'"TPp
DESCRIPTION OF THE CLIFTON QUADRANGLE.
By Waldemar Lindgren.
GEOGRAPHY. volcanic flows, chiefly of basalt, which cover a very formation is chiefly the semiconsolidated detritus At the town of Metcalf two important tributaries large area along the New Mexican boundary between of the Gila conglomerate. join Chase Creek. From the west Coronado and Location and area. The Clifton quadrangle lies San Francisco and Salt rivers and occupy the north Traces of the same plateau extend northward along Santa Rosa gulches descend in narrow canyons between meridians 109° 15' and 109° 30' west lon ern, eastern, and western parts of the Clifton quad .San Francisco River to the margin of the quadran with precipitous grade, draining the eastern slope gitude, and parallels 33° and 33° 15' north latitude. rangle, leaving a comparatively small area in the gle. In the same manner it is indicated along of Coronado Mountain. Three thousand feet west It is 17.25 miles long and 14.5 miles wide, and has central part in which the older rocks come to light. Eagle Creek by level-topped bluffs and by the of Metcalf they join, and continue down to Chase an area of 249.76 square miles. The whole area These heavy lava flows effectually hide the range basin in the lower courses of Whitewater and Tule Creek in an open valley with a bowlder-covered falls within the eastern part of Graham County, in structure in this vicinity and produce an irregular creeks. bottom several hundred feet wide, bearing ample the southeastern part of the Territory of Arizona. topography without central or dominating features. The central part of the region contains two evidence of the frequent occurrence of violent The dividing line between Arizona and New Mex The detrital plains developed so extensively between strongly marked features, the first being the dome- cloudbursts on the flanks of Coronado Mountain. ico is 11 miles distant from its eastern boundary, the ranges and along Gila River are represented by shaped and flat-topped mass of Coronado Moun From the east King Gulch descends in a narrow, and the Mexican frontier lies 115 miles south of a considerable area in the southeastern part of the tain, the second the Copper King Ridge, extending extremely rocky canyon broken by one sudden its southern boundary. quadrangle. The structure of the older rocks is as a series of abrupt red bluffs for 6 miles along San drop of a hundred feet, and having a grade of Outline of geography and geology of province. intermediate between that of the Plateau Region Francisco River from Markeen Mountain almost to 500 feet in 1 mile; it heads 3 miles to the north The Territory of Arizona may be divided into three and that of the Mountain Region, and the Clifton Sardine Creek. Coronado Mountain reaches an west, near Malpais Mountain, 7000 feet high, physiographic regions (see fig. 1). The northeast quadrangle would perhaps best be regarded as the elevation of 7400 feet and slopes gently westward which, as its name implies, is carved in jagged ern part of the Territory is included within the broken edge of the plateau. The slightly inclined toward Eagle Creek, while it drops more rapidly outlines from the great Tertiary lava flows. A Plateau Region. In this province the bedded sedimentary rocks occupy high levels in the central on its north and south sides. The Copper King debris fan of great bowlders at the mouth of the and northern parts of the quadrangle, while toward Ridge has an elevation of 6800 feet at its highest canyon shows the torrential character of the water the south and southeast on the whole they sink suc point, but slopes off to the northeast to 5500 feet., course, which ordinarily is entirely dry. cessively lower along profound dislocations. In The two are separated by the canyon of Chase The most prominent feature of the topography detail they very frequently form monoclinal blocks Creek, cut to a depth of 1000 feet. at Metcalf is Shannon Mountain, rising in pyram-" faulted on either or both sides. South of Coronado Mountain lie two smaller and idal form 1200 feet above the town, with The third province, the Desert Region, occupy greatly cut-up plateaus. The first is marked by the yellowish-gray lower slopes broken by rough ing the southwestern part of Arizona, is similar in Morenci hills, which rise to an average elevation of crags of decomposed porphyry, and surmounted general structure to the Mountain Region, but the 5000 feet and contain small peaks of porphyry and by the black iron cap of the outcrops of the ranges are lower and are separated by broad desert short ridges or sloping tables of limestone. The Shannon mine. plains. It can not be sharply distinguished from watercourses here spread out in open basins near Above Metcalf the canyon of Chase Creek con the adjoining province. their headwaters, but cut through the rim of the tracts again and for 1|- miles forms a less conspic The main drainage of the Mountain and Desert mountains in narrow canyons. Gold Creek, uous duplicate of the lower granite canyon. The regions is transverse to the ranges, through Gila Morenci Canyon, and the several intervening grade is about 200 feet to the mile. Garfield Gulch, and Salt rivers. gulches are of this character. The second pla on which several important mines and prospects are teau finds expression in the level-crested ridge situated, enters from the east. Above this gulch TOPOGRAPHY. south of the Coronado mine; its elevation is about the most conspicuous features are the great granite 6000 feet. bluffs on the west side, which drop off almost per Relief. Looking northward toward Clifton from The general level of the flat ridges or gentle pendicularly for a thousand feet to a sloping mass the valley of Gila River one can distinguish sev domes of Coronado and Copper King is con of de*bris near the creek. The head of Chase Creek eral high ridges and complexes of rugged hills on tinued in the well-marked basaltic plateau which is only a few miles distant, among the high lava the horizon, but neither from this place nor from occupies the whole northeast corner of the quad peaks of the northern part of the quadrangle. The FIGK 1. Map showing physiographic regions of Arizona. better points of vantage nearer the foothills is it rangle and which has been so deeply and sharply total drainage area of Chase Creek is about 22 square The Clifton quadrangle is in the central-eastern portion of the State around possible to discern any well-defined range system the town of Clifton. scored by Sardine Creek. Above this rise again miles. Scale, approximately, 1 inch=100 miles. or any dominating central feature. Topograph the high, irregular ridges about Granville, marking The area which drains directly into San Fran ically the whole mountain region north of the the once dome-shaped rhyolitic and basaltic masses cisco River north of Clifton possesses divers topo rocks lie nearly horizontal and consist chiefly of river appears as a maze of short ridges, minor which now have been deeply dissected by the several graphic features. The well-graded river, which Paleozoic sediments resting on granite and schists plateaus, and peaks. branches of Whitewater Creek. Here is found the has a fall of 20 feet per mile, emerges from the of pre-Cambrian age. Colorado River with its sev The geological structure explains this condition highest elevation in the quadrangle 7947 feet. older rocks at Clifton, where it has carved pictur eral affluents forms the main drainage line, and has of affairs very clearly. A core of older rocks In the southwest corner of the quadrangle, west esque cliffs from the lavas underlying the gravel eroded those wonderful deep and abrupt canyons granites, limestones, and sandstones lying chiefly of Eagle Creek, a number of black basaltic ridges terraces of the Gila formation. For a few miles for which the region is famous. Volcanic masses between the ^two most important northern tribu rise to elevations of 6520 feet. They probably above Clifton it flows in a canyon about a thou of large volume and comparatively recent origin taries of the Gila in this region and reaching ele form a part of a large dome-shaped mass of basalt sand feet deep, with moderate slopes, which occa cover the plateau in many places, the best known vations of over 7000 feet, was first deeply and flows which stretches far westward into the Apache sionally break into precipitous bluffs of limestone being the imposing extinct volcano San Francisco irregularly eroded, and later, during the Tertiary Reservation. or granite. Above this point the canyon may be Mountain. The southern boundary of the Plateau period, was covered by immense masses of volcanic Chase Creek Canyon, cutting throuhg the heart said to be a double one. The* tortuous river course Region is for a long distance marked by steep cliffs flows, chiefly rhyolites and basalts, varying greatly of the copper-producing district, is a most interest is adjoined by steep lava bluffs from 500 to 700 of horizontal strata, which form a very conspicuous in thickness and character. A constructive drain ing and picturesque topographic feature. Three feet high, beyond which is a gentler slope that landmark. age was laid out over the lava flows and extensive miles northwest of Clifton the monotonous gray gradually leads up to the high, black lava peaks The second province, called the Mountain Region, erosion followed. The result of these conditions is bluffs of semiconsolidated gravels are replaced by on the east side. On the west side this gradual adjoins the plateau on the southwest and extends an extremely irregular topography. granite walls, ranging upward to a thousand feet ascent leads up to precipitous, dark-red, granite in a broad belt through the Territory from north The lowest point in the quadrangle, with an ele in height. Near the Longfellow incline the gran bluffs, 1500 to 2000 feet high, in places flat- west to southeast. It is characterized by a great vation of 3350 feet, is in San Francisco River near ite on the west side is capped by bluffs of quartzite topped, which are surmounted on the south by number of short, nearly parallel ranges which the southern boundary, and the highest point, 7947 and limestone, while^. a similar, though smaller, the great masses of Markeen and Copper King rarely exceed 50 miles in length and 8000 feet feet, is a sharp basalt peak in the northern part. faulted-down quartzite table caps its eastern slope. mountains, rising 3300 feet above the river, and on in elevation and which are separated by valleys A more careful consideration brings the many For 1^ miles above the Longfellow incline the the north by the lava peaks of Malpais, all of which deeply filled with fluviatile and lacustrine deposits. confusing features into a semblance of order. Sev canyon is very narrow and deep. The prevail form part of the divide between Chase Creek and The general trend is northwest and southeast, but eral plateaus may be discerned, some of them very ing rock is an altered granite, which is impreg San Francisco River. The canyon of the latter this changes near the Mexican and New Mexican faintly marked and all of them greatly dissected by nated with decomposing pyrite; owing to this it stream is not the result of a single and simple borders to more nearly north and south, and the deep canyons. Different causes, such as sedimen weathers in most fantastic forms, overhanging period of erosion, but is rather the consequence of region is continued by the short ranges in New tation and uplift, or volcanic accumulations, have cliffs alternating with deeply incised gorges and orographic movements and at least two periods of Mexico and by the Sierra Madre of Mexico. To contributed to form these plateaus. The lowest needle-like pinnacles, the dark-red color of the erosion. the north it continues through the Basin Range and best defined is the plateau of the Gila con rock lending additional weirdness to the scene, The canyon of Eagle Creek is cut in volcanic system of Nevada and Utah. glomerate, which stretches along the foot of the especially when colors and shadows are empha rocks except where it intersects the narrow granite These short ranges ordinarily consist of Paleo mountains in the southeastern part of the quad sized by the setting sun. A little stream of bright- ridge of Coronado Mountain. The northern part zoic sandstones and limestones, resting with marked rangle, with a general elevation of 4000 to 4500 green water trickles along the bottom, numerous of this canyon is rather open, but at the point unconformity on pre-Cambrian schists and granites. feet. It descends gently southward from the edge mining tunnels are opened along the sides, and the where it passes through the rhyolite tuff south of The prevailing structure is monoclinal, due to fault of the mountains and extends from Eagle Creek available level space is frequently insufficient for the pump station its walls form almost perpendic ing, which often finds topographic expression in the to the eastern margin of the quadrangle. The the track of the Coronado Railroad, which follows ular and very picturesque bluffs about 500 feet high. steep frontal scarps of the ranges. In places the lower parts of the two main watercourses trench the canyon up to Metcalf. Drainage. Three main lines of drainage, con older rocks are covered by flows of basalts, rhyo- it to depths reaching 700 feet, leaving grayish or A mile below Metcalf the canyon widens as the verging southward, intersect the quadrangle from lites, and andesites of Tertiary age. brownish bluffs of lavas or gravels lining the softer porphyry is entered, and small spaces of north to south. San Francisco River lies on the Near Clifton the features described above are not watercourses. The plateau is furrowed by a maze alluvial gravel appear, probably brought down east side, Eagle Creek occupies a corresponding so clearly developed. The boundary between the of shallow, spreading ravines, rapidly deepening from the great amphitheaters of the Coronado and position on the west side, and Chase Creek, a trib Plateau and Mountain regions is obscured by heavy to box-like canyons near the main rivers. The Santa Rosa canyons. utary of San Francisco River, flows through the central part. A transverse drainage by secondary rangle, but they are being rapidly removed by the base lie 200 feet of probably Cambrian quartz naked eye. Under the microscope it proves to watercourses, trending chiefly southeast or south woodcutters, whether on the public domain or not. itic sandstone, succeeded by 200 to 400 feet of consist of an interlocking aggregate of quartz con west, is fairly distinct in the southern half of the Yellow pine begins to appear at the highest Ordovician limestones. About 100 feet of Devo taining many small foils of sericite with an orienta quadrangle, but westward- and eastward-draining elevations, and several square miles about the nian (?) shale and argillaceous limestones cover the tion parallel to the schistosity. creeks are strongly developed in the northern part, headwaters of Whitewater Creek, Pigeon Creek, Ordovician beds, and the uppermost part of the Smaller and ill-defined masses of amphibolitic heading in a high divide between San Francisco HL Canyon, and Sardine Creek are covered with Paleozoic sediments consists of heavy-bedded lime rocks occur subordinately in the prevailing quartz River and Eagle Creek. merchantable timber of this kind, the trees often stones of Carboniferous age, with a thickness of itic schist. Several of these were noted in Sardine The principal stream of the region is San Fran reaching a diameter of 2 or 3 feet, For many 500 feet. Creek. The microscope shows them to be greatly cisco River, which heads in New Mexico, about years sawmills have been actively at work here, The Paleozoic strata are overlain in certain areas pressed and to consist of a felted mass of amphi- 100 miles farther north, among the Mogollon, and the best lumber is cut out. by Cretaceous shales and sandstones that have a bole needles with a little zoisite and a few feldspar Tularosa, Datil, and San Francisco ranges, and Along the principal rivers and creeks the cotton- thickness of several hundred feet, and are at least grains. They are probably pre-Cambrian intru- joins the Gila 12 miles below Clifton, Ariz. wood trees grow to imposing size, and their bright- in part equivalent to the Benton group. A second sives of dioritic character, very much altered by About 40 miles north of Clifton it receives an green foliage contrasts strongly with the dull brown unconformity, much less pronounced than the first, metamorphic processes. important tributary called Blue River, which of the lava cliffs usually lining the stream beds. exists between the Paleozoic and the Cretaceous. Structure. The schistosity of the Pinal forma heads among the basaltic plateaus of the Prieto Fairly large live oaks occupy the broad washes Great masses of granitic and dioritic porphyries tion varies so capriciously in strike and dip that Range in Arizona. There are few other tribu in some localities, as in the middle part of Horse were intruded in the older rocks after the deposi it has not been possible to unravel its structure. taries of importance, the principal one being shoe Gulch, southwest of Coronado Mountain. tion of the Cretaceous series, and form stocks, dikes, Moreover, many sets of joint planes appear in the Chase Creek, which heads among the high lava Culture. The population of the Clifton quadran laccoliths, and sheets. bluffs at the head of Chase Creek and greatly com peaks 12 miles north-northwest of Clifton. It gle is almost wholly, directly or indirectly, depend All of the above-mentioned rocks have parti plicate the structure. Planes of sedimentation are carries permanent water from Garfield Gulch to ent on the copper-mining industry. There are cipated in an uplift and a warping or doming shown in places, but the thickness of the beds can below the Longfellow incline; beyond that place three towns Clifton, Morenci, and Metcalf. Clif succeeded by faulting. The effects of vigorous not be deciphered with certainty. the water which it contains is derived from the ton is picturesquely but inconveniently situated faulting are especially striking. These movements In Sardine Creek the schistosity strikes east-west concentrating works at Morenci. along the narrow bottom lands of San Francisco took place during latest Cretaceous or earliest Ter and dips about 70° S. The same strike and a dip Along the bold scarp of Copper King Ridge the River and Chase Creek, at an elevation of 3500 tiary time. of 55° S. were noted in the deep canyon at the river receives only a few gulches as tributaries, but feet. The railroad terminus and the large smelt During the Tertiary age enormous masses of south end of the main schist area, but close by Sardine Creek, 9 miles long, flowing in a canyon ing plants of the Arizona Copper Company and the lavas basalt and rhyolite, with some andesite are heavy benches, probably indicating stratifica 1500 feet deep in the northeastern part of the Shannon Copper Company aie located here, and covered all the rocks described above. These lavas tion, which dip 32° NE. At the lower end of the quadrangle, joins it just east of the boundary. the population numbers several thousand. Morenci now form a broad frame inclosing the comparatively same canyon closely spaced sheets standing nearly The upper course of this creek contains permanent lies at an elevation of 4800 feet, at the head of little-exposed older rocks in the center. Tertiary vertical and striking north-northwest were observed. water of excellent quality. Morenci Canyon. The principal mines of the sediments are not known in the quadrangle. The two principal bluffs referred to above show a The next important stream of the region is Eagle Detroit and Arizona companies, concentrating Erosion has sculptured the rock masses of the very marked structure. Heavy benches of quartz Creek, which joins the Gila a few miles below the plants of both, and smelting works of the former quadrangle since early Tertiary time, and a part ite striking northeast stand nearly vertical or are mouth of the San Francisco. Eagle Creek flows are found in its immediate vicinity. The popula of the removed detritus that carried away by the slightly curved, dipping north or south at steep southward and southeastward and is about 40 tion of Morenci probably exceeds 6000. Here streams during Quaternary time still lies spread angles. In all probability they represent stratifi miles long, its source being among the basaltic also the situation is inconvenient and access to the out at the foot of the mountains as coarse and cation, and if so the beds must have a thickness of mountains of the Prieto Plateau. Like the San town is difficult, for the slopes are so steep that roughly bedded deposits the Gila conglomerate. at least 2000 feet. - At the head of Sardine Creek Francisco, it is bordered by narrow bottom lands streets are largely dispensed with and the neces A change of level during later Quaternary time a banding occurs with a strike of N. 31° E. and along nearly its whole southerly course, and it sary supplies are carried to the houses by packing increased the erosive power of the streams and a dip of 55° SE. This probably also represents flows in a canyon deeply incised in the volcanic on horses or burros. Metcalf, situated on Chase forced them to cut through the Gila conglomer stratification. rocks. It is a permanent stream and, like the San Creek at an elevation of 4400 feet, is a smaller set ate in box-like canyons a few hundred feet in Intrusives. The foot of the bluff at the contact Francisco, is subject to sudden freshets, during tlement where the mines of the Shannon Company depth, in which the waters now flow 'over sandy with the basalt marks an important fault, bringing which the volume of the water is for a short time and some of those belonging to the Arizona Cop beds along well-graded river courses. the Carboniferous down at least 1000 feet. Near amazingly increased. The tributaries from both per Company are located. The majority of the this line an irregular mass of granite is contained DESCRIPTION OF THE ROCKS. sides are merely dry gulches which carry water population in these three mining towns are laborers in the schist, although its intrusive origin is not only during times of heavy precipitation. In of Mexican nationality or Mexican descent. Pre-.Cambrian Rocks. clearly proved. In the various branches of Sardine the northern part of the quadrangle it receives The Arizona and New Mexico Railroad con The old basement upon which the Paleozoic and Creek some aplitic rocks and small dikes of pegma Tule and Whitewater creeks from the east, which nects Clifton with Lordsburg, on the main South later sedimentary systems have been deposited and tite appear near the eastern limit of the schist area. head at the divide between Eagle Creek and San ern Pacific line, in New Mexico. The Morenci through which the much later intrusions of por The quartz-sericite-schists of the Pinal formation Francisco River and which contain a few small Southern Railroad, a narrow-gage line, connects phyry and overflows of basalt and rhyolite have were undoubtedly once quartzose sandstones and perennial springs in their upper courses. Morenci with a station on the former road on Gila forced their way will first be described. Although have been greatly altered by regional metamorphism. Climate and vegetation. The climate, like that River. The four complete loops in the last mile the Cambrian system has not been proved to exist Age. In the absence of more detailed studies of southern Arizona in general, is arid, and this is of this road near Morenci form a remarkable fea in this region by full paleontological evidence, there of the fundamental rocks of Arizona, it will be clearly shown by the character of the vegetation. ture in railroad construction. Finally a local rail can be little'doubt that the Coronado quartzite rep best to simply designate the Pinal schists as pre- The temperature in the low valleys, with elevations road belonging to the Arizona Copper Company resents the Cambrian period, and it is certain that Cambrian. The profound unconformity between of about 3500 feet, frequently rises above 100° F. extends from Clifton to Metcalf along Chase Creek. its base marks the most prominent unconformity in them and the Cambrian quartzite marks a most in the summer, and snow rarely remains on the The wagon roads are few. One follows San the early geological history of this vicinity. The important break in the geological history of the ground in the winter, although hard frosts are of Francisco River upstream from Clifton and forms pre-Cambrian basement consists chiefly of granitic region. common occurrence. At the elevation of Morenci, the means of communication with the ranches on rocks, but to a smaller extent also of schists. GRANITE. 