of this lava-capped mountain shales appear again, and about a mile south of Round Mountain the metamorphic rocks replace them. This rock appears like a tufaceous porphyry, containing much chlorite.

A considerable area of level land stretches north from Round Mountain. The underlying rock is shale and sandstone with some thin seams of coal. A high ridge of volcanic tufa rises on the east, while westward, wherever the erosion has been great enough, the Metamorphic Series rises through the Cretaceous. Near Montgomery Creek an area of the older series extends east of the stage road. The rock is generally either faintly porphyritic and fragmental, having a dark base mottled with red, or of a dia basic character with an excess of feldspar. The height of Montgomery Creek is 2,160 feet. From this point north and east for many miles the country is entirely volcanic.

The surface of the country from the top of the mountain north of Montgomery Creek to the Big Bend of Pitt River is a nearly level plateau, having an elevation of 3,000 feet, and sloping very gently westward. The deep cañons of Hatchet and Roaring Creeks have been eroded in the western end of this plateau. At the spot where the upper road to the Bend crosses Roaring Creek there is an outcrop of the Cretaceous shale. This is seen again along the road which descends to Big. Bend, where it is said to contain some thin coal seams. Sandstones and shales outcrop also north of the Bend, dipping gently to the northeast, with an exposed thickness of about 400 feet. They extend up the river a short distance, also up Nelson Creek and down the river to the mouth of Kosk Creek. This creek forms the dividing line between the lavas and the older series, and it is evident that it is also the boundary between this series and the Cretaceous beds. The latter extend up the east side of the creek till hidden by the lava. Kosk Creek has cut its channel at this junction of the lava and the older rocks nearly to its source, and it has been reported that coal exists toward the head of the creek. The region north to the McCloud is one which it is almost impossible to traverse, and very little is known about it. It consists of rounded ridges rising 6,000 to 7,000 feet, perfectly barren of trees, and covered with thick brush.

The Big Bend Hot Springs issue from an ancient intrusive rock, seeming to be a diabase, though largely feldspathic. The springs vary from warm to boiling, and are scattered thickly along the river for a quarter of a mile, with a large volume of water in places. The rock along the river for 5 or 6 miles below the mouth of Kosk Creek is chiefly a massive, crystalline one, like that at the springs. Big Cañon opens into Pitt River 7 miles below the bend. On the ridge between it and Pitt River a feldspar porphyrite outcrops, quite similar to that west of Kosk Creek, but in places it is highly amygdaloidal and scoriaceous. Slates appear in Big Cañon. They strike very regularly a little west of north; dip almost vertical. The color is black to purplish. A few scattered fossils were found in them and in the washed bowlders in the bed of the creek. The cañon has been eroded in the strike of the slates, and by following it up a larger collection could undoubtedly be made. The most prominent fossil is a large-ribbed bivalve shell not found in place at this point. The character of these fossils indicates a Mesozoic age. Some of the fossils, as well as the slates, resemble the Triassic of Indian Valley, Plumas County. They are certainly younger than the Carboniferous, and, according to our present accepted stratigraphy, must be older than the Cretaceous.

In the cove, near the mouths of Hat and Roaring Creeks, there is a considerable area of sandstone and conglomerate exposed, the lava having been worn away. It terminates often in precipitous cliffs, and the very rapid descent to the deep cañon of Pitt River has given rise to several beautiful falls.

Below Big Bend, Pitt River flows for many miles in a deep, narrow cañon. Its course has been cut at the junction of the Chico conglomerates with the older series, and the conglomerates are exposed in great thickness in many places along the cañon. The lavas are stratified, showing many successive flows, often fragmental at the bottom.

One half mile west of Round Mountain there outcrop slaty argillites, much contorted; strike east and west, dip 40° north. Here occurs a small vein of black quartz, carrying a large percentage of galena and zinc-blende. Other deposits of these minerals of small extent are found between this point and the Afterthought Mine, on Crow Creek.

Several small pieces of a silver-white metal were obtained from Mr. Iles, 5 miles southwest of Round Mountain, and are now in the museum of the Bureau. They proved on investigation to be native zinc, not certainly known heretofore as occurring in nature. According to Dana, it has been reported from Australia and Tennessee, but under circumstances not wholly free from suspicion. All efforts to obtain more specimens, or to have the location of the vein divulged, have been in vain. There is, of course, some doubt with regard to the genuineness of the metal, but from the fact that a small piece of rock remains adhering to one of the specimens, and that another shows a crystalline structure, such as could hardly be artificially produced, it seems to me they must be genuine.

