656 CENTRAL MINERAL REGION OF TEXAS. 



PART III. 

 SUPPLEMENT. 



MAY 15, 1891. 



Circumstances entirely beyond my control have prevented the publication 

 of the complete results of the survey of the Central Mineral Region. The 

 plan of this Report, as provided for, included a full review of the geology of 

 the district, illustrated by a colored map outlining the areas of the various 

 stratigraphic systems, a series of sections across the whole region, and a state- 

 ment of the facts upon which my conclusions have been based. No one 

 can regret more than myself the necessity which compels me to forego, I 

 trust but temporarily, the publication of what has been thus laboriously de- 

 termined. The map is now on exhibition in the office of the Survey, and 

 this, with the detailed sections, must be appealed to in support of the generali- 

 zations which have already been advanced. In this place I can only present 

 such facts as can conveniently be arranged, in addition to the material pre- 

 sented in my 1889 Report. Since the issue of that volume, one year ago, 

 no one has given the area one-thousandth part of the study represented by my 

 survey, and no geologic report has been made by anyone who has gone over 

 one-tenth of the area, even hastily. All the work done prior to 1889 is clearly 

 indicated, without prejudice, in my report for that year. 



The remarks which follow are offered simply as a resume of facts, intended 

 to show in bare outline the foundation for my own opinions, which must 

 stand or fall upon the final verdict to be rendered by those who make them- 

 selves as competent to judge by an equivalent amount of study of the facts 

 themselves. 



ARCHBAN ROCKS. 



THE BURNETIAN AND FERNANDIAN SYSTEMS. 



The study of the Archean Systems (Burnetian and Fernandian) has been 

 continued in the field and office since the last Report with as much diligence 

 as other necessary work has allowed. The stratigraphy has been worked out 

 as fully as can be advantageously done until the petrography is studied.* A 

 few general words seem necessary, in order to make clear some portions of 

 my 1889 Report, which perhaps have not been explicit enough. 



* Arrangements have been made to put this important work in the hands of a specialist of 

 high repute. When his report is ready, I propose to give a more thorough discussion of the 

 geologic history. — T. B. C. 