4800 feet, the summers are cooler and light snow the upper river. Another extends from Metcalf to FINAL SCHIST. may remain on the ground for a few days. In the Pigeon Creek, and was built chiefly for the con Occurrence and distribution. A normal granite, mountains, at elevations of from 6000 to 8000 feet, venience of the sawmills of that vicinity. There Name. In the Globe and Bisbee folios the name consisting of orthoclase, albite, quartz, and biotite, the summers are delightfully cool, and a few feet is no wagon road between Clifton and Metcalf or Pinal schist is applied to the fundamental crystal generally underlies the Paleozoic sedimentary series. of snow may remain for several weeks during the between Morenci and Metcalf, but a good road line metamorphic rocks of the Pinal Range and The orthoclase prevails over the other constituents winter. Of the total precipitation, which for ele connects Clifton with Morenci. the Mule Mountains. These are shown to consist and may be so abundant as to cause transitions to vations of 5000 feet probably averages 12 to 15 Little remains to be said about the population chiefly of quartz-sericite-schist of sedimentary origin quartz-syenites and even syenites. inches, a part falls in July and August and the outside of these towns. There are scattered set and to be separated from the oldest Paleozoic strata Broadly speaking, the granite exposed by the remainder usually in the autumn or winter. The tlements of miners at Coronado, Copper King by a profound unconformity. Although Clifton is erosion of the Paleozoic rocks forms an irregular rainstorms are often violent and are apt to pro Mountain, Garfield Gulch, and other places. A 80 miles east of the Pinal Range and 130 miles belt several miles wide, extending diagonally across duce destructive freshets in San Francisco River few ranches are located along San Francisco River north of Bisbee, the similarity in geological relations the quadrangle between the sunken limestone blocks and Eagle Creek. After the heavy showers in above Clifton and at some places successful attempts and lithological character of certain schists of the of the southern foothills and the heavy lava flows earliest spring or late summer the hills are for a have been made to raise fruit, including peaches. Clifton quadrangle to those referred to above is so of the northern mountains. There are two promi brief period covered with verdure and flowers. The climate is too cold for citrus trees. Along the great that the application of the name Pinal schist nent dome-shaped masses, rising to elevations of The lower foothills are for the most part prac narrow bottom lands of Eagle Creek Mexicans have to them appears fully justified. 7000 feet, separated by the deep trench of Chase tically barren, bearing only a few desert bushes located and are engaged in truck growing by irriga Distribution. The Pinal schist outcrops in two Creek and scarred by many deep ravines. Coro and cactus plants. In many places, however, tion on a small scale. distinct areas in this quadrangle, separated by a nado Mountain forms the western dome, while the the thorny, long-stemmed bush known as Fou- A sawmill was in operation on Pigeon Creek in high basaltic ridge. The larger area, which occu complex of Markeen and Copper King rises between qwiera splendens grows thickly. During the 1902, and camps of woodcutters are frequently pies scarcely 2 square miles, is situated at the heads San Francisco River and Chase Creek. spring months the bare stems of this bush are found in places where the juniper grows large of Chase Creek and the south branch of Sardine Several smaller areas of granite are inclosed covered with brilliant scarlet flowers. Up to ele enough for firewood. Small herds of cattle browse Creek. Its principal features are two high, pre between the faulted blocks northwest of Morenci; vations of 6000 feet the ridges generally support over the hills along Eagle Creek and San Fran cipitous bluffs of dark brownish-red color. The the Copper King granite extends across Chase Creek no arboreal growth, although a number of spe cisco River, but the range appears overstocked. northern and larger of the bluffs rises to a height and follows the margin of the foothills for several cies of agave, yucca, and low cactus, not com There is no cattle ranch of importance within the of 1000 feet and is covered with quartzite and miles south of Morenci; and a smaller detached mon on the lower plains, are found on them. quadrangle. The breeding of goats is attempted limestone. The second area forms a narrow strip area outcrops a couple of miles southeast of Clifton Above 6000 feet, in sheltered locations, stunted in a few places with fair success. exposed by erosion in the main fork of Sardine between the Gila conglomerate and the Coronado trees of juniper and cedar are fairly common, Creek for a distance of 1 mile. quartzite. The boundaries of the areas are formed and are extensively used as firewood. A growth GENERAL GEOLOGY. Character. The Pinal schist is usually reddish by the covering or intruding later formations, which of manzanita bushes*and stunted oak is also found or reddish brown, not differing greatly in color may consist of Cambrian quartzite, irruptive por on the higher slopes. Preliminary statement. The oldest rocks of the from the Cambrian quartzite. The cleavage is phyries, Tertiary lavas, or Quaternary gravels; or Groves of such vegetation cover the upper part Clifton quadrangle are pre-Cambrian\granite and usually imperfect, but in Sardine Creek fissile again by fault lines which may bring any one of of the slopes, of Coronado, Copper;King, and Mal- quartzitic schists, separated by an important uncon varieties occur, with a satiny luster on the sur the formations present in the area in contact with pais mountains, as well as areas at corresponding formity from the covering Paleozoic strata. The faces. Its texture is ordinarily so fine that the the granite. elevations all over the northern part of the quad latter comprise a total thickness of 1500 feet. At individual grains are rarely recognizable by the The prevailing color of the granite is red, rang- ing from a yellowish red to deep brownish-red quadrangle. There are strong reasons, however, ficult to perceive; the underlying granite appears on the Bisbee quadrangle is referred to as the Bolsa tones, all due to the finely disseminated ferric for believing that the Final schist is the older of disintegrated, bearing evidence of pre-Cambrian quartzites and has a thickness of 500 feet. No oxide so common in the orthoclase. The out the two pre-Cambrian terranes and that the granite weathering. Thin strata of olive-colored shale fossils have been found at either of these localities. crops are large and rounded, but do not exhibit, is intruded into it. The contacts between the two were observed in a few places near the top of ORDOVICIAN SYSTEM. except locally, a very marked "woolsack structure." are poorly exposed, but the irregular mass of gran the formation for instance, on the summit of In places where erosion has not acted with unusual ite projecting into the schist at the foot of the bluff Coronado Mountain and in the gulch just south LONGFELLOW FORMATION. vigor the surface is covered by a thin layer of coarse near the head of Chase Creek and the dike-like of the Longfellow incline on Chase Creek. General character and distribution. Under this sand due to disintegration. The steep slopes of bodies of aplite and small masses of pegmatite a Two miles southwest of Morenci the following formation name are grouped from 200 to 400 feet of ravines and fault scarps, especially those on the mile farther north form strong points in favor of section was observed: strata conformably overlying the Cambrian Coro west side of Chase Creek above Metcalf, show a that view. Geological section of Coronado quartzite 2 miles southwest of nado quartzite and consisting of limestones that prominent sheeting or jointing, the joints usually Morenci. are usually more or less dolomitic and gradually Paleozoic Sedimentary Rocks. having a northeast to north direction and standing Feet. grow more siliceous near their lower limit. The White quartzitic sandstone...... 50 almost vertically, separating the rock into thick General statement. Above the granite lies a Banded pink and maroon quartzitic sand upper 150 feet always form a prominent bluff of benches. thickness of about 1500 feet of Paleozoic stratified stone, forming precipitous bluff...... 162 brownish limestone, while the lower 250 feet con Conglomerate with quartzite pebbles...... 10 The weathering on Copper King Mountain is of rocks, comprising the Cambrian, Ordovician, Devo Sandstone ...... 3 tain more shaly strata, usually forming a more a similar character, the gentle sandy slopes con nian (?), and Carboniferous systems. They have Conglomerate with quartzite pebbles...... 8 gentle slope leading down to the steep quartzite trasting with the imposing dark-red cliffs facing been subdivided into the following formations: Coarse sandstone...... 10 bluff underneath. Granite. San Francisco River. Irregular joint planes divide The formation is extensively developed in the Coronado quartzite (probably Cambrian). Total...... 243 the outcrops into angular blocks. Longfellow formation (Ordovician). southern marginal mountain region. Bluffs of it The granite of Chase Creek between Morenci and Morenci formation (probably Devonian). Petrography. The rock is usually thick bedded, line San Francisco River for about 2 miles north Metcalf is altered by quartz cementation and pyritic Modoc limestone (Mlssissippian, or Lower Carbon though sometimes delicately banded in detail, and of Clifton, the areas forming deeply faulted blocks impregnation; oxidation has given it specially bright iferous) . shows various colors from light pink to darkest at the foot of Copper King Mountain. An area red and yellow colors, while the outcrops are ex Tule Spring limestone (Mississippian and Pennsyl- maroon; the distinguishing color of the outcrops aggregating a few square miles is exposed east and tremely rough and irregular, with pinnacles and vanian, or Lower and Upper Carboniferous). is dark brown. Properly speaking, it is a hard south of Morenci, and here again the formation deep recesses. Fresh granite is obtainable only While the first four formations are generally dis quartzitic sandstone of varying grain, most com constitutes a series of faulted blocks. Another at points of intense erosion or where mining oper tributed wherever the Paleozoic strata occur, the monly, however, showing grains averaging 1 mm. block, about 1 square mile in area, lies north of ations have penetrated the decomposed surface. Tule Spring limestone, which contains the Upper Near the base are intercalated beds of coarser grain Gold Creek on the slope toward Eagle Creek. The coarse-grained character remains constant over Carboniferous, is found only in the northern part which at many places change into coarse conglom Many smaller detached masses occur in the north the whole area. of the Clifton quadrangle. There is no known erates. The clastic grains almost universally con ern part of the quadrangle near the line where the Petrography. The typical granite as shown, unconformity in the whole Paleozoic column, sist of light-gray granitic quartz, are generally older formations dip below the great lava flows. for instance, at Sycamore Gulch, near the Poland though by no means all the subdivisions of the rounded, and contain abundant fluid inclusions. Detailed sections. One of the type localities prospect, is a reddish-brown, coarse-grained rock, systems have been shown to be present. Grains of sericitized orthoclase are occasionally examined is on the west side of Chase Creek Can consisting of reddish, only occasionally light-green, Compared to other places in Arizona the thick found, but no other rocks are represented. The yon. The best section obtained runs northeast feldspar grains, averaging perhaps 5 mm. in diam ness of the Paleozoic column is slight. In the cement consists chiefly of sericitic particles, mixed from the high limestone point one-fourth mile eter, light-gray quartz in smaller grains often inter- Globe quadrangle 1700 feet of Paleozoic strata with fine granitic detritus. The whole indicates south of Modoc Mountain, the beds being well grown with the feldspar, and a small amount of have been measured, and in the Bisbee quad very clearly derivation by slow processes from a exposed below the Carboniferous and Devonian black biotite in inconspicuous aggregates; occasion rangle over 5000 feet. disintegrating granite, the feldspar of which has along the steep slope of the canyon. ally a grain or two of hornblende is present, but had ample time to become converted into sericite CAMBRIAN (?) SYSTEM. Geological section of Longfellow limestone in Chase Creek never, so far as known, any muscovite. The fer- and kaolin. Canyon one-fourth mile south of Modoc Peak. CORONADO QUARTZITE. romagnesian silicates are rarely seen in specimens In a few places near Morenci this quartzite car Feet. from the surface, having been decomposed to dull General character and distribution. Resting ries pyrite and chalcocite, developed metasomat- Buff limestone...... 15 Quartzitic sandstone...... 10 grayish or greenish secondary minerals. immediately on the granite basement, the Coro ically by secondary processes, in both quartz grains Bluff of brownish-gray cherty limestone..... 140 In thin section the large grains of orthoclase are nado quartzite has a wide distribution and is and cement, and is mined as ore. Shaly limestone...... 90 everywhere easily recognized. It consists chiefly The conglomerate consists exclusively of well- Coarse gray sandstone...... 10 most prominent. Microperthite is also very com Sandy and shaly limestone (base)...... 115 mon, occurring in intergrowth with orthoclase. A of heavy beds of brown, pink, or maroon quartz- washed cobbles and pebbles of a hard quartzite or Total...... 380 few grains of plagioclase with narrow striation were itic sandstones. Its lowest member is a quartzite quartzitic schist; neither granite nor aplite was noted in some specimens. They are greatly seri- conglomerate up to 50 feet thick, but this is miss found in it at any of the numerous places at which The section given below begins at the top of the citized, making determination difficult, but appear ing in many sections. Several smaller areas of it was examined. The pebbles are undoubtedly bluff which overlooks Chase Creek If miles south to be albite. Quartz abounding in fluid inclusions this formation conspicuously crown the summit derived from the pre-Cambrian quartzite referred east of Morenci, but here the upper part of this is always present, but often as small grains and in and western slope of Coronado Mountain. The to as Final schist, large outcrops of which occur in formation is not fully represented. micropegmatitic intergrowth with orthoclase or largest area, covering several square miles, lies a the northern part of the quadrangle. The absence Geological section of Longfellow limestone If miles southeast perthite. Magnetite and zircon are accessories. thousand feet lower, on the south side of the great of granite fragments affords still further evidence of of Morenci. The structure of the rock is normally granitic. Coronado fault fissure, and forms a fault block the deep pre-Cambrian disintegration of the granite. Feet. In nearly all specimens from near the surface broken by many minor dislocations, but on the Conditions of deposition. While the even bed Buff limestone...... 8 Bluffs of brownish cherty limestone ...... 110 the feldspars are clouded by kaolin and sericite, whole dipping gently westward. Minor patches ding of the body of the Coronado formation shows White sandstone with cross-bedding...... 15 while the biotite is entirely converted to sericite cover the granite in the upper Chase Creek Val deposition in a large body of water, and while the Calcareous shales, lead gray to maroon or yellowish gray in color...... s...... 75 and chlorite. Occasional modifications occur, but ley, or are bounded by short fault planes, and marine origin of the top strata is proved by the are seldom conspicuous. As mentioned above, the similar areas cap the granite bluffs farther east, occurrence of fossil shells, it seems probable that Total...... -i...... ,...... 208 orthoclase may locally increase, changing the rock overlooking San Francisco River. At lower ele the lowest conglomerate is a fluviatile deposit grad A part of the lower shales is probably displaced by to a quartz-syenite. Hornblende may increase, vations a continuous band of this formation begins ually merging into a marine formation. Its very an intrusion of porphyry which here separates the as shown in the cuts of the Coronado Railroad, near the Longfellow incline, on the west side of irregular occurrence and thickness, as well as the Longfellow limestone from the Coronado quartzite. 850 feet above the place where the wagon road Chase Creek Canyon, and after following the disintegration of the underlying granite, seems to The section at Square Butte, 2 miles southeast of leaves Chase Creek and ascends the - hill toward canyon for about 2 miles swings southwest with tend to this conclusion. The pre-Cambrian land Morenci, is more complete: Morenci. This rock is a normal granular aggregate the foothills facing the gravel plains of the Gila surface was evidently of gentle outline except for Geological section of Longfellow limestone at Square Sutte, of orthoclase, microperthite, and quartz, probably conglomerate and continues to a point 3 miles some projecting masses of old quartzites and schists. 2 miles southeast of Morenci. also a little individual albite with rather abundant south of Morenci. A few exposures of the for The present surface of contact between the granite Feet. Brownish bluffs of limestone with cherty prisms and grains of green hornblende and a con mation resting on granite are found also on the and the Coronado formation is greatly modified by bands...... 200 siderable amount of magnetite or ilmenite. The east side of San Francisco River. warping and dislocation. Brown limestone with bands of quartzite.... 50 quartz is present in only moderate quantity, and In many places erosion has left only a thin cover Age and correlation. The determination of the Sandy limestone with some thin strata of quartzite; near bottom thin strata of shale 150 partly in granophyric intergrowth with the feld of quartzite upon the granite. Where the whole Coronado formation as Cambrian is largely circum Total...... 400 spars. Sericite, chlorite, epidote, and pyrite have thickness of the formation remains, as near stantial, being based chiefly on its well-defined posi developed as secondary minerals. Morenci, it attains a maximum of 250 feet, but tion as a distinct division of quartzose sediments Near Garfield Gulch, 2 miles north of Metcalf, Local modifications of still more basic character this is not maintained at all exposures; near the below Ordovician limestone and above an uncon in Chase Creek Canyon, the series, of which the are very uncommon, the only one observed being mouth of Apache Gulch, due south of Morenci, formity of the first importance. The only fossils whole thickness seems to be present, amounts to in the bottom of a gulch 2 miles south of the point only from 100 to 150 feet are exposed. The basal thus far found in this formation were discovered only 140 feet. The upper part consists of heavy where the Coronado vein crosses the ridge summit. conglomerate, consisting of a maximum of 50 feet of by Mr. Boutwell in olive shales 25 feet below the brown limestone, the middle of gray sandy lime The granite here contains a small mass consisting well-washed quartzitic cobbles, cemented by granitic top of the quartzite, in a section just south of the stone, and the lower division of lime shales. chiefly of hornblende, soda-lime feldspar, and grains sand and gradually changing into sandy beds, is Longfellow incline in Chase Creek. They consist At the small isolated limestone mass of Shannon of magnetite or ilmenite. exposed at the bluff forming the summit of Coro of small lingula-shaped shells determined by Mr. Mountain, near Metcalf, 200 to 250 feet of dolo Dikes. Dikes of coarse pegmatite are almost nado Mountain and at many other localities, but C. D. Walcott as a lingulella similar to those found mitic limestone were measured lying between the wholly absent, but in.many.places appear irregu is not a universal feature. At the foot of the in the middle Cambrian of the section in the Grand Morenci shales and the Coronado quartzite/ The lar masses or well-defined dikes of granitic aplite, Longfellow incline it is only 2 feet thick. Canyon of the Colorado. The species could not color is yellowish brown, the upper part being a medium-grained rock identical in composition Near the mouth of Apache Gulch, south of be identified. heavy bedded and the lower more shaly. with the normal granite, but of a more even- Morenci, the conglomerate is lacking, sandstones The quartzites at the base of the Paleozoic section The most northerly exposures are at the head grained, "sugary" texture. These aplitic dikes resting directly on the granite. have a very wide distribution in Arizona. Mr. of Chase Creek and Whitewater Creek and in the are genetically connected with the granite and have In the great fault block covering the .western E. T. Dumble (Trans. Am. Inst. Min. Eng., vol. 31, lower canyon of Sardine Creek. The thickness is not been separated from it on the map. Dikes of slope of-the ridge south of the Coronado mine p. 14) describes such quartzites from the Dragoon, here from 200 to 300 feet and the formation ^pre rhyolite, basalt, or various intrusive porphyries clearly defined stratification ; planes are often want Whetstone, Chiricahua, and Mule mountains, and serves the same general character, the upper part are abundant in places and are described under ing; the basal conglomerate is occasionally present refers to them as the Dragoon quartzites. A sim being formed of a high bluff of brownish cherty their proper headings. in slight development, while as frequently it is ilar but much thicker and more variable group limestone and the lower part of impure and shaly Origin. The intrusive character of the granite missing. In such cases the exact line of demarca of formations is mapped on the Globe quadrangle maroon limestones, with some" beds of brown sand is inferred, no direct proof being available in this tion .between granite and detrital rock may be dif as the Apache group. The equivalent formation stone, forming a gentler slope. Clifton. \ Petrography and analyses. A typical specimen the Globe or the Bisbee district; in both places, The limestone underlying the shales appears in CAEBONIFEEOUS SYSTEM. apparently, Devonian limestones directly overlie most typical form at Morenci, while north of Met- of the cherty limestone shows that it is composed MODOC LIMESTONE. chiefly of coarsely crystalline calcite in irregular the Cambrian rocks. calf a corresponding member could not be found. grains, with but little dolomite; few of the rocks A broad belt, in which the Ordovician strata are Analysis of clay shale from the Morenci formation near General character and distribution. The Modoc thus far examined consist of typical dolomite, but abundantly developed, is found in western Nevada, Morenci. formation, which represents the Mississippian series, certain irregularly distributed strata of the forma extending from the vicinity of Eureka down to [W. F. Hillebrand, analyst.] equivalent to the Lower Carboniferous, consists of Per cent. tion contain a considerable amount of magnesia. within 40 miles of the great bend of Colorado Si02 ...... 61.25 about 170 feet of coarse blue or gray limestones, The rock contains many small quartz grains, prob River and the Arizona line. A18 0 3 ...... 15.60 with subordinate strata of quartzite and dolomite. Fe20 3 ...... 1.35 The gray limestone, which forms a prominent cliff, ably largely of clastic origin. The chert occurs in The distribution of the system within this area FeO...... 3.04 irregular bands or nodules which, under the micro is discussed in the reports on the explorations MgO...... 4.16 is the characteristic part of the formation. scope, appear as an aggregate of greatly varying along the fortieth parallel,in the monographs by CaO...... 3.40 The areas covered by the Modoc limestone are not N&,O...... 44 grain, some of it consisting of irregular quartz Hague and Walcott on the Eureka district, arid K2 0...... 6.74 extensive, aggregating scarcely more than 1 square grains, while other parts contain much cryptocrys- in a recent bulletin by Mr. J. E. Spurr (Bull. H2 O 100°...... 62 mile, but the formation is of the greatest interest U. S. Geol. Survey No. 208). The point nearest ...... 2.09 and importance in connection with contact-meta- talline and fibrous chalcedonic material. Ragged TiO 2 ...... 66 calcite grains lie embedded in this mass, giving to Clifton in this belt is about 300 miles distant COg ...... None. morphic phenomena and copper deposits. Small distinct evidence of the metasomatic origin of the in a westerly direction. Along the Grand Can PgO5 ...... 08 areas outcrop on the top of some bluffs along the SO3 ...... None. chert from siliceous waters by replacement of calcite. yon of the Colorado River the Ordovician is not MnO (partly MnO8)...... 07 river north of Clifton; others cover Modoc Moun The normal rocks contain no pyrite or other sul thus far known; neither does it occur in south BaO...... Faint trace. tain near Morenci and the opposite (west) side of western Colorado. On the other hand, Mr. G. B. SrO ...... None. Morenci Canyon; still others cap Shannon Moun phides. The Longfellow limestone is, as a rule, Li sO...... Trace. too siliceous to be used for quicklime or smelting Richardson has recently found the system strongly ...... :...... 25 tain and several hills in the watershed of Garfield flux. A number of partial analyses made of it at developed at El Paso and other places in western ...... 03 Gulch and on the divide between Chase Creek and ZnO...... 03 Morenci in the laboratory of the Detroit Copper Texas. North of this point it is known to occur Knight Creek. Company show that it contains from 55 to 91 per in eastern Colorado, as, for instance, in the Pikes Total. 