REPORTS OF GEOLOGISTS. lxXXV 



cross-sections, for the purpose of showing the inclination, thickness, and se- 

 quence of the rock sheets. Much time has also been devoted to the tracing 

 of the boundaries and areal distribution of these different strata upon the 

 surface, and also to office work in mapping and recording the results thus de- 

 termined. 



RECONNOISANCE. 



I have made several trips for the purpose of ascertaining the boundaries of 

 my district and locating my assistants upon them. In addition to these, 

 many visits have been made by me to the rocks in the vicinity of Austin 

 for the purpose of ascertaining their sequence and denning their character- 

 istics. 



CROSS-SECTION WORK. 



Three accurate parallel cross-sections of the region have been commenced 

 and progressed towards completion. These approximately follow the breaks 

 of the Red, the Brazos, and the Colorado rivers, respectively, and are further 

 explained in the report of the work of Mr. Taff, which is appended. These 

 cross-sections have been made with great care and accuracy, and when com- 

 pleted will be of incalculable value in all stratigraphic and common deter- 

 minations. 



The tracing of the areal extent of the formations determined by the cross- 

 sections has been faithfully performed by Messrs. J. A. Taff, C. C. McCul- 

 loch, N. F. Drake, and J. S. Stone, as will be seen in their appended reports. 

 Over 2204 miles of partings (boundaries) have been traced and located, fixing 

 permanently the lines of demarcation between the different characters of the 

 country composing the surface of the region. These boundaries are abso- 

 lutely essential to all geologic questions that can arise concerning the region 

 and are a fundamental and essential portion of the work. The main subdi- 

 visions of the district have been accurately located, including the Upper and 

 Lower Cross Timbers, the Grand Prairie, the Black Prairie, and the boundary 

 between the Cretaceous region and the Bast Texas region on the east, and 

 the Central Texas feature's on the west. 



ECONOMIC INVESTIGATIONS. 



The foregoing operations have all been essential and preliminary to a thor- 

 ough economic investigation of the region. All lines of economic work, 

 however, have progressed hand in hand with these preliminary surveys, as 

 fast as possible, and already results of value are foreshadowed and are being 

 described and recorded as rapidly as accuracy will permit. 



