78 APPENDIX TO THE REPORT OF THE SECRETARY. 



details of new routes of communication and of incomplete meanders, 

 and Tvas further employed upon detailed work. A detachment mean- 

 dered north and westward from the Eio Grande at Los Lanos, opposite 

 Fort McEae, through the basin of the Little Colorado to Camp Apache, 

 Arizona, and thence eastward again to the Eio Grande, making mean- 

 ders of considerable precision along three natural routes of communica- 

 tion from the drainage basins of the Gila Salt Eiver and Colorado Chi- 

 quito to the Eio Grande. 



Another party extended the triangulation southward to connect with 

 astronomical station at Fort Bliss, Texas; also connecting with the 

 astronomical monument of the Mexican Boundary Survey at E»l Paso, 

 Texas, and the monument on that part of the boundary-line on the west- 

 ern bank of the Eio Grande. 



The following list shows the number of the principal observations 

 made : 



Sextant latitude stations 90 



Bases measured. 5 



Triangles about bases measured 64 



Main triangulation stations occupied 62 



Secondary triangulation stations occupied 21 



Miles measured on meanders 10, 298 



Cistern barometer stations occupied 1, 141 



Aneroid barometer stations occupied 7, 057 



Magnetic variations observed , 165 



Mining camps visited 12 



Mineral and thermal sjirings noted 20 



The estimated area occupied by the survey during the season, includ- 

 ing main triangulation and i^reliminary reconnaissance work, was 35,000 

 square miles. The area from which detailed topographical data were 

 gathered sufficient for a map, on a scale of one inch to four miles, was 

 approximately 27,500 miles. 



Besides the topographical work, one party in the Colorado section Avas 

 devoted entirely to geological examination, under the charge of Pro- 

 fessor J. J. Stevenson, assisted by Mr. J. C. Eussell. Its area of opera- 

 tions was along the Spanish ranges between the Eio Grande and Cana- 

 dian Eivers, in the northern i^art of New Mexico, where its labors were 

 greatly facilitated by the use of the completed topographical maps. The 

 section of the liguitic group was worked out, and twenty-six beds of lig- 

 iiitic coal were recognized as present at most localities within the area 

 where the horizon was reached. Much labor was bestowed upon a study 

 of the axes, the structure of which was found to be exceedingly comrdi- 

 cated, requiring further detailed examination. Quite large collections 

 were made of igneous rocks and fossils, about three hundred s])ecimens 

 of the former being obtained from seventy localities, forming a complete 

 series illustrating the lithology of the injected dikes, volcanic overflows, 

 and extinct craters of the region. 



The fossils, numbering over thirteen hundred specimens, are from 



