58 REPORT OF THE SECRETARY. 



Invertebrate Paleontology, by F. B. Meek, 029 pages, with 85 wood- 

 cuts and !•"> plates. 

 Catalogue of Publications, second edition. 



3. Exploration of the Rocky Mountain Region by Prof. J. W. Poicell. — 

 As -""ii as the appropriation for the fiscal year of 1S70-77 could be 

 • i. the surveying corps left Washington and proceeded to the rende- 

 vouz caiup at Gunnison, Utah, where tbe field parties were organized 

 under the general superintendence of Prof. A. H. Thompson, geogra- 

 pher of the expedition. While en route they were joined by Capt. 

 Clarence E. Duttou, of the Ordnance Department, U. S. A., who had 

 been assigned for duty on this survey by the Secretary of War, and di- 

 rected to make an examination of the immense fields of igneous rocks 

 in Southeastern Utah. 



The field organization as finally completed differed somewhat from that 

 of previous years — the geographic and geological work being assigned to 

 separate parties, each practically independent in all movements, though 

 working uuder the same general plan and within the same territorial 

 limits. It is believed that better results can be and have been secured 

 by this separation of distinct branches of the . survey than by the old 

 method of attaching a geologist to a geographic party or a geographer 

 to a geological party. 



Five parties were organized — one under Prof. A. H. Thompson, to 

 continue the triangulation ; one topographic party under Mr. Walter 

 H. Graves, another under Mr. John H. Kenshaw ; one geological party 

 under Mr. G. K. Gilbert, another under Capt C. E. Dutton. 



The party under Professor Thompson continued the expansion of the 

 primary triangulation resting on the base-lines measured in preceding 

 years at Kanab and Gunnison, Utah. The area embraced in this sea- 

 son's work amounts to about 10,000 square miles, the instrument used 

 being a ten-inch theodolite of peculiar construction, designed especially 

 for this work by Professor Thompson. 



Topographic party Xo. 1, in charge of Mr. Graves, extended the 

 secondary triangulation over an area of 6,000 square miles, lying be- 

 tween the Wasatch 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 

 locations and perspective profile sketches, will enable him to construct 

 a map of his district on a scale of 4 miles to the inch. The principal 

 topographic characteristics of this region are long lines of unscalable 

 cliffs, the escarped edges of terraced plateaus, of which the country is 

 composed, and deep, narrow canons with vertical walls, both presenting 

 well-nigh impassable barriers to travel. 



The only considerable bodies of irrigable lands found are along the 

 valleys of the Green and San Rafael Rivers. The only timber-lands are 

 on the Sevier plateaus at an elevation of from 8,000 to 11,500 feet. 



