Description of the Redding Quadrangle

DESCRIPTION OF THE REDDING QUADRANGLE

By J. S. Diller.

INTRODUCTION. lava and tuff intermingled with the sedimentary hay, stands first among the farm products, with conveniently distinguish it from the plain of the Sac­ rocks and covering them in many places. The barley next, and small amounts of corn, oats, and ramento Valley proper. The Piedmont Plain is Location and area. The Redding quadrangle whole body of sediments and lavas is penetrated rye. The orchards yield prunes and peaches for for the most part dry, sterile, and usually strewn lies in the northern part of California and is by many dikes and masses of coarse granular plu- shipment, with grapes, pears, almonds, figs, and a with numerous lava fragments, making the roads bounded by meridians 122° and 122° 30'. west tonic rocks, such as granodiorite, gabbro, and ser­ few apples for home consumption. The genera­ across it extremely rough, in strong contrast with longitude and parallels 40° 30' and 41° north pentine. This complex of sedimentary and igneous tion of electricity for light and power is a thriving the sand and gravel plain of the Sacramento Valley. latitude. It measures a little over 34 miles from rocks was uplifted, forming the Klamath Moun­ industry. Fishing deserves mention, and the prop­ This arises from the fact that the Piedmont Plain north to south and nearly 27 miles from east to tains, at the close of the Jurassic, Erosion agation of fish is of great importance. McCloud is generally underlain by volcanic material in the west, and contains about 905 square miles, a lit­ and subsidence during the Cretaceous brought River, on account of its large supply of cool water, form of lava flows or agglomerate tuff, and it is tle less than one-fourth the area of Shasta County. the Klamath Mountains down to sea level, but the temperature rarely rising as high as 60° even evident that in origin the Piedmont Plain is inti­ It comprises the central portion of the county, at the close of the Cretaceous they were again during the summer, has an abundance of salmon mately related to the upbuilding of the Lassen embracing the north end of the Sacramento Val­ uplifted and with various later oscillations and and trout. Of the latter there are two varieties, Peak volcanic ridge. Backbone Ridge, north of ley, and Redding is its chief town. ...._.....-..-..-.._ consequent erosion have been carved to their the rainbow and the Dolly Varden. The former Furnaceville, marks the northern limit of the Outline of the geography and geology of the present form. has been hatched and distributed to many parts Piedmont Plain, where it reaches the canyon of region. The broad mountain belt of the Pacific Climate. Separated from the Pacific by a prom­ of the world. A station for hatching salmon was Pit River, but northwest of Sugarloaf it crosses the coast of the United States, approximately 150 inent mountain range, the Redding quadrangle established at Baird, on the McCloud, in 1872 and canyon and appears on the divide between Pit miles in width, extending through northern Cal­ partakes somewhat of the arid climate of the has been in operation more or less actively ever River and Squaw Creek. In this portion of its ifornia and Oregon, is naturally divided into three interior, which, however, is partly ameliorated since. The output of the station, amounting in course Pit River marks approximately the boun­ mountain ranges, the Coast, Cascade, and Sierra by mountains in the north and east. The cli­ some years to many millions of partially developed dary between the Piedmont Plain and the Klamath Nevada, and two valleys, the Sacramento Valley mate of the quadrangle differs considerably in eggs, is largely distributed to other hatching sta­ Mountains. different parts. The range in temperature and tions of the State for final development. The run of California and the Sound or Willamette Valley KLAMATH MOUNTAINS. of Oregon. rainfall in the Klamath Mountains is probably of salmon in the McCloud in 1903-4 was said to In California the Sacramento Valley separates quite unlike that of the northern part of the be the greatest ever known up to that time. Over The divides. The portion of the Klamath the Coast Range from the Sierras. In northern Sacramento Valley, where the only available 32,000,000 eggs were taken at the McCloud station Mountains which lies within the Redding quad­ Oregon the Willamette Valley separates the Coast observations were made by the Weather Bureau. in 1903 and more the year following. rangle occupies its northern two-thirds and and Cascade ranges, but in the northwestern part The mean annual temperature for twenty-two embraces all the country not included in the of California and the southwestern part of Oregon years previous to 1899 is 62.4°, ranging from TOPOGRAPHY. Sacramento Vajlley proper and the Piedmont an average of 45.2° in January to 81.9° in Plain. The hills and mountains are arranged is an irregular group of mountains, the Klamath RELIEF. Mountains, in which all the ranges meet and form July. The highest temperature recorded was chiefly in four ridges, running approximately an irregular upland 200 miles in length between 114° and the lowest 18°. The average annual Attention has already been called to the fact that north and south and forming the divides between the heads of Sacramento and Willamette valleys. precipitation for the same time is 25.56 inches, the Redding quadrangle embraces parts of three the principal streams. Named from the east, these Each of these great topographic features may be almost the whole falling between October 1 and great topographic provinces, namely, the Sacra­ are the Brock Mountain divide, between the Great regarded as outlining a geologic province. The May 30. June to September inclusive are dry mento Valley, the foothills of the Lassen Peak Bend of Pit River and Squaw Creek; Town Moun­ Redding quadrangle embraces parts of three of months, with only occasional small showers in volcanic ridge (Cascade Range), and part of the tain divide, between Squaw Creek and the McCloud; these provinces the north end of the Sacramento the valleys, though they are more common in the Klamath Mountains. Hirz Mountain divide, between the McCloud and Valley, part of the Cascade Range, and part of mountains. According to observations at Red the Little Sacramento; and the Clear Creek divide, SACRAMENTO VALLEY. the Klamath Mountains and contains records Bluff, the general movement of the air is from lying west of the Little Sacramento. more or less complete of the geologic history of the mountains on the north and east into the The north end of the Sacramento Valley, lying The Brock Mountain divide is most regular in all three provinces. The course of events in the valley. During the summer months, however, between the foothills of the Klamath Mountains the southern part, where the ridge, attaining a development of each province is in strong contrast there is a well-marked northerly movement of on the west and north and those of the Lassen height of 3000 feet, is formed of limestone. In a with that in the others. These events are briefly the air, which is in part due to a strong west­ Peak volcanic ridge from Millville to Bella vista small way the limestone is extremely rough and as follows: erly indraft through the Golden Gate and its on the east, is characterized by a broad plain of jagged, owing to the peculiar fluting which results The Sacramento Valley is a depression between subsequent deflection northward through the val­ gravel and sand, across which the river and its from weathering. Farther north igneous rocks the Sierra' Nevada, Coast Range, and Klamath ley. Killing frost rarely occurs as late in the tributaries have cut valleys rarely as much as 100 become more abundant and in Bagley Mountain Mountains and has long been receiving the mate­ spring as March 30 or as early in the fall as feet in depth and ranging from one-fourth mile to rise to a height of 4437 feet. rial washed down from the mountains. During November 7. 4 miles in width. The floors of these valleys are The Town Mountain divide is the most rugged the Cretaceous period it was still covered by the Vegetation. Although the greater part of the generally flat, being the flood plains of the adja­ mountain ridge of the quadrangle, having a suc­ sea, and also in part during the Tertiary; but since Redding quadrangle is forested, most, of it is cent streams, and are covered with fine alluvial cession of five prominent peaks over 4000 feet high that time it has been above sea level and drained but sparsely covered with small trees and scrub, soil which, when well watered, is excellent for within a distance of 12 miles. The high peaks are by Sacramento River, whose floods have made the and other portions, particularly large tracts of agricultural purposes. The sand and gravel plain all composed of igneous rocks, arranged in sheets deposits which form the present surface of the the gravel plains in the Sacramento Valley and is well illustrated by the Stillwater and Millville dipping eastward and presenting steeper slopes valley. the dry, stony plain of the Piedmont, are tree­ plains, at an altitude of about 500 feet, gradually with a succession of small cliffs to the northwest. The Cascade Range, which is represented in the less but afford fine pasturage for much of the rising to the north. The alluvial valleys are West of .Town and Horse mountains is a lower but Redding quadrangle by the western edge of the year. In the lowlands and the foothills of the represented along Cow Creek, Stillwater Creek, very prominent ridge of gray limestone, which Lassen Peak volcanic ridge, is purely volcanic, Klamath Mountains several varieties of oak and the Sacramento below Redding. This sand farther south, beyond Pit River, appears in Gray consisting of intermingled lavas and tuffs piled up (chiefly Quercus douglasii) and the digger pine and gravel plain, rising nearly 100 feet above Rocks. Bear Mountain, a short distance to the around the craters from which they were erupted. (Pinus sabiniana) are most common, with man- the alluvial valleys, represents the ancient flood southeast, is capped by igneous material. So many volcanic vents were active in the same zanita and live oak generally prevailing in the plains of the streams during the Redding epoch, The Hirz Mountain divide widens and increases belt that the volcanic cones which were built up underbrush. About the higher summits pines before the streams had cut their present valleys. in height northward to 5355 feet in High Moun­ about them coalesced and formed a prominent increase and timber becomes more valuable, but It is interesting to note that the plain, especially tain, also called Nawtawakit Mountain, the highest range, with a long, gentle slope coming down to none of it is lumbered except in the northwest around the north end of the valley from Buckeye point in the quadrangle, near the middle of its the Sacramento Valley. corner of the quadrangle, at Lamoine, where there by Lilienthal to Calkins, extends beyond the limit northern boundary. The divide is very irregular, The Klamath Mountains are not the direct result is a box factory. of the sand