99.81 Detailed descriptions. The several sections stud cent of calcium carbonate and 0.5 to 35 per cent of Peak quadrangle. Mr. Ellis Clark (Traris. Am. This limestone, about 75 feet thick, is nearly black ied at Morenci are practically identical. One of magnesium carbonate, the latter figure being very List. Min. Eng., vol. 34, 1894, p. 138) reports when fresh, extremely fine grained, and breaks them extends from the summit of a high limestone exceptional. From 5.4 to 27.6 per cent of silica is its presence, possibly together with Silurian, at the under the hammer with a ringing sound into point one-fourth mile south of Modoc Mountain present. The increase of this constituent toward Lake Valley silver mines, in the southern-central shelly fragments. The outcrops are well strati down toward Chase Creek, forming the upper part the base of the formation is very noticeable. part of New Mexico, and more careful search will fied in thin benches which appear peculiarly pitted of a complete general section from Carboniferous to The Longfellow limestones exposed on Shannon probably show its presence at many other points by weathering and have a bluish-gray color, alter Cambrian and to the granite; another extends west Mountain are largely metamorphosed; many of in that Territory. ing on oxidation to a yellowish tone. In thin sec ward from the first railroad loop below the Morenci them would seem to be somewhat dolomitic in tions the rock is very fine grained, consisting chiefly smelter. Cretaceous strata here cap the Modoc for DEVONIAN SYSTEM. composition. An analysis made for the Shannon of calcite, though some small rhombohedrons of mation. Beginning from the top the following suc Copper Company of a hard, blue, fine-grained MORENCI FORMATION. dolomite are present. Minute cubes of pyrite are cession is noted at these places: limestone from the Black Hawk tunnel 30 feet General character and distribution. Between scattered through the mass. Geological section of Modoc formation at Morenci. above the top of the Coronado quartzite runs as A specimen from the lower part of this member, the Modoc limestone of the Carboniferous and the Feet. follows: Longfellow formation of the Ordovician there is taken opposite the smelter of the Detroit Copper 1. Blue, coarse, fossiliferous limestone, in conformably intercalated a group of strata which Company, gave the following result: benches 2 to 3 feet thick...... 4-10 Analysis of limestone from Black Hawk tunnel. 2. Light-gray, coarse limestone with cri- have been tentatively referred to the Devonian sys Analysis of limestone of the Morenci formation from vicinity noid stems, 2-foot benches, vertical Per cent. tem. The rocks consist of about 100 feet of clay of Detroit smelter. joints (referred to as the " Gray Cliff" CaCO3 ...... 39.2 [ L. B. Wallace, analyst.] member)...... 75-85 MgCO 3 ...... 22.9 shales underlain by 75 feet of compact and fine Light grayish-brown dolomitic lime SiOa ...... 27.0 Per cent. stone...... 60 grained argillaceous limestone; this lower part is, SiO ...... 6.4 Fe8Os ...... 8.3 4. White or reddish calcareous quartzite however, missing in some parts of the Clifton quad Fe ...... 1.5 A12 O 3 ...... 3.0 forming sharply defined stratum..... 15-17 rangle, and as it can not conveniently be mapped ..... 42 CaO ...... 46.8 5. Massive bench of gray limestone (re It is probable, however, that the specimen ana separately it has been grouped with the shales into MgO...... 9 ferred to as the " coralliferous lime- .stone ")...... 8-10 lyzed contained some pyroxene and epidote, due to one formation. , Cu...... 2 metamorphic processes. Though not occupying large surface areas, the S ...... None. Total...... 162-182 Age and correlation. Fossils are very scarce Morenci formation is ordinarily present wherever The total percentage of carbonates would be 85.4. On Shannon Mountain the dolomitic stratum throughout the Longfellow limestone. In the the compassing formations occur, as on San Fran Silica and alumina are both high, indicating admix seems to be lacking. The section observed here lower, shaly part, the only occurrence of fossils thus cisco River north of Clifton, in the vicinity of ture of clayey substance. is as follows: far found is in the section If- miles southeast of Morenci, near Garfield Gulch, and in the lower Age and correlation. While no fossils have been Geological section of Modoc formation on Shannon Mountain. Morenci, where, 20 feet above the top of the quartz- part of Sardine Creek. It usually forms a gentler found in the shales, the argillaceous limestone con Feet. ites, a few small lingulas were found, together with slope between the bluffs of Modoc and Longfellow tains at many points near Morenci a scant fauna "Gray Cliff" limestone ...... 132 crinoidal remains. Mr. C. I). Walcott states that, limestone. of corals and gasteropods, all of them noticeably Quartzite ...... 20 " Coralliferous limestone "...... 10 while no very certain determination of age can be In the most northern Paleozoic areas, southeast stunted and small in development. On these Prof. based on them, they probably indicate the upper of Grey Peak and about Granville, this formation H. S. Williams reports as follows: Total...... 162 most part of the Cambrian; there is thus a possi has not been observed in its customary place, In the faulted limestone block just west of the bility that a part of the Longfellow formation may although it appears with a thickness of 75 or The material presents a few fragments of fossils and is mouth of Garfield Gulch, in Chase Creek Canyon probably all from a single formation . Th ere is very little, be of Cambrian age. The best fossils were found in 100 feet in the areas 2 miles north of Coronado however, that is thoroughly diagnostic of a particular above Metcalf, the brown dolomitic stratum is again a layer of yellowish-gray shaly limestone at the top Mountain and at the head of the south fork of horizon. The species are : absent and the formation consists simply of 150 feet of the same section and consist of gasteropods and Sardine Creek. of light-gray bluffy limestone, equivalent to No. 2 fragments of trilobites, the latter in part very large. Petrography and analyses. The clay shale is a ? Zaphrentis sp ...... A small form. in the first section. Crinoid stems...... Too imperfect to A similar fauna was found one-half mile farther fissile black rock, fairly hard when fresh but crum identify generically. Petrography and analyses. In contrast to the northwest on the same ridge, in the same strati- bling easily and softening on exposure. The weath Loxonema sp...... f Not sufficient for siliceous limestone of the Longfellow formation, ? Pleurotomaria sp...... { specific definition. graphical position, and also in a gulch one-quarter ered outcrops are light gray to reddish in color. Schizophoriacf. ivanofiTsch. A small imperfect the Modoc limestones are exceptionally pure. mile northeast of Newtown, in the same vicinity. Under the microscope it shows the usual crypto- specimen, described The top stratum in the first section consists of The fossils were submitted to Mr. E. O. Ulrich, crystalline aggregate of clay shales, occasionally below. coarse bluish, almost pure limestone. The second who states that they are on the whole so poorly with minute greenish flakes and fibers, probably The specimen of ScMzophoria approaches the OrtMs stratum, the "Gray Cliff," as it may be appro preserved and incomplete that specific identifica consisting of glauconite. Small cubes of pyrite ivanqfi Tsch. type of Eussia more closely than our east priately designated, is likewise a coarse granular tion is difficult. Still the general aspect of the occur sparingly. Calcium carbonate is often ern forms of ScMzophoria McFarlani, which is quite rock of dark-gray color on fresh fracture, but collections and, in particular, the "association" of entirely absent. A slightly hardened but other consistent with the hypothesis that it belongs to the weathering in lighter-gray tints. Specimens from generic types leave no doubt concerning the age wise typical rock taken 40 feet east of the big dike same fauna as that of the Devonian sent by Eansome Morenci consist of'large, irregular grains of calcite, from the Globe quadrangle. indicated by the fossils. crossing the trail from Newtown to the top of the Although the typical species of the Globe and Bisbee the only other constituents noted being a few shreds The four lots all indicate practically the same Longfellow incline, near Morenci, gave the com quadrangles Devonian are not present, the ScMzophoria of bright-red ferric oxide or hydrate. This gray time interval (it is not unlikely that they are all position shown by the accompanying analysis. is so diagnostic of the same general fauna that I am of limestone is extensively used as flux, being quar derived from the same bed), which the evidence The analysis indicates a fairly typical clay shale, opinion that you will be safe in calling it Devonian, ried at Morenci by both of the principal mining in hand warrants placing in the Beekmantown age the high percentage of K 2 O being characteristic of though nothing in the lot will certainly exclude it from companies and on Shannon Mountain by the Shan (early Ordovician). many of these rocks. Less common is the large either Silurian or Carboniferous so far as the present non Copper Company. The companies interested evidence goes. I would classify the horizon as prob All four lots contain a species of Raphistomina amount of CaO, which evidently is not present as ably Devonian, awaiting more perfect fossil evidence have made many technical analyses of it, a few of or of some related gasteropod genus, an Ophileta, carbonate, but as some silicate. The rock is some for a closer correlation. which are here quoted: a Dalmanella similar to D.hamburgensis Walcott, a what hardened by the adjacent intrusive mass and Partial analyses of limestones from the Modoc formation. species of Camarella or Syntrophia, a new type of slight changes may have taken place, transforming A well-developed Devonian horizon has been Cephalopoda near JEndoceras, an early type of Asa- some carbonates to amphiboles. The copper and found by Mr. F. L. Eansome at Bisbee, Ariz., Mg- A12O3 Insolu CaCO3. SiO2. and phus, a small Dikellocephalas (/), and a larger tri- zinc present in minute quantities are also believed consisting of 340 feet of dark-colored, compact C03. Fe2O3 * ble. lobite related to Bolbocephalus. to be derived from the intrusive rock; at least, the limestones with some intercalated shales, which Limestone quarry of Four miles west of Morenci, on the slope toward clay shale far away from the porphyries never he names the Martin limestone. At Globe, Ariz., Arizona Copper Com pany at Morenci, Mo- Eagle Creek, is a large area of the upper part of shows the presence of copper in weathered out the same geologist has discovered 700 feet of buff 95.52 0.69 0.92 1.06 Longfellow limestone. Flat gasteropods similar to crops where a small quantity of that metal might and gray limestones, which he refers to the same Limestone quarry of Detroit Copper Com Raphistomina were observed in the center of this easily be visible as green carbonates. In the sec age, but which seem to present petrographically pany at Morenci, near area and near the principal trail crossing it. tion near Morenci, one-fourth mile south of Modoc no similarity to the Clifton-Morenci occurrence. smelting plant...... 94.00 1.00 2.70 Limestone quarry on So far as known this is the first discovery of the Mountain, the shale contains near its top strata a In the Grand Canyon section Mr. C. D. Walcott Shannon Mountain, occurrence of the Ordovician system in Arizona. dark-gray fine-grained dolomite, weathering yel found 100 feet of Devonian strata resting with slight 82.50 9.54 1 34 1.66
No rocks indicating this age have been found in lowish red. unconformity on the Cambrian Tonto group. * Mostly ferric oxide. It will be noted that the rock from Shannon sippian series are also present. The rocks which Menophyllum excavatum. clearly corresponding to the base of the Pinkard Leptsena rhomboidalis. Mountain, though similar in appearance and tex here conformably cover the Devonian Morenci Rhipidomella michelini. formation, and overlain to the north by the shales ture to that from Morenci, contains much more shales, or the Ordovician Longfellow limestone Schuchertella insequalis. of Silver Basin. magnesium carbonate. where the shales are absent, consist of at least Chonetes loganensis. Thin strata of epidotized brown and greenish Productus gallatinensis. The beds immediately underlying the "Gray 500 feet of heavy-bedded bluish-gray limestones Spirifer centronatus. shales cover the summit of Modoc Mountain, over Cliff" limestone consist of heavy benches of light which unquestionably represent both the Missis Spirifer striatus ? lying the uppermost stratum of the Modoc formation. Syringothyris carteri ? brownish-gray limestone, weathering drab, and con sippian and the Pennsylvanian. In a general way Cleiothyris sp. Relations. There is evidently an unconformity taining a few minute crystals of pyrite. In thin the lower 200 feet are equivalent to the Modoc for Camarotoechia metallica. between the Mississippian and the Cretaceous, for mation, although its several members recognized at various points near Morenci the Pinkard forma section it proves to be a fine- and even-grained 2. One-half mile N". 63° E. from Granville: dolomite. farther south can not be identified, and the upper tion overlies various members of the Modoc forma Productella concentrica. tion. The same relation is also indicated by the Partial analyses of dolomite underlying pure limestone near 300 feet represent the Pennsylvanian. It is not Productus (several indeterminable fragments). the Morenci smelter. possible, however, to draw a dividing line, and the Spirifer near S. striatus var. madisonensis. fact that in the northern part of the quadrangle [ L. R. Wallace, analyst.] whole has therefore been included in a single for Reticularia cooperensis. the Pennsylvanian covers the lower part of the same system conformably, while at Morenci Creta CaCO3 MgCO3 SiO2 Fe2O3 A120S mation named the Tale Spring limestone, after 3. One and five-eighths miles N. 7° W. of Tule Springs, a typical locality in the northwestern part of the on north side of main ridge north of Tule Creek, 15 feet ceous strata rest directly on the Mississippian lime West end of quarry...... 57.50 37.60 0.8 1 8 0.4 quadrangle. The three principal exposures of this below the top: stones. It is rather an unconformity by erosion 56.00 36.00 1 0 fl 8 formation are at the head of Tule Creek, where Zaphrentis sp. than a profound structural break. Pure dolomite ...... 54.35 45.65 faunas of both the Mississippian and Pennsylva Cystodictya sp. Age and correlation. Fossils were found in a Rhipidomella cf. michelini. nian are present; at the headwaters of Whitewater Spirifer near S. peculiaris and S. subcardiiformis. calcareous sandstone overlying shale in a gulch Bed No. 4 in the first detailed section under Creek and about Granville; and in the limestone Spirifer keokuk. one-half mile southeast of the porphyry hill with lying the brown dolomite is very constant near bluffs on both sides of the canyon of lower Sar Syringothyris sp. bench mark 5175, 2^ miles south-southwest of Morenci, and is also developed at many other dine Creek, in the northeastern part of the quad 4. One-fourth mile N. 30° W. of Tule Springs, 150 to Morenci. The elevation is here close to 4000 places. The most northern locality where it- rangle. 200 feet below top of knob: feet. The fossil bivalves are well preserved and has been observed is on the divide, between The Tule Spring limestone generally forms bluffy Schuchertella insequalis ? some of the species are rather abundant. On this Knight Creek and Chase Creek. It consists of ridges with light-colored bluish-gray exposures of Chonetes loganensis. collection Dr. T. W. Stanton reports as follows: a hard, quartzitic sandstone, the grains being well heavy benches. The ridges generally slope west Productus Isevicosta. Spirifer centronatus. The fossils submitted include: rounded and cemented by calcite. The basal mem ward with the prevailing slight dip of the beds. ber of the formation is a heavy bed of bluish-gray The main spur of the western area on Tule The determination of faunas indicates that the Mactra sp. related to M. warreneana M. & H. Corbula sp. limestone which apparently does not contain much Creek consists of gray cherty limestone, the sili limestones about Granville and Mitchell's camp Cardium sp. dolomite. ceous brown and pink bands of which contain belong to the Mississippian series; that the west Astarte ? sp. Cyrena? sp. Age and correlation. TheModoc limestone is fos- brachiopods and corals. The next spur, forming ern part of this main area, just north of the bend Turritella sp. siliferous throughout, well-preserved species being the divide between Tule and Whitewater creeks, in Whitewater Creek is Pennsylvanian; that the Dentalium sp. found in the top, basal, and intermediate members. shows gray to dark-gray coarse limestone, locally northeast extremity of the western area, adjacent Glaucoma coalvillensis Meek. Tugnellus fusiformis Meek. The determinations by Dr. G. H. Girty show that cherty and containing several horizons of rich to Corral Spring, is Pennsylvanian; and that the the formation throughout belongs to the Mississip- faunas. At the south end of this spur the lime area immediately to the south of this and north of The last two species are characteristic forms of the stone overlies laminated brown sandstone, impure Tule Springs is Mississippian. The present posi Colorado group, and elsewhere are known only in the pian series of the Carboniferous system i. e., to the upper part of the Benton group and its equivalents. Lower Carboniferous. The determinations are as mottled maroon and olive limestone, and brown tion and structure of these areas fail to show any follows: shales of the Longfellow formation (Ordovician). division between the two series, nor do lithologic At the eastern side of Silver Basin, 1^ miles and stratigraphic characteristics indicate any divi southwest of Morenci, a great number of small 1. On the trail to Silver Basin, 1£ miles southeast of Below this and somewhat farther up the creek a Morenci, from coralliferous limestone, basal member of small area of the Coronado quartzite outcrops. sion, although it was specially sought in the field. specimens of Astarte n. sp. occur in the lowest hori Modoc formation: Fossils. The following fossils have been deter Accordingly, for the present at least, pending more zon of the Pinkard formation, almost immediately Rhipidomella michelini ? mined by Dr. G. H. Girty: detailed stratigraphic work, it is not practicable to above the basal member of the Modoc formation. Spirif er centronatus. divide the Mississippian and Pennsylvanian in this While these fossils afford no conclusive evidence as PENNSYLVANIAN SERIES. Serainula humilis. quadrangle. to age, there can be no doubt that the strata are 2. Section one-fourth mile south of Modoc Mountain, 1. One and one-half miles west of Grey Peak: equivalent to the fossiliferous horizon described CRETACEOUS SYSTEM. Morenci, from coralliferous limestone: Chsetetes milleporaceus. above. Notwithstanding careful search no fossils Zaphrentis ? sp. Zaphrentis sp. Productus cora. While the Jurassic and Triassic systems are have thus far been found in any other part of the 3. Gap 1000 feet south of Modoc Mountain, from cor Marginifera wabashensis. absent in this area, Cretaceous sedimentary rocks Pinkard formation. alliferous limestone: Spirifer cameratus. have been found in the vicinity of Morenci. Spirifer rockymontanus. Cretaceous and Jurassic strata are known from Zaphrentis sp. Squamularia ? perplexa. the Plateau Region of northeastern Arizona, Mr. Spirif er centronatus or S. forbesi. PINKARD FORMATION. 2. Three-fourths of a mile N. 5° E. of Tule Springs, E. T. Dumble recently discovered the Cretaceous 4. Eight hundred and fifty feet S. 18° E. from Modoc on nose of spur; elevation, 5980 feet. Occurrence and character. This formation con at Bisbee, and Mr. F. L. Ransome has described it Mountain, top of "Gray Cliff" limestone, No. 2 of first Fenestella sp. sists of a series of sandstones and shales of undeter more in detail in the text of the Bisbee folio; over detailed section: Schizophoria resupinoides White (non Cox). mined thickness, which, however, certainly exceeds 4000 feet of Cretaceous strata are here present, Orthis sp. Orthotetes robusta ? 200 feet. The best exposures are found in Silver Aviculipeeten sp. which are referred to as the Bisbee group and sub 5. Eight hundred and fifty feet S. 18° E. from Modoc Pseudomonotis kansasensis ? Basin Creek, 2 miles southwest of Morenci, and in divided into four formations. The upper surface Mountain, elevation 5100 feet, heavy blue limestone, Myalina apachesi. the Eagle Creek foothills, 4 miles distant in the at Morenci, as at Bisbee, is everywhere one of ero No. 1 of first detailed section : Pleurophorus sp. Lepetopsis ? sp. same direction. The gently upturned strata here sion and thus the original thickness is in both cases Lithostrotion ? sp. Bellerophon cf. crassus. surround an oval mass of diorite-porphyry, intruded unknown. From considerations of topography it Menophyllum sp. Bulimorpha chrysalis. in them. In the porphyry stock of Gold Creek Favosites sp. Phillipsia major ? is scarcely likely, however, that the total thickness Granatocrinus sp. many smaller and partly metamorphosed patches of at Morenci ever approached that at Bisbee. The 3. One and one-tenth miles ST. 6° E. of Tule Springs, Platycrinus sp. the same strata occur. Modoc Mountain at Morenci Bisbee group belongs certainly in part and prob Fenestella sp. west slope of knob just west of Corral Spring, 20 feet Schuchertella insequalis ? above basalt in creek bottom: is capped by a small area of the same strata, and a ably as a whole to the lower or Comanche series, Spirifer near Spirifer keokuk. somewhat larger mass is exposed on the ridge over while the Morenci Cretaceous is /referred to the Spiriferina sp. Monilipora sp. Productus inflatus. looking the head of Morenci Canyon on the south Colorado group, which belongs in the upper part 6. Spur If miles south of Granville, bench of corallif Productus nebraskensis. and west sides; it is here again intruded and partly of the Cretaceous system. At Globe and other erous limestone, elevation 6500 feet: Spirifer rockymontanus. Seminula subtilita. metamorphosed by porphyries. points in the interior of Arizona the Cretaceous Leptsena rhomboidalis. Dielasrna hastatuin. The lowest part of this formation consists of has thus far not been found. Spirifer centronatus. Aviculopecten sp. black shales which occupy considerable areas in Athyris lamellosa. QUATERNARY SYSTEM. Camarotcechia metallica. 4. On main trail from Tule Springs to Metcalf, on slope Silver Basin; the upper part is made up of- alter descending to Whitewater Creek, 25 feet above bottom nating shales and yellowish-gray sandstone, in No sediments of Tertiary age have been found. 7. Gap between Chase Creek and Knight Creek, ele of canyon; elevation, 5245 feet: vation 6500 feet, limestone, in part cherty: places calcareous. A section carried eastward The volcanic flows of that period apparently always Schizophoria resupinoides White (non Cox). from the top of the hill one-fourth mile south rest on a deeply eroded land surface. Strata of Schuchertella insequalis ? Squamularia ? perplexa. Chonetes loganensis? Aviculipeeten sp. west of the Morenci smelter shows the following Quaternary age are, however, extensively devel Spirifer centronatus. Monopteria sp. succession, the beds here being somewhat metamor oped, the most important formation being known Spiriferina sp. Myalina apachesi ? Camarotoechia metallica. Schizodus wheeleri ? phosed : as the Gila conglomerate. Pleurophorus sp. GILA CONGLOMERATE. As is well known, the Mississippian (Lower Phillipsia major. Geological section of Cretaceous sedimentary rocks southwest of Morenci smelter. General character and distribution. This name Carboniferous) series is extensively developed 5. On main trail from Tule Springs to Metcalf, at bot- Feet. throughout the West. At Globe, Ariz., Mr. Ran- of Whitewater Canyon, 500 feet east of trail: Top of hill; elevation, 5140 feet. was first applied by Mr. G. K. Gilbert to extensive some has found this series present in the upper Reddish hard shales, containing some epidote 50 and deeply eroded valley deposits extending along ScMzophoria resupinoides White (non Cox). Heavy light-gray quartzitic sandstones (with part of the Globe limestone, while at Bisbee 700 Productus cora. some interbedded shale)...... 50 Gila River from the mouth of the Bonito up into Aviculipeeten ? sp. Black, fissile shales...... 30 western New Mexico. Mr. Gilbert (Mon. U. S. feet of strata are referred to the same horizon under Myalina apachesi. Banded green and yellowish-brown shales.... 45 Geog. Surv. W. 100th Mer., vol. 3, Geology, 1875, the name of the Escabrosa limestone. Pinna? peracuta. Top of Modoc limestone at the base of the Bdmondia sp. series. p. 540) characterizes the formation as follows: TULE SPRING LIMESTONE. Allerisma? sp. Lepetopsis sp. Total...... 175 Thev bowlders of the conglomerate are of local origin, Occurrence and character. In the southern part and their derivation from particular mountain flanks is of the quadrangle and up to latitude 33° 10' the 6. Knob 13, 1.1 miles southwest of Grey Peak : On the trail to Silver Basin, 1^ miles southwest often indicated by the slopes of the beds. Its cement is Modoc formation, belonging to the Mississippian Fusulina sp. of Morenci, is an outcrop of the Morenci shales calcareous. Interbedded with it are layers of slightly Productus cora. series of the Carboniferous system, is the only covered by a thin bench of limestone, evidently coherent sand and of trass and sheets of basalt, the lat Productus inflatus. ter, in some cliffs, predominating over the conglomerate. terrane of that age known. But in the northern Spirifer cameratus. corresponding to the base of the Mississippian (the One thousand feet of the beds are frequently exposed, third 6f\the quadrangle fossils of the Pennsyl- MISSISSIPPIAN SERIES. coralliferous limestone, No. 5 in detailed section). and the maximum exposure on the Prieto is probably vanian (TJpper Carboniferous) series have been 1. Near Cabin Mitchell's camp, three-fourths mile Above this lie knotty arenaceous shales of greenish- 1500 feet. They have been seen at so many points by found in several places, and faunas of the Missis- j north of Grauville: gray color and a thin layer of yellowish limestone, Mr. Howell and myself that their distribution can be Clifton. 