and hated by both whites and Indians, but the frequent expeditions against them are generally rather barren of results. It is difficult to get them to fight a respectable number of armed men, and on the approach of the various expeditions organized against them they have almost invariably scattered through their mountain fastnesses, where it is in vain to follow the small bands of five or ten who remain together. These Indians have done more to retard the settlement of Arizona and the development of her mines than all other causes. As soon as a miner's camp was formed within their range, they would hover about until they had stolen the last of the working stock and killed or driven off the last one of the miners. Very few mining-camps have been able to outlast this continual danger, and those that have so far withstood the Apaches have done so at a fearful cost of property and human life. So long as this tribe is allowed to roam all over Arizona, it is in vain to expect that any settlements can permanently maintain themselves.

Besides the Apaches, the Hualpais or Wallapis, living in the Cerbat Range, near the Diamond River, and in part of the Aquarius Range, are the only dangerous Indians. This tribe has come into the forts during last summer, professing to be tired of war, and suing for peace. Since then they have really been friendly; the portion living in the Aquarius Range alone having committed some new depredations. Should they remain peaceable, some of the most promising mining districts in the Territory would be opened.

GENERAL GEOLOGY OF ARIZONA.

It is not within the province of this report to give a detailed and connected description of the geology of Arizona; nor were the means and the time at the disposal of Mr. Eilers, during his visit in that Territory, sufficiently ample to enable him to make more than a cursory examination of the routes traveled over, and a more extended one of the mining districts proper. His observations extended from Fort Yuma over the Gila River route to Maricopa Wells, and thence to Tucson, from Tucson to the Gila, at Adamsville and Florence, thence to the Salt River at the upper crossing, to Camp McDowell, Phoenix, Hassyampa Cañon, Wickenburg, Camp Date Creek, Kirkland Valley, Skull Valley, Prescott, the greater part of the Sierra Prieta from its northern terminus, the Granite Mountain, to its southern extremity, the Bradshaw Mountain, including all the mining districts of this range; from Prescott by the northern or Mojave road to Camp Tollgate, thence through parts of the Aztec and Aquarius Ranges to the Cerbat and Black Mountains, thence to the Colorado River at Fort Mojave, and down that river to La Paz, thence east to Wickenburg and back to Tucson. For other portions of the Territory, notably the country along the Great Cañon of the Colorado, the Colorado Chiquito, and parts of the country north and east of the same, I have freely used the excellent report of Professor Newberry; and for that portion of the country lying north and east of Tucson, along the line of the thirty-second parallel road, that of Dr. Thomas Antisell. The lowest portion of Arizona Territory, topographically, is the region in the vicinity of the mouth of the Gila River, as a glance at the map and the river system of the coun try suffices to show. The elevation above the sea-level, at Fort Yuma, is only 200 feet. From here eastward, an apparently level country, but rising gradually and imperceptibly, extends to the line of New Mexico. From this plain rise isolated mountains and mountain ranges, suddenly and without that gradual elevation which a series of foot-hills impart

to mountains in other countries. No valleys, as generally understood, lie between these "lost mountains," but the level, sandy plain extends directly and with nearly the same level from the foot of one mountain to that of the other. This peculiar configuration of the surface is also met with on the La Paz and Wickenburg road, and for a considerable distance along the road from Fort Mojave, toward Prescott; also along the entire length of the road from Tuscon to Wickenburg and some distance north of that town. All the main mountain chains have here a northwest and southeast trend, and the only exceptions to this general direction are furnished by the Black Mountains and the Cerbat Range, in the northwestern corner of the Territory, the axis of their upheaval running very nearly north and south.

