC GROUP. 



The Paleozoic rocks of Central Texas are made up of sandstones and lime- 

 stones, and their exposures occupy all the territory outside of the crystalline 

 rocks which is not covered by the so-called "mountain limestone," or Creta- 

 ceous. Excepting a few small patches of Carboniferous rocks on the borders, 

 and limiting the area to what is known as the Central Mineral Region, this 

 statement is explicit enough as a general description of the strata included in 

 the present review. For the certain detection of minor terranes a knowledge 

 of the fossils is necessary, but the descriptions here given will aid in their 

 determination roughly. They lie chiefly as irregular fringes around the bor- 

 ders of the earlier rocks and adjacent to the Cretaceous escarpment, except 

 upon the north, where the contact with the Carboniferous forms much of the 

 boundary line. We have representatives of the Cambrian and Silurian sys- 

 tems in profusion, and there is also a rather persistent but moderate develop- 

 ment of the Devonian, as the writer now regards it. The Niagarian (Upper 

 Silurian) Period has no representatives which can certainly be recognized as 

 such at the present writing, although it is possible that the upper part of our 

 provisional Silurian may really belong to that system. 