In descending the Reed road the first outcrop of the older series is a chloritic feldspar porphyry, with a somewhat tufaceous appearance. Two miles west of Round Mountain a large body of limestone outcrops on both sides of Cedar Creek. This extends along the creek for 1 miles; at one spot forming cliffs 200 feet high. This height represents about the thickness of the limestone, for it dips west at an angle of not more than 10°. As the mouth of Cedar Creek is approached the strata, chiefly slates, become much steeper, with a strike a little north of west. Limestone again appears at the mouth of Cedar Creek, where it contains numerous poorly preserved fossils, chiefly brachiopods and corals of Carboniferous age. The limestone west of Round Mountain also contains similar fossils. One and a half miles below the mouth of Cedar Creek there is another mass of limestone, having a thickness of about 1,000 feet. Thin beds of limestone, alternating with slate, occur near the larger one. It is probable that all these bodies of limestone belong to the same horizon, but have been separated by the folding and crushing which has taken place.

The group of mines of which the Afterthought is the most important, is situated on Cow Creek, in Sec. 11, T. 32 N., R. 2 W. The veins occur in or near the contact of slate and porphyry. The direction of the veins

is northwest and southeast; dip to the northeast. The ore is quite base, carrying copper (often as high as 50 per cent), gold, silver, and some lead and zinc-blende. It is due chiefly to this rebellious character of the ores that the extensive operations begun here proved a failure. The depth reached in the Afterthought is said to have been 80 feet; the point at which the more base ores were met.

North of the Afterthought Mine is a considerable area of slaty rocks, often finely cleavable. These apparently dip south at a high angle, but a banding across them in the opposite direction seems to show that the cleavage lines are not those of sedimentation. The same thing is noticeable a mile north on the west side of the creek, where the slates show plainly a dip south at a small angle, while the cleavage is nearly vertical. A little farther north these banded strata are conformable with the limestone, dipping 60° to 80° southwest. Between the Afterthought Mine and the limestone there is a large body of quartz porphyrite. In places this shades into a schistose rock, closely resembling a sedimentary one, but it is to be distinguished from the latter by the fact that the schistose structure runs uniformly in one direction, northeast and southwest, with a vertical dip, while that of the real sedimentary varies greatly within short distances.

Below the Afterthought Mine, to the point where the road leaves the creek, the formation is chiefly a dark quartz porphyry. What is known as the Backbone road follows down the divide between Cow Creek and Pitt River. The ridge is high and narrow, with a very abrupt descent to the river. The highest point of this ridge for a mile consists of gray and black slate; strike north 30° to 40° west, dip vertical. Farther west the ridge is covered with lava, but there are occasional outcrops of the older series. This underlying rock is generally a dark flinty one, often with minute crystals of feldspar, and a flowage structure much resembling an ancient lava. Northwest of the lower end of the Reed toll road, the rock, where not covered by lava, is a massive green one, with traces of a porphyritic structure. It is undoubtedly an intrusive porphyry. The Reed road after leaving Cow Creek passes over lava tufas for several miles. West of this, blocky argillites are met; strike north 30° to 40° west, dip 50° northeast. These are followed by a mile of dark crystalline rock, which is overlaid by Chico sandstones on the west. The sandstone is replaced by shale toward the mouth of Cow Creek. These shales, wherever exposed in the foothills, form a heavy adobe soil. Characteristic fossils are abundant. The sandstone is but scantily covered with soil, and weathers out in great knobs and dome-shaped masses. On Dry Creek the shales are well exposed, showing a dip from 5° to 80° and numerous faults. Sandstone carrying an abundance of fossils outcrops on Stinking Creek. Near the mouth of the creek numerous brackish sulphur springs break out. The water is very disagreeable to the taste, and deposits both salt and sulphur. This region was recently the scene of a petroleum excitement, but no trace of oil could be found. The sandstone rises northward in higher barren ridges for a mile, and terminates in a conglomerate resting on the Metamorphic Series. The latter consist of slates, which strike north and south, dip 30° to the west. They are black, hard, and jointed, and cut by dioritic dikes. Farther north, in a gulch which heads in Bare Mountain, the slates are extremely metamorphosed; strike west 15° south, dip 80° south. Dioritic dikes continue to be numerous. Up the gulch as far as the Copper City road the diorite porphyrite dikes continue. Their outlines are very irregular and they often appear as mere bunches, but preserve a general northwest and southeast direction. The slates as a whole are so metamorphosed that there is no noticeable contact phenomena. The strike is north, to north 15° west, dip 20° to 30° west, for 2 miles southwest of Bare Mountain.

It is probable that granite underlies this region at no great depth, and that the numerous porphyritic dikes are offshoots.

Between Bare Mountain and Silverthorn Ferry, argillites are the prevailing rock. They lie nearly flat. At the river the strike is north 40° west, dip 40° southwest. Thin strata of limestone are occasionally seen. Between Copper City and the ferry, the rocks, though greatly broken, strike northwest and dip southwest.