and gravel that fill the Sacramento but its crest keeps close to the McCloud, where the of upbuilding, like the other two provinces, but are Population and industries. The Redding quad­ Valley, and that this extended border is cut into limestone and igneous rocks, though near the larger mainly the product of upheaval .which raised above rangle, though covering less than one-fourth of the hard rqcks. stream, resist erosion more effectively than the thin the sea a long succession of sedimentary and igneous Shasta County, includes its most populous por­ sandstones and shales on the side toward the PIEDMONT PLAIN. rocks. tion. The county had a population in 1900 of Little Sacramento. The Klamath Mountains contain the oldest rocks 17,318; of this number 2946 lived in Redding, In the southeastern part of the quadrangle, The top of the Clear Creek divide, which attains of the region, and in this' respect are like the Sierra and it is probable that the whole quadrangle con­ drained by Cow Creek and its tributaries, is a an altitude of over 5000 feet, lies just outside the Nevada farther southeast. Large masses of lime­ tains scarcely less than 12,000 inhabitants. series of low, flat ridges running northeast from Redding quadrangle, but the greater portion of its stone and other sedimentary rocks of Devonian The principal industry is mining, and Red­ the vicinity of Bella vista and Millville toward eastern slope, with several points rising to over and Carboniferous age occur, as well as some- older ding is the outfitting and business center. Crater and Magee peaks, which, like Lassen Peak, 4000 feet near Sacramento and Little Sacramento crystalline schists. There is a small proportion of Shasta County has long been noted for its gold, were once active volcanoes and belong to the Cas­ rivers, is included within the boundaries. Triassic and Jurassic rocks, and the whole is cov­ and lately copper and silver have become impor­ cade Range. The broad, even crests of these ridges, Klamath peneplain. About the level of the ered here and there by remnants of a once con­ tant. Agriculture, including fruit raising, is of separated by relatively narrow canyons in which highest summits the slopes become gentler and tinuous sheet of Cretaceous sandstones, shales, and much less importance, though with irrigation its the present streams flow, are evidently parts of a the crests flattish, approximating a general plain. conglomerates. At times while .these rocks were relative value might be greatly increased. The once continuous plain which gradually rises north­ This suggests that before the deep valleys were forming, especially before the middle Devonian fine pasturage afforded by the Sacramento Valley eastward from an elevation of 500 feet on the gravel carved by the present streams they were con­ and during the latter part of the Carboniferous during the rainy season favors stock raising and plain of the Sacramento Valley to nearly 5000 feet nected in a landscape of gentle relief, in which and the greater portion of the Mesozoic, volcanoes wool growing, for the animals may be kept in the as it approaches the volcanic peaks of the range. the hills were low and rounded and the valleys were active in the Klamath Mountain region, mountains during the summer; but this resource As this plain belongs to the foothills of the moun­ broad and shallow. In the Redding quadrangle giving rise to extensive sheets of contemporaneous is limited. Wheat, which is raised chiefly for tains, it may be designated the Piedmont Plain to this high plain of gentle relief is scarcely per- ceptible, owing to the later destructive erosion Redding. The following table shows the height Rises of 15, 16, and 20 feet are not uncommon. ceous and full of radiolarian remains, which by the large streams; but in some other por­ of the water level of the river in July, 1900, at The height of the river varies from day to day, produce minute spots visible with a hand lens. tions of the Klamath Mountains the plain is a number of points in the quadrangle, named from even in the dry season. The oscillations are The shales are conformable with the limestone, well developed arid gives to the uplands of the north to south, and gives an idea of its water power: related to the rate of melting of the Mud Creek the whole series generally striking about N. 60° region in which it occurs the character of a pla­ Elevation of water level of Sacramento and Little Sacramento Glacier on Mount Shasta, for within twelve to E. and dipping 30° SE. teau. To facilitate reference to this feature it has rivers, July, 1900. twenty hours after a particularly warm interval A large body of limestone occurs also in the been designated the Klamath peneplain (Bull. U. the McCloud rises at the fishery and is clouded divide between Little Backbone and Squaw creeks, 8. Geol. Survey No. 196, 1902, p. 15). Distancebe­ stations.tween with light-colored sediment like that coming from along the trail from Kennett to the Mammoth Fall Earlier river valleys. The Klamath Mountain Locality. Date. Elevation. per glaciers. McCloud River is a narrow, rushing mine, and several small masses partly or com­ mile. valleys of the Redding quadrangle are in general stream between steep, wooded, rocky slopes and pletely surrounded by metarhyolite crop out narrow and canyon-like in their lower parts, with affords an especially attractive water power. near the crest at an elevation of from 3800 to Feet. Mi. Feet. Within the quadrangle the river falls nearly steep slopes, while the upper parts, involving the Railroad bridge one-half 4400 feet, in sees. 13, 18, and 19, nearly 6 miles crests of the ridges, are much wider and are char­ mile south of Portuguese 450 feet in 21 miles, or at the average rate of northwest of Kennett. These isolated masses, as acterized by gentle slopes. These wide upper parts Flat...... Tnlv 28 1277 21 feet to the mile. The fall is not quite as great shown by their abundant fossils, were once directly have been called for convenience the earlier valleys, Railroad bridge 1 mile as that of the Little Sacramento, but as its volume connected not only with one another but with the to distinguish them from the canyon-like portion south of Portuguese Flat July 28 1263 i 28 is over four times as large, and regular, it is much larger masses of limestone and shale already referred below, designated the later valleys. Mouth of Slate Creek, near more efficient. Recognizing the McCloud as an to. The separation in most cases is clearly due to Slatonis...... 1222 H 27+ One of the best preserved of the earlier valleys Mouth of Little Dog Creek, important water power, several companies are now erosion, which has removed the intervening mate­ is that of Pit River. The flat divide south of this one-half mile below preparing to utilize it in an electric plant, rial, as will be shown later, to form the Bragdon. river and east of Sherman is the border of the Delta...... 1086 4 34 The northernmost locality of the Kennett for­ Piedmont Plain. The lavas of the Lassen Peak Railroad bridge 1 mile DESCRIPTIVE GEOLOGY. mation exposed in the Redding quadrangle is in volcanic ridge forced the Pit to the western border July 27 1049 4 49 the SE. J sec. 33, T. 35 K, R. 5 W., on the slope SEDIMENTARY ROCKS. of the partially developed peneplain, and beyond Railroad bridge 2 miles north of Little Sugarloaf Creek. The area is small July 26 1083 1 16 Jones Valley the river cuts across a portion of the and the rocks are chiefly dark shales, in some Gregory (Baird Spur) ...... July 25 938 4 24 In the Redding quadrangle, besides a large num­ Klamath Mountains directly to the Sacramento. Railroad bridge 4 miles ber of igneous rocks, fifteen sedimentary formations places decidedly cherty, with radiolarian spots, It is in this portion that the early valley, at July 24 839 4 20 have been recognized and outlined upon the areal and ferruginous sandstone rich in corals. an elevation of about 1500 feet, is well preserved Railroad bridge near El- geology map. Collectively they contain a more The Kennett formation of the Backbone region and may be well seen looking westward through July 24 737 5 24 complete record of the geologic history of northern crosses the river a short distance above Morley, the valley from Sugarloaf, 2 miles northwest of Mouth of Pit River...... July 20 639 5 20 California than has yet been found in any other where near the water's edge the shales are rich Kennett bridge...... July 20 624 2 8 Furnaceville. The level of the broad, shallow Keswick bridge ...... July 20 511 12 9 quadrangle. in fossils. To the northeast they disappear for old valley of the Pit is scarcely 500 feet below some distance, being covered up by the Bragdon Mouth of Middle Creek .... July 20 495 2 8 DEVONIAN SYSTEM. the flat Backbone Ridge which divides it from July 4 456 6 6.5 formation, but reappear west of Baird; at this Little Cow Creek, and is in very strong contrast KENNETT FORMATION. point the limestone ledges are few and smaller, with the narrow, deep, canyon-like valley contain­ The greatest fall, 49 feet per mile, is near Delta. Lithologic character. The Kennett formation and sandy shales and sandstones largely predomi­ ing the present river. The average fall per mile for 25f miles north of the (Jour. Geol., vol. 2, p. 591) is made up chiefly of nate. Considerable limestone occurs in sec. 16, Traces of earlier valleys may be followed in the mouth of Pit River is nearly 25 feet, and the aver­ black shales, often cherty, with some thin-bedded near the head of Bailey Creek, on the east slope uplands along the McCloud and Little Sacramento, age fall for 16 miles between the mouths of Pit sandstones, inclosing in many places lenticular of O'Brien Mountain. Small masses crop out also but for various reasons they are not so well marked River and Middle Creek is 9 feet. Below Middle masses of gray, highly fossiliferous limestone. The in sees. 9 and 21. Farther south and southwest a as that of the Pit. This earlier-valley epoch is given Creek the rapids continue for a mile to the long thin gray sandstones occasionally contain a large mass of shales, containing a ledge of fossiliferous great interest by the discovery of Potter Creek cave stretches of still water which characterize the mean­ amount of material derived from volcanic rocks. limestone, outcrops in the SE. ^ sec. 17, near the at the level of the earlier valley. The cave con­ dering stream in the Sacramento Valley, where the One of the best sections of these rocks, though Buckeye road. Similar ledges rich in fossils occur, tained bones of forty species of animals, of which fall to tide water averages scarcely 2 feet to the mile. it certainly does not include the whole of the Ken­ surrounded by igneous rocks, in the southeastern at least seventeen, including the mastodon, ele­ Sacramento River is not navigable in the Red­ nett formation, may be seen on the left slope of part of sec. 25, about 3 miles west of Lilienthal. phant, and tapir, are extinct. The character of ding quadrangle. It is comparatively shallow, Backbone Creek 3J- miles north of Kenuett, where Slates with some limestone, formerly burned for the fauna in good part indicates low relief, and, as with occasional riffles of gravel. 