1. Compact gray grits. 2. Gray clay shales with seams of coal and plants, 4 feet 6 inches. 3. Bluish argillaceous grits, 2 feet 6 inches. 4. Contorted black clay shales, with seams of coal, 5 feet 6 inches. 5. Coal, 2 feet 6 inches. 6. Black, compact clay shales, 3 feet. 7. Coal, 7 inches. 8. Carbonaceous clay shales, 8 inches. 9. Coal, 3 inches. 10. Clay shales and argillaceous grits. [Specimens of the coal brought to San Francisco by M. Rémond, are anthracite, evidently of superior quality. J. D. W.] The middle member of the Triassic series consists of quartzites, or metamorphic sandstones; these are both coarse and fine grained, and sometimes brecciated. They vary in color, from white to red, and are often much altered in the vicinity of the metalliferous veins. The upper member of the series, as seen in the Cañada de la Tinta, is made up of rounded pebbles of black jasper and gray quartzite; in the Cañada de los Mimbres, below Los Bronces pebbles of specular iron are included in the mass. The dip of the formation is very irregular, both in direction and amount. At San Antonio de la Huerta, Tecoripa, and San Marcial, argentiferous veins of various ages occur in the lower and middle members of the Trias. At San Marcial, marine (?) shells are found in the clay slates, near the silver mines; [but those which have been obtained, are too imperfect for recognition; they were referred to Mr. Meek for examination. J. D. W.] At San Marcos, between San Antonio de la Huerta and the Real Viejo, metamorphic jaspery slates occur in connection with the carboniferous limestones; they are probably of Triassic age. Gold is found in the gulches between the quartzite ridges, as in the Cañada de la Higuera, near Los Bronces in the Cañada de la Iglesia, between the latter place and San Antonio de la Huerta, and generally where the quartzites occur. JURASSIC (?) ROCKS. In the eastern part of the Magdalena and Altar districts, are valleys with low hills and ridges of auriferous clay slates, with interstratified beds of porphyry and diorite. Localities of these rocks are Cerros de la Barajita, between Querobabi and Santa Ana; Cerritos de la Tierra Colorada, where the formation contains beds of variously colored limestones, entirely made up of fossils, South of La Magdalena this formation rests on metamorphic sandstones and shales. [The reasons for referring these rocks, with doubt, to the Jurassic formation, have been already given; see page 246.] CRETACEOUS ROCKS.