lxXXVi REPORTS OF GEOLOGISTS. 



ILLUSTRATION. 



Several weeks were devoted to the procurement of suitable illustrations of 

 the Cretaceous areas, and for this purpose I have secured through the agency 

 of Mr. 0. ~W. Eddy, the photographer of the Survey, a magnificent suite of 

 negatives, illustrating the characteristic structure, weathering, topography, 

 building material, fossils, and vegetation of the Cretaceous regions. These 

 pictures will be invaluable in illustrating the unique natural conditions of 

 the region. 



OFFICE WORK. 



I have spent much time upon the necessary work of preparing the results 

 of observations for publication, and in study of material. In order to render 

 the work accurate much library research has been necessary, and this was 

 done in the libraries of the East, during the summer, in ascertaining the work 

 of previous investigators, in order to avoid unnecessary duplication, and in 

 the verification of details. Many pages of manuscript have been prepared, 

 and numerous technical papers published, containing concise preliminary 

 definitions, which must necessarily precede all results of permanent economic 

 value. 



Messrs. Taff, McCulloch, and Stone have all been employed for a few 

 weeks each in office work for my division. 



WORK OF ASSISTANTS. 



Most of the details of the work have been carried out by the able young 

 assistants whom you have placed at my disposal. 



Mr. J. A. Taff. — One of these, Mr. J. A. Taff, has been constantly engaged 

 upon the work, he having general charge of the field work. The faithful- 

 ness and accuracy of his labors are worthy of special commendation. In 

 addition to his services in the field, he has done valuable work as a draughts- 

 man in the office. He has traced, mostly on foot, over 2000 miles of part- 

 ings, and accurately located them. In addition, he has made over 200 miles 

 of instrumental cross-sections. A brief summary of his work is as follows: 



The Basal Trinity Beds were traced from the Colorado .River, at the west 

 line of Travis County, through Burnet, Lampasas, Mills, Brown, Comanche, 

 Erath, Eastland, Hood, Parker, Jack, Wise, Montague, and Cooke counties 

 to Red River, a distance of 400 miles. 



A section was made along Red River basin from Nacona, Montague County, 

 through Montague and Cooke to Denison, in Grayson County; length 10 

 miles. A section was next made across Red River basin, at Gainesville, 

 Cooke County, followed by one across Red River basin at Denison. The 



