PALEOZOIC ROCKS. 659 



of uplift are invariably absent, but the later ones can be more or less dis- 

 tinctly traced through the members of this system. 



Secondly. There are enough localities exhibiting the juxtaposition of the 

 Texian with the underlying Fernandian, and their nonconformity, to leave no 

 doubt of the more recent formation of the Texian and the historical separa- 

 tion of the two. In the area south and southeast of Packsaddle Mountain, 

 also in that southwest of Sharp Mountain, and in portions of the country 

 north of Lockhart Mountain, all in Llano County; in the region north and 

 northeast of Mason, and in Beaver Creek valley and elsewhere in Mason 

 County, as well as in other sections, the evidence is unquestionable. 



Thirdly. The derivative character of certain of the Texian beds is a most 

 marked feature. 



Fourthly. The distinctive character of the intrusives, and their transection 

 of the earlier rocks where the record is visible, as well as the bending of the 

 Fernandian schists at times into the later Texian trend at junction points, all 

 attest the correctness of the interpretation put upon the facts in these pages. 



Fifthly. The distribution of the Texian exposures and their relations to 

 the existing topography are shown by the Geologic Map and sections to admit 

 of no other explanation than that here given, notwithstanding the remarkable 

 exigencies to which the region has been subjected all through the ages since 

 the deposition of these strata. 



PALEOZOIC ROCKS. 



The field work of 1890 included the mapping of the Paleozoic outcrops as 

 far as the Cretaceous border upon the east, south, and west, and to the Car- 

 boniferous border upon the north. A few patches of Carboniferous intrud- 

 ing within the tract thus outlined were also worked in to avoid the necessity 

 of special excursions to the region by colleagues upon the Survey. These 

 last will be briefly noticed in this sketch. 



THE CAMBRIAN SYSTEM. 



In the last Report the Cambrian strata were provisionally divided into 

 three series. The facts upon which this arrangement was based were given, 

 and it was admitted that no conclusive paleontologic confirmation had been 

 obtained. The subject stands very much in the same situation now, although 

 such evidence as I was able to glean in 1890 has served to strengthen some- 

 what my belief in the unconformities reported. The chief difficulty with 

 such problems in our field is that the present dip of the strata is often a re- 

 sultant of several movements, including at times three or four more recent 

 than the close of the Cambrian Period. The contacts of the Cambrian base 



