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Show 97 Maroou aud Newberry, whose valuable reports accompany those of Lieutenants Whipple and Ives, on the routes surveyed by them through Arizona and New Mexico. The horizon here termed after Hayden " Triassic " has been referred previously to this formation by Professor Marcou also, who had the opportunity of examining it in Texas and the Indian Territory. So far as the latter region is coucerned, I can confirm the identification, having examined bones from the red beds of that couutry which appear to be those of Belodonts. Dr. Newberry terms it in Arizona the " salt group," or " sali-ferous sandstones," referring to it as probably including both Triassio aud Permian strata. The formations here called Jurassic are partially included by Professor Marcou in his Triassio series, and are termed by Dr. Newberry the " variegated marls/' who is inclined to refer them to the Jurassic. APPENDIX G 2. GEOLOGICAL AND MINERALOOICAL REPORT OX PORTIONS OF COLORADO AND NEW MEXICO, BY DK. O. LOKW, MINERALOGIST AND CHEMIST. UNITED STATES ENGINEER OFFICE, GEOGRAPHICAL EXPLORATIONS AND SURVEYS WEST OK THE ONE HUNDREDTH MERIDIAN, Washington, D. C, April 22, 1675. SIR: I have the honor to submit herewith a report upon the agricultural resources and geological structure of those portions of Southern Colorado and Northern New Mexico that were traversed by party No. * 2, division 2, to which I was attached in the season of 1874. Special attention was given to the examination of the chemical composition of rocks, soils, aud minerals, a subject too often neglected. Collections were made of all the rocks and minerals mentioned in this report, and the preparation of a separate list is not deemed necessary. Very respectfully, your obedient servant, O. LOEW, MineraJogical Assistant. Lieut. GEO. M. WHEELER, Corps of Engineers. CONTENTS. The Valley of the Arkansas River- The Sierra Mojada and Sangre de Cristo Mountains- The Gray Back Placers- Cerro Blanco San Juan range- Composition of basalt from Abiquiu- The mountain region of Abiquiu- Analysis of a zeolite- The Nacimien to Desert- Analysis of a sandstone- Analysis of the garnets of Fort Defiance- Analysis of chrysolite from Fort Defiance- From Mount Taylor to the Placer Mountains- Analysis of turquoise from Los Cerillos- The mountains between Santa Fe" and Las Vegas- Analynis of hydraulic limestone from Las Vegas- Analysis of a green feldspar from Bear Creek- Climatological notes- Temperature of rivers and creeks. THE VALLEY • OF THE ARKANSAS RIVER AT PUEBLO, COLORADO. The cretaceous strata, everywhere conspicnous along the base of the main Rocky Mountain range, and forming the principal body of the adjoining plains, are well exposed in the channel which the Arkansas River has formed. The limestones, with their characteristic shells, among which is fnoceranuts in great numbers and large size, the sandstones, the clays, the slates, and the coals, in short, all varieties of sedimentary deposits, are mot with, as well as their manifold transitions, as calcareous sandstone, arenaceous limestone, argillaceous lime, and sandstones, & c. The limestone frequently contains particles and lumps of iron pyrites, in cms ted with rust, an occurrence I have noticed also with the cretaceous limestones at Las Vegas, N. Mex. The sandstones occnr in a number of localities- for instance, five miles above Pueblo- are fine- grained, of great uniformity, and in demand, a great deal being shipped to Chicago for building purposes. There is no coal in the immediate vicinity of Pueblo, as far as I could ascortain, but farther up are a number of beds ; for instance, at Carlisle, a farm twenty miles above Pueblo, there is exposed a seam of bituminous coal 6 inches thick, overlaid by strata of sandstones and shales to a height of more than 40 feet. Thick b^ d. s of coal are found farther np the river near Canon City; also mineral oil. An analysis of the coal has |