865 feet of sediments are fully exposed in the fol­ lime, occur in sec. 6, east of Newtown, also west of pointed out by Mr. Sinclair (Science, new ser., vol. Pit River joins the Little Sacramento near the lowing order, beginning at the top: Newtown on the road to Old Diggings. A larger 17, 1903, pp. 708-712), is quite out of harmony middle of the quadrangle, and just above the junc­ Partial section of Kennett formation on Backbone Creelt belt of slaty shales stretches more or less continu­ with the present topography of the region. tion carries more than fifteen times as much water north of Kennett. ously from near Waugh to Clear Creek, a mile Later river valleys. Later valleys in the Kla­ as does the Little Sacramento. Like the latter, it Feet. below Horsetown, where several lenses of lime­ math Mountains occur along all the present is without falls, but contains a succession of rapids 1. Shales, mostly dark, with thin sandy beds 140 stone occur. 2. Massive, light-colored limestone with little streams, but their most striking development is from the Great Bend to its mouth, a distance of chert, but full of corals...... 100 The separate areas of Devonian sediments noted found along the larger rivers, especially the Pit, about 30 miles. Its water level in September, 3. Thin bedded sandstone and shales which above, about a dozen in number, are all charac­ McCloud, Little Sacramento, and Sacramento, are cherty and gray below. Near the mid­ terized by essentially the same fossils and are 1900, near the mouth of the McCloud was 688 dle part is a limestone lens 10 to 15 feet where the canyon-like valleys are narrow and feet, and at Bully Hill Bridge, 7 miles farther up, thick...... 300 doubtless only remnants of a continuous sheet deep, with steep slopes to the water's edge, leaving was 760 feet, giving the river an average fall of 4. Thin-bedded limestone, crowded with which once covered the whole area, but which massive branching and cup corals. Cherty little or no space for roads or cultivation. 11 feet to the mile for the last 11 miles of its nodules and bands in bluish limestone, has since been much deformed and reduced by In. these later valleys, especially along the Sac­ course. Pit River rises in the vicinity of Goose becoming whitish and without chert be­ erosion to its present fragmentary state. low...... 250 Thickness. Only the lower part of the Kennett ramento, there are terraces which appear to mark Lake, nearly 100 miles east of the Redding quad­ 5. Siliceous shales, 10 feet of banded chert at intervals of stability, permitting the streams under rangle, but does not receive its most important top, succeeded by sandy shales, black formation is usually exposed. Its maximum pre­ favoring local conditions to widen the valley tributaries until it reaches Fall River and Hat shale, and fine shaly sandstone, very thin served thickness is about 865 feet. To judge from bedded ...... :... 75 slightly. Their best development is in the vicin­ Creek, which are strong and regular streams from the amount of Bragdon sediment derived from the ity of Keswick, where the terraces are capped by the perpetual snows of Mount Shasta and Lassen The sandstones of this section were not examined Kennett, the latter may have lost much of its patches of gravel like that of the Sacramento Val­ Peak, and which increase its flow to more than ten microscopically, but farther down Backbone Creek, original thickness by erosion, but in some places ley and represent an epoch when Sacramento River times its volume above the mouth of Fall River. where they are well exposed, the basal beds con­ its upper part is covered unconformably by the flowed at a level about 200 feet above its present The comparatively constant water supply during tain many grains and occasional small pebbles of Bragdon. bed, in a somewhat wider valley. Following the the summer makes Pit River an excellent logging microporphyritic igneous rocks, apparently iden­ Paleontologic character. Fossils have been found river farther north, we find remnants of the old stream, and it has been used for that purpose to tical with portions of the Copley metaandesite in nearly all the areas of the Kennett formation, valleys on the spurs from the east in the very transport wood and lumber for the mines and and Balaklala rhyolite. The cherts, wherever but they are most abundant and varied in the sharp bends near the mouth of Sugarloaf Creek, smelters at Bully Hill and Keswick. examined microscopically, were found to contain region north and west of Kennett, from which and beyond this the terraces are capped by a sheet McCloud River is the chief tributary of the Pit traces of radiolaria. place they can be easily reached. of lava which came from Mount Shasta. At Delta within the quadrangle. It rises at the southeastern The limestone, which forms a much larger por­ The fossils collected in the Kennett formation gravel of the old river bed is preserved beneath the base of Mount Shasta and has a length of over 40 tion of the Kennett formation in this section than were referred to Prof. Charles Schuchert for study, lava. miles, nearly half of which is in the Redding elsewhere, resists erosion much more effectively and he has furnished the following report: In comparing the stream valleys of the Klamath quadrangle. From the lavas at the base of Mount than the shales and thin sandstones about it, so Mountains with those of the Piedmont Plain and Shasta great springs coming from the snows about that it forms prominent ledges which may be The section of the Backbone locality given by Mr. the Sacramento Valley it appears that in the Pied­ the summit gush forth in .the McCloud Canyon, seen for miles; but as the lenses are of small Diller has one general fauna indicative of the middle Devonian. The general age has been known for some mont Plain only the later valleys are found, while and give to the river a large and regular supply of extent they do not determine important topo­ years, but the collections of 1902 have given us a defi­ in the Sacramento Valley proper only the very water, with a surface temperature, as already stated, graphic features. nite section and also species that are known to occur in latest occur, corresponding to that below the Kes­ rarely as high as 60°, even in midsummer. The Distribution. The Kennett formation occurs in other American localities. This is especially true of wick terrace. cool canyon of the McCloud, well supplied with the western and southwestern parts of the quad­ the fossils of the lower shale zone, which repeats the fish and game, is a delightful summer resort, and rangle, where its distribution is in marked contrast fauna of the Eureka and White Pine districts of Nevada DRAINAGE. much of the land has already been bought by San with that of the other formations, being in iso­ and. the middle Devonian of Iowa. The species that are common to at least two of these regions are ScMzoplioria The Little Sacramento rises in the lower moun­ Francisco people for that purpose. Stream meas­ lated patches scattered sparsely over an irregular striatula, Stropheodonta canace, Gypidula lotis, Pugnax tains at the western base of Mount Shasta. About urements (September 23, 1902) have shown that area 20 miles in length and 10 miles in greatest altus} Atrypa missouriensis, and Cyrtina missouriensis f. 30 miles from its source it enters the Redding the river at Johns Camp and at the United States breadth. Taking these species in connection with the corals of quadrangle and with many meanders follows a fishery contains 1272 and 1275 second-feet respec­ The two divides to the southwest of Backbone the limestones, as Heliolites porosa, Endophyllum or Spon- direct general course across the western part of tively, with a fall of about 21 feet to the mile. The Creek, on both sides of Little Backbone Creek, gophyllum, and Phillipsastrcea, one sees plainly that the California middle Devonian belongs to the "Euro- Asiatic the quadrangle, receiving with the Pit and the McCloud is usually lowest in September, just before expose parts of essentially the same section as that province." This province extends east in North Amer­ McCloud the drainage of the entire area. Below the rains begin. Mr. Livingston Stone, of the given for the slope northeast of Backbone Creek. ica as far as central Missouri, eastern Iowa, Milwaukee, the mouth of the Pit it is known as the Sacramento. McCloud fishery, reports 9 feet of rain and a rise Above the Golinsky mine on Quarry Ridge the Wis., and Petoskey, Mich. East of these places occur It has no falls, but is full of rocky rapids until the of the river to 26 feet above low-water mark Feb­ black shales beneath the limestone have a thick­ the middle Devonian faunas of the " North American Sacramento Valley is reached, a few miles above ruary 2, 1881, when the fishery was washed away. ness of about 50 feet. They are somewhat sili­ type." Relation to volcanic rocks. Everywhere within the McCloud. Except the stem, the smaller end had been greatly eroded before the Bragdon was Southward from the fishery the distribution of the Redding quadrangle the exposed Kennett for­ of the pear-shaped area lies within the Redding deposited upon it. In fact, the erosion was so the Baird is less regular. In the vicinity of Pit mation is limited below by a mass of ancient vol­ quadrangle and is trenched by the Little Sacra­ great that the Devonian sediments were in some River the metaandesite, augite-diorite, and gran- canic rocks. This relation is most evident a few mento from Portuguese Flat to Morley. places completely washed away, allowing the odiorite cut it off, but it appears again south of miles north and northwest of Kennett, where the As compared with the Kennett formation in dis­ Bragdon sediments to be deposited directly upon Gray Rocks and as a narrow belt extends along Kennett formation lies on the crests of the divides, tribution, the Bragdon is remarkable for its con­ the pre-Kennett (probably pre-Devonian) volcanic the western border of the McCloud limestone to exposing the ancient lavas and tuffs beneath. tinuity. It is interrupted at only two points on rocks. The residual character of the Devonian the Sacramento Valley. These ancient volcanics, especially the tuffaceous Dog Creek by an area of volcanic rocks and on areas between the ancient volcanics and the Thickness. The total thickness of the Baird ones, are arranged in more or less distinct sheets, Little Sugarloaf Creek by a small mass of Devo­ Bragdon is well illustrated along the border of formation is not easily determined, on account of and the Devonian sediments overlie them in places nian shales. There are several small outliers; one the latter from Bailey Creek to the head of the irregular limits of the exposures, due to intru- with approximate conformity. As the sediments is a mile southeast of Bayha, and the other half a Backbone Creek. sives, but it is certainly 650 feet and possibly much are soft and fine the contact is not well exposed. mile east of Morley. more. The tuffs at the base are approximately 500 BAIRD FORMATION. Locally traces of shale breccia were found near the Thickness. Within the Redding quadrangle the feet thick, and