6 given in general terras. Beginning at the mouth of the in it without timbering) and is roughly stratified porphyries. The great warpings and dislocations Fresh rock is almost impossible to obtain, the best Bonito, below which point their distinctive characters by small streaks of sand. On the whole, the deposit followed these intrusions. being bleached and traversed by a network of are lost, they follow the Gila for more than 100 miles contains little sand and few indications of cross- quartz veinlets. Specimens from a railroad cut INTRUSIVE ROCKS. toward its source, being last seen a little above the bedding. The material consists of rhyolite, basalt, just south of King Gulch show on fresh fracture mouth of the Gilita. On the San Francisco they extend PORPHYRIES. 80 miles; on the Prieto, 10; and on the Boiiito, 15. granite, and porphyry, all subangular, the fragments pale greenish-gray color and contain closely massed Where the Gila intersects the troughs of the Basin attaining a diameter of 2 feet, but averaging about General character and distribution. The por dull-white feldspar crystals, at most 2 or 3 mm. Range system, as it does north of Ralston, the con 8 inches. Some of the material on top of the bluff phyries form an almost continuous series of light- in length. There are also well-defined bipyra- glomerate is continuous with the gravels which occupy seems better rounded than the rest. South of San gray acidic or predominatingly feldspathic rocks, midal quartz crystals several millimeters in diam the troughs and floor the desert plains. Below the Francisco River the same formation continues over ranging from diorite-porphyry through monzonite- eter, and sparingly represented biotite crystals Bonito it merges insensibly with the detritus of Pueblo the undulating foothills down to the Gila, but the porphyry to granite-porphyry. Between the last converted into chlorite. The groundmass is fine Viejo Desert. It is, indeed, one of the " Quaternary gravels" of the desert interior, and is distinguished from conglomerate becomes distinctly finer in size of peb two divisions no line can be drawn, but the diorite- grained, and now consists chiefly of sericite and its family only by the faut that the watercourses which bles. At Gila River the formation rests against porphyry occupies a somewhat more individual quartz; sericite has also largely invaded the feld cross it are sinking themselves into it and destroying it, hills of basalt and other lavas. position. spar phenocrysts, especially the orthoclase. The instead of adding to its depth. Mode of deposition. The Gila conglomerate is The area covered by intrusive porphyry on the feldspars consist partly of orthoclase and partly unquestionably of fluviatile origin. It was depos general map hardly amounts to 8 square miles. of sharply defined albite crystals. A partial anal The Gila conglomerate occupies about 30 square ited during an epoch in which the lower reaches of The rock is extensively developed in the Morenci ysis of this rock by Dr. W. F. Hillebrand gave miles in the southeast corner of the Clifton quad the rivers gradually lost their eroding and trans hills between Eagle Creek and Chase Creek, but the following percentages: Si() 2 , 69.13; CaO, rangle. It skirts the flanks of the Morenci hills porting powers, while disintegration progressed also reaches up from the canyon of the latter on the 0.22; Na 2 O,C 3.01; K 3 O, 3.94. and the southeastern slopes of Copper Mountain, rapidly in the mountains/' especially in the loose north and east flanks of Copper King Mountain. Besides a large amount of quartz the rock would attaining marginal elevations of about 4500 feet, masses of lava which then covered so much of this The principal area forms a stock extending with thus contain 23.5 per cent of the orthoclase mole the ridges sloping thence southward at a grade of quadrangle, and intermittently torrential streams jagged contacts for 7 miles in a northeast direction cule, 25.1 per cent of the albite molecule, and 1.1 100 to 200 feet to the mile until they abruptly brought down vast masses of the crumbling rocks. from the Eagle Creek foothills by Morenci to 1 per cent of the anorthite molecule. It is clearly drop off into the canyon of the San Francisco, 400 The climatic conditions were then probably very mile north-northeast of Metcalf, where it splits up a granite-porphyry, the large amount of individ to 500 feet deep. A long bay of this formation similar to those of the present time. into very numerous dikes, all having a northerly ually developed albite being especially notable. extends northward into the mountain area, follow The volcanic outbursts of the Tertiary took place or northeasterly trend. The northern half of this The stock at the head of Placer Creek is similar ing the western side of the river up to a point 10 under conditions of active erosion, the different stock and its dikes chiefly break through granite, in character, but the rock is fresher and contains miles north of Clifton, where it forms small patches flows being often deeply dissected before the erup while the southern part is surrounded by Creta more biotite as well as a little secondary epidote, a on basalt and rhyolite at elevations of 4500 feet. tion of the next mass. This epoch of erosion doubt ceous shales and sandstones, Cambrian quartzites, mineral which is absent in the porphyries of the The thickness exposed near Clifton is 600 feet, less continued for a short time after the close of the or Ordovician limestones, and breaks up into a Metcalf basin. Its presence indicates an approach while along the river canyon, due east of Copper igneous activity, for the Gila conglomerate was complicated mass of dikes and sheets near the to monzonitic and dioritic modifications. Many of King Mountain, it reaches almost 900 feet. Along deposited on an uneven and in places deeply dis point where the older rocks dip below the basalts the dikes east and west of Metcalf also belong to San Francisco River it does not extend more than sected surface. A deep and narrow canyon was which fill the valley of Eagle Creek. A narrow the granite-porphyries, though quartz-monzonite 25 miles north of the Gila. cut corresponding to the present San Francisco branch breaking through Cretaceous sediments con facies are more common. The material of which the Gila formation is River, with a course parallel, but about a mile nects this area with an oval mass of porphyry 1^ Petrography of the quartz-monzonite-porphyry. built consists almost exclusively of coarse suban- farther west. This course is clearly marked by square miles in extent and almost entirely sur The rocks of the great stock at Morenci and Gold gular gravels, appearing more or less distinctly the bay of gravels now cut across by Chase Creek rounded by slightly upturned Cretaceous sedi Gulch basin, together with many dikes, belong stratified by nonpersisting streaks or lenses of between Clifton and the Morenci foothills with ments. This mass is evidently a laccolith. Dikes to this type, which, as well as the preceding divi sand, and containing fragments of all the older out exposing the bed rock. So far as known, and rounded masses of the same rock occur in the sion, has a close structural and genetic connection rocks of the mountains. In most places basalts the Gila conglomerate has not been warped or gently rolling Cretaceous area east of the laccolith. with the ore deposits. Between Morenci and Met and rhyolites predominate, as is natural to expect dislocated by faulting in this area; though studies At Shannon Mountain and Morenci, where the calf quartz cementation and pyritic dissemination when we consider that at the time when these extended over a wider field may possibly modify porphyry adjoins Paleozoic strata, the latter, close are generally present and are often accompanied deposits were being accumulated a much larger these conclusions. No volcanic tuffs are inter- to the contact, contain a number of well-defined by extensive sericitization. In this area the out part of the quadrangle was covered by volcanic bedded with the gravels in this quadrangle. dikes. A persistent sheet of porphyry follows in crops are reddish or yellowish red and weather in flows than at present. Other rocks may, however, Age. No fossils have been found in the forma places the division plane between the Coronado irregular, craggy form. The rock is most typically locally preponderate for instance, below the area tion. Mr. Gilbert, followed by Mr. Ransome, who quartzite and the Longfellow limestone. Again, developed in the Gold Gulch basin, where miner- of porphyry a few miles southwest of Morenci, has described its occurrence in the Globe quadran in the western portion of the great stock, the latter | alization is slight or absent, although weathering where the gravels consist almost exclusively of gle, assigns an early Quaternary age to it and no breaks up. into a network of dikes and sheets, disintegrates it easily to a sandy yellowish soil coarse diorite-porphyry, often, indeed, difficult to evidence from this region conflicts with that con chiefly intercalated between the Ordovician strata. and slightly rounded outcrops prevail. Entirely distinguish from the deeply weathered outcrops clusion. North of Metcalf, in Garfield Gulch and at the foot fresh rocks are not easily found. Specimens from of the great lava masses of Malpais Mountain., are the divide between Gold Gulch and Morenci Can of the same rock. Along the lower part of Eagle TERRACE GRAVELS. Creek volcanic rocks are extremely abundant in the several smaller areas of porphyry, appearing as stock- yon are light colored, with fairly abundant green Gila conglomerate, and the dividing line between Small benches of terrace gravels appear at inter like masses in granite, but frequently changing to ish biotite foils up to 2 mm. in diameter; the feldspar this and the underlying basaltic and rhyolitic tuffs vals along San Francisco River and Eagle Creek, sheet intrusions where in contact with limestone. prisms of light yellowish-gray color are closely in places becomes indistinct. especially in the lower part of the stream courses. Summing up, it may be said that the porphyries massed and reach a length of 3 to 4 mm., while Along San Francisco River and Chase Creek Such sandy gravels are found on Eagle Creek in usually occur in the granite as stocks and dikes, the quartz phenocrysts rarely attain 2 mm. in erosion has in many places produced steep or nearly small bodies, 100 or 200 feet above the creek in while in the Paleozoic sediments they are apt to diameter and show no well-defined bipyramidal perpendicular bluffs, usually pitted by reason of its lower course' and 50 feet above the creek near take the form of sheets or sills. In the Cretaceous form. ' _'. the gradual weathering out of the larger pebbles. the northern margin of the quadrangle. Similar sediments again the tendency is to form laccolithic Under the microscope orthoclase, albite, and Where volcanic rocks predominate the conglom benches are found along San Francisco River; the masses, probably because of the lighter load and oligoclase, with an occasional crystal of labrador- erate is often well cemented and in many places Shannon smelter is built on one of them, which greater flexibility of the covering sediments. ite, are shown to be present. The plagioclastic along railroad cuts and tunnels it is even necessary is exposed 1 mile below Clifton, rising 60 to 100 The northeastern half of the principal stock, from feldspars often show fine zonal structure. The to blast it. feet above the water level. Several small remnants Morenci to Metcalf, consists of granite-porphyries groundmass is coarsely microcrystalline, consist From Morenci down to Clifton the gravels are of these terrace gravels occur along the river marked by porphyritic quartz crystals. Many ing of quartz and unstriated feldspar grains, roughly stratified and largely subangular; the peb between Clifton and Evans Point. These grav of the dikes, also, conform to this type. From with occasional octahedrons of magnetite. Seri bles rarely attain a diameter of 1 foot. Volcanic els, indicating a temporary check in the erosive Morenci nearly to the southwest end of the stock the cite is present in the feldspars, while chlorite rocks, granite, limestone, and quartz-porphyry are power of the stream, are much more recent than prevailing rock consists of monzonite-porphyry, has formed from the biotite; a little secondary mixed. They are not greatly consolidated, though the Gila conglomerate, and are referred to the containing quartz in the groundmass only; the epidote also occurs. A partial analysis of this forming small cliffs in places. The gravels contain late Quaternary. same is, as a rule, true of the dikes near Morenci, rock gave the following percentages: SiO.,, 69.30; a considerable amount of sand, but this, is intimately while the smaller areas inclosed in the mesh of CaO, 1.67; Na.2 O, 5.56; K 2 O, 2.39. ALLUVIUM. mixed with the coarse material and rarely occurs in altered sediments near the Eagle Creek basalts Similar porphyries make up the largest part of isolated streaks. The color of the Gila conglomer The most recent Quaternary formation is the generally consist of diorite-porphyry. Diorite- Copper Mountain and form the matrix of the chal- ate is reddish to grayish white, especially in places alluvium contained in San Francisco River and porphyry also makes up the great laccolithic mass cocite ore, but as a rule sericitization prevents exact where long-continued exposure has had opportunity Eagle Creek. Both streams are well graded and in the southwestern foothills and the dikes of that determination. to oxidize the iron. occupy a continuous strip of sandy bottom land, vicinity; it also appears in Garfield Gulch and One of the freshest porphyries obtainable in the In Ward Canyon the gravels rest against the in some places, however, only 100 or 200 feet near the head of Placer Gulch. mines at Morenci was collected in the first level of granite along a steep fault plane, and patches of wide. The alluvium along San Francisco River In short, it would seem that granite and mon the Ryerson mine, in the crosscut to the Welling gravel lie on the plateau 400 feet higher toward is ordinarily 400 feet wide, but increases to zonite-porphyry chiefly occur as stocks or dikes, ton vein, 100 feet north of the Ryerson stopes. the north, at an elevation of 4300 feet. These 2000 feet between Clifton and the mouth of while diorite-porphyry forms most of the sills, The rock is similar to the one just described, probably were once connected with the great table Ward Canyon. sheets, and laccoliths. though not quite so fresh. It shows the same of gravel south of the canyon, and this seems to Near Metcalf porphyry breccias occur both in the closely massed, small, usually striated feldspar Cretaceous and Tertiary Igneous Rocks. show that there has been no considerable disloca mass of the rock and along the granitic contact. prisms; the greenish biotite foils are here rather tion since their deposition. General statement. Aside from the basal pre- In the latter case the breccia often contains granite scanty; individual quartz phenocrysts are seen, but Along the main river the gravel bluffs begin Cambrian intrusive granite described above, there fragments and the contact becomes indistinct. the light greenish-gray flinty groundmass is more almost immediately below Clifton, where they rest is a second and much younger series of igneous Petrography of the granite-porphyry. As stated abundant. The feldspar phenocrysts consist of against granite and basalt and continue for many rocks which occur as stocks, dikes, sheets, and lac above, the north end of the great porphyry stock, albite and oligoclase, with some orthoclase. The 1 miles. Excellent exposures are seen 1^ miles below coliths in the lower Cretaceous, Paleozoic, and pre- from Morenci to beyond Metcalf, consists of granite- groundmass is fine grained and microcrystalline, the new Shannon smelter, especially on the west Cambrian formations. The time of their intrusion porphyry, forming a belt from 1 to 2 miles wide. with much quartz and orthoclase. Of secondary side. The sandy river bottom is here from 300 to falls between the middle Cretaceous and the middle Within this area the rocks are almost universally minerals sericite, chlorite, and pyrite are present 600 feet wide; in several places there are narrow Tertiary, but they antedate the Tertiary lavas, which affected by the introduction of quartz, pyrite, and in moderate amounts, but this does not seriously terraces of gravel, at most 100 feet above the creek. are spread out over their eroded surface. Porphy sericite. The yellowish or reddish-brown outcrops, alter the composition of the rock. As this speci The bluffs, which in places are almost perpendicu ries of granitic, monzonitic, or dioritic affiliations tinted by oxidizing pyrite, are apt to appear in men would seem to most closely represent* the lar, rise to a height of about 400 feet; the conglom predominate; diabase occurs in subordinate amounts extremely rough topographic forms, as is well prevailing rock of Copper Mountain, it was ana erate is well cemented (railroad tunnels will stand and would appear to be somewhat later than the shown at Metcalf near the mouth of King Gulch. lyzed, with the following result: 7
Analysis of quartz-monzonite-porphyry from Ryerson mine, orthoclase, the latter irregularly distributed within a considerable thickness of similar beds once cov The Cretaceous sandstones and shales on Modoc No. 211, Clifton collection. the small quartz grains. As usual, the biotite is ered the now exposed laccoliths how much, it is Mountain and on the hills south and southwest of [W. F. Hillebrand, analyst.] Per cent. converted into chlorite and some epidote, the latter impossible to say; the Cretaceous at the present Morenci are altered to quartzites and epidote- 8iOt ...... 68.04 also replacing some of the andesine; some calcite is time is only a few hundred feet thick, but as the amphibole schists, the latter of dark-green color ALO,...... 17.20 FeaOB...... 34 present in the groundmass and phenocrysts, but Bisbee beds exceed 4000 feet in thickness the pos and increasing size of grain as the porphyry is FeO...... 67 very little sericite was noted. sibility of solidification at a considerable depth approached. The Modoc limestone, as well as the MgO...... 1.05 Petrography of the diorite-porphyry. These rocks must be conceded. underlying dolomite, is most susceptible to change; CaO ...... 2.21 Na2 O...... 5.33 have usually a light-yellowish or greenish-gray Contact metamorphism. At the contacts of the a whole block of this formation extending from K S O...... 2.65 color, weathering to dull brownish yellow; they granitic, more rarely of the dioritic, porphyries, Modoc Mountain to the Copper Mountain fault H 8 O 100° ...... 60 H 2 O + 100° ...... 1.23 form rounded outcrops in a sandy soil, the abun certain changes have taken place in the adjoining has been almost bodily converted into a mass of ...... 41 dant detached fragments being generally also sedimentary rocks. Shales and limestones have calcium-iron garnet. The same applies to the ...... 01 rounded, but rather by disintegration than by CO...... None. suffered the greatest alteration, while sandstones exposure of the same formation in the next block P2 0 5 ...... 12 transportation. The Gila conglomerate below and quartzites are but little altered. The granite between the Apache and the Copper Mountain MnO...... 06 these porphyry hills consists nearly exclusively is not affected. These changes are of the char fault exposed south of the smelter. It is entirely BaO...... 10 SrO...... 03 of cobbles of the same rock. The diorite-por acter usually described as contact metamorphism, converted to garnet and epidote for 2000 feet from Li s O...... Paint trace? phyry, as stated on page 6, in most cases forms and extend from a few feet to about 2000 feet the contact, while the underlying shale and lime Vg O 3 ...... Faint trace. laccolithic masses in Cretaceous sediments, or from the contact. In limestones epidote, garnet, stones remain almost entirely unaltered. FeS, *...... : .24 Cu,S?*...... 02 sheets or sills, more rarely dikes, in the Paleozoic diopside, magnetite, chalcopyrite, pyrite, and zinc Next to the porphyry, bordering it for 1^ miles, ZnS?*...... :...... 03 strata, A common place of intrusion of these blende have developed, while in the shales tremo- lie more or less disturbed masses of Morenci shales MoO,...... None. sills is between the Coronado and Longfello\y for lite and epidote are the principal minerals formed. and Longfellow limestone. The shale is converted Total...... 100.34 mations. A specimen of this rock shows abundant A great mass of diorite-porphyry, apparently a to dense greenish rocks rich in epidote, amphibole, *0.14 per cent S; condition of zinc and copper problematical. prisms of white feldspar up to 4 mm. in length and laccolith, 1^ miles by 1 mile in size, is intruded in and pyrite, while the limestone contains garnet, A fairly large amount of CaO and a strong pre of narrow dark-green hornblende up to 1 cm. in the Cretaceous strata 3 miles southwest of Morenci. epidote, pyroxene, amphibole, specularite, magnet ponderance of sodium distinguishes this porphyry length, together with a few grains of black iron ore. The sedimentary rocks are very little altered at the ite, pyrite, chalcopyrite, and zinc blende, all irreg from that of the Metcalf type. A rough calcula These phenocrysts are embedded in a scant green contact; at most a hardening and some develop ularly massed and distributed. Garnet, however, tion shows the rock to contain the following: ish groundmass. In thin section the beautifully ment of epidote are noticeable. The same applies does not form large bodies, as in the Modoc lime developed feldspars prove to be a rather basic to the smaller areas of porphyry northeast of this stone. Smaller, less altered masses of limestone Proportion of minerals in quartz-monzonite-porphyry from Ryerson mine. labradorite with zonal structure; the hornblende is mass. One of them, one-half mile south of are sometimes contained in these areas. Per cent. of ordinary greenish-brown color, while the ground- Morenci, forms the top of a hill and apparently The almost entire absence of biotite, muscovite, Orthoelase molecule...... 16 Albite molecule...... ;...... 45 mass consists of small, thick, rectangular prisms, in rests on Cretaceous sediments, shales, and sand and feldspars among the contact-metamorphic min Anorthite molecule...... 10 part orthoclase; between these is a still finer micro- stones, .which are reddish and in places contain erals is notable. Biotite...... 6 crystalline mass of unstriated feldspar and quartz. much epidote, but are otherwise not much altered. From Morenci to Metcalf the porphyry stock Quartz...... 22 Titanic iron ore...... 1 Small amounts of chlorite and epidote are present, The metamorphism becomes more intense farther borders against granite, but at the latter place a Total...... 