REPORTS OF GEOLOGISTS. lxXXvii 



contact between the Eagle Ford shale and the chalk was then determined 

 from four miles south of Denison through Grayson, Collin, Dallas, Ellis, Hill, 

 and McLennan counties to a point on Brazos River one mile below the mouth 

 of Aquilla Creek, McLennan County, a distance of 164 miles. Mr. Taff then 

 took up the location of the Trinity sand contacts and the study of the Creta- 

 ceous rocks, west of the main Cretaceous border, in Eastland, Callahan, 

 Taylor, Nolan, Coke, Runnels, and Coleman Counties. Ten miles of basal 

 Cretaceous contact was located in Eastland County, 109 miles in Callahan, 

 154 miles in Taylor, 234 miles in Nolan, 68 miles in Coke, 39 miles in Run- 

 nels, and 80 miles in Coleman County. This was followed by construction 

 of a section from base of Trinity sands, 10 miles west of Dublin, across 

 Erath and Bosque counties, to Walnut, Bosque County, a distance of 40 

 miles. The following sections were then made: 



1. From Dallas across Dallas, Tarrant, and Denton counties to Decatur, 

 Wise County, a distance of 60 miles. 



2. Across Bosque River basin at Alexander, Erath County, and at Iredell, 

 Bosque County. 



3. Down the Colorado River basin from the mouth of Hamilton Creek, 

 Burnet County, across Burnet and Travis counties, to Austin — 32 miles (in 

 this latter section he was assisted by Mr. Drake). In company with Mr. 

 Stone, the Cretaceous and Tertiary contact was then traced from Webber- 

 ville, Travis County, across Travis, Williamson, Milam, Falls, Limestone, 

 Navarro, Henderson, and Kaufman counties to three miles east of Terrell. 



Mr. N. F. Drake. — Mr. Drake also performed faithful service in the field 

 during the months of July, August, and September, tracing out the bound- 

 aries between the various regions, as shown below. 



The Upper Trinity sand contact was traced from Decatur, Wise County, 

 southward across Wise, Parker, and Hood counties to Acton, Hood County — 

 90 miles. 



The boundary of the Exogyra Arietina clay located from Brazos River at 

 Bosqueville, McLennan County, across McLennan, Bell, Williamson, and 

 Travis counties to Austin — 125 miles. 



The Basal Austin Chalk contact was traced from the Brazos River, at 

 mouth of Bosque River, across McLennan, Bell, Williamson, and Travis 

 counties to Austin — 125 miles; and the Austin Chalk Ponderosa Marl con- 

 tact from Austin to twenty miles into Williamson county. Mr. Drake was 

 then transferred to work under Prof. W. F. Cummins. 



Mr. C. C. McCulloch spent the months of May and June in the field and 

 did the following work: 



Upper Trinity contact was traced northward from Decatur, Wise County, 