In Middle Arizona, especially in the Prescott country and north of it, around the San Francisco Mountain, the surface wears a different aspect. The Sierra Prieta and the Aztec Range send foot-hills out in every direction, and especially their flanks sink very gradually down to the level of the high plateau surrounding the San Francisco Mountain toward the northeast and to the mesas sloping toward the Colorado on the southwest. The country here has attained a considerable elevation above sea-level, the town of Prescott, located in the valley of Granite Creek, near the northern terminus of Granite Mountain, being over 6,000 feet above the sea, while the Tonto and San Francisco plateaus to the east and northeast of Prescott reach an altitude of from 8,000 to 9,000 feet. The San Francisco, a grand volcanic cone, is the highest mountain in Arizona, its top towering over 11,000 feet above the sea. North and northeast of the San Francisco an immense mesa, increasing in altitude toward the Navajo country and the Utah line, stretches for hundreds of miles.

The Mogollon Range, in the eastern part of Arizona, presents the most marked exception to the general northwest and southeast direction of the mountains. Its axis runs very nearly east and west, and joins the Sierra Blanca, also an east and west range, which extends beyond Arizona into New Mexico. The plains along the Lower Gila are entirely made up of Quaternary and Tertiary deposits, which also form the Great Sonora Desert to the south of that stream. The first mountains which the traveler meets on his way up the Gila, after leaving the granitoid knoll on which Fort Yuma is located, and through the middle of which, singularly enough, the Colorado runs at present, are those in the neighborhood of Gila City. Their low foot-hills contain the gold-placers, which at one time caused considerable excitement, and have been again worked since last summer by a San Francisco company. They are sixteen miles east of Fort Yuma, and appear to be the southern continuation of the Castle Dome Range on the north bank of the river, having, like the first, a northwest and southeast trend, and being separated from it by the Gila River and low foot-hills, which on both banks of the river are made up of the same materials, namely, granitic rocks and metamorphic slates, the latter leaning against the foot of the more elevated ridge, which is entirely composed of syenite. The slates of the foothills stand almost vertical, and are much contorted, containing a great number of quartz-bands, running in all directions. The low hills immediately at the river-bank are entirely denuded of gravel, while those nearer to the main ridge are thickly covered with angular granitic and slate detritus. East of these hills no more mountains are encountered until, twenty-eight miles farther over a large sandy plain, Antelope Peak is reached. This mountain rises about 500 feet above the level of the Gila, and presents an abrupt, almost vertical face toward that river. It

is entirely made up of a coarse quartzy conglomerate and of brown micaceous sandstone, which in many places seems to be metamorphosed and becomes jasper-like. No fossils were observed. At the foot of the precipice mentioned above lie large masses of the conglomerate broken off from above and scattered in all directions. Nothing of interest breaks the monotony of the river-bottom and the terraced mesa above, until the Big Horn Mountains are reached, which consist of the same materials as Antelope Peak, but they repose here on a granitic basis. Northeast of these mountains, on the opposite side of the river, occurs a hot spring at the foot of a series of erupted hills, which is much visited by invalids. It is located on Colonel Woolsey's ranch, and is well known throughout Arizona. Fourteen to sixteen miles east of this place the traveler enters on one of the most extensive volcanic overflows met with in Arizona. It is thirty-five miles broad from west to east, and extends for a much greater distance from north to south. The material is a dark basaltic lava, which covers the plateau to the depth of from 2 to 25 feet. The Gila River has cut through this overflow from east to west, and this cañon, as well as several side cañons, across which the road leads, afford a fine opportunity to study the formation. In nearly every place where the lower edge of the lava is exposed, a thin layer of yellowish white soft sandstone is found underlying it. It contains no fossils. This sandstone occupies evidently a vast portion of Southwestern Arizona. I have found it on the plains north of the Salt River, and also north of Florence. It is difficult to determine the source of the enormous mass of eruptive material which covers the plain; for although it is certainly slightly inclined toward the southwest, and several cones are visible at a distance north of the Gila, to which the lava extends, and in the neighborhood of which the hills, too, are capped with thick layers of the erupted material, it is difficult to imagine that these floods could have traveled sixty or seventy-five miles without cooling, and the overflow may have come, at least in part, from the southeast, where in the distance several crater-shaped mountains are also visible. The lava plain is broken in one place by several hills, through a cañon of which the road leads, and where whitish trachytes, containing much olivine in the seams, and red porphyries are exposed to view. On the basalt mesas, the "inal pais" of the Mexicans, the Cereus giganteus, is found in abundance, and in beautiful specimens.