100 but no pyrite. A partial analysis gives the follow north, and appears to be due to the vicinity of the small area of the Paleozoic series directly adjoins ing percentages: SiO 2 , 61.20; CaO, 5.11; Na 9 O, contact of the main stock. Along the Eagle Creek the granite-porphyry and is cut by several dikes While exact data can not be obtained, the rock 5.70; K 2 O, 1.35. foothills north of Gold Creek diorite-porphyry projecting from it. The phenomena described at probably contains equal quantities of orthoclase Typical specimens of the porphyry from a point again prevails and contains many slab-like inclu Morenci are here repeated. Practically the whole (mostly in groundmass) and albite, aggregating 38 1 mile north of the place where Gold Gulch enters sions of Ordovician limestone of various sizes, but area is affected by the alteration. Chalcopyrite per cent, against 24 per cent Ab 2An. It would the Eagle Creek basalt flows conform exactly to at the contacts of these practically no alteration and pyrite form abundantly, together with garnet, thus represent an almost typical quartz-monzonite- the above description. This porphyry forms a is visible. The same applies to the long sill of pyroxene, and epidote. The small downfaulted porphyry, if the relation of granular rocks as complicated stock-like intrusion in the Longfellow diorite-porphyry intruded all along the contact limestone area at the mouth of Garfield Gulch is defined by Professor Brogger is applied to their limestone. In reality it is probably a sheet with between the Coronado quartzite and the Long unaltered, except where a little epidote and mag porphyries. Dikes of similar porphyries fresh many intercalated and parallel strata of limestone. fellow limestone, and to the little stock of the netite appear in the immediate contact of the small enough to be determined were noted from the Entirely similar are the rocks from one of the small same rock which occupies the basin of Garfield dikes of diorite-porphyry traversing it. Longfellow mine and from the stope level of the laccolithic masses in Cretaceous strata 2 miles south Gulch north of Metcalf. The stock of quartzose porphyry at the head of Copper Mountain mine at the head of the incline. west of Copper Mountain, and the large laccolith 3 From all this it appears that the diorite-por Placer Gulch has exerted a somewhat capricious A gradual increase in calcium, iron, and magne miles south-south west of Copper Mountain conforms phyry exerts a very slight action on the surround alteration. While the limestone adjoining on the sium brings us to another series of quartz-monzo- to the same type. ing sediments, whether they be limestone or shale. north is not noticeably altered, the many small nite-porphyries, similar in appearance to those just The porphyry from the small stock on Garfield Very different conditions obtain at the contacts inclusions of the same rock in the southern part of described except that hornblende sometimes occurs Gulch at the Mammoth mine is perhaps rather a of the quartz-bearing porphyries, mainly quartz- the stock are partly converted to epidote and mag with the biotite and the fine-grained flinty ground- monzonite-porphyry. It is slightly brownish in monzonite-porphyry and granite-porphyry. The netite, and frequently show copper stains. The mass is of a darker-greenish color. Quartz is not color and contains abundant small and well-defined Cretaceous strata which cross' Gold Creek in long dike traversing limestone near the head of present as phenocrysts. This kind of porphyry is crystals of a triclinic feldspar well filled with seri irregular masses, deeply indented and torn by the Sycamore Gulch has changed the rock but little, not represented in the great stock, nor in any cite and calcite, probably andesine, together with porphyry, are decidedly altered. The shale and epidote appearing only in places. other large areas, but is common among the dikes. pseudomorphs of epidote and chlorite after horn fine-grained sandstone are very much hardened, The stock at the head of Silver Creek, near the To this class belong some dikes in the second level blende in a microcrystalline groundmass of unstri becoming sometimes even flinty and of black or northern margin of the quadrangle, is composed of of the Arizona Central mine at Morenci, one occur ated feldspar and quartz. dark-green color. They contain a little epidote, diorite-porphyry and has not changed the sur ring near the breast of the Hudson crosscut and The porphyry stock on upper Silver Creek, pyrrhotite, and pyrite, besides more or less green rounding -rockv the other on the northwest wall of the Arizona northeast of Malpais Mountain, is a normal dio hornblende, which has developed in the mass of The general mode of occurrence of this peculiar Central vein, 200 feet northeast of the shaft. Both rite-porphyry of light color and similar to the typi the shale and in the cement of the sandstones. In alteration decidedly forbids its classification with are grayish-green porphyries with small and closely cal specimens described above. places the sandstone has acquired a quartzitic either regional metamorphism, common hydro- massed but inconspicuous feldspar crystals. The Fine-grained dark-green (melanocratic) porphy appearance, but withal the alteration does not metamorphism, or hydro thermal metamorphism. rectangular prisms consist chiefly of andesine; there ries do not occupy large areas. A specimen col compare in intensity with that suffered by the The determining factor is evidently the presence are a few small quartz grains and fairly abundant lected 2 miles southwest of Copper Mountain, near Paleozoic limestones. of a quartz-bearing porphyry and there need be prisms of hornblende; the groundmass is micro- the contact of the great stock with the Cretaceous At the mouth of Pinkard Gulch, where the no hesitation in referring these changes to contact crystalline, fine grained, in places micropoikilitic, rocks on the south side, is of this kind and con Ordovician shaly limestone is greatly cut by dikes metamorphism. and evidently contains orthoclase. Of secondary tains many slender hornblende needles. Under and masses of porphyry, some of the included DIABASE. minerals epidote and pyrite are the mOst promi the microscope these prove to be of pale-green masses are almost wholly converted to epidote, nent. color and partly altered to bastite, while the with magnetite and garnet; copper stains are Distribution. A. dark-green medium-grained The long and prominent dike extending south groundmass consists of long prisms of feldspar, abundant, and many small prospects have been rock, which proves to be diabase, occurs at ward from Modoc Mountain consists of a similar probably labradorite, together with small needles opened. Between this place and the Soto mine, widely distant places in scant development as rock. The abundant phenocrysts are andesine of hornblende and a little magnetite. This t}^pe where Gold Creek crosses the Soto fault, which dikes and, more rarely, as sheets. Occasional and oligoclase, with some orthoclase. The ferro- probably belongs to the dioritic lamprophyres. separates Ordovician limestone from granite, the dikes are found in the Gold Creek basin in magnesian silicates are mostly decomposed, one The diorite-porphyries rarely contain copper same phenomena are repeated; garnet and epidote monzonite-porphyry; at the Virginia, Trinidad, prism of hornblende, now converted to chlorite ores and seldom pyrite; chlorite, much epidote, occur abundantly at the contacts and also along Brunswick, and Garfield mines, at or near Gar- and epidote, being noted. The groundmass is calcite, and a little sericite are the principal sec certain strata. But the alteration is not always field, in granite; at the Coronado mine between microcrystalline, consisting of quartz and unstri- ondary minerals. extensive and some limestone masses seem to have granite and quartzite; and in the lower part of ated feldspar. Some sericite and much epidote Age. It is not possible to separate on the map escaped almost entirely. Sycamore Creek as an intrusive sheet or horizon are present, the latter here and there replacing the different classes of porphyry described above For 1 mile northeast and southwest of Morenci tal dike in granite. In no place are the dikes whole feldspar crystals. except by artificial lines. Beyond question they the stock of quartzose porphyry abuts against more than 100 feet wide, and usually they are Many dikes east of Chase Creek also belong to solidified from one magma, intruded about the the whole sedimentary series, which is less cut up much less. They are connected with a class of this class for instance, that which is followed by same time. While it may not be advisable to by the intrusions than in the Gold Creek basin. fissure veins carrying copper, but it is only a the Copper King vein. draw too wide-reaching conclusions from the data, Alteration has developed on a large scale; over an small division, containing as its most important Under this heading may also be described an it would seem as if the deeper parts of the magma average distance of 1500 feet from the contact the representative the Coronado vein. In develop unusually fresh dike rock from the Montezuma were the more acidic, while the upper and mar sedimentary rocks are greatly transformed, in places ment and interest the diabase of the Clifton .dis mine, Morenci, Waters shaft level, 135 feet ginal parts more nearly approached dioritic types. to a width of even 2000 feet. There is very mate trict is far inferior to that at Globe, Ariz., described northwest of the main vein. In thin section it The magma invaded the upper crust after the dep rial difference in the manner of alteration of the by Mr. Ransome. shows well-defined and abundant. phenocrysts of osition of the Cretaceous beds (equivalent to the various strata. Dikes both inside and outside of Petrography. The freshest rock is;.exposed in andesine up to 2 mm. in length, while there are Benton), and the probably late Tertiary lavas flowed the altered zone are followed by bands of meta Sycamore Gulch, where there are no copper depos few, if any, orthoclase crystals. Both hornblende over their deeply eroded surface. Hence their morphosed rocks. The alteration shows no depen its connected with it. The rock forms dark-gray and biotite, with a few grains of black iron ore, are eruption may be safely placed in the latest Cre dence upon fissures or veins, the only factor which rounded outcrops and is a typical medium-grained present. The groundmass is microcrystalline, con taceous or in the earliest Tertiary. The magma seems to have any influence being the proximity of diabase, composed chiefly of'labradorite. and augite, sisting of quartz and minute prismatic crystals of invaded Cretaceous beds, and it seems certain that intrusive bodies. with normal diarbase structure. Clifton. 8
The Coronado vein follows in part of its course cisco River, poured down westward, covering the Creek. The thickness of the flows amounts to bluff a few hundred feet high on the west side, but a diabase dike up to 70 feet wide, but the rock is upper basin of Eagle Creek, and, narrowing down 800 feet on Malpais Mountain and on lower Eagle is soon covered by the white tuffs of the rhyolite usually greatly altered. A specimen from a small to a thinner stream, filled the lower basalt canyon Creek, while on Enebro Mountain it somewhat of San Francisco River. vein 200 feet above the Horseshoe shaft and the of Eagle Creek. Renewed Quaternary erosion has exceeds 1000 feet. The Sunset flows of basalt appear in flat-topped same distance south of the main vein is fairly fresh reexcavated the trench, but along its steep buttresses The Malpais flows form flat-topped ridges with ridges, sloping eastward and bordered by steep and is a typical fine-grained diabase. Although enough of the rhyolite tuff remains to show the yellowish-gray outcrops, often showing well-marked bluffs in which several superimposed flows are much augite still remains between the feldspar former configuration of the canyon. bedding and at a distance being easily mistaken discernible. The outcrops are black to reddish prisms, most of it is converted into chlorite. The for limestone beds. The slopes are almost invari brown. The rock is very fine grained, dull black, feldspar contains some sericite. A little pyrite is RHYOLITE. ably steep and bluffy, sometimes breaking into and often extremely scoriaceous; the dark-brown also present. Rocks from the dike along the main Clifton flows. The light-reddish or pink bluffs perpendicular cliffs. These characteristics are most olivine crystals are plainly visible. In the prin vein are dull dark green and very much altered, which rise to a height of 400 feet east and west of pronounced along lower Eagle Creek, where bed cipal areas it forms a typical basalt, holocrystalline showing lath-like sericitic feldspars, chlorite replac the river at Clifton consist of rhyolite which rests ding and vertical jointing combine to produce ero rather than glassy, but the lower flows sometimes ing augite, and leucoxene replacing ilmenite. on granite and is covered by basalt, andesite, and sion forms of picturesque and striking appearance. present facies connecting them with the andesites, The Black lode follows a diabase dike up to 40 the Gila conglomerate. The bluffs reveal at least By far the larger part of the Malpais flows are and the line between the two groups may be very feet wide, similarly altered; the other occurrences two thick flows, which are gently inclined north composed of tuffaceous rocks in which the bedding difficult to draw. mentioned in the preceding section are also of the ward, but the difference between them is only is well marked, sometimes strikingly so, as along Mulligan Peak, northeast of Clifton, is built up same type. slight. The rocks show a light-reddish ground- Eagle Creek, where the beds dip 7° to 9° E. West of flows which probably also belong to this divi Age. As a dike of diabase breaks through por mass with abundant small feldspar crystals and of Malpais Mountain the initial dip is 7° W., and sion. Its black pyramid rises conspicuously 500 phyry in Gold Creek basin, 2 miles due west of I scattered biotite foils at most 3 mm. in diameter. in the main area north of Knight Creek the slope feet above the plateau of andesite and doubtless the railroad station at Morenci, it seems likely that The porphyritic feldspars, which are generally not is 7° to 10° N. or NW. represents a local eruptive vent. It is built up of the diabase is somewhat later than the porphyry, well-developed crystals, are chiefly oligoclase. The The rock is soft, usually light reddish or pink, many northward-sloping flows, beginning with but it is not probable that the times of their erup felsophyric groundmass, banded or streaked and in weathering to a pale yellowish brown, and contains dark, fine-grained, vesicular basalts with inter tion differed much. part spherulitic, contains many small, irregular in a porous and earthy matrix of rhyolitic character calated beds of black or dark-brown agglomer grains of quartz. A partial analysis by Mr. a great number of angular fragments of lithoidal, ates, and is capped by a black flow of olivine-basalt RHYOLITE, BASALT, AND ANDBSITE DIKES. George Steiger of a rock collected near the rail more rarely glassy, rhyolite. The fragments are related to olivine-andesite, containing many pheno- Dikes of rhyolite, basalt, and andesite are road station at Clifton gave the following per seldom more than a few inches in diameter. In crysts of plagioclase 1 cm. long. described with their effusive equivalents under the centages: SiO 2 , 67.38; CaO, 1.55; Na 2 O, 2.16; places, especially near the bottom of the series, Under this heading may also be mentioned a heading "Tertiary lavas," following. K 2 O, 5.96. This indicates that the rock is a basalt fragments become abundant, and actual very straight and conspicuous dike which, with an rhyolite, although affiliated with the dacites and transitions to basaltic tuffs may be thus formed. east-west direction, cuts across the granite on the TERTIARY LAVAS. the trachytes. At many points normal felsophyric rhyolite in northwest side of Limestone Gulch. It consists of General statement. North of Clifton the Tertiary So far as known this rhyolite, which covers com large irregular masses is mingled with the tuff and a dark-gray, medium-grained olivine-basalt with lavas cover enormous areas. The southern edge of paratively small areas, is the oldest of the extru tuff-breccias for instance, on the spurs of Mal holocrystalline diabasic structure. the great lava fields, which probably extend north sive Tertiary lavas. Besides the bluffs mentioned pais Mountain, on Enebro Mountain, and in Chase Prieto flows. The latest eruptions of basalt have ward for 100 miles or more, is in the central part above, the white tuffaceous flows which cover the Creek 1 ^ miles southeast of the latter peak. Mass been comprised under the general name of the of the quadrangle, a few miles north of Metcalf. limestone west and south of Mulligan Peak and ive rhyolite, associated with tuffs, is also embedded Prieto flows, named after the Prieto Plateau, north In addition, the same eruptive rocks practically which in turn are covered by basalt belong to as small individual flows in the basalt of Eagle of Sardine Creek. They cover two large areas, cover the eastern side of the valley of San Fran this division. Thin flows of the same rhyolite Creek just south of Coronado Ridge. Large dark- the first occupying the whole of the most northern cisco River down to the latitude of Clifton and are embedded in the superjacent basalt south of gray masses of a pure rhyolite glass are found part of the quadrangle and extending down to almost the whole valley of Eagle Creek down to Mulligan Peak and north of Limestone Gulch. mingled with felsophyric rhyolite near the summit Malpais Mountain and Garfield Gulch. Minor Gila River. Within the central parts of the San Francisco flows. Rhyolitic flows appear of Enebro Mountain and on the southwest slopes areas are exposed below the rhyolite north of mountains, where the copper deposits occur, they again on San Francisco River north of Evans of Malpais Mountain. At Grey Peak 75 feet of Knight Creek. The second area, which in all are almost absent. In some places erosion may Point, where they cover the early basalt and basaltic breccia resting on basalt form the ( base probability is of contemporaneous origin, covers have removed them, but it is not likely that they andesite and are in turn covered by the thick ment upon which lies a mixed breccia of basalt the whole southwest corner of the quadrangle to ever covered the domes of Coronado and Copper basalt of the Prieto flows. Two smaller areas lie and rhyolite, which finally passes into normal the foot of the Coronado Ridge and the Morenci King mountains. Their age can not be determined on the east side of the river, but the principal banded and partly glassy rhyolite. hills. A maximum thickness of 2000 feet is with exactness, but many considerations point to development is on the west side; the area grad Well-defined dikes of rhyolite of moderate width observed on Sardine Creek and the southwestern the late Tertiary as their time of eruption. Cop ually widens toward the north and near the cut the basalt ridges south of Malpais Mountain mass of basalt is probably equally thick. Toward per deposits do not occur in them. They have boundary line of the quadrangle the rhyolite occu and the granite of Hickory, Colorado, and Dor- Malpais Mountain and Knight Creek the thick suffered very little from the great faulting move pies the whole .valley, extending from the foot of sey gulches on the slope toward San Francisco ness diminishes to a few hundred feet. Wherever ments, which in the main must have preceded the Prieto escarpment across the river and for sev River. Their direction is generally northwesterly. not too deeply modified by denudation, the later their eruption. eral miles eastward beyond the boundary. The Another dike of rhyolite, 75 feet wide, extends basalt tends to form level or ploping ridges bounded Succession. A repeated series of deposits of thickness also increases from 100 or 200 feet at northwestward from Grey Peak and breaks through by steep erosion slopes upon which the individual rhyolite and basalt, with subordinate andesite, Evans Point to 1000 feet on lower Sardine Creek. the basaltic flows. flows are distinctly outlined. The color of the characterizes the Clifton volcanic series. The A prominent bluff on the north side of Hack- The lava probably issued from many points, outcrops is characteristically black, contrasting first eruptives were rhyolites, massive and tuffa- berry Gulch consists in part of massive felsophyric Malpais and Enebro mountains being the most strongly with the light-buff colors of the rhyolitic ceous, which now form the reddish bluffs on both and partly glassy rhyolite, and is evidently a local prominent loci of igneous activity. Enormous vol tuffs, and changes to dark brown or reddish brown sides of the town of Clifton. The rhyolite was focus of eruption. Over the largest part of the area umes of wat&r must have accompanied the erup only where agglomerates or very vesicular rocks covered with black, fine-grained basalts, over the rock is a light yellowish-gray tuff, with abun tions. The fragmental rocks caused by successive form a part of the series, as commonly happens which poured out heavy sheets of gray or brown dant small and angular fragments of felsophyric explosions mingled with the water, descended the near Malpais Mountain, or in the narrow strip pyroxene-andesites, sometimes containing olivine. rhyolite and occasionally scoriaceous basalt. It flanks of Enebro Mountain, and filled the valley exposed below the rhyolite north of Knight Creek. This is well exposed in the bluff northeast of Clif is entirely similar to the later tuffs of the Mal of Eagle Creek as a succession of mud flows. The Massive flows predominate; volcanic tuff-brec ton. A few miles farther north, on the river, this pais flows. The outcrops form yellowish-gray domes of Coronado and Copper King mountains cias or agglomerates are present, however, in the is covered by thick flows of scoriaceous basalt, bluffy ridges, in which the several flows are were clearly not covered by these eruptions, nor lower part of the series near the underlying rhyo having their origin somewhere near Sunset Peak often distinctly indicated. Toward the upper were the Morenci hills flooded by them. lite tuff of lower Sardine Creek and Pigeon Creek, and thinning out very much along the river. limit the basaltic detritus in the tuff increases at the western base of the Coronado Ridge and the A second eruption of rhyolite took place, this rapidly, and the line of division between the BASALT. Morenci hills, and at a few other places as subor time in the form of light-yellowish or brownish two series of flows north of Sardine Creek can Clifton flows. At Clifton, as well as on the dinate intercalated flows. The thickness of indi tuff breccias. Most of these seem to have flowed not be exactly drawn. The rhyolite tuff grad hills south of Mulligan Peak, the rhyolite is directly vidual basalt flows averages about 30 feet, although down from the upper river, 10 miles north of Clif ually changes into a basalt tuff or tuff-breccia, covered by flows of basalt, best exposed on the some may greatly exceed this figure. In the north ton, but there was also one local eruption of mass and at an elevation of 4500 or 5000 feet the mass bluff at the junction between the river and Chase west corner of the quadrangle, on the abrupt slopes ive rhyolite near the mouth of Hackberry Gulch, ive basalt flows begin. Similar conditions exist Creek. It rests upon the sloping surface of rhyo of a flat ridge toward Eagle Creek, fourteen indi a few miles north of the town. on Pigeon Creek, along the northern boundary of lite, and is in turn covered by andesite. A thin vidual flows may be counted, and many more are This eruption was succeeded by numerous basalt the quadrangle, where 100 feet of mixed tuffs sep bed of rhyolite tuff is intercalated in it south of exposed in the prominent escarpment north of Sar flows, aggregating 1500 or even 2000 feet in thick arate basalt and rhyolite at elevations of 5500 feet. Mulligan Peak, just as on Limestone Gulch a flow dine Creek. The individual flows may show a ness, well exposed by the deep trench of Sardine The tuff flows have a dip of 7° to 10° NNW. or of basalt is contained in the upper part of the rudely columnar jointing, rarely, however, of Creek. These basalts also show in dark-brown NW., changing in the southern part of the area, rhyolite. The greatest thickness of the Clifton striking regularity. Excellent instances of curved Outcrops on the north side of Garfield Gulch, along San Francisco River, to WNW. flows of basalt is about 300 feet. and twisted joint planes, such as are often seen though they are there only about 300 feet thick; Malpais flows. The most extensive rhyolitic The rock is a compact, dull dark-gray to brown near loci of volcanic eruptions, were observed they also form the basement of Malpais Mountain. flows of the quadrangle succeeded the principal ish-gray, fine-grained basalt containing in places along Eagle Creek, \\ miles north of the pump To the same epoch belong probably also the basaltic eruption of basalt and covered its deeply eroded large and well-developed crystals of olivine. In station. Smaller flows of rhyolite are sometimes flows which form the whole southern valley of surface. The eruption of this rhyolite, which for most of the outcrops a considerable amount of fer intercalated in the basalt, as shown, for instance, Eagle Creek and the high ridges west of it. A convenience will be designated the Malpais flows, ric oxide has developed. along Eagle Creek south of the west end of the considerable epoch of erosion followed the second closed the Tertiary epoch of igneous activity. Sev Sunset flows. The second outburst of basalt fol Coronado Ridge. Thin basalt flows are interca great basaltic eruptions; Eagle Creek excavated its eral smaller areas occupy Malpais Mountain and lowed the andesite of Hackberry Gulch, and was in lated in the later rhyolite tuff on Whitewater canyon to a depth at least as great as it has attained the ridges west and north of it; the largest area lies turn covered by the rhyolite of San Francisco Creek, 2 to 4 miles west of Granville. at present, and the northern basalt hills were deeply in the northwestern part of the quadrangle and River. Its flows, which have a maximum thick As revealed by the microscope the structure trenched. extends from Enebro Mountain westward down ness of 500 or 600 feet, descend over the slopes of the basalts of the Prieto flows is monotonous After this came the third and last great rhyolite to Eagle Creek and for many miles west of the of the andesite from the vicinity of the high vol and offers few points of interest. They are almost eruption, which appears to have originated from boundary. A partly eroded branch follows Eagle canic point of Sunset Mountain (elevation, 6977 without exception normal olivine-plagioclase-basalts the high points near Malpais Mountain and the Creek Canyon down to the southern boundary of feet), 3 miles east of Harper ranch, and extend of fine grain, with a strong tendency to holocrys summits near the head of Whitewater Creek. The the quadrangle, and fills a trench deeply cut in the down to the river; the largest area lies between talline diabasic-granular structure. A little glass yellowish-gray masses of tuff breccia, similar to basalt flows. A small remnant of the rhyoiitic the river and the eastern margin of the quadrangle. is, however, very commonly present, pressed in those of the second rhyolite eruption in San Fran flows covers Grey Peak, north of Whitewater It crosses the river at several places and forms a between the pyroxene grains and feldspar laths, 9 producing what is known as intersertal structure. result of this movement, with which faulting intensity, after the outbursts of the Tertiary lavas. an elevation of 7200 feet, and the strata dip away Many of the rocks from the northwest corner of was probably associated, we have little informa The influence of this epoch upon the topography gently to the northwest, so that in the limestone the quadrangle are, however, rather coarse and tion, owing to the fact that the bedding is largely of the region is very strikingly marked. area on Tule Creek the elevation of the lower part entirely holocrystalline. Basaltic glasses are very obliterated. It is certain, however, that it affected Dips and strikes of the beds. Gentle westerly, of the Tule Spring limestone is 5000 feet; this rarely observed. In the southwest corner of the a considerable part of Arizona, for similar schists northwesterly, or northerly dips averaging 15° would correspond to an average dip of 6° or 7° quadrangle normal basalts likewise prevail, but are found at the Grand Canyon, at Globe, and at prevail over practically the whole quadrangle in NW. The block is broken by several small dis transition forms to andesite with phenocrysts of Bisbee. In the area at the head of Chase Creek the Paleozoic beds. In the northerly area on Tule locations, but probably none of large size. feldspar are also present. The