It is difficult to give an intelligible description of the mines about Copper City. It has been many years since any work has been done here, and the old workings are inaccessible. The great excitement occurred in 1862-63. Mills were afterward erected, and as the ore appeared to be present in inexhaustible quantities no regular system of development was entered upon, but it was obtained in the easiest possible way, generally from surface openings. The ore is what might be termed medium grade, carrying both silver and gold. When the undecomposed portions were reached, which was generally but a short distance down, the free milling processes were of no use; and after an attempt to remodel the works so as to adapt them to a reduction of base ores, they were wholly abandoned. At the time of my visit only a few prospectors were at work on Bully Hill and vicinity, and a part of these were engaged in placer mining.

The mineral deposits at Copper City occur generally in a feldspar porphyry, which has been intruded through the slates in great masses and not in the narrow dike form. There is not much regularity about these bunches, and the slates in consequence dip and strike in every direction. The mineralization is no more regular than the geological features. The ore bodies are not veins in the usual sense of the term. The only veins in the district are quartz, and they are barren. The ore occurs, however, in irregularly mineralized areas in the porphyry. These might be termed chimneys, and are in all probability as permanent in their downward continuation as fissure veins, but far more irregular. The body of porphyry at Copper City containing the ore deposits extends northerly, though not continuous, about 2 miles, terminating in dikes. These bodies of porphyry are generally elongated in a northwest direction. The mineralization in this district shows feebly as far south as Silverthorn Ferry, and northward it does not extend much beyond Bully Hill. It is not certainly known whether this porphyry is a part of that great area extending in a westerly direction from the Peck Mine. There is certainly no prominent mineral deposit in the intervening region. The porphyry at Copper City often presents that tufaceous character noted in other places, and the origin of which is so puzzling. The ore is gray copper, containing gold, silver, antimony, and copper. Zinc-blende and galena are often present, and also iron and copper sulphurets. On the surface the mineralized areas are represented by a red spongy mass, in which the gold is free or partly so; the other minerals being reduced to carbonates or oxides. The character of the ore is much the same as that at the Peck and Afterthought Mines. The gangue contains no quartz, but instead a large quantity of heavy spar and calcitic compounds derived from the alteration of the porphyry.

A great amount of work was done on the Excelsior Mine at Copper City. Two tunnels, one 1,100 feet, the other 400, were run without striking the ore, and a shaft was sunk 125 feet on the top of the hill. Beautiful specimens of native silver were found near the surface in this mine

when first opened. The mine is said to have been abandoned on the supposition that it was worked out, but I see no reason for thinking that the deposits are on the surface merely. The ore in this mine was characterized by a large amount of zinc-blende.

The Exeter Mine was opened to a depth of 60 feet. The body of ore opened up is supposed to be better defined than most of the deposits in this district. All the ore milled was taken from near the surface, where it was easily worked. The direction of the ledges is northwest and southeast, but it is not likely that this regularity continues far.

Bully Hill lies about 2 miles north of Copper City. It is a great mass of mineralized feldspar porphyry, red, and easily decomposed on the surface. The red gossan capping is distinguishable from a long distance. The surface has been worked off and milled over a considerable area, and the gulches below, though worked for years, still contain much placer gold. Everywhere the hill seems to have been worked down to the undecomposed ore, and then abandoned.

The Jenny June Mine has a shaft down 100 feet. Most of the work was done on the mine in 1862, when a tunnel 1,000 feet long was run. The ore is not as base as in most of the mines.

The Popejoy Mine has been opened by a tunnel and shaft. A large body of ore was struck in this mine, but only the decomposed portion was touched.

The Recorder Mine lies on the north side of Bully Hill. A 200-foot tunnel has been run and a body of almost pure copper sulphurets struck.

The Bully Hill ores are, as a rule, easier to work than those at Copper City.

In summing up the characteristics of this district it may be said that the amount of ore is immense, but it is medium low grade with rich spots; that, while it has paid abundantly near the surface, no method has yet been successful with the base, undecomposed ores. Carrying as they do gold, silver, and copper, some method will yet be devised to reduce them on a paying basis.

Between Bully Hill and Madison's, 5 miles above, on Squaw Creek, slaty rocks are the only ones seen. In fact, up Squaw Creek, nearly to the boundary of the county, no more intrusive rocks appear.

The great beds of limestone which form the summit of the divide between Squaw Creek and Pitt River for a number of miles, strike across Squaw Creek about 9 miles above Madison's and become less prominent northward. In fact, it is not continuous, but swells in bunches, then pinches out. It is conformable with the slates, having a vertical dip, and contains very poorly preserved fossils. Traces of fossils appear also in the slates, but no specimens could be obtained. This belt of limestone extends north to the summit of the divide between Squaw Creek and the McCloud River. In this section the hills are brushy and steep, with very little good timber. The valleys are narrow and contain but a small amount of level land. The country is picturesque, but almost unknown, except to prospectors. The height of the valley at Kelley's is 1,500 feet. Strata of a coarse, fragmental rock are interspersed in the slates; frequently they contain rounded pebbles of felsitic and porphyry-like appearance.

Five miles north of Madison's, the limestone, which at the point where Squaw Creek crosses it, dips 80° southwest, turns and apparently

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