256 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



proceeded to the rendezvous camp at Gunnison, Utah Ter- 

 ritory, where the field parties were organized under the 

 general superintendence of Professor A. H. Thompson, geog- 

 rapher of the expedition. While en route they were joined 

 by Captain Clarence E. Dutton, of the Ordnance Department 

 U. S. A., who had been assigned by special orders from the 

 Secretary of War for duty with this survey, and directed to 

 make an examination of the immense fields of igneous rocks 

 in Southeastern Utah. 



The field organization as finally completed differed some- 

 what from previous years the geographic and geological 

 work being assigned to separate parties, each practically 

 independent in all movements, though working under the 

 same general plan and within the same territorial limits. 

 It is believed that better results can be and have been se- 

 cured by this separation of distinct branches of the survey 

 than by the old method of attaching a geologist to a geo- 

 graphic party, or a geographer to a geological party. 



Five parties were organized : one, under Professor A. H. 

 Thompson, to continue the triangulation ; one topographic 

 party under Mr. Walter II. Graves, another under Mr. John 

 H. Renshaw ; one geological party under Mr. G. K. Gilbert, 

 another under Captain C. E. Dutton. 



Tiie party under Professor Thompson continued the ex- 

 pansion of the primary triangulation, resting on the base- 

 lines measured in preceding years at Kanab and Gunnison, 

 Utah. The area embraced in this season's work amounts to 

 about 10,000 square miles, the instrument used being a 10- 

 inch theodolite of peculiar construction, designed especially 

 for this work by Professor Thompson. 



Topographic party No. 1, under the charge of Mr. Graves, 

 extended the secondary triangulation over an area of 6000 

 square miles, lying between the Wahsatch Mountains on 

 the west and the Green and Colorado Rivers on the east. 

 Mr. Graves also made a complete plane-table sketch of the 

 country surveyed, which, taken in connection with his angles 

 for location and perspective profile sketches, will enable him 

 to construct a map of his district on a scale of four miles to the 

 inch. The principal topographic characteristics of this re- 

 gion are long lines of unscalable clifts, which are the escarped 

 edges of terraced plateaus of which the country is composed. 