the overlying fossiliferous beds about contact, suggesting faults. The presence of igneous broad area of the Bragdon formation is so affected Lithologic character. The formation next suc­ 150 feet. material associated with chert in the Backbone by small folds that its thickness is difficult to deter­ ceeding the Bragdon is of great thickness and Fauna and age. The fauna of the formation Creek Devonian sandstones confirms the view mine, but farther north, on Hazel Creek, where the consists chiefly of tuffaceous rocks, above which was listed 'in 1894 by Prof. J. P. Smith (Jour. that the volcanics are older than the Devonian Bragdon occupies a definite belt between the Ken­ there are siliceous and calcareous shales and sand­ Geol., vol. 2, pp. 595-597), who calls it the Baird, sediments resting upon them. Generally, however, nett and the Baird, it has been estimated at about stones, more or less tuffaceous and usually rich in and remarks: "In a paleontological sense the the sediments of the Kennett formation are so fine 2900 feet, after making due allowance for folds and fossils. The Baird, as originally named by Prof. Baird shales are homotaxial with the Waverly, that they do not contain a conspicuous record of faults. It is possible, however, that the maximum J. P. Smith, included only the fossiliferous upper while stratigraphically they probably are not, but their source. thickness in the -Redding quadrangle may be as portion. It is here extended downward to include would agree more nearly in position with the The Kennett formation is limited above by the much as 6000 feet. the tuffaceous rocks and the adjoining sandstones higher divisions of the Lower Carboniferous unconformably overlapping Bragdon formation, Fossils and age. Fossils have been found in the and shales which overlie the topmost Bragdon of the Mississippi Valley." It is "equivalent to whose sediments were derived chiefly from the limestone pebbles of the Bragdon conglomerate conglomerate. the Lower Carboniferous of the Eureka district, erosion of the Kennett. In many places the Ken­ and also in the sandstones and shales interstratified Tuffs. In the Baird formation, beneath the Nevada," nett was completely washed away and the Bragdon with the conglomerate; those in the pebbles are highly fossiliferous portion at the top, is a mass Relation to adjacent formations. The Baird is overlaps upon the older volcanics. These relations older than the Bragdon formation and belong to of tuff ranging from a few score to 500 feet in conformable with the Bragdon below, as well as are well exposed along the border of the Bragdon, the formation from which the pebbles were derived, thickness and usually of strong colors, red or yel­ with the McCloud limestone above. The line from the upper part of Backbone Creek across the while those of the sandstones and shales mark the low to white, in contrast with their associated frag- between Baird and Bragdon, as already explained, Sacramento and around the northern shoulder of age of the Bragdon. Since the age of this forma­ mental rocks. Northwest of Baird, on the road is determined by the topmost horizon of the pecu­ O'Brien Mountain to Bailey Creek, west of Baird. tion has been a matter of discussion, the evidence from the fishery toward Radcliffe's, tuffs are well liar Bragdon conglomerate, and there was contin­ bearing on that subject requires fuller treatment exposed for about three-fourths of a mile. They uous sedimentation from one to the other, with but CARBONIFEROUS SYSTEM. than it would otherwise receive. are soft and friable, and locally they are bedded slight change in the character of the sediment. MTSSISSTPPIAN SERIES. Fossils collected from pebbles in the conglom­ and distinctly fragmental. A few smooth, round South of the Black Diamond mine the Baird is BRAGDON FORMATION. erate at a large number of localities throughout the pebbles, one of banded chert, and another larger well exposed, lying in conformable contact beneath Lithologic character. The Bragdon formation, Bragdon area were referred to Professor Schuchert one of rhyolite, were found inclosed in the fine the McCloud limestone; but from the same mine named by Mr. O. H. Hershey (Am. Geol., vol. 27, and Dr. Girty, and all of them so far as determin- tuff. With these exceptions the coarsest material northward the Baird is separated from the McCloud p. 238), is composed chiefly of thin-bedded, inter- able, with one possible but doubtful exception seen here is sandstone thickly peppered with small limestone by an irregular belt of augite-diorite stratified shale, sandstone, and conglomerate. The found on Bailey Creek, were reported as Devonian, white grains of kaolin, among which stand out intruded between them and breaking them into shale is dark, often black, in beds ranging from a like those already known in the Kennett region, grains of quartz and reddish andesite. The exceptional aspect of these rocks suggests at few inches to 60 feet in thickness. The sandstone and show clearly that the conglomerate is later PENNSYLVANIAN SERIES. than the middle Devonian. once that they are tuffs, and there can be no doubt is generally less than 2 feet in thickness and rarely M'CLOUD LIMESTONE. over 10 feet. It is for the most part gray and nor­ In the sandstones and shales fossils were found that they are composed chiefly if not wholly of vol­ mal in composition, though sometimes dark, hard, at half a dozen localities. An important occur­ canic material. Many of the fragments are lapilli, History. The McCloud limestone lies strati­ and flinty, like some forms of quartzite, and in rence is upon the divide southwest of Nawtawakit and the others are broken crystals of feldspar and graphically next above the Baird formation, though places decidedly tuffaceous. or High Mountain, where the sandstones, conform­ quartz, with a trace of deep-brown hornblende and generally separated from it by intruded augite- The conglomerate constitutes the most character­ ably interbedded with characteristic Bragdon con­ flecks of chlorite representing some decomposed fer- diorite. It was early noted by Trask (Rept. on istic portion of the formation. It is generally glomerate, contain shells which Dr. Girty reports romagnesian silicate; but definite traces of pumi- Geology of Coast Mountains, 1855), who collected composed in large part of black and gray pebbles as "Paleozoic and without much doubt early Car­ ceous or glassy fragments could not be found. fossils near Bass's ranch, Stillwater, and first deter­ of cherty quartz with others of sandstone, shale, boniferous, related to the Baird." The fossils, A mile farther northeast, on a prominent spur mined its age. The Geological Survey of California and limestone derived from the Kennett formation. among which is a large "Spirifer of the striatus running from the limestone to the left bank of (Geol. of California, vol. 1, pp. 326-327), under The limestone pebbles disappear by weathering, type," occur in several beds well exposed and are McCloud River, rhyolitic and andesitic sandstones Prof. J. D. Whitney, visited the same locality and leaving holes on the surface, which give to the con­ undoubtedly of the Bragdon horizon. contain Baird fossils, and along the river nearly added much new information, but more notable glomerate a peculiar porous aspect. The beds of Perhaps the most important locality is beside opposite the mouth of Greens Creek beds rich in data as to its distribution and fauna have been con­ conglomerate are usually less than 10 feet in thick­ the railroad 1^ miles northeast of Lamoine, where fossils contain also distinct particles of volcanic tributed in later years by Messrs. H. W. Fairbanks ness, but sometimes attain a maximum of nearly fossils were found in the sandstone adjoining the material, chiefly of andesitic types. (Ann. Rept. Cal. State Mining Bureau, vol. 11, p. 50 feet. Quartz and chert pebbles prevail in the Bragdon conglomerate. From this locality Dr. One of the best examples of fine tuffaceous con­ 35 and map of Shasta County; Am. Geol., vol. 14, smaller and finer beds, and sometimes also in the Girty reports Schizodus sp., Loxonema sp., Pleu- glomerates in the Baird formation outcrops near p. 28) and J. P. Smith (Jour. Geol., vol. 2, p. 599). larger beds, where the pebbles are not over an inch rotomaria f sp., and Straparollus aff. S. luxus. the McCloud on the unfinished road to Middle Lithologic character. The limestone is dark gray in diameter. As the beds become coarser pebbles There is no room for doubt that these fossils Salt Creek. It is made up wholly of volcanic and massive below and lighter colored and some­ of sandstone become most abundant, while those of belong to the Bragdon and are not derived from material, some of it andesitic and crowded with what thinner bedded above, with many nodules limestone also generally increase in number and an older formation, and Dr. Girty remarks that feldspar microlites, but most of it rhyolitic. Some and sheets of gray chert, often containing silicified size. Conglomerate extends throughout the area if this be admitted "no other conclusion is pos­ fragments are devitrified, showing traces of the fossils. of the Bragdon formation, but appears most abun­ sible than that the Bragdon is a Paleozoic forma­ original perlitic cracks; others contain anhedral The largest and most accessible exposures of the dantly along the Little Sacramento. Much of it tion. Indeed, it is fairly safe to say that the quartz embedded in a mosaic of quartz and feld­ McCloud limestone are at Gray Rocks, near Bayha, along the river is fine, but some is coarse with horizon is not later than Baird, for the local spar. It lies not far beneath the McCloud lime­ the old Bass's ranch locality, and farther north on one exception much coarser than that found else­ faunas have many points of resemblance with stone and is permeated by carbonate of lime. McCloud River opposite the United States fishery. where. A short distance above Elmore, on the left that of the Baird and none at all with those of The prominent horizon of tuffs of wide extent in The two localities are separated by quartz-augite- bank of the river, some of the'smooth, round cob­ the overlying Carboniferous formations." the Baird indicates contemporaneous volcanic activ­ diorite, which cuts the limestone. bles of sandstone in. a bed of conglomerate attain a This matter is more fully discussed in the Amer­ ity, though no definite flows of lava were found Topography. The McCloud limestone generally maximum of 2 feet in diameter, though they are ican Journal of Science, vol. 19, 1905, p. 386. associated with the tuff. resists weathering more effectively than the asso­ generally not over 6 inches. Relation to adjacent formations. The inference Fossiliferous sediments above the tuffs. The sili­ ciated quartz-augite-diorites, so that it usually gives Igneous material is rare or entirely wanting in drawn from the fossils that the Bragdon is of Car­ ceous and calcareous shales and sandstones at the rise to bold outcrops and, where large, becomes many of the conglomerates, but in others it is boniferous age and lies between the Baird and the top of the formation, to which the term Baird was one