To the east the road leaves now the river and passes across a peninsula formed by the Sierra Estrella and the Gila River for forty-five miles, where it reaches the Maricopa Wells. The Sierra Estrella consists principally of syenites, which are sunburnt and dark on the outside. Looking at the outline of the crest of a part of this range from a certain position to the east of it, it shows a striking resemblance to a man's head. This is called Montezuma's Head by the Pima Indians.

Above Maricopa Wells the road strikes the river again at the Pima villages. Here the Gila has formed very extensive bottom-lands, which stretch away to the cañons, where the Gila breaks through the Pinal Mountains, a distance of about thirty-five miles. At Sacaton the Tucson route leaves the Gila in a southeast direction. The whole distance to that place the road leads over a level country, consisting of gravel and sand mesa, which is only in a few places broken through by syenitie and porphyritic upheavals, viz, between Sacaton and Bluewater, where in the cañon gneiss is exposed besides syenite, and at the Picacho and the point of the mountain, both composed of a reddish trachytic rock. East of Tucson the mesa is traversed by several extensive mountain ranges, the most important of which are the Sierra Catarina, the Sierra

Calitro, and the Pinal Range, the continuation of which toward the south are the Chiricahui Mountains. The Sierra Catarina consists of granite, trachyte, porphyry, basalt, and sandstones on its southern extremity, the latter overlaid by basalt and porphyry. Dr. Antisell thinks these sandstones are Devonian, as they underlie the Carboniferous limestones appearing farther to the east in the Sierra Calitro. In the valley of the San Pedro gypseous (cretaceous) rocks underlie the whole depression between the Sierra Catarina and the Sierra Calitro according to the same authority, and these are covered toward the south near the head of the San Pedro by Tertiary gravel conglomerate.

The Calitro Mountains are made up principally of a thick red sandstone formation capped almost throughout by Carboniferous limestone, which in turn is in some places covered by trappean rocks. The next range to the east is the Chiricahui Mountains, which consist of granite overlaid on its flanks by the sandstones and limestone mentioned before. Between the two last-named mountains lies the Playa de los Pimas, an extensive plain, under which the sedimentary strata appearing on the flanks of the ranges dip from both sides. To the northwest of the Chiricahui Mountains rises the Piñaleno Range, of which the former is only a southern extension. It is one of the longest ranges in Arizona, reaching northwest as far as the Rio Verde in the vicinity of Camp McDowell. It is composed of the same materials that compose the Chiricahui Mountains, but reaches a much higher elevation.

North of the Gila and Salt Rivers and west of the Verde, the country looks very much like that immediately west of Tucson. It is an im mense plain, which rises to the northeast and north until it reaches the Tonto plateau in the first, and the foot-hills of the Sierra Prieta in the second, direction. The mountains in the vicinity of the Upper Salt River crossing consist of granite, on which rest red sandstone and course conglomerates dipping to the west. The same conglomerates compose the isolated hills to the south of the road from Salt River crossing to Phoenix, while north of that road appear metamorphic slates in the mountains. The plain is here underlain by a thin layer of soft, gray sandstone, probably the same which underlies the basalt overflow mentioned as occurring on the Gila River. In some of the arroyos of this plain a light-colored, soft limestone is visible, underlying the sandstone, very similar to that found at Tucson, which is considered Cretaceous. No fossils were noticed in either of these strata.

On the road from Phoenix to Wickenburg the road leads continually over the mesa without striking any of the "lost mountains" visible on both sides at a distance. The mesa is thickly covered with gravel and detritus from the mountains to the north and northeast, and no rock in place is visible until, about twenty miles south of Wickenburg, the cañon of the Hassyampa is reached. Here are exposed for the whole length of the cañon proper, about fifteen miles, great masses of red and gray sandstone, frequently metamorphosed, and never exhibiting a distinct stratification. In fact, this district has evidently been greatly disturbed, as becomes apparent, on the road from Wickenburg to the Vulture mine, and also on that to La Paz, where the metamorphic slates stand almost vertical.

