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Show 106 PALEONTOLOGY. The fossils number 4,500 specimens, and come from all portions of the area examined. They have had their first ( geological) use in identifying the several formations in a great number of localities, and promise to reward richly their paleontological study. A preliminary examination has been made of the invertebrates by Mr. F. B. Meek, the paleontologist, and upon his judgment an estimate has been made of 150 quarto pages of text and 30 plates for the description of the new forms. The vertebrate remains, including bones of mastodon, horse, camel, rhinoceros, & c, have been submitted to Prof. O. O. Marsh, who will report upon them. The collections were made by the geologists and mineralogists of the expedition, and by Assistant George M. Keasby, who accompanied one of the parties in New Mexico in the last season with the special errand of gathering vertebrate remains. MINERALOGY. During the field- season of 1871, Acting Assistant Surgeon W. J. Hoffman accompanied the expedition as naturalist and mineralogist, and in 1873 Dr. O. Loew joined the survey as mineralogist and chemist. Besides the collections of these gentlemen, a great many specimens of minerals and especially of ores have been gathered by the officers in charge of parties and by the geologists. The entire accumulation numbers 1,600 specimens. Dr. Loew has prepared a report to be included in the geological volume, comprising, with a rhume of the results of previous years, a full account of his chemical and other investigations. It is now ready for the press, will fill 45 pages, and includes- 1. A report on the agricultural capacities and lands of portions of New Mexico and Arizona, with notes on the geographical distribution of plants, and on several cosmical phenomena. 2. The analyses of all mineral springs encountered, of saline efflorescences and incrustations; also analyses of soils and plants, of coal-specimens, ores, kaolins, and of a fossil resin hitherto unknown. 3. A description of the volcanic rocks of New Mexico and Arizona, with numerous analyses. In some of these rocks, cobalt and nickel were found, an occurrence heretofore not observed. 4. Tables comprising the minerals collected, their occurrence in Nevada, Utah, Arizona, New Mexico, and Colorado. These comprise the collections of the last four years, and are arranged after the chemical system of Professor Dana. Numerous mining- districts in Colorado and New Mexico were visited, the ores and their geological occurrence described, and specimens collected. In Colorado, especial attention was paid to the mines of Gold Hill, Central, and Georgetown. The predominating ores of Gold Hill are the tellurides of gold, silver, and lead; those of Central, auriferous pyrites; those of Georgetown, argentiferous galena. The principal gold- mines of New Mexico are situated in the Placer Mountains, 30 miles south of Santa F6, where the precious metal is found free in placers as well as in iron- pyrites. The chief silver- mines noted in this Territory are those at Silver City and Fort Bayard, where chloride of silver occurs in gypsum and slate, |