of the principal factors in the topography, abundant and appears to have been derived chiefly Kennett formations is confirmed by its strati- first applied, are largely tuffaceous also. They are forming prominent ridges and peaks. from the Copley metaandesite. Some of the sand­ graphic position in the section from O'Brien well exposed on the right bank of McCloud River Caves. The massiveness of the McCloud lime­ stone beds are dark and closely resemble igneous Mountain to McCloud River. On the McCloud a short distance above the Baird fishery, and farther stone and its purity under certain conditions of rocks (Bass Mountain diabase), with which they near the fishery the Baird is well exposed, and on north at least as far as CampbelPs. Locally the internal drainage have afforded the opportunity are frequently associated in the field. These sand­ the slope of O'Brien Mountain the Kennett lime­ limy and cherty shales and hard sandstones are for the development of large caverns. One of stones were observed at one point west of Little stone outcrops. Between them on Bailey Creek nearly free from igneous matter, but generally it these near Potter Creek, a mile southeast of the Sacramento River. They are most abundant east is the Bragdon, dipping eastward beneath the prevails even where fossils are abundant, so that fishery, and another opposite Johns Camp, 7 miles of the river and northeast of Delta, in the upper Baird. From this point the two adjoining for­ there is no striking contrast between the upper and farther up the McCloud, have been found by Dr. part of the Bragdon. They are composed of the mations can be traced northward for many miles lower portions of the Baird as here defined, and no J. C. Merriam and his assistants to contain deposits same minerals, though in angular fragments, as the in essentially the same relation. They are con­ paleontologic break, for Baird forms go down into inclosing numerous bones of Pleistocene animals; Bass Mountain diabase chiefly plagioclase and formable and represent continuous sedimentation. the Bragdon. these will be noticed more fully in connection with augite. These sandstones in part possibly rep­ The boundary between them is marked by the Distribution. From the fishery the Baird for­ the origin of the earlier river valleys. resent contemporaneous volcanic activity during upper limit of the characteristic Bragdon con­ mation extends northward in a narrow belt up Distribution. The limestone can be traced more the latter portion of the Bragdon. glomerate. McCloud River for a dozen miles and then passes or less continuously for 25 miles from the north Distribution. The large area of Bragdon in the The Bragdon rests upon the Kennett formation into the high hills west of the river. On the east end of the Sacramento Valley near Lilienthal northwestern portion of the Redding quadrangle is and is made up largely of sediments derived from it is limited generally by augite-diorite, which northward to Nawtawakit Mountain, where it part of a still larger, irregularly pear-shaped mass the Kennett. It is evident that the two forma­ sends many dikes through the Baird into the passes beyond the quadrangle boundary. Near which extends from Trinity River northeast to tions are unconformable and that the Kennett Bragdon, which limits the Baird on the west. Lilienthal it begins with a series of small limestone Redding. lenses, apparently included in Dekkas aiidesite ice Or glass particles. Near the base of the Nosoni on the east and upon the andesites and rhyolites of due to folding, which brings down the Pit forma­ and worn down to the level of the valley plain. opposite Horse Mountain, adjoining the McCloud the volcanic belt on the west. The shales are black tion in Jones Valley and causes it to extend west­ Although much metamorphosed and in some places limestone, are gray calcareous shales and thin sand­ to gray, and weather whitish. Under the micro­ ward beyond Bear Mountain. To the south it wholly crystalline, they contain distinct traces of stones containing many of the characteristic long, scope they usually show many round spots, which disappears beneath the Cretaceous of the Sacra­ fossils definitely fixing their age. Farther north slender Fusulina. Overlying these shales is a bed occasionally contain distinct remains of minute mento Valley. they rise above the plain and form hills increas­ of tuff succeeded by a greater thickness of small- marine organisms, probably in most cases radiolaria. Thickness. The total thickness of the Pit forma­ ing in prominence to Gray Rocks. For 10 miles bedded, somewhat tuffaceous sandstone, which is In some places the shales are highly siliceous, well tion has not been accurately measured, but careful beyond Pit River the escarpment of McCloud lime­ capped by a lens of limestone about 30 feet in bedded, and of a greenish gray color. estimates in the field indicate that it is probably stone forms one of the principal topographic features, thickness. Farther up the ridge are purplish Tuffs. The tuffs are usually of fine angular somewhat oveE 2000 feet. but it is very much cut up by quartz-augite-diorite shales and tuffs with characteristic fossils, and sand ejected from active volcanoes and in the Fossils and age. Fossils are uncommon in the into irregular patches of limestone separated from the whole assemblage of Nosoni strata is overlain field closely resemble interbedded sheets of altered greater part of the formation, and yet traces may be one another by distances varying from a few feet by the mass of andesites forming the summit of andesitic or rhyolitic lava. Occasionally they are found at many places. They are usually ammon­ to over 2 miles. How much of this irregularitvo / Horse Mountain. coarse, more distinctly fragmental, and locally ites, but rarely so preserved that even their generic may be due to the original lenticular character of Distribution. The Nosoni forms a north and silicified. determination is possible. At the top of the for­ the limestone is not known, but there can be no south belt lying next east of the McCloud lime­ One of the best sections for studying the inter­ mation, however, there are several hundred feet of doubt that it is mostly due to the dissecting igneous stone and extends from the northern border of the bedded shales and tuffs of the Pit formation is on shales and tuffs in which fossils are more abun­ rock. The largest mass is that opposite the fishery. Sacramento Valley to beyond the boundary of the the spur from Brock Mountain to Squaw Creek, dant and have been referred by Prof. J. P. Smith Two other large masses occur in the Hirz Mountain quadrangle. The belt widens to the north. In along the line between Tps. 34 and 35 N. There to the upper Triassic, though it is possible that the region, but farther north, in the western portion the vicinity of Pit River the Nosoni formation is are within about a mile, from the limestone crest to less fossiliferous and larger portion below may of Nawtawakit Mountain, there is a considerable cut off by the intruded quartz-augite-diorite, but the creek, at least a dozen beds of tuff, ranging belong to the middle Triassic. decrease in size. beyond that point it begins again with a consider­ from 5 to 20 or more feet in thickness, between Relation to adjacent formations. The relation Thickness. In thickness the McCloud limestone able amount of andesitic or basaltic tuff. the more abundant dark shales. Some of the tuff of the Pit formation to those which are next earlier varies from 200 feet or less near the south end, Northwest of Town Mountain the Nosoni is beds can be traced along the strike north and and later is in the one case complex, but in the where it appears in small lenses, to approximately again cut off by the quartz-augite-diorite, which south for a mile or more and dip to the east con­ other sharp and definite. Everywhere the Pit for­ 2000 feet in the prominent rugged mountain includes masses of the McCloud limestone, but the formably with the shales. The tuffs are generally mation rests upon volcanic rocks, either andesites formed by it a short distance northeast of the formation reappears beyond Dekkas Creek, where dark gray, with occasional quartz grains, and closely or rhyolites, or upon their associated tuffs, and it fishery. andesitic tuffs and conglomerates begin to form its resemble some forms of rhyolite-porphyry; but a is evident that these volcanic rocks, which form the Age. The fossil fauna of the McCloud limestone greater portion and continue to increase in bulk thin section shows that the whole is made up of prominent hills from Horse Mountain to Salt Creek, was long ago made known by Mr. F. B. Meek in rapidly in that direction. In the northern portion angular fragments of quartz, altered feldspar, some Mountain inclusive, are older than the Pit forma­ vol. 1 of the Paleontology of California, and in of the field the tuffticeous beds lie for the most part ferromagnesian minerals, magnetite, and lapilli. tion and lie conformably beneath it; but the vol­ reviewing it Prof. J. P. Smith, who collected exten­ below the fossiliferous shales and sandstones, though An occasional curved form like splinters of glass canic activity which gave rise to this great mass of sively in the field, says that the McCloud limestone small masses of such strata are occasionally found is found altered to quartz. These beds sometimes lavas continued at intervals throughout the deposi­ is "in part equivalent to the Coal Measures." interbedded with the tuffs. A good example of contain lapilli which are distinct to the naked eye, tion of the Pit formation, giving rise within it to Relation to adjacent formations. Throughout this kind occurs on the southeastern slope of Naw­ but frequently they do not appear in the field to interbedded flows, intruded sheets, and dikes, as the greater part of its extent in the Redding tawakit Mountain at an elevation of about 2000 be fragmental rocks. The sharp, angular character well as to numerous beds of tuff. For this reason quadrangle the McCloud limestone is bounded feet. of the grains of igneous minerals, with the asso­ the relation of the Pit formation to the associated both east and west by quartz-augite-diorite, but Thickness. Opposite the fishery, on the west­ ciated volcanic particles, shows that the material is igneous rocks appears complex. On the other for over 2 miles south of the Black Diamond mine ern slope of Horse Mountain, the Nosoni forma­ practically a volcanic sand. hand, the Pit formation at many points may be it lies conformably between the Baird and the tion is well exposed, with a total thickness of over On the new road from Squaw Creek to the lime­ seen to lie conformably beneath the Hosselkus Nosoni formations. 