points of eruption stratification is fairly well preserved, and the strata and White water creeks dips range from 10° to The Coronado block slopes gently westward. from which these enormous masses of basalt issued stand usually at steep angles, with a northeasterly 15° NW., changing about Granville to almost due At the eastern side of Coronado Mountain the are not definitely located. strike. The superimposed schistosity, which is north. South of Enebro Mountain they are 14° base of the Cambrian quartzite is at an elevation of more clearly indicated than the bedding, is also to 20° NW. On Coronado Mountain they trend 7000 feet, while 6 miles farther west, just outside AKDESITE. steep, but its strike diverges decidedly from that west, northwest, or north and amount to from 8° of the quadrangle, the same contact is at an eleva There were two distinct eruptions of andesite of the bedding. It is worthy of note that at no to 20°. The large blocks between the Coronado tion of about 4300 feet, giving again a dip of 6° or within this quadrangle. The earlier andesite later period have any of the rocks of the quadran fault and the porphyry stock show dips averaging 7° W. On the northern and southern slopes of occupies an area of about 6 square miles, which gle been affected by regional metamorphism pro 17° due west, although local irregularities occur, in Coronado Mountain small patches of quartzite lie extends from Clifton beneath Mulligan Peak north ducing schistosity on a large scale. ward along the river up to a point northeast of The intrusion of granitic magmas into the sedi Harper ranch. It covers the Clifton flows of ments was undoubtedly accompanied by violent basalt and is in turn overlain by the basalt of the ruptures, and the contact lines of schist and gran Sunset flows. The andesite forms sloping ridges, ite are probably determined by these dislocations. of dark-brown, sometimes dark-gray, color, in In the present case the schists may very likely which individual thin flows are much more rarely occupy a large area in the northern part of the observed than in the basalt. The exposed thick quadrangle underneath the volcanic flows. ness of the flows is probably not over 600 feet, v .0'','^ '''" 'v -y- 'V~^Y^Y.;-)C-Yi;Yv and their general slope is westward. North of MOVEMENTS DUE TO THE INTRUSION OF THE Limestone Gulch a subordinate flow of rhyolite PORPHYRIES. ;/ ^&ff#v'.'vv'. : ; «:> tt .; '-f <>YC-V ^mfattx- is intercalated in the andesite. During the unbroken period of sedimentation In many parts of the area the rocks exhibit a from the Cambrian to the Carboniferous the strata '''''''''-'-' close affiliation with basalts and occupy in fact an remained horizontal. The unconformity between - intermediate position. The color in specimens is Cretaceous and Carboniferous is not strongly reddish or reddish gray and small phenocrysts of marked and, during the deposition of the former, feldspar crystals ',.p to 5 mm. long are usually the older strata preserved an approximately hori visible in the dense groundmass. Pyroxene- zontal position. The first marked disruption of andesites predominate and some contain olivine, the stratified formations, which were at least 1500 although in the extreme northern part of the area feet thick and probably much more, for the orig there are biotite-andesites, in which the feldspar inal thickness of Cretaceous sediments is in doubt, crystals attain a length of 8 mm. The ground- occurred at the intrusion of the porphyry. That mass is hypocrystalline, with relatively small this movement was most violent can not be doubted, amounts of glass and a predominance of feld for a body of magma 7 miles long by 2 miles wide spar laths and small grains of pyroxene. At could not be intruded in the basement granite and many places it shows a distinct basaltic character. overlying sediments without seriously affecting the The later andesite is of a more distinctive type position of the latter. The magma, which prob and occurs as dikes and smaller intrusive bodies ably did not reach the surface, must have bulged in the Prieto flows of basalt northwest and south the uppermost Cretaceous strata; it certainly dis east of Tule Creek. One of the dikes, which is 20 located the Paleozoic rocks extensively, injected feet wide, straight, and very sharply defined, is con itself between the beds, and tore large parts away tinuous for 1^ miles west-northwest of Tule Creek. from the edges of the fractured masses. A most It intersects basalt and Tule Spring limestone, but important structural line was determined by this is overlain by rhyolite. intrusion. The direction of the stock was north The rocks are very similar in all exposures and east and the dike system at its north end, as well show a black to dark-gray, very fine-grained as the mineral lodes formed later, followed the same groundmass, in which lie embedded scattered phe strike. Certain prominent fissures with northeast nocrysts of small, fresh feldspar laths and slender strike, soon to be filled with cupriferous minerals, hornblende needles. The microscope shows phe were opened shortly after the intrusion. Some nocrysts of labradorite and long prisms of dark- what later began the principal faulting movements, brown hornblende, more rarely hypersthene, in a the general results of which consist in a settling and hypocrystalline trachytic groundmass, chiefly con breaking down of the edge of the mountains toward sisting of slender laths of andesine or labradorite the Gila Valley. and often showing fluidal structure. Fragments of granite engulfed in the porphyry are seen near Metcalf, both east and west of Chase GEOLOGICAL STRUCTURE. Quaternary Intrusive Pre-Cambrian Creek. Similar partly or wholly isolated fragments gravels. porphyries. granite and schists. GENERAL CHARACTERIZATION. of the Paleozoic series are found at the contacts at FIG. 2. Generalized geologic map of Clifton quadrangle, showing the major faults. Metcalf and at Morenci. In Gold Gulch irregular Arrows show dip and downthrown side of faults. Under the designation "structure" are described masses of both Cretaceous and Paleozoic rocks are Scale, approximately, 1 inch--2 miles. those changes of position which sedimentary or in like manner embedded in the intrusive rock, part probably produced by the intrusion of por on the curved surface of the granite, with divergent igneous rocks have suffered by the intrusion of which had a tendency to inject itself between the phyry. Exceptional westerly dips of 37° were dips up to 20° (see areal geology map), showing noted in the Devonian at the extreme west end that the granite itself, the fundamental rock of the magmaso or byv more Ogradual earth movements,* planes of stratification and form sills and lacco including warping, doming, folding, and faulting. liths. Near the foothills of the Eagle Creek of the Coronado fault. Blocks south of Morenci block, has been deformed in dome-like shape. The movements of this order which have taken basalts several parallel thin slabs of limestone dip 8° to 20° WSW. or more rarely SW. Between the two blocks is a structural depression place in the Clifton quadrangle may be divided as up to one-fourth mile long lie inclosed in diorite- Along the eastern side of the quadrangle similar in which several smaller blocks of the Paleozoic follows: porphyry and dip 20° W. Within the Cretaceous relations prevail. South of Sardine Creek the dips sediments have sunk from 1000 to 2000 feet below (l^xThe pre-Cambrian folding, probably accom area the tendency of the porphyry to form lacco are 10° to 30° NW. or N., and the same applies to the general elevation. On the north side these panied l>y faulting. liths is more marked than in the Paleozoic rocks. the areas farther south, at Hackberry Gulch, Lime smaller blocks are separated from the Pinal schists (2) The pre-Cambrian disturbance of sediments The Cretaceous strata dip gently away from the stone Gulch, and south of Mulligan Peak, while the by a displacement of nearly 2000 feet, divided into due to granitic intrusions. western side of the large laccolith 2 miles south- limestone north of Clifton and west of the river at least two probably nearly vertical faults. On (3) The late Cretaceous or early Tertiary dis southwest of Morenci, and appear to dip under dips 25° to 30° W., similarly to the Morenci blocks. the south side they are limited by a curved fault turbance of sediments, due to intrusions of granitic neath it on the eastern side. The bulging of the An exceptional dip of 55° NNW. was observed in the plane which evidently has a decided northward dip and dioritic porphyries. pliable sediments under the influence of the intru Ordovician limestone 1 mile northeast of Clifton. and is excellently exposed in Knight Creek. (4) The late Cretaceous or early Tertiary dom sion of a large mass of porphyry which did not Distribution of faults. Faults belonging to this On the south and east the Coronado and Pinal ing and faulting. find outlet to the surface is believed to have been epoch are extremely common in the prevolcanic blocks are bordered by two dislocations of the first (5) The late Tertiary warping and faulting. the cause of these disturbances. areas of the quadrangle, and the minor ones, at importance, indicated in fig. 2 as the Coronado Of these the fourth is of preeminent importance, least, appear most abundant in the sedimentary and Pinal faults. Probably the two are practi owing to its profound influence on the present con PRINCIPAL EPOCH OF DOMING AND FAULTING. areas, partly because more easily identified here cally continuous, though the direction swings figuration of the region and the distribution of the General features. After the irruption of the by the aid of a comparatively thin series of beds. from nearly due east in the former to north-north several formations. The resulting structures are porphyry, but before the epoch of the great lava The fault planes divide the rocks into blocks of east in the latter. Along the Coronado fault a shown graphically in the structure sections. flows, occurred important earth movemerrts^during variable extent and shape (see fig. 2). They are, large block to the south, including the whole of which the horizontal strata were deformed so as to however, nearly always monoclinal, the beds dip the Morenci hills, has sunk from 1000 to 2000 THE PRE-CAMBRIAN MOVEMENTS. acquire gentle dips, and profoundly faulted into a ping to the west and north at gentle angles, as has feet, the smaller figure occurring at the Coronado After the sediments which now constitute the series of blocks which descend toward the south or been stated.- mine and the larger at the point in Horseshoe Pinal formation were deposited and before the southeast. This epoch of important disturbances The two most important blocks in the north Gulch where the dislocation is covered by Tertiary irruption of the granitic magmas these sediments occurred during the latest Cretaceous or perhaps western part of the quadrangle culminate in the lavas. The fault plane is well exposed in the were closely folded and converted to schists by rather during the earlier Tertiary. In fact, the Coronado Mountain and Pinal Point. In the Pinal Coronado mine and is, in fact, followed by the regional metamorphism. Regarding the general movements continued, but with greatly lessened block the base of the Coronado quartzite lies at Coronado copper vein. It dips 70° S. and is Clifton. 10 accompanied by a zone of friction breccia at most Coronado quartzite and granite has here elevations quartzite, by thin sheets of friction breccia. The length intervened between these two events and 200 feet wide. Irregular masses of diabase lie of from 4000 to 4500 feet, and the block has thus second dislocation is called the Apache fault zone, laid bare the central masses of the porphyry stock. along"the~fault plane. about the same elevation as those near Morenci. and along it the east side has dropped about 800 On the other hand, the faults do not continue into Steep granite bluffs with very well-defined joint Three smaller areas of Longfellow limestone just feet, the throw probably diminishing to the north, the capping lavas. The main period of faulting, ing and sheeting, striking north-northeast and dip east of the boundary of the quadrangle and north at the point where it crosses the extreme western then, falls between the latest Cretaceous and the ping 70° ESE., border Coronado Mountain on the of Limestone Gulch indicate that the Nortiz block head of Morenci Gulch. middle Tertiary. east and indicate that the fault line has swung continues for some distance eastward with gentle Parallel to this fault and half a mile west is the Minor faults north of Malpais Mountain and around and here follows a north-northeast strike. rise. fault along the east side of Silver Basin, which on Whitewater Creek show, however, that small The dislocation is splendidly shown near the mouth The Nortiz block is separated from the narrow shows a downthrow on the west side of about 200 dislocations have occurred subsequent to the erup of Garfield Gulch, where a sunken limestone block Clifton block by a dislocation with a throw of 800 feet. tions of Tertiary lavas, and in the eastward exten lies at the foot of an imposing scarp, and the or 900 feet, which follows approximately the trend There are many other faults of minor importance sion of the Prieto Plateau beyond the boundary of sharply denned fault plane dips about 50° ESE. of the river between Evans Point and Clifton. As which can not be described here in full. One of the quadrangle a fault was observed in a rhyolite From this point northward it is partly hidden seen from the map and the sections it has peculiar these is parallel to Chase Creek south of the Con bed inclosed in basalt; its vertical throw is about under the lavas which fill the bottom of the characteristics. The fault plane is here evidently centrator fault, and is indicated by the fact that 200 feet. It is possible that movement has taken canyon, but the bold bluff of the escarpment a curved surface, beginning parallel to a plane of the quartzite beds on the east side of the creek lie place on some of the older fault lines subsequent continues on the west side up to the head of stratification in the Longfellow limestone, cutting several hundred feet lower than on the west side. to the Tertiary eruptions. The persistent but gen the south fork of Sardine Creek, where the ver obliquely across the Coronado quartzite, and enter At the point in Chase Creek where the Morenci tle dip of the rhyolite tuff toward the fault plane tical throw is again measured to 2000 feet and the ing the granite just below the base of the quartz road turns up the hillside the breaking up of the along the San Francisco River north of Harper fault plane also has a decided eastward dip. ite. The effect has been to draw the Longfellow strata into small blocks is excellently illustrated. ranch suggests this possibility, as does also the The Copper King block, to the east of the Coro limestone down over a granite surface gently slop A small area of Coronado quartzite has here become basaltic escarpment rising above Prieto Plateau nado block, has a similar elevated position. Both ing westward at an angle of about 20°. The sur detached from the main mass and settled along fault between Sardine and Pigeon creeks. It is certain may indeed be considered as "horsts," or isolated face of the broad granite salient on the east side of planes almost to the level of Chase Creek. that the main faulting preceded the volcanic flows, masses bordered by fault lines and surrounded by the river just south of Evans Point practically coin Summary. Faulting has taken place along two but on the other hand the freshness of the fault sunken crust fragments. The Copper King block, cides with the fault plane. The contact of lime principal directions, (1) east-west and (2) north- escarpments, wherever exposed by erosion of the which culminates in the mountain of the same stone and granite is well exposed on the west side northeast to south-southwest, and in each case the lavas, indicates that one event followed the other name, extends in a north-northeast direction along of the river at Evans Point. It dips here gently blocks to the south and east are those which occupy very closely. All these facts tend to place the the west side of San Francisco River from Chase northwest and the granite and limestone are sepa the relatively depressed position. This general epoch of faulting well into the Tertiary period. Creek to Sardine Creek. Its highest elevation is rated by a layer of very soft granite, 1 foot thick, statement finds corroboration in the Coronado At Globe, in central Arizona, where similar 6825 feet, and as its granitic dome is not covered containing well-rolled cobbles of hard granite, evi east-west fault, continued in the Pinal fault extensive shattering has taken place, Mr. Ran- by quartzite beds except at the north end its exact dently produced by the friction. Eight feet above trending north-northeast, and, a few miles far some (Geologic Atlas U. S., folio 111) finds that relative height can not be determined, though it is the contact the limestone contains a streak of gra ther south and east, in the Soto and Concentra the principal faulting has taken place after the probable that the now eroded quartzite once cov nitic sand, which again incloses granite cobbles up tor east-west faults, continued in the San Francisco eruption of certain dacitic surface lavas, but before ered its summit at an elevation of about 7000 feet. to 10 inches in diameter. On the south the Nortiz fault, trending north-northeast. Many minor faults the deposition of the Gila conglomerate and certain The dip of the block is evidently gently north or block is bounded by an extremely well-marked fault trending northwest or northeast divide the larger associated basalts. The time of this faulting is ten northwest, for near its north end at Silver Creek which follows Ward Canyon with an east-southeast blocks. The principal fault planes are not verti tatively placed in the middle of the Tertiary period. the Coronado quartzite caps the granite at an ele trend. The fault plane dips 60° or 70° S. and small cal, but dip south or east at angles ranging from Origin of the faulting. The difficult question of vation of 5000 r^et. On the north side the block masses of downfaulted limestone may be seen along 45° to 70°. The minor faults near Morenci, of the origin of the crust movements described in the dips below the lavas at Sardine Creek. On the the bottom of the canyon. As far as can be made which the Copper Mountain fault is an example, above paragraphs remains unanswered. It is held west, separating it from the Coronado block, lies out on account of covering gravels, the vertical dip 60° or 70° NE. Still flatter fault planes are by many that such phenomena are due to the a structural depression, or "graben," the lowest throw is about 600 feet. exemplified by that south of Evans Point, where breaking and settling of the crust due to gravity, portion of which is marked by the Paleozoic series The region south of the Coronado fault and west the dip is only 20° and where the Longfellow and the fact that all of the faults are normal tends on Shannon Mountain and at the mouth of Gar- of Chase Creek is cut up into five large and many limestone over a large area has been drawn down to confirm this. On the other hand, several of the field Gulch, referred to above. The dislocation smaller blocks (see fig. 3), the strata of practically over the granite. most important fault planes have dips of from 60° which separates Shannon Mountain from the Cop all of which dip west or southwest at angles rang The faults are in all cases normal, accompanied to 45°, and many of the minor ones are still flatter. per King block probably consists of a series of ing from 10° to 20°. The first large fault south by a relative depression of the hanging wall. The In such cases it would seem that gravity opposed northeast-trending faults between Placer Gulch of the Coronado is the Soto (fig. 2), along which a greatest depression has usually taken place' imme by friction could not have accomplished the and Markeen Mountain, but these faults are not further drop of from 400 to 800 feet has taken diately along the fault plane; a little farther away results observed, but rather that actual stretching distinctly traceable and therefore are not shown on place. The throw diminishes toward the western the thrown block is very apt to rise gradually or movements have taken place and that these were the map. The downthrow on the northwest side end of the fault. The nearly vertical fault plane, by step faulting. The greatest vertical throws are aided by gravity. of Markeen Mountain is at least 2000 feet. Farther striking east-west,'is exposed in the Soto tunnel in those of the Pinal fault (2000 feet) arid the San GEOLOGICAL HISTORY. northeast the throw on the west side of Copper Pinkard Gulch. Francisco fault (over 3000 feet). King block diminishes, but is more clearly marked The Concentrator fault is almost an eastern Unequal settling is of common occurrence; the SEDIMENTARY RECORD. along the Malpais fault zone; the fault plane prob continuation of the Soto, and may be studied difference in throw for points 2 miles apart along The oldest records are less well preserved in the ably dips northwest at moderate angles. At the along the slopes of Chase Creek Canyon 1 mile the fault may reach 1000 feet. In some cases this Clifton quadrangle than in any other parts of south end of the Malpais fault the drop is only a northeast of Morenci. Granite and Coronado involves considerable changes of dip of the strata. Arizona, but still reach back to pre-Cambrian few hundred feet, and it diminishes still further up quartzite have been brought into juxtaposition Faulting shows decided influence on "topography. time, when a low, gently undulating land area of toward Silver Creek. from the bottom of Chase Creek Canyon to the All of the principal faults are strikingly marked red, coarse granite, with more prominent points of On the south side the Copper King block is sep summit of the hill at the Arizona Copper Com by prominent scarps. This is especially empha harder quartzitic schists, was spread out where the arated from the depressed area of the Morenci hills pany's concentrating plant, a vertical distance of sized in the Pinal, Coronado, San Francisco, and hills of Morenci and Coronado now lift their sum by the steep Concentrator fault, along the south 1000 feet. A narrow block just south of the main Ward Canyon faults, the height of the fault scarp mits high above the sea level. Dim indications side of which a drop of at least 2000 feet has taken fault plane has suffered the greatest dislocation, for being in all cases about the same as the vertical hint at a far older basement on which these quartz- place. The throw diminishes greatly west of Chase CORONADO MTN. Creek. On the east side the Copper King block is Gc limited by the San Francisco fault, which is the greatest dislocation in the quadrangle and extends parallel to the Pinal fault. The total dislocation as measured at Evans Point is at least 3500 feet, although it is probable that this amount is to some extent distributed on subordinate faults and joint FIG. 3. Cross section along line E-E on areal geology map. planes not easily traceable in the granite. The Qg, Gila conglomerate; Kp, Pinkard formation; Cm, Modoc limestone; Dm, Morenci formation; Ol, Longfellow formation; Co, Coronado quartzite; gp, granite-porphyry; gr, pre-Cambrian granite. Vertical and horizontal scale, approximately, 1 inch=l mile. throw diminishes considerably northward, and at the point where the canyon of Silver Creek breaks immediately to the south lie several parallel step throw. No doubt this remarkable preservation of ite schists were deposited, at mountain-building through the fault block the actual composite nature faults along which the contact of granite and fault scarps was aided by the lava floods which forces which compressed the sediments between of the fault is discernible. The dislocation finds quartzite gradually rises until it occupies its nor soon covered the broken blocks and which have them and made them schistose, at an intrusion of topographic expression in the imposing dark-red mal elevation in this block about 4500 feet. been only comparatively recently removed by ero red granite which almost engulfed the sediments, granite bluffs which for several miles follow the The Concentrator fault continues across Chase sion. and at a long period of erosion which planed down river on the west side. The actual fault plane is Creek, rapidly gaining in vertical throw as it The drainage is very decidedly influenced by the rough topography produced by the orogenic all along hidden by lavas or gravels and since it approaches Markeen Mountain. At the southern the faulting. The course of San Francisco River forces to the smooth outlines of the plain referred can not be definitely located it has not been shown foot of this mountain the downthrown quartz north of Oroville follows the fault line; other to above. Animal and vegetable life probably did on the geologic map, but is shown in the structure ite block is exposed and has evidently suffered instances are furnished by Chase Creek above not grace that barren land, but the rains and the sections. At Evans Point the plane lies only a a dislocation of at least 2000 feet. The throw Metcalf, Horseshoe Gulch, Morenci Gulch, Apache storms beat on its surface then, as now, for under short distance west of the exposures of Longfellow continues to increase until the Concentrator fault Gulch, and Ward Canyon. neath the covering sediments is clear evidence of limestone, which dip 20° W. or NW. along the reaches the San Francisco fault. A doming or bending of the crust, including the weathering, disintegration, and oxidation. west bank of the river. South of the Soto and Concentrator faults the granite, either preceded or accompanied the faulting. At first streams flowed over its surface, accumu Topographically as well as