Directly northwest of Wickenburg, over a level mesa and eighteen miles distant, rise the Martinez or Date Creek Mountains. They are entirely composed of granite and syenite, much crossed by dikes of greenstone-slate and quartz. Following the road from Camp Date Creek to Prescott north, an elevated table-land is crossed, which is entirely cov ered with scoriæ. It forms the divide between Martinez Creek and the

head-waters of the Santa Maria. Bell's Cañon, a grand cut through vast granitic accumulations, which are frequently crossed by quartzite dikes, is passed in descending in the valleys to the north, which are formed by the creeks running into the Santa Maria. These valleys form beautiful basins, and are covered with a fertile soil. The geology of this region is very interesting, but the party being very weak the immediate vicinity of the trail could not be left on account of the hostile Apache-Mojaves, which swarm in these rocky defiles. The great bulk of the rocks, howevever, is granitic, but metamorphic rocks abound, and in one of the valleys large masses of white sandstone standing isolated in the valley, as left by erosion, were noticed, and opposite, more than one thousand yards distant, the same beds could be observed forming the margin of the valley toward the east and disappearing under the gravelCovered mesa. Vegetation is here improving continually, as the road approaches nearer to the Sierra Prieta, and the whole surface rises very rapidly. In the valleys live oak, cedar, and a dense chaparral of a small bush-like oak are met with until at the northern base of the Granite Mountain, around which the road leads, the first juniper and pine forests are met with. The western and northern base of the Sierra Prieta, the northwestern terminus of which is Granite Mountain, is flanked by a broad belt of metamorphic slates, which extends west to Williamson's Valley, the slates standing steepest nearest to the main granite ridge. Granite Mountain presents a very imposing spectacle. Rising 3,000 feet above the valley north of it, its rugged sides are covered with immense granite boulders, which are piled up in the most picturesque manner. Its greater part is uncovered by vegetation, but on the northern slope the ravines coming down from the central ridge are thickly covered with large pine to the top. Toward the southeast it runs out into the pine and grass covered Sierra Prieta Range. This range contains all the mining districts in the vicinity of Prescott, and, as I shall refer frequently to its geological structure, I will here dismiss it, saying only that it is made up principally of granitic rocks, which are often cut by dikes of porphyry and greenstone, and flanked by metamorphic slates in every direction. It is over sixty miles long and about thirty-five miles wide. To the east and north of it stretch the Tonto and San Francisco plateaus, separated from it by the Val de Chino and the Agua Frio Valley. The Tonto plateau is reported to be underlain by limestone and sandstone, and as it is only part of the great tableland to the east accidentally cut off from it by the deeply eroded valley of the Verde, the latter is probably formed by the same rocks. Still farther to the east lies the great Mogollon Range, the geology of which is not known. It is the home of the most dangerous portion of the Apaches, and has not yet been explored satisfactorily.

In Northern Arizona the sedimentary strata underlying the extensive plains and table-lands stretching almost unbroken from the Colorado River to New Mexico and north into Utah Territory are better exposed to view than in other portions of the country. The Great Cañon of the Colorado has been eroded over 6,000 feet deep, and exposes all the sedimentary strata of the region down to the underlying granite. Dr. Newberry, in his admirable report on the geology of the ronte explored by Lieutenant Ives's party, in the latter part of 1857 and spring of 1858, says, in relation to this stupendous cañon, and the country to the east and northeast of it:

"That portion of the central plateau which lies west of the Rocky Mountains varies in elevation from 5,000 to 8,000 feet; the smaller number representing the altitude of its surface where deeply eroded. Its average altitude in the vicinity of our route may be estimated at 6,000 feet.