500 feet from the McCloud limestone below to stone quarry at the south end of Brock Mountain limestone. the andesites of Horse Mountain above. Farther the tuffs are large and vary more in the size of the HOSSELKUS LIMESTONE. NOSONI FORMATION. north, however, there are greater accumulations of particles, but the bulk is of fine material. Higher Lithologic character. Next above the McCloud volcanic material, and the thickness increases to a up Squaw Creek and on the slopes of Winnibulli Lithologic character. The Hosselkus limestone, limestone is a formation composed very largely of maximum of about 1200 feet on the eastern slope Mountain they are somewhat coarser. They repre­ named from a locality in Genesee Valley, Plumas andesite or basalt tuffs and tuffaceous conglom­ of Nawtawakit Mountain. sent contemporaneous volcanic aetivit}^ but flows County, Cal., where a limestone of the same fauna erate and a few flows of lava, but locally inter- Fossils and age. Fossils are common and some­ of rhyolite have not generally been found associ­ occurs (Bull. Geol. Soc. America, vol. 3, pp. 369- stratified with these volcanic products are shales times abundant in the shales and more or less tuff­ ated with them. Their source appears to be to the 412), conformably overlies the Pit formation. It is and sandstones, in part calcareous, and often rich aceous sandstones, and among them one of the southeast, where rhyolitic rocks of the same age best exposed in Brock Mountain, of which it forms in fossils. The formation is well exposed on most useful in the field for recognizing the horizon occur. the entire summit. Nosoni Creek, hence the name Nosoni formation. is a long, slender Fusulina. Productus, too, is Physiographic expression. The physiographic Prof. J. P. Smith (Jour. Geol., vol. 2, p. 606) It includes the "McCloud shales" of Smith and occasionally abundant. " expression of the Pit formation is complex. In has thoroughly studied this limestone in the Brock Fairbanks, as well as the pyroclastic rocks with This fossiliferous horizon was discovered by Mr. general its shales and thin sandstones are much Mountain region, and considers it in three divi­ which these shales are so intimately associated. H. W. Fairbanks and first described by Prof. softer than the adjacent formations east and west, and sions, each characterized by numerous fossils and Pyroclastic rocks. The greater portion of the J. P. Smith (Jour. Geol., vol. 2, p. 602), whose they have determined the course of Squaw Creek lithologic features. The lowest division, the Tra- Nosoni is made up of fragmental volcanic rocks, conclusion was that the strata here called Nosoni and its valley; but the valley is hilly and irregular chyceras beds, about 50 feet in thickness, consists but it includes also a small number of contem­ "are the probable equivalents of the Robinson beds owing to the local occurrence of hard beds of tuff of rather hard, pure limestone, thin bedded, dark poraneous flows. All belong to essentially the of the Taylorsville region and of the Little Grizzly or intruded sheets or dikes of rhyolite which resist bluish, and with abundant fossils. Next above same type of lava, near the dividing line between Creek beds of Plumas County, which seem to form erosion much more effectively than the surround­ come the Atractites beds, about 100 feet in thick­ the augite-andesites and the basalts, but on account the top of the Carboniferous formation." ing shales, and some of the hills, as for example ness. They are hard and siliceous, and while fos­ of the prevalence of intersertal structure and the Relation to adjacent formations. The Nosoni Winnibulli, approach in size those on the sides of sils are very numerous it is almost impossible to occurrence of olivine the lavas are regarded as conformably overlies the McCloud limestone oppo­ the valley. get out good specimens. Finally, the Spiriferina mainly basalts. site Horse Mountain and farther south, but to the Distribution. The Pit formation enters the beds include the upper 50 feet of hard, siliceous, The rocks are dark and compact, with uneven north the accumulation of so great a mass of pyro­ northern part of the quadrangle from the north­ somewhat more massive limestone, in which Spiri- fracture. In most cases they are holocrystalline, clastic rocks beneath the main horizon of fossils east in Mewittipom Mountain, at the head of ferina is the most common fossil. These subdivi­ decidedly microporphyritic, and made up chiefly suggests an unconformity. However, the occur­ North Fork of Squaw Creek, where the upper part sions are not sharply marked. In general the of plagioclase, with much augite, less magnetite, rence near the bottom of the pyroclastics of small of the formation is well exposed. Seventy-five feet limestone is much thinner bedded and darker than and occasional olivine or iddingsite. The tabular lenses of shale bearing essentially the same fossils of gray shaly slates, in part calcareous, immediately the McCloud limestone, with which it might other­ phenocrysts of labradorite are inclosed in a ground- as those above and the close affinity of the fauna underlie the Hosselkus limestone, and beneath the wise be confused. Small ammonites are the most mass having intersertal structure modified by flu- with that of the McCloud limestone strengthen the shale there is much imperfectly bedded tuff, includ­ noticeable fossils of the Hosselkus limestone, while idal movement, giving the lath-shaped crystals of evidence in favor of conformity. ing small patches of gray, greenish, or brownish, cup corals characterize the McCloud limestone. labradorite a parallel or stream-like arrangement, The general dip of the Nosoni formation is to rarely banded radiolarian chert. The shales, like Distribution. As already indicated, the main with the granular augite and oxides of iron the east, and there is no doubt that it is overlain, the limestone, strike N. 80° E. and dip 56° SE., mass of the Hosselkus limestone is exposed in between them. Augite occurs sparingly among most likely with unconformity, by the great mass but just beyond the northern border of the quad­ Brock Mountain, where by a gentle fold its out­ the phenocrysts, but olivine or iddingsite is more of andesitic rocks forming Horse, Town, Minnesota, rangle the strike is turned much more to the east crop belt is widened to 2 miles. Along the strike common, though neither appears in the ground- and Salt Creek mountains. The volcanic rocks by the Grizzly arch, whose axis runs in that direc­ the outcrop is continuous for 7 miles. To the mass and both are sometimes entirely absent. are nearly or quite alike, and the only guide in tion. In the western portion of Mewittipom Moun­ north, beyond Brock Mountain, a small lens of Where hypocrystalline the feldspars are less drawing the line has been the occurrence of fossils tain, at the head of Chatterdowen Creek, the tuff Hosselkus limestone appears on North Fork of developed in a general matrix of unindividualized characteristic of the Nosoni formation. No char­ and sandstone dip southwest beneath a syncline in Squaw Creek, and a mile beyond it a larger mass material, deeply stained by oxide of iron. It is acteristic fossils have been found in this great body which the Pit formation turns southward across in which deformation has widened the belt. rarely amygdaloidal, with amygdules of chlorite of volcanic rocks next above the Nosoni, but in the the Redding quadrangle. On the steep slopes of Another small lens appears in sec. 19, T. 36 and calcite. Most of the lava is altered and chlo­ strata overlying the volcanics characteristic Triassic Mewittipom a great thickness of the reddish Pit N., R. 2 W., and still another beyond the limits rite with calcite becomes abundant. forms occur, and they are so different as to sug­ shales and tuffs is well exposed. The lower half of the quadrangle, in sec. 1, T. 36 N., R. 3 W., The fragmental material is in rare cases coarsely gest a decided break somewhere between the of the formation was examined on the divide where it forms a narrow syncline, rising to the agglomeratic. Conglomerate tuffs with pebbles a Nosoni and the Pit formations. between the forks of Chatterdowen Creek, where northwest and marking the point where the strata few inches in diameter are common, but the most greenish siliceous sandstone with conchoidal frac­ are turned eastward by the Grizzly arch. On the TRIASSIC SYSTEM. abundant form has lapilli not over half an inch ture is underlain by black and reddish fossiliferous southern slope of Mewittipom Mountain the Hos­ in greatest dimension. The fragments are rarely PIT FORMATION. shales of great thickness that rest upon the andesites selkus limestone appears again in several exposures holocrystalline. Some are hyalopilitic, looking Lithologic character. The Pit formation (the and tuffs of the Town Mountain belt of volcanics. with sharp curves. At the point where it crosses more like lapilli from andesitic than from basaltic Pit shales of J. P. Smith: Jour. Geol., vol. 2, Extending southward the belt of the Pit forma­ the northern border of the quadrangle the lower eruptions. They become more abundant to the p. 502) is composed largely of dark and gray tion spreads out, at first slowly, but near Pit River portion has abundant small ammonites, while the south. Fine tuffs are rare. None were found shales, thin-bedded sandstones, and many layers more rapidly, until along that stream it has a width upper part is very irregularly cherty and siliceous, containing remnants or pseudomorphs after pum­ of tuffs. It lies beneath the Hosselkus limestone of at least 12 miles. This widening of the belt is with many brecciated patches. Southeast of Brock Mountain, a short distance beyond Pit River, the BROCK SHALE. along Pit River between Flat Creek and Potem shale. The overlap, however, must be small, for limestone disappears, except for one or two small Name and character. The Brock shale conform­ Creek. West of Flat Creek the Brock shale the narrow belt of Brock shale continues for miles lenses, for 5 miles; it reappears on Cedar Creek in ably overlies the Hosselkus limestone in Brock occurs, in the upper 100 feet or more of which without conspicuous variation. The shale is absent large masses, nearly 3 miles in length, which form Mountain, whence the name, and has a thickness occasional specimens of Pseudomonotis were found. in Bear Mountain, however. occasional prominent cliffs by the stage road of about 400 feet. In the lower 300 feet or more The basal conglomerate, with prominent fragments The relation of the Modin formation to the over­ between Furnaceville and Round Mountain. An adjoining the limestone the shales are dark, some­ of andesitic lavas and fossiliferous calcareous nod­ lying Potem formation appears to be one of con­ interesting feature here is that the limestone is, in what calcareous, and frequently contain Halobia. ules, occurs just east of the mouth of Flat Creek, formity, though the Modin epoch closed at a time part, at least, overturned and rests upon later for­ Above these come sandy shales, gray and reddish and similar conglomerates occur at several other of vigorous volcanic activity, especially in the mations. On the spur southwest of the mouth of in color and characterized locally by Pseudomonotis points farther east, especially at the mouth of Lick vicinity of Bagley Mountain. Cedar Creek two limestones occur, one 60 feet and subcircularis. Creek and in the northwestern part of sec. 7, T. 34 the other approximately 100 feet thick, separated Distribution. The Brock shale is well exposed N., R. 1 W. Careful search has shown that some POTEM FORMATION. by 150 feet of dark