structurally, the low Paleozoic series is broken by three principal north This is best shown by the exposures of quartzite lating in their beds pebbles of resistant quartzite est exposed block in the quadrangle is that on the westward-trending faults. The first oiie is the on Coronado Mountain. Whether the granite was from neighboring areas. The uneven distribution west side of the river from Evans Point to Clifton; Copper Mountain fault, which follows the course actually somewhat plastic or was deformed along of this basal conglomerate proves that the land this may be called the Clifton block. The base of of Morenci Canyon and along which the northeast joint planes is left undecided. Possibly both kinds area was accentuated, while the fairly even thick the Coronado quartzite is calculated to lie at an erly block has moved down 225 feet vertically and of movement took place. ness of the covering quartzite shows that the elevation of about 2300 feet, or 3800 feet below its 70 to 90 feet horizontally toward the southeast. Age of the faulting. The dislocations took place topography was not of a rough character. Inti position on Coronado Mountain. The fault plane dips 60° or 70° NE. and is well after the intrusion of the granite- and diorite-por- mate mingling of sandy conglomerates with sandy On the east side of San Francisco River lies what exposed in the Morenci mines, as well as along phyries, but before the eruption of the principal disintegrated rock also indicates an epoch when mav be termed the Nortiz block; the contact of Morenci Canyon, where it is followed, in the lava flows. An epoch of erosion of considerable the sea had not yet invaded this land, though the 11 invasion was not distant and the waves soon cov sisted of thrice-repeated flows of rhyolite and of eroded and had, in fact, a topography almost as ores at Morenci and Metcalf are among the most ered the low hills. Abrasion by the sea and eio- basalt, with subordinate flows of andesite. In pronounced as the present. As now, the Coro important in Arizona. sion by the streams soon accumulated the Coronado places they are 2000 feet thick and practically nado and Pinal blocks drained westward. Only a brief description of these is here given, sandstones, in the uppermost part of which scant surround the old granitic buttresses. During the maximum stage of volcanic activity, for the subject has been treated in detail in Profes shell remains point to a Cambrian age. Submer Next followed a second epoch of erosion, accom perhaps just after the Prieto flows of basalt, the sional Paper No. 43, United States Geological Sur sion and deposition continued unbroken during panied by the deposition of thick detritus in front most prominent topographic forms consisted of vey, to which the reader is referred for additional the Ordovician period, but the sediments soon of the mountains the coarse accumulations which broad, monotonous lava plateaus, which rested information. became prevailingly calcareous. The Silurian have been called the Gila conglomerate; much against the central area of older rocks, without, PRODUCTION AND DEVELOPMENT. seems to be absent, though no unconformity can material for this was supplied by the enormous however, fully covering them. San Francisco be observed between the Ordovician Longfellow volcanic masses north of the plains. This epoch Valley still existed, though partially filled by The ore deposits were discovered in 1872, but limestone and the covering rock, which is prob is referred to the early Quaternary. flows coming down from the east. The plateau for many years their development was slow, as ably Devonian. The sea again grew more shal Renewed activity of the streams took place dur was most strongly developed in the northern part only rich ores could be utilized and as the district low, but no granite or quartzite remained above ing the late Quaternary and on the sloping plains of the quadrangle, where the Prieto Plateau was far distant from established lines of communi water to supply quartzose sediments; these came of the Gila conglomerate the abrupt little canyons extended across the present Sardine Creek toward cation. Since 1890, however, the progress has from more distant quarters. The limestones of the present day were excavated. Malpais Mountain. The high basaltic escarp been rapid and at the present time, when large became argillaceous and soon changed into clay Lastly must be mentioned the gradual changes ment west of the Prieto Plateau has been referred bodies of low-grade ore are utilized, the produc shales. Both of these terranes have been referred which have been going on since the mineral depos to under the heading "Geological structure;" its tion has reached high figures. Two strong com to the Devonian on rather scant evidence from the its were first exposed by erosion a continuous origin is not satisfactorily explained. A thin panies, the Detroit Copper Company and' the meager fauna. oxidation, solution, and redeposition of minerals, debris cover of rhyolite was distributed over the Arizona Copper Company, have contributed by Above the Morenci shales, in a deepening sea, among these the copper ores, within the zone easily surface of the Prieto Plateau from the succeeding far the greatest part of the production since was deposited a series of limestones, first dolomitic, accessible to surface waters. Inconspicuous and rhyolite eruption, before the Sardine Creek drain 1882, and since 1902 a third, the Shannon then remarkably pure and rather coarse, the Modoc slow as these processes are, they have resulted in age had been fully established. Copper Company, has been added. The mines and Tule Spring limestones of the Mississippian the transformation of poor primary ores into the After the basalt eruptions erosion was extremely of the Detroit Company are located at Morenci, and Pennsylvania!! epochs. Throughout the whole rich and extensive bodies which have placed the active. The present general course of Eagle Creek those of the Arizona Company at Morenci and of the Carboniferous animal life was abundant and Clifton-Morenci district among the first ranks of was laid out in the depression between the south Metcalf, and those of the Shannon Company at rich faunas may now be collected in many places. copper producers. western basalt dome and the Coronado and Morenci Metcalf. The time interval between the Carboniferous hills, and was excavated as a narrow canyon to In 1902 the total production rose to 49,500,000 PHYSIOGRAPHIC RECORD. and the middle Cretaceous is not represented by practically its present depth. The last eruptions pounds of copper and in 1903 it had attained 53,- any sediments; there is, on the contrary, evidence Under this heading it is proposed to discuss of the rhyolite tuff of Enebro Mountain then 400,000 pounds, with a value of about $7,400,000. of an epoch of erosion, for the Cretaceous rests briefly the origin of the present topographic forms. followed as thick mud flows, filled the depression Of the production in 1903 the Arizona Company unconformably on the Mississippian at Morenci, 'The subject has already been referred to briefly in between Coronado Mountain and the basalt ridge contributed 30,228,000 pounds, the Detroit Com where the Pennsylvania!! is not present. The the section on topography. north of Tule Creek, and poured down the narrow pany 16,558,232 pounds, and the Shannon Com disturbance was, however, not great and the The present surface forms are influenced by (1) canyon of Eagle Creek, filling it to a level of 4500 pany 6,600,000 pounds. The ores mined average Cretaceous strata were deposited on the nearly the eruption of lavas, (2) sedimentation, (3) fault feet, as is well shown by the remnants of tuff 3 to 4 per cent of copper. The monthly output of horizontal, partly eroded Carboniferous. During ing and doming, and (4) erosion. along its present course. Over the constructive ore in 1902 was about 60,000 short tons. Of this, the last subsidence under the Cretaceous sea the The first agency has determined the roughly surface of this tuff the present course was then 47,000 tons were classed as concentrating ore and sediments deposited consisted of coarse sandstones plateau-like form of the northern, eastern, and established, and the creek has again reached its 12,000 tons as higher-grade smelting ore with 6 and carbonaceous shales, indicating moderate depth western lava fields, which, however, the fourth former depth by erosion through tuff and the to 10 per cent copper. The Arizona Company and clearly not derived from the granite of this agency (erosion) has greatly modified. The sec covering Gila conglomerate. smelted the lowest grade of ore, while the Detroit vicinity, but rather from somewhat distant land ond agency has determined the sloping plain of At this time a general consequent drainage was Company averaged somewhat higher. The ores of areas. The total thickness of the Cretaceous is the Gila conglomerate at the foot of the mountains. laid out over the sloping volcanic tables. As the Shannon Company were in 1902 exclusively unknown; the larger part of the series may, in The third agency has outlined the two principal shown by Sardine, Whitewater, Tule, and Knight oxidized ores containing about 8 per cent copper, fact, have been removed by erosion. blocks of Coronado Mountain and Copper King creeks, it was very irregular and probably followed but since then this company has also begun the This long .era of deposition without far-reaching Ridge, caused the step-like lowering of the areas of chance inequalities of the surface. Sardine Creek mining of concentrating ore. By far the larger orogenic disturbances was followed by intense older rocks south of the Coronado fault, and deter is distinguished by the deepest and most, sharply percentage of ore mined in 1902 consisted of sul intrusive activity, beginning in the earliest Ter mined the course of San Francisco Valley. Owing incised canyon. phide ore containing pyrite and chalcocite. Of tiary or in the latest Cretaceous. Masses of acidic to the protective influence of the covering lavas this San Francisco River, which previous to the vol oxidized ores about 13,000 tons per month were porphyries, with some diorite-porphyries, broke factor has been far more important in shaping the canic epoch found its outlet by way of Limestone mined at Metcalf and a steadily diminishing through the crust, filled great spaces made for great features of .this region than of areas where Gulch and Clifton, was by the eruption crowded amount of 1500 tons per month at Morenci, mak them by gradual or violent dislocations, and con erosion has had full sway in its work of destroy toward the fault scarp and flowed in the narrow ing a total of 14,500 tons, or about one-fourth the gealed to stocks, sheets, dikes, and laccoliths in ing the topographic evidences of dislocation. As channel now filled with Gila conglomerate just total production. The output of oxidized ore at the disrupted granite and sediment. These intru shown above, under the heading "Geological struc south of Rocky Gulch. The course of Chase Metcalf will continue for a number of years and sions practically form one connected mass, extend ture," faulting has influenced stream courses in a Creek was determined by the filling of the deep possibly increase. The oxidized ore mined by the ing from Eagle Creek to Copper King Mountain, remarkable degree. depressions near Sardine Creek and Malpais Arizona Copper Company at Metcalf is the lowest and have been exposed only by erosion. The fourth and by far the most important Mountain, referred to above, and .the drainage grade utilized in the district and probably con The intrusive bodies were thus consolidated far agency, as far as the details of topography are was forced southward. tains on an average less than 3 per cent. below the surface at that time; just how far below concerned, is erosion. Several epochs of erosion This most important epoch of erosion, during The total output of the district to the end of is doubtful, but at any rate the distance can not can be distinguished: which all the principal present features of the 1903 is estimated to be about 201,600 short well have been more than a few thousand feet for (1) The pre-Cambrian land and marine erosion mountain mass became established, began in the tons of copper, having a value of approximately their upper portions, and it may have been less. which modified the surface of the granite and latter part of the Tertiary during and shortly after $60,500,000. The porphyries in cooling produced far-reaching schists before the deposition of the Coronado the volcanic activity, and has in fact continued until Clifton is second in importance in Arizona as a metamorphism of such of the adjacent sediments as quartzite. the present day, although at one time the erosive copper-producing camp. In 1903 Bisbee produced were susceptible of this alteration, and the intro (2) The post-Carboniferous to Upper Cretaceous power was checked by the rising of the level of 62,500,000 pounds of copper, Clifton 53,400,000, duction of sulphides of various kinds accompanied erosion which slightly modified the monotonous deposition in the valleys and the formation of the and United Verde 28,600. The production of the contact metamorphism. Shortly after the con land surface before the deposition of the Pinkard Gila conglomerate. When these detrital rocks were Arizona is at present a little more thai! one-fifth of solidation fissures broke open, following the gen formation. spread like a sloping plateau in front of the moun the total production of the United States. eral northeast direction of the stock and dikes, and (3) The post-Cretaceous erosion. tain area to a marginal elevation of 4500 feet the The Morenci and Metcalf districts are not dis became filled with cupriferous pyrite, zinc blende, The last epoch is the only one that is important principal drainage Lines of the higher part of the tinguished by the great depth attained in mining. and other minerals. Soon after this intrusion a in connection with a discussion of the present sur quadrangle were the same as those of to-day, but At Metcalf all of the deposits are worked by open great uplift must have taken place, raising the face forms. Erosion began after the great uplift when in the latter part of the Quaternary the rivers cuts or tunnels, as they occur near the surface of heavily sediment-laden crust to high elevations which followed the intrusion of the granitic and began to attack and erode the detrital material the Shannon Mountain. At Morenci, where the more and producing in it, as well as in the underlying dioritic porphyries, probably during the earlier lower stream courses were established along new important deposits underlie Copper Mountain, two partly plastic granite, gentle dome-shaped swells part of the Tertiary, and had accomplished a con lines on the gravel table. San Francisco River of the largest mines, the Copper Mountain and or anticlines. The uplifted area later broke into siderable amount of work, the details of which deviated from its old course at Rocky Gulch and the Humboldt, are still worked by tunnels, while fragments, which gradually settled down, forming are unknown, when its whole system of attack turned almost due south for several miles and then others, like the Arizona Central and the Ryerson, monoclinal blocks around the more resistant but- was profoundly changed by the great dislocations to the southwest. Likewise were established lower are opened by shafts less than 400 feet in depth. tres^es of Coronado and Copper King mountains which took place and which outlined a very dif Chase Creek and the many long consequent gulches The celebrated Longfellow deposit was mined from and fracturing still further as they settled. ferent plan of drainage. which traverse the constructive mesa of the Gila four tunnel levels, the Manganese Blue by a shaft The country was now a land area with rough topo Very shortly afterwards the lava flows over conglomerate to join San Francisco River. The 400 feet deep, and the Detroit by a shaft about graphic features, to which the faulting contributed whelmed the country and previous topographic river deepened its box-like canyon rapidly and 300 feet deep. important elements. Active erosion following the forms were to a great extent blotted out. north of Clifton soon began to erode the older OCCURRENCE AND GENERAL FEATURES OV ORE DEPOSITS. epoch of faulting has not entirely effaced this influ Before the lava flows the structural depression of rocks underneath the gravels. With shorter inter ence, and, though obscured by the Tertiary lava San Francisco Valley existed, but whether it was ruptions, accompanied by the formation of gravel The geographical distribution of the copper flows, the fault scarps are still dominant features, occupied by a river of the same size as the present terraces along the canyons, this deepening process deposits is practically coextensive with the great visible in the granite bluffs of Coronado and Cop stream is very doubtful. The depressions now cov continued, until now the river is 600 feet below porphyry stock and its dike systems. The depos per mountains and the downthrown valley between ered by the Gila conglomerate also existed then, the general level of the gravel plateau. its occur either in the porphyry or close to its con them. During this epoch of erosion the principal but Chase Creek probably did not. Instead, there tacts, or along dikes of porphyry in some other valleys, like those of Chase Creek and San Fran was a very pronounced depression beginning near ECONOMIC GEOLOGY. rock. Areas in which no intrusions have taken cisco River, were carved. The valley of the latter the head of the present Chase Creek, extending in MINERAL EESOURCES. place are practically barren. This intimate con is, however, primarily of structural origin, being a northerly direction across the present Sardine COPPER. nection with the porphyry is certainly a most determined by the great San Francisco fault. Creek, and probably also draining northward. The Clifton quadrangle contains many copper important fact. There is only one small division Volcanic eruptions of great volume took place The lava contacts show that the country over deposits. This is, in fact, the only metal pro of deposits namely, that connected with the dia in the later part of the Tertiary period. They con- which the fiery streams poured out was deeply duced in large amounts, and the deposits of copper base dikes which deviates from this rule. Clifton. 12
Practically all types of deposits contain copper not only at the contact of the main mass of por less extensive zone of chalcocite or copper glance, and crosscuts underneath the town are somewhat as the most valuable metal. Gold and silver occur, phyry forming the southern slope of Copper deposited by secondary processes and replacing the damp, especially in the Manganese Blue and Ari as a rule, only in minute quantities, except in some Mountain, but also in the hills between Morenci pyrite. zona Central mines. The mines at Metcalf are of the outlying districts, where they become more and the Longfellow mine, in which dikes have The most important vein system is that which, situated on Shannon Mountain, from 500 to 1200 important. The two principal mining centers, produced contact-metamorphic minerals along their under the general name of the Humboldt lode, feet above Chase Creek, and here, too, the work Morenci and Metcalf, which are 3 miles apart, sides. Wherever alteration has not masked the extends from northeast to southwest through Cop ings are dry, except at one place in the Shirley are both situated at the main contact of the por phenomena magnetite, pyrite, chalcopyrite, and per Mountain at Morenci. The outcrops of this tunnel, where a winze struck some standing water. phyry stock and the series of Paleozoic limestones. zinc blende accompany in various proportions the vein are practically barren, but at the depth of The few shafts and prospects sunk in the bottom Elsewhere the intrusive rock generally adjoins contact-metamorphic minerals and are intergrown about 200 feet the deposit becomes productive and of Chase Creek are the only places containing per granite or Cretaceous sediments. with them in such a way that the contact-meta contains chalcocite associated with pyrite. There manent water. The Copper King mine, situated The ores consist of chalcocite, chalcopyrite, mala morphic origin of these ores appears beyond doubt. are usually one or more central seams of massive a few hundred feet below the summit of Copper chite, azurite, chrysocolla, brochantite, cuprite, and In many places the ores have accumulated along chalcocite, some of which are fairly persistent. King Mountain, has a shaft 600 feet deep, and in native copper. Covellite and bornite are practically certain horizons in the sedimentary series, evidently These seams are ordinarily adjoined by decom it some crevices containing water have been found, absent. Brochantite, the basic copper sulphate, is more suitable than others to the processes of alter posed porphyry, now consisting chiefly of sericite but this soon drained out and no more has since very commonly present, especially in oxidized veins ation which produced the deposits. These contact- and quartz, together with pyrite and chalcocite. come in. in porphyry, and, in fact, constitutes in places ah metamorphic deposits, it is believed, were derived These extensive impregnations of the country rock The present stand of the water level, except important ore. On account of its similarity to from the water and the metallic substances which are rarely confined by distinct walls, but gradually along the creeks, is practically unknown. It and intimate intergrowth with malachite it has were originally contained in the magma of the fade into the surrounding porphyry. That these probably rises as a slightly curved surface from usually been overlooked. porphyry, and which were released by decreasing deposits are genetically connected with fissure veins, the creek levels toward the high hills. The total The following-named minerals have been found pressure at the time of the intrusion of the rock however, can not be doubted. In lower levels the amount of water stored below this water level is in the district: Native copper, native gold, quartz, into higher levels of the earth's crust. We may ore is apt to change to pyrite and chalcopyrite. likely to be small. chalcedony, rutile, magnetite, hematite, limonite, thus speak of these deposits as contemporaneous Both the Arizona Copper Company and the Detroit DEPTH OF OXIDIZED ZONE. pyrolusite, coronadite (a new mineral, chiefly PbO with the cooling and solidification of the porphyry. Copper Company are now working the low-grade and MnO 2 ), cuprite, pyrite, chalcopyrite, zinc As to form, the ore deposits in limestone are bodies of chalcocite ore accompanying the veins. The presence of products of direct or indirect blende, galena, molybdenite, chalcocite, diopside, often wholly irregular, but more frequently, per The reserves thus far opened assure a high produc oxidation shows the depth to which the oxidizing tremolite, garnet, epidote, muscovite, chlorite, ser haps, tabular in shape, because of the accumulation tion for many years to come. waters or the sulphate solutions have penetrated. pentine, asbestos, kaolin, willemite, calamine, diop- of the minerals along certain planes of stratification. Parallel veins, somewhat narrower, but similar in In that part of the porphyry area of Copper tase, chrysocolla, copper-pitch ore, morencite (a new Oxidizing waters have very greatly altered the character, are opened by the Arizona Central mine, Mountain which has been explored the average mineral, chiefly a ferric silicate), calcite, dolomite, deposits in limestone. The sulphides have been also at Moreuci. These veins are partly in por depth of the lower limit of the chalcocite zone is zinc carbonate, malachite, azurite, libethenite (cop converted into carbonates, and malachite and phyry, partly in contact-metamorphosed limestone. 400 feet, but it increases in places to 500 or even per phosphate, not previously found in the United azurite are the most common ores. Cuprite also While malachite and azurite sometimes occur, they 600 feet. The sulphate solutions descended to States), brochantite, alunite, gypsum, spangolite occurs extensively, and seems to form as a rule in are by no means as prominent as in the limestone this depth from the surface, and along important (basic chlorosulphate of copper and aluminum), the Devonian shale. Chalcocite and other sul deposits, and frequently the leached surface zone is fissures they may have gone somewhat farther. chalcanthite, goslarite, epsomite, and gerhardtite phides are almost entirely absent. The zinc immediately adjoined by the chalcocite ore. They not only followed fissures, but penetrated (basic copper nitrate forming green crusts on blende has been carried away as sulphate of zinc, The Coronado mine represents a different type the porous, sericitized porphyry with considerable weathered surfaces of porphyry and associated which is frequently found in efflorescence on the of deposits, formed on a fault fissure between gran ease. On the other hand, the altered limestones with a copper chloride, possibly atacamite). walls of the tunnels. The magnetite and garnet ite and quartzite, indicating a, throw of at least and shales are very compact, nonporous, and The deposits containing payable copper ore take which originally formed a part of these deposits 1000 feet. The fissure is followed in places by impervious. Where circulation was facilitated by many widely differing forms, as follows: have also undergone decomposition, the resulting a diabase dike, which shows some effect of crushing fissures, as in the Manganese Blue and Joy mines, minerals being silica and limonite. and movement on the vein. The outcrops contain the rocks may be partly oxidized to a depth of 400 Deposits in limestone and shale, not connected wit1": fis sure veins, all carrying oxidized ores almost exclu The celebrated Longfellow mine is worked on copper carbonates and silicate, but these minerals feet, but this is generally a maximum. There is sively ; rarely chalcocite: one of these deposits, occurring as, roughly speak change at slight depth to chalcocite, and it is no well-defined plane expressing the depth of oxi Irregular bodies near contacts of main stock or dikes. ing, a funnel-shaped mass in the Ordovician lime believed that the ore minerals still farther down dation; on the contrary, it proceeds in an extremely Tabular bodies near contacts of main stock or dikes, stone, between two large porphyry dikes. Farther consist chiefly of pyrite and chalcopyrite. capricious manner, entirely fresh pyritic ores being following stratification. west along the main porphyry contact is the Mon- Somewhat different again are the fissure veins frequently found very close to the surface. Tabular bodies following contacts of porphyry dikes. tezuma mine, and still farther the Detroit and the on Markeen and Copper King mountains. The Fissure veins: SUMMARY OF GENESIS. Normal veins in porphyry or in any of the other Manganese Blue mines. Both of the latter mines granite of this complex of hills is cut by a great rocks near porphyry contacts. Include central were worked on several tabular ore bodies, three number of porphyry dikes, which generally have It has been shown that the intrusions of stocks veins and surrounding partly replaced porphyry, or more in number, occurring in horizons ranging a northeasterly direction. Along many of these and dikes of granite-porphyry and quartz-monzo- forming together a lode. Carry chalcocite as the from the Ordovician to the Pennsylvanian. All of dikes movement and fissuring have taken place, nite-porphyry, which took place in late Cretaceous important ore; in upper levels also sometimes these deposits are now almost exhausted. They con and varying amounts of copper ores have been or early Tertiary time, produced an important con oxidized ores. tained a large quantity of very rich carbonate and deposited. The veins contain comparatively little tact metamorphism in'adjoining shales and lime Normal veins following porphyry dikes in granite. Chalcocite and oxidized copper ores. oxide ore. These ore bodies were, however, much gangue, the copper minerals being chiefly distrib stones of Paleozoic age. This metamorphism Normal veins following diabase dikes. Chalcocite smaller in extent than the large masses of chalcocite uted through the altered porphyry or through the resulted in metasomatic development of garnet, and oxidized copper ores. ore which now form the main support of the camp. granite adjoining the dike. At the surface a small epidote, diopside, and other silicates, accompa Stockworks. Irregular disseminations in porphyry, The Shannon mine at Metcalf contains several amount of carbonates may be found, but they nied by pyrite, magnetite, chalcopyrite, and zinc quartzite, and other rocks. Contain chalcocite ore bodies of similar origin. A fragment of the change at slight depth, sometimes only a few feet blende. The sulphides are not later introduc and oxidized copper ores. Paleozoic series outcrops on Shannon Mountain, from the surface, into an ore composed of chalco tions, but are contemporaneous with the other The above classification is based on the occur and is cut by an extensive system of porphyry cite and pyrite, which still farther down appears to contact minerals. rence and form; a more general genetic system, dikes, which in the lower part of the mountain change into pyrite and chalcopyrite. The most The contact zone received very substantial addi including the unpayable pyritic deposits, would join the main part of a large intrusive body of prominent deposit on this system of veins is in tions of oxides of iron, silica, sulphur, copper, and show a somewhat different arrangement. porphyry. At several horizons the limestones are the Copper King mine, which is situated only a zinc enough to form good-sized deposits of pure Native copper, all of the oxysalts of copper, and greatly altered, the final product generally being few hundred feet below the summit of Copper magnetite and very low-grade deposits of chal chalcocite are wholly secondary minerals produced copper carbonates and limonite, with some quartz. King Mountain. The main mass of porphyry copyrite and zinc blende, all of which are entirely by direct or indirect oxidation from primary pyritic In some places the ore bodies are less affected by between Morenci and Metcalf shows evidence of unknown in the sedimentary series away from the ores. In all of the divisions given above, this pri oxidation, and their original character of garnet, very strong mineralization throughout. A great porphyry. mary ore consists of pyrite and chalcopyrite, with epidote, magnetite, and sulphides may be plainly number of fissure veins have been encountered in The porphyry magma, as shown by the charac some zinc blende and molybdenite. The scant seen. it, although most of them are neither persistent nor ter of the fluid inclusions in its quartz crystals, con gangue of the veins consists of quartz, while the Oxidation by surface waters, as at the Shannon strong. Close to the surface the ores are apt to tained much water which held dissolved various deposits in the first division are usually accom mine, also diffused much copper as chalcocite in spread through a considerable mass of rock, and salts, among them some of the heavy metals. Sodic panied by garnet, epidote, magnetite, diopside, or some of the porphyry dikes, and the Metcalf mine, in some cases important bodies of chalcocite, due chloride and ferric oxide probably predominated. by their products of oxidation. on a lower spur of the same hill, consists chiefly of to secondary deposition on pyrite from solutions It is believed that it contained all of the sub Contacl-metamorphic deposits. There is no evi a body of extremely decomposed porphyry con containing copper, have resulted. stances mentioned above, and that large quantities dence that ore deposits were formed in this region taining chalcocite and carbonates. Very probably The granite adjoining this porphyry is some of this gaseous solution (for the critical tempera before the intrusion of porphyry. This event this copper has migrated into the decomposing por times also thoroughly altered and impregnated ture must have been exceeded) dissolved in the appears to have had most intimate connection phyry from bodies of contact-metamorphic rock at with pyrite and chalcopyrite. This may be seen magma were suddenly released by diminution with the origin of all the copper deposits in the higher elevation, parts of which are probably now in the narrow canyons of Chase Creek for a mile of pressure as the magma reached higher levels region. Wherever the porphyry came into con eroded. above the Longfellow incline. While a number of and forced their way through the adjoining sedi tact with the granite or the quartzite little altera Fissure veins. At many places in the district more or less well-defined veins have been opened mentary beds, the purest and most granular lime tion can be observed; but wherever the porphyry the copper deposits consist of fissure veins, cutting here, the results have not been encouraging. stones suffering the most far-reaching alteration adjoins the limestones or the shales of the Paleo alike porphyry, granite, and sedimentary rocks. Several smaller deposits of oxidized copper ores and receiving the greatest additions of substance. zoic series the sedimentary rocks have undergone From the available evidence it would seem as if are found near Garfield Gulch and along Placer It is thus held that a direct transfer of material very extensive contact metamorphism, resulting in these veins had been formed a short time after the Creek. from cooling magma to adjacent sediments took the formation of large masses of garnet and epi consolidation of the porphyry. In lower levels place. The formation of garnet indicates large CONDITIONS OF GROUND WATER. dote. This alteration is particularly observable at the veins consist of pyrite, chalcopyrite, and zinc gains of ferric oxide and silica. These contact- Morenci. The whole Paleozoic series is affected, blende, magnetite being noticeably absent. At the Permanent water has not thus far been encoun metamorphic deposits often occur at the immediate but more particularly the pure limestone of the surface many of the veins have been completely tered in any of the mines in this district. Morenci contact of the main porphyry stock and the lime Mississippian, which for a distance of several leached, and now show nothing but limonite and is situated on the hills, from 800 to 1500 feet above stones, but more commonly they seem to be con hundred feet from the contact has been con silicified porphyry. This rule is, however, not the principal streams, Chase and Eagle creeks, and nected with dikes of the same porphyry close to verted into an almost solid mass of garnet. The a general one, as, especially in porphyry, oxidized the deepest workings in no place reach farther the principal mass, these dikes being probably shales have suffered less from this metamorphism, ores are sometimes found in the outcrops of the than 600 feet below the surface. A little seepage more highly charged with inagmatic waters. but near the porphyry are apt to contain epidote deposits. Between the leached outcrops and the from the surface takes place in case of heavy rains, It is shown that fissures and extensive shattering and other minerals. This metamorphism appears deep ores of pyrite and chalcopyrite is a more or or from the local water supply, and some drifts developed both in porphyry and in altered sedi- 13 ments after the congealing of the magma, and that changes in the water level. Disintegration and irregular veins cut these rocks, and pockets of gold short distance north of Clifton show, according these fissures and seams were cemented by quartz, erosion removed the iron cap (the product of direct associated with limonite have been found in several to Mr. J. Colquhoun, the following composition: pyrite, chalcopyrite, and zinc blende, forming nor oxidation of the primary vein) and began to oxidize places. The veins are small, 110 great depth has Sodium chloride, 4.1 to 6.9 grains per gallon; car mal veins, largely of the type of replacement the exposed chalcocite zone. In practically all the been attained by the workings, and the deposits, bonate of lime, 5 to 5.3 grains per gallon; total veins. The amount of copper contained in these veins the surface zone of poor ore is due to the which farther down will doubtless contain sulphide salts, 14.05 to 20.3 grains per gallon. Below Clif is usually small, though in places possibly large direct oxidation of chalcocite. The solutions from ore, have not yet proved to be of much value. ton the increase in salts, chiefly chloride of sodium, enough to form pay ore. The bulk of the this part descend and add richness to the upper About twenty years ago the gulch was worked for becomes very noticeable. The Shannon smelter, 1 veins consists of pyrite. Two classes of veins part of the remaining chalcocite zone. placer gold and the ruins of several arrastres are mile below Clifton, experienced at first consider may be distinguished. The usual type is prac still visible near the foothills of Eagle Creek able difficulty in procuring a supply of sufficiently tically always connected with granite-porphyry MINOR METALS. between Gold and Horseshoe gulches. fresh water. or quartz-monzonite-porphyry, occurring in these Iron. Both at Morenci and at Metcalf the sedi The copper ores of Morenci and Metcalf, whether Several hundred miner's inches are taken out rocks or along dikes of the same. The smaller mentary contact-metamorphosed rocks contain irreg occurring as contact deposits or as fissure veins, just above Limestone Gulch and conducted in a class consists of those connected in their occurrence ular bodies of magnetite, which near the surface is contain only traces of gold. At the Copper King flume to the Arizona Copper Company's smelter. with diabase dikes. The genesis of the former usually partly or wholly changed to limonite. The mine, however, a certain amount of gold perhaps A plan to supply the town of Clifton with water type wil\, be discussed first. largest mass of magnetite was found in the Arizona $8 per ton is found in the ore, and from, this taken out at a point farther up has recently been As far as the metallic minerals are concerned Central mine and was about 150 feet long, 40 feet point northeastward, as noted above, this tenor in executed. A pipe line from Clifton supplies the there is a striking similarity between the veins wide, and 80 feet thick. Other large masses were gold increases. mines and concentrators of the Arizona Copper connected with porphyry and the contact-meta- mined in the Manganese Blue mine. Both mag Company at Morenci. Four miles below Clifton morphic deposits, the principal difference being in netite and limonite are used for fluxing purposes NONMETALLIC MINERAL RESOURCES. is another pump station from which the necessary the magnetite, which is not found in the veins by the smelting works and a varying but not very Coal. No coal is found in the Carboniferous amount is forced up to supply the Detroit Copper proper and occurs only subordinately in certain large amount is mined each year. beds of this quadrangle, but the Cretaceous strata Company's works at Morenci, the total head being of the altered wall rocks. A relationship is also Considerable amounts of massive pyrite are found (Pinkard formation) contain much carbonaceous approximately 1700 feet. clearly seen in the remarkable action of the vein on the lower levels of some of the veins at Morenci, shale, and in one place, at least, material has been Eagle Creek carries a fair stream of water, which solutions on the adjoining wall rock wherever this is especially in the Joy and Montezuma mines, where found deserving the name of coal. The locality is gets rather low during the dry season. The sandy limestone, tremolite and diopside being formed in it the bodies attain 20 and even 40 feet in thickness. about 2|- miles south of Morenci, in a tributary to bed contains, however, a large amount of excellent by replacement. On the whole, iron and silica are In 1903, 420 tons of pyrite were mined per month Silver Basin Creek one-half mile southeast of bench ground water. At the station 4 miles west-south the main substances added during the vein forma in the Joy mine and utilized at Clifton to manu mark 5175, near the place where Cretaceous fossils west of Morenci from 30 to 40 gallons per minute tion, as well as during contact metamorphism. facture sulphuric acid for the purpose of leaching have been found. The beds of coaly shale dip of this ground water is pumped up against a head A study of the fluid inclusions in the vein copper ores from Metcalf, the total amount of sul gently southwest. The percentage of ash is very of .1500 feet to supply that town for domestic quartz proves conclusively that the veins were phuric acid produced in that year being 3471 tons. high and the value of the coal is very problem purposes. formed in the presence of aqueous solutions and Zinc. The veins of Morenci contain, in their atical. The beds were discovered in 1903 or 1904, The small amount of water in Sardine Creek is that these solutions were at a high temperature, lower levels, a notable amount of zinc blende. after the geological work on the quadrangle had not utilized. for they contained various salts in part those of The same mineral is usually present in the con been completed. SPRINGS. heavy metals, probably iron which have been tact-metamorphosed limestones at Morenci and Limestone. The purest limestone in this region separated during the cooling of the crystallized Metcalf, and the oxidized ores of this kind are is that of the upper 100 feet of the Modoc forma In the southern part of the quadrangle perma quartz. This eliminates entirely the possibility apt to contain even more. Zinc appears to be tion, which is exposed on Modoc Mountain and at nent springs are rare. A small spring is located a that the veins were deposited by cold surface concentrated in the partly oxidized "iron cap," of other places near Morenci, on Shannon Mountain little north of Gold Gulch. Another, which has a waters and points to three possible methods of Shannon Mountain, representing the metamor near Garfield Gulch, and at several other localities. volume of several miner's inches, issues among the deposition: (1) By atmospheric waters heated by phosed Modoc limestones. It is not probable that It offen contains 94 to 96 per cent of calcium car desolate ravines in the basalt area a short distance contact with the cooling porphyry, (2) by ascend the metal is present in economically important bonate. Two quarries are located on Modoc Moun west of Eagle Creek and is utilized for irrigation. ing magmatic waters, or (3) by a mixture of both. quantities. tain and one on Shannon Mountain; these supply the A third, also of fairly large volume, is found in In any case the metals must have been derived Lead. No important lead deposits have been the needs of the three smelting works of the district. the upper part of Limestone Gulch. Very little from the porphyry, or from deep-seated sources discovered in the quadrangle, though the Paleozoic Near Morenci an almost pure dolomite underlies water issues along the southern base of Coronado below the porphyry, for, as stated above, the limestones in some places contain small bodies of the pure limestone. The Longfellow and Morenci Mountain, but ordinarily a limited supply may be presence of porphyry is the only common factor lead ore. Several of these small deposits, usually formations contain chiefly impure and more or found in a shallow well where the trail crosses in all occurrences. In view of the evidence of irregular form, are included in the Longfellow less siliceous limestone. Horseshoe Gulch. North of Coronado Mountain of the fluid inclusions in the quartz, together limestone south and southwest of Morenci. The Quartzite. Near the foot of the Longfellow the water is a little more abundant. In addition with the similarity of the products of the vein- Hormeyer vein, which is located 1-J- miles east- incline and in the Lone Star tunnel at Morenci to the two springs noted on the map along Tule forming processes to those of contact metamor southeast of Morenci, carries some oxidized lead quartzite is mined for the purpose of lining copper Creek and north of it, permanent water may be phism, it is reasonably certain that parts of the ores, as well as gold. Small amounts of oxidized converters. The total amount needed is not large. found on at least the two northern branches of mineral solutions were derived directly from and lead ores occur in the Stevens prospects in lime At the former locality the quartzite contains some Whitewater Creek near its head, and also in the formed part of the porphyry magma, and probably stone near the mouth of Garfield Gulch and also pyrite and one-half of 1 per cent of copper. At middle part of Knight Creek. Along Chase Creek they were derived entirely from this source. It in the veins of the Polaris Company on Dorsey both places the quartzite is taken from the Coro springs appear at several places between Metcalf seems likely that the fissuring which took place Gulch. An irregular deposit of yellowish oxi nado formation. and the head of the creek; also on Garfield Gulch. after the cooling opened vents of escape for mag dized lead ores has been worked in the Longfel Kaolin. For the local requirements of the The headwaters of Sardine Creek, HL Canyon, and matic waters under heavy pressure at lower levels, low limestone 1J miles south-southeast of Enebro smelting works kaolin has been mined at the Pigeon Creek also contain permanent flowing water. and that they ascended in these fissures, depos Mountain, or 2 miles north-northeast of the mouth Longfellow and East Yankie mines, where it Along the foot of the Copper King Ridge many iting the heavy metals and the silica and acquiring of Garfield Gulch. Some ore had evidently been occurs in great purity associated with limonite springs occur for instance, at Hickory Gulch, at the same time carbon dioxide from the sedi shipped from this prospect, and a sample assayed and derived partly from porphyry, partly from Dorsey Gulch, Sycamore Gulch, Quail Spring, ments which they traversed. It remained for the 24 per cent lead, with traces of gold and silver. clay shale. and Silver Creek. The water sinks as soon as it surface waters, as erosion gradually exposed the In the mines of Morenci and Metcalf lead minerals Building stone. Among the materials available reaches the volcanic formations at the base of the deposits, to alter and enrich them in manifold are almost unknown. for building stones the dark-brown, banded quartz ridge. A large spring issues near Sardine Creek forms. Silver. The ordinary copper ores of Morenci ite of the Coronado formation should receive first just below the limestone canyon, and small streams From the evidence presented above, it must be and Metcalf contain only traces or very small mention. It forms excellent and easily dressed of water trickle from the volcanic rocks at the base concluded that some of the deposits, especially amounts of silver. Even the copper bullion material and has been used in the construction of Malpais Mountain. the fissure veins, were laid bare by erosion and rarely carries more than 4 or 5 ounces of silver of large buildings at Morenci, the quarry being Mineral springs. The salt springs along San attacked by surface waters at an early date, prob per ton. Ore from the Stevens properties, near located along the road in the gulch three-fourths Francisco River south of Clifton, referred to above, ably before the principal faulting movement and Garfield Gulch, carried a little silver, and the same of a mile south of the town. Many beds of the are the only strong mineral springs known; their certainly before the eruption of the Tertiary is true of the veins on Dorsey Gulch. Narrow Longfellow limestone also furnish good building temperature ranges from tepid to hot. basalts and rhyolites. Oxidation has thus -acted silver-bearing veins were at one time prospected at stone. In Clifton the rhyolite occurring in a large One of these spring issues near the river 300 on them for a very long period. Granville, in the northern part of the quadrangle. bluff on the west side of the river has been used feet south of the Clifton railroad station and has a The irregular and tabular deposits in limestone Gold. The gravels of the Gila conglomerate, to advantage. With this exception, the volcanic temperature of 160° F. An analysis made for the and shale have obtained their present form partly resting in front of the older rocks on lower San formations are not well adapted for building Arizona Copper Company by Mr. J. D. Audley by direct oxidation and partly by the influence of Francisco River and Eagle Creek, are sometimes purposes. Smith gave the following result: sulphate solutions derived from the disseminated gold bearing, although the metal usually occurs WATEE SUPPLY. Analysis of spring water from San Francisco River near chalcopyrite due to contact metamorphism. A only as very fine flakes. The late Quaternary Clifton. STREAMS. Grains per United great enrichment has taken place, due to decrease bench gravels along the San Francisco above States gallon. of volume and addition of copper from the circu Clifton contain gold in a somewhat more con San Francisco Kiver forms the principal source Sodium chloride...... 301.54 Potassium chloride...... 28.90 lating sulphate solutions. Some of the oxidized centrated form, and at Oroville attempts have of water supply, ample at all times for the require Magnesium chloride...... 7.11 deposits in shale, however, may be due wholly to been made to work them by the hydraulic method, ments of town and smelter and for some irrigation. Calcium chloride...... 78.99 Calcium sulphate...... 4.76 adsorption exerted by the kaolin in the shale on but the results were not encouraging. This gold is No detailed measurements of its volume have been Calcium carbonate...... 22.05 these sulphate solutions. probably derived from a system of veins outcrop made. The quantity of water carried varies con Silica...... 4.37 The history of the veins, especially those which ping on lower Dorsey and Colorado gulches, a few siderably and is subject to very sudden increase Oxide of iron and alumina...... 43 Organic matter...... 2.75 traverse the porphyry stock or follow porphyry miles north of Clifton on the west side of San by heavy freshets. The water a few miles north dikes, is\more complicated. It has been shown Francisco River. Work has occasionally been of Clifton is of excellent quality, but near that Total solids...... 450.90 that oxidation dates back to Tertiary time, and done on these veins and at one time a stamp mill town it becomes more saline on account of the Wells in the bottom lands opposite the Shannon that the water level was then considerably higher was erected at Evans Point. Lately the Polaris numerous salt springs which discharge their con smelter contained 200 to 300 grains of sodium than it is at present. By the action of descending Company has been actively prospecting the veins. tents into it. Some of these are found 1 mile chloride per gallon. sulphate solutions on pyrite, chalcocite was depos Another gold-bearing district is that of Gold north of Clifton; others carrying a large volume A hot spring with a small volume of weak min ited very extensively, and very likely the great Gulch, 2 or 3 miles west of Morenci. The diorite- of water containing much sodium chloride enter 2 eral water issues near the bed of Eagle Creek, at vertical extent of the chalcocite zone, ordinarily porphyry here contains many included masses of miles below the town and at other places. Sam the pump station. from 200 to 500 feet, is due to slow and gradual limestone and other sediments. Many narrow and ples of the normal river water from the dam a June, 1905. Clifton.