GEOLOGICAL REPORT

BY

CUMMINGS CHERRY.

To the Members of the Cincinnati Mining & Land Association of Sonora, Mexico:

GENTLEMEN:

In the Articles of Agreement entered into the thirteenth day of July, 1865, it was desired that in locating lands under the grant therein described, I should have special regard to the greatest concentration of minerals, together with water, fire-wood, timber, salt, water-power, and accessibility to market. In my April report from Sonora, I remarked that I had determined upon securing the San Juan del Rio Ranche, for the reason that "among all the lands owned, operated or abandoned, which I had seen in my tour of investigation, I believed the lands which would be comprised in a survey of this property, contained the greatest concentration of the advantages which were deemed requisite to a location of your grant." In after investigations, I saw no reasons to induce me to change this conclusion; and that it was not arrived at hurriedly, or without due investigation, you will understand when I inform you that before determining it, I visited the minerales of Hermosillo and vicinity, (Ubarbold, El Aguaje and Subiate,) of San Miguel, San Jose de Gracia, Babiacara, Heupaca, Banamachi, Babicano ra, Cumpas, San Juan Bautiste, Oposura, Tepache, Lam Pa sos, Promontorio, San Juan del Rio, Valenzuello, Nacosari. Fronteras, Bacuáchi, Cananea, Santa Cruz, Planchas de

Plata, Sarique, Magdalena, Santa Theresa, Agua Priets, Cajon de la Brisca, and very many others whose names I could not ascertain; that, in fact, I visited every section of Northern Sonora wherein I was informed or imagined there existed mineral veins or deposits. I afterwards succeeded in securing this San Juan del Rio property for you, as you will perceive from my General Report, and the documents herewith accompanying.

LOCATION, EXTENT AND TOPOGRAPHY.

The lands of San Juan del Rio, which comprise those of the ancient Ranche of this name, are situated on the Yaqui River, the river coursing through the longitudinal centre of the tractin latitude 30° 40' North, and longitude 109° West. They are 5 leagues North of the Mexican town of Oputo, about 15 leagues South of the Arizona line, and 20 leagues West of the Chihuahua line. The distance from the port of Guaymas is 90 leagues. The official survey names the extent of lands, as designated by the boundary monuments which were erected, to be slightly less than four square Mexican leagues, though by accurate measurement there are undoubtedly six leagues or more.

The topographical features of the lands are parallel mountain ranges, the intervals between which are plains having a gradual descent from the sierras into a valley of bottom lands of considerable extent. The plains are not always regular, being cut up by creek beds and tributary cañons, or broken by occasional low spurs or ranges of the loftier sierras, and forming in their intervals almost isolated valleys and plateaus; thus giving to the face of the country a mixed or corrugated appearance.

The main mountains are the first steppes of the Sierra Madre, west, lying parallel with the river and forming respectively the East and West limits of these lands. They

rise to a hight of 5000 to 7000 feet and are dissimilar in topography to those parallel ranges yet further West, which, as they approach the California Gulf, become more irregular and broken in their appearance, or those of the North West, which form isolated peaks or detached groups.

ANCIENT HISTORY.

This property forms the centre of a very ancient mining district, whose "mines were legion and ores unsurpassed in richness." Being among the first spots selected by the cultivated Jesuits for the building up of a future home, they quickly brought into subjection the luxuriant wildness of its valleys, and developed the veins of wealth buried in its rugged mountains, until, in the language of those who lived and wrote in those days, it became the "most delightful spot in Mexico." Even at this late day, when we view the evidences of the former existence of a large and flourishing community, in the ruined haciendas and smelting furnaces, and stumble over the dilapidated acequias [irrigating canals] and among the tangled fruit shrubberies, mounds and tumulis, with lines of earth-works, and find fragments of pottery upon every ridge, and note, in all these ruins, a finish and design bespeaking for their projectors a higher grade of civilization than has since visited this unfortunate country, we can imagine how it were possible to make it worthy of even such extravagant encomiums. On March 5th, 1742, when prosperity was at its hight, and the towns were teeming with people and wealth, the Apache Indians made a descent upon it; and in a few hours the settlements of Oputo, Tren, Nori, Toapatz, Terras, Joriquipe, Cherunivava, Pinal, Garrigon, Reál Viejo, Aguaje, Huacal, Nacosari, and Peña were laid waste. The people of Toapatz, Tren, Nori and Joriquipe were all massacred, and there were very few survivers from any. A few venturesome spirits repopulated

Cherunivava; but two years after the reál was again attacked, and its people killed and houses destroyed. Since then no effort has been made to settle these old reáls. In 1800, or shortly after, the mines of the Sierra Valenzuello were discovered by gambucinos, the first who had ventured thus far since the depopulation, 60 years before. So productive were the mines that their fame spread to the southern towns and neighboring State, and soon, a considerable mining population had gathered. The mining reál of San Juan del Rio was quickly built up, forming a large town; reduction furnaces were erected, and prosperity and activity again ruled. Had this activity been permitted to continue, but a short time would have elapsed until the long abandoned mines of the Jesuits would again have been made to yield their tributes of riches to the adventurous; but the Apaches again swarmed in on the almost defenceless people, and being emboldened by the slight resistance shown, they attacked the town, and but few survivors were left to tell the result. Oputo, 5 leagues below, has lately been repopulated; but none of the native inhabitants except an occasional party of gambucinos have ventured farther North.

GEOLOGY AND MINERALOGY.

Geologically the formations of San Juan del Rio differ very materially from those of the more westerly ranges, and particularly, of the North West, (for a description of which see General Report); and in proportion to this difference is the increased degree of mineral wealth. The main ranges consist principally of the granitic and metamorphic rocks, the leading crests being capped by a compact gray sienite, having a crystalline base of amphibole, greenish in cast, scattered through which are grains of orthoclase (glassy feldspar), and crystals of actinolite.

I have seen the orthoclase form the main compound, ac