shales. The whole set of beds in Pit River, with Pseudomonotis rather common of the limestone nodules contain imperfect fossils. Lithologic character. The Potem formation is dips to the southwest and is evidently overturned. in the synclinal ridge running north into the lime­ The basal tuffaceous beds are well exposed on composed of sandstones, shales, and tuffs. The It is possible that the limestone has been repeated stone of Brock Mountain. The same shale can be Squaw Creek, just above the mouth of North Fork, thin-bedded sandstones and gray, sometimes slaty by faulting, but this seems improbable, for the two traced as a narrow, probably continuous belt north­ and contain scattered limestone fragments, gener­ shales predominate in its lower part and make up have largely different faunas. In the upper one, westward across the quadrangle. Pseudomonotis ally a few inches in diameter. They are fossilif­ the greater portion of the formation. They are exposed at Eilers, corals are more abundant than in was not found at as many points as Halobia, but erous and, like those at Bear Mountain, throw more or less calcareous and contain a few small the lower. since it is rarely as abundant as Halobia this is not definite light on the derivation of the limestone lentils of limestone. Tuffaceous conglomerates The Brock Mountain belt of the Hosselkus surprising. Near the northern limit of the quad­ fragments from an older formation. occur sparingly in the lower half of the forma­ limestone, which has just been ,traced across the rangle, on the slope of Mewittipom Mountain, the Sandstones and shales. The most common rock tion, but in the upper part they are most abun­ northeast portion of the Redding quadrangle from shale is well characterized by its fossils and has its of the Modin formation above the tuffaceous beds dant in fact, nearly all the sediments of this Mewittipom Mountain through Brock Mountain to full thickness overlain by tuffaceous conglomerate along Pit River is a very fine gray sandstone, part are of igneous material. Some of this mate­ Cedar Creek, is remarkable for its eastward curva­ containing calcareous fragments. The Brock shale usually thin bedded and associated with slaty rial may have been furnished by contempora­ ture at both ends a feature of structural signif­ is also exposed on Cedar Creek, but owing to an shales. Interbedded with these were found lime­ neous volcanic activity, but most of it was derived icance. overturn it here apparently underlies the Hossel­ stone lenses 13 to 20 feet long and 12 to 18 inches by the ordinary processes of erosion from a wide Twelve miles southwest of the Brock Mountain kus limestone. A thin sheet of Brock shale may in thickness. They resemble the nodules found in expanse of volcanic rocks. belt, about Bear Mountain, there are isolated out­ be present on Bear Mountain, but it was not iden­ the tuffaceous conglomerate, but are far above them Distribution. The Potem formation occurs in crops of the Hosselkus limestone of so great impor­ tified by fossils. and contain no fossils. the Redding quadrangle in one area only, along tance structurally that they are considered by Relations and age. There is no doubt concern­ Limestone lentils. In a portion of the Modin the northeastern border, in the vicinity of the themselves. The principal exposure is on the ing the conformability of the Brock shale and the formation south and southwest of Bagley Moun­ Great Bend of Pit River. Its fossiliferous shales northwestern slope of Bear Mountain, near the Hosselkus limestone, but the relation of the shale tain, among the shales and thin-bedded sandstones, and sandstones are well developed on Potem center of sec. 12, T. 33 N., R. 4 W., where a to the overlying Modin formation has not been there are a number of small lenses of limestone, Creek, which may be taken as the type locality. dark-gray fossiliferous limestone, locally 50 feet in definitely determined. It seems probable, how­ one of which, in the southern part of sec. 15, T. 36 In the Lassen Peak folio this formation was thickness, occurs with a dip of 52° E. beneath the ever, that the two formations are unconformable. N., R. 2 W., has a thickness of nearly 100 feet and called the Bend formation, but as that name had mountain. This limestone horizon lies between The age of the Brock shale is certainly Triassic. a length from north to south of over a mile. It prior use in Texas, Potem is here substituted. the shales and thin-bedded sandstones which form Concerning the fossils from this shale Dr. Stanton includes two layers of shale, has yielded a number Thickness. The total thickness of the Potem the base of the mountain and the tuffaceous sand­ reports as follows: of fossils, and may be traced in a series of small formation can not be closely estimated, but a study stone and conglomerate which form its upper part, The shales immediately overlying the Hosselkus lime­ lenses for over 4 miles. of the section along Pit River on both sides of the and can be traced at intervals all around the moun­ stone contain two fossiliferous horizons a lower one, Distribution. As shown on the areal geology mouth of Potem Creek leads to the conviction that tain, dipping into it in such a way as to indicate extending up 300 or 400 feet, which has yielded only a map, the Modin occupies two distinct areas. The it must be at least several thousand feet. the existence of a shallow syncline with the axis of Halobia,, very closely related to the one that occurs in main belt-like area, 3 by 15 miles, extends north­ Fossils, age, and correlation. Concerning the the fold nearly north and south. An outcropping the limestone and below it, and an Atractites, while the ward from Cedar Creek across Pit River to the fossils of the Potem formation, of which he made mass of the limestone 50 feet thick occurs on the higher horizon is locally filled with Pseudomonotis subcir­ northern boundary of the quadrangle, where it large collections, Dr. Stanton remarks: cularis Gabb. Wherever the Halobia and the Pseudo­ southwestern slope, and another of nearly the same monotis were found in the same section they were always turns eastward and finally disappears beneath the thickness on the northwestern slope. It is overlain great field of Tertiary lavas. The smaller area, less Overlying the beds [Modin] just discussed and cov­ found in separate beds, with the same stratigraphic rela­ ering a considerable area near the eastern margin of the in part by a thin body of shales which are capped tionship to each other and to the limestone. than a square mile in extent, occupies the summit quadrangle is another formation characterized by a well- by conglomerates composed largely of igneous mate­ of Bear Mountain. marked Jurassic fauna, including several species that JURASSIC SYSTEM. rial. The limestone, especially on the southwestern Thickness. The outcrop of the Modin forma­ occur in the Hardgrave sandstone near Taylorsville. slope, is much broken and looks like limestone con­ MODIN FORMATION. tion has a width of about 3 miles and an average Among the forms may be mentioned Rhynchonella, glomerate. The top is irregular and is covered by Lithologic character and name. The Modin for­ dip, almost wholly in one direction, of over 50°. Pecten acutiplicatus Meek, Pecten (Entolium), Pinna ewpansa Hyatt, Modiola, Gervillia, Lima, Trigonia (sev­ a thin shale. The basal portion of the overlying If there is no faulting it is well within reason to mation is an extensive succession of tuffaceous beds, eral species), Goniomya, Pholadomya, and Ammonites tuffaceous conglomerate contains numerous frag­ overlain by a greater mass of compact, fine gray estimate its thickness at 3000 feet. This estimate of Coroniceras type, etc. It is probable that horizons ments of the fossiliferous limestone beneath. shaly sandstones and shales, with a few small includes the tuffaceous beds at the base, which in somewhat higher than the Hardgrave sandstone are Around the north end of Bear Mountain, where lenses of limestone. It is named from Modin Bear Mountain reach their maximum thickness of included in the formation, but some of the types that ledges of limestone were not seen, its former pres- Creek, near the mouth of which, in the northeast­ about 400 feet. seem later, as indicated by their occurrence in the Tay­ .ence is indicated by numerous limestone frag­ ern part of the quadrangle, the formation has Fossils and age. Among the fossils in the lime­ lorsville region, are immediately associated with the Hardgrave species. This fauna is very distinct from ments in the conglomerate. The limestone is well stone fragments of the basal tuff on Squaw Creek yielded most of its fossils. all those that precede it in this region. characterized as Hosselkus by numerous fossils, Tuffaceous bed. At the base of the Modin for­ Dr. Stanton recognizes "Pseudomonotis sp. related among which are bones of large reptiles common mation is an extensive bed of volcanic conglom­ to Pseudomonotis subcircularis Gabb," and remarks: So far as yet known the Potem formation is the to the limestone of Brock Mountain (Merriam, erate that possibly marks a definite horizon of "This lot seems to be derived from the upper Tri­ equivalent of the "Hardgrave" sandstone of Tay­ J. C., Bull. Geol. Dept. Univ. Cal., vol. 3, pp. volcanic activity, though no certain flows of lava assic, but the tuff in which the limestone fragments lorsville (Bull. Geol. Soc. America, vol. 3, pp. 63-108). were discovered at that level, unless it be in the were found is more probably of Jurassic age." 369-412), and most likely also of the "Mormon" Thickness and lenticular character. The lentic­ north end of Bear Mountain. The source of the Dr. Stanton has collected a large number of fos­ sandstone, for the small Rhynchonella occurs in the ular character of the Hosselkus limestone is evi­ material was not found. The fragments in the tuff sils, chiefly from the shales, sandstones, and lime­ gray sandstone of both localities; but the still later dent from its areal distribution. The largest lentil, are mainly andesitic, with a dense groundmass of stones above the basal tuff of the Modin formation, faunas of the " Thompson " limestone, " Hinchman " that of Brock Mountain, has a thickness of 200 feldspar microlites. There are a few phenocrysts and reports as follows: tuff, and "Bicknell" sandstone of the Taylorsville feet. The next largest is that of Cedar Creek, of augite and more of altered plagioclase. The Between the Pseudomonotis subcircularis horizon [Brock region have not yet been found in the Great Bend which is about 160 feet thick. To the north and degree of crystallization in the groundmass is gen­ shale] and the beds yielding a well-characterized Juras­ region. It is possible that they are covered up by west the thickness decreases. On the east end of erally lower than that of the earlier volcanic rocks. sic fauna [Potem formation] comparable with that found younger formations east of the Great Bend or that Mewittipom Mountain it is not over 75 feet, and The fragments are generally angular to subangular, at Taylorsville there is a broad belt in which a great they may have been completely removed by erosion. the lentils about Bear