12 Hill — l\iland(jlo(jij of Lite Trliuiij Dlvlaion. 



II.—I'O.SITION AND CJIARACTEliLSTiaS OF THE TRINITY 



DIVISION. 



Fuller details concerning the extent and occurrence of the 

 Trinity Division have Ijeen largely set forth during the past 3'ear 

 in a })ublication l)y the writer,-i^ and much of its stratigraphic 

 details and some of the final maps as made by him and his as- 

 sistants, INIessrs. J. A. Taff, J. S. 8tone, W. T. Davidson, and N. 

 F. Drake, have l)een printed still later. f 



The details of the formation can be appreciated by referring 

 to the pul)lished descriptions of three tyj)ical sections, made at 

 widely separated intervals, showing the increasing thickness of 

 the beds to the southward. 



The first of these, made by the writer while emi)loyed upon 

 the work of the Arkansas State survey, is describ^l in the re})ort 

 upon the Neozoic geology of southwestern Arkansas. ;|; 



The second represents the beds as they occur in the vicinity 

 of the Paluxy and Brazos rivers, in north central Texas, and 

 was made by the writer and his assistants, Messrs. J. S. Stone and 

 W. T. Davidson, and published in the report '' On the Occur- 

 rence of Underground Water," § and later in the Third Annual 

 Report of the Geological Survey of Texas. || In this region the 

 beds of the Trinity Division attain an established thickness of 

 alxHit 47") feet. 



'J'he third and southernmost section was made along the l)anks 

 of the Colorado river between Austin and the Paleozoic contact 

 in Burnet county by the writer and his assistants, Messrs. J. A. 

 Taff and N. F. Drake. The rocks of the Trinity Division attain 

 unusual develoi)ment in this region and are very satisfactorily 

 exposed. A profile 1] illustrating this section is iDublished in the 



*" On the Occurrence of Artesian and Other Undergronnd Waters in 

 Texas, New Mexico, and Indian Territory West of the Ninety-seventh 

 Meridian" (pp. 41-1()G of "Final Keports of the Artesian and Underflow 

 Investigation, etc., to tlie Secretary of Agricultnre." 52d Congress, 1st 

 Session, Ex. Doc. 41, part 3, Washington, D. C, May, 1892). 



flteport on the Cretaceous Area Nortli of tlie Colorado Uiver, Ijy J. A. 

 Taff. Austin, Texas, Septendjer, 18i)2. 



J Op. fit., pp. 116-12(i. 



^Op. cit, pp. llJ-lll'. • 



II Op. cit., pp. o07, :J10, oil. 



lILoc. cit., pp. 90-Ul. 