Mountain scarcely reach 50 thickness of rocks is represented and from which fossils Overturn of a part of the Potem. The shales but some appear to be waterworn. They are rarely were collected at many localities. In the field these feet. as large as a foot in diameter. Coarse and fine are were considered Jurassic, and I still think, that most if and sandstones along Potem Creek and the slope The lack of continuity in the outcrop of the intermingled without assortment, as if pyroclastic. not all of them are of that period, but the paleontologic west of it dip southwest, like the bulk of the Hosselkus limestone is certainly not due to intruded The most remarkable feature of the conglomerate evidence is not so complete as is desirable. The fossils Modin formation, with which they have been igneous rocks, for it is bordered on both sides by is found in the fragments or nodules of limestone at most localities belonged to few species and were either overturned, but farther east, between Potem Creek shales which apparently continue, more or less which it contains. poorly preserved or belonged to persistent types that and Pit River, the general dip is more nearly nor­ would not aid in discriminating Jurassic from Triassic. unbroken, between the outcrops of limestone. One of the best exposures of this conglomerate is mal, to the northeast. It is important to note, Nor does its lenticular character appear to be in Bear Mountain, where it overlies the Hosselkus Overturn of the Modin formation on Pit River. however, that the position of the strata in the due to displacement by which the intervening limestone and crops out all around the mountain, One of the features of the Pit River section of the Modin formation is decidedly variable, a condition portions were removed, for the remnants are really of which it forms the entire tabular summit. The Modin formation is its general dip to the west due to the fact that it has been greatly compressed lenticular in shape, thinning to an edge regularly fossils in the fragments of limestone contained in instead of to the east, as is the case with all the in all directions. parallel to the bedding, as if due to limitations in the conglomerate are, at least in part, the same older formations of that region. Slaty cleavage is Relation to adjacent formations. The relation of -the conditions of deposition. as those of the Hosselkus limestone, so that the often well developed and generally dips eastward the Potem to the adjacent formations is not always Fossils, age, and relation to adjacent forma­ source of the fragments in this case seems evident. at a high angle. It seems evident that at this clear, especially that to the Modin. Along a por­ tions. The Hosselkus limestone is especially The material with which they are associated is vol­ point the Modin formation, like the Brock shale tion of their contact both have essentially the same remarkable for its fossil cephalopods and reptiles. canic, and it appears as if the limestone fragments arid the Hosselkus limestone, has been overturned strike and dip and appear conformable, though at The former are being investigated by Prof. J. P. were dislodged by volcanic action, a view which as a result of the sharp bend to the east along that point both are overturned; but elsewhere they Smith, of Stanford University, and the latter by would account for their irregular and unexpected Cedar Creek. are separated by prominent masses of andesitic Prof. J. C. Merriam, of the State University at distribution. Relation to adjacent formations. The fragments lavas and tuffs such as form Bagley Mountain and Berkeley, Cal. The age of the former is upper A much larger complete section of the Modin of Triassic limestone contained in the basal tuff­ the point south of Pit River opposite the mouth of Triassic, and it lies with apparent conformity formation, affording excellent exposures of the tuff­ aceous conglomerate of the Modin tend to show Potem Creek, indicating an epoch of vigorous vol­ between the Pit formation and the Brock shale. aceous conglomerate beds at the base, is found that the Modin lies unconformably upon the Brock canic activity and a probable unconformity between Redding. 6 them, a view which is strengthened by the fact that gravel, sand, and clay, with occasional beds of coaly PLIOCENE SERIES. south, at Red Bluff, the type locality, sand pre­ the faunas of the two formations are unlike. material, and has a thickness not exceeding 50 feet. vails associated with small beds of fine gravel. TUSCAN TUFF. The next formation younger than the Potem is Sands, often micaceous, are by far the most abun­ The Red Bluff formation occupies the central the Chico, which is Cretaceous. The two forma­ dant. The best exposures of the lone formation Lithologic character. The Tuscan tuff is almost portion of the Sacramento Valley west of the tions are found in contact near Round Mountain, are outside of the quadrangle, along the western wholly andesitic, ranging in texture from coarse Piedmont region. It forms the gravel plains of just east of the Redding quadrangle, and are strik­ border of the Sacramento Valley, as well as to the agglomerates, in which there are unassorted angular the Redding region, laps up over the edge of the ingly unconformable, indicating one of the most east on Little Cow Creek and about the Great Bend fragments a yard in diameter mingled with frag­ Piedmont Plain on the east, as well as over the profound interruptions known in the sedimentation of Pit River to the head of Kosk Creek, where it ments of all sizes, down to dust. Fine-textured edge of a peneplain cut in the older rocks around of that region. is certainly over 1000 feet in thickness. gray tuff, often distinctly stratified, is by far the the northern and western borders of the Sacra­ It crops out around the borders of the valleys most abundant. It is composed of small fragments mento Valley, and connects directly with the ter­ CBETACEOUS SYSTEM, and canyons of the Piedmont region in the Red­ of andesite, sometimes pumiceous, with broken crys­ race level which follows up the river by Keswick CHICO FORMATION. ding quadrangle, forming a narrow belt between tals of andesine and hornblende, embedded in a fine and Copley about 200 feet above the present level Lithologic character. The Chico formation is the Chico below and the Tuscan tuff* above. On gray matrix composed of minute angular particles of the river. It rests unconformably upon all older composed chiefly of yellowish sandstone, often the one hand, it is difficult to decide in some places of volcanic glass, which constitute the major part rocks. Much of the Tuscan tuff, which is next to pebbly, passing toward the base into conglom­ whether the nonfossiliferous beds overlying those of the rock. In the basal portion sands and grav­ it in age, was removed by erosion before the Red erate and upward into gray shales. It is decid­ well characterized by Chico fossils are Cretaceous els occasionally occur interstratified with the tuff. Bluff was deposited. edly softer than any of the older formations. or lone, and on the other, the tuffs of the Tuscan Along the eastern border of the quadrangle the It is evident that during the Red Bluff epoch Distribution. It may be said in general of the formation and gravels of the lone appear to be upper part of the tuff locally contains fragments of Sacramento River and its tributaries were supplied distribution of the Chico formation that it extends interstratified, and therefore the upper boundary is dacite and basalt, but even where most abundant with a large amount of gravel and sand, which throughout the Sacramento Valley, but is covered not always evident. In general, however, where they form only a small portion of the tuff. they carried to the great valley for deposition. by later formations, except around the valley bor­ the lone is best developed there is little difficulty Distribution. The Tuscan tuff was named from The presence of occasional bowlders suggests float­ ders where the cover has been washed away. A in recognizing it. its occurrence about Tuscan Springs, in the Las­ ing ice as an agent of transportation, and it is not great bulk of it lies southwest of the Redding Fossils and age. The fossils of the lone forma­ sen Peak quadrangle. It extends throughout the improbable that glaciers in the higher mountains quadrangle along the western border of the Sac­ tion are chiefly leaves and occur most abundantly northern part of the Sacramento Valley, but is had a considerable share in furnishing both the ramento Valley. To the northeast it extends in the sandstones and shales on Little Cow Creek generally covered by the Red Bluff formation sediments and the water for the streams of the through Lassen Strait, between the Klamath above Phillips's sawmill and near the head of Kosk except around the valley borders. It outcrops Red Bluff epoch. Mountains and the Sierra, and possibly connects Creek, where the following, determined by Dr. along the eastern side of the valley almost con­ The older portion of the Red Bluff formation, with the Chico of northern California and Oregon. F. H. Knowlton, were collected: tinuously from Chico Creek to Little Cow Creek which is covered up in the Sacramento Valley, pos­ Within the quadrangle it is limited in its distribu­ and forms the broad stony plains of the Piedmont sibly records events closely related to those chron­ Little Cow Creek. tion to irregular patches along the borders of the region, represented by the Swede Creek Plains and icled by the interesting bones in the Potter Creek Sacramento Valley. Ficus asiminsefolia ? Lesq. others in the southeastern part of the Redding cave, on the McCloud, which show that elephants, Populus Zaddachi ? Heer. The "Horsetown beds," which are here included Platanus dissecta Lesq. quadrangle. The canyons cut across these plains mastodons, tapirs, camels, and many other forms in the Chico, appear only in two small areas near Laurus californica ? Lesq. and afford excellent exposures of the tuff, which is now extinct enlivened the ancient landscape. the southwest corner of the quadrangle, about a Salix n. sp. found to include occasional flows of lava. The Cinnatnomum n. sp. ALLUVIUM. mile from Larkin. On the Sacramento above Zizyphus n. sp. plains are underlain by layers of unassorted mate­ Redding the Chico is well exposed, and again rial containing many angular fragments which The alluvium is the fine silt, sand, and gravel Near head of Kosk Creek. at Sand Flat, east of Buckeye, where it has been weather out on the surface and make it exceed­ of the flood plains near the level of the present fruitlessly bored for oil. Sabalites californicus Lesq. ingly stony. Around the northern border of the streams. On the surface fine material generally Ulmus californica Lesq. prevails and affords by far the larger part of the On Dry Creek shales appear overlying the Ficus tilisefolia Al. Br. valley from Little Cow Creek to Horsetown the sandstone and conglomerate at the base of the Populus Zaddachi Heer. lack of continuous exposure, as shown on the map, agricultural soils of the region. It is well devel­ formation and dipping about 10° S. The basal Quercus convexa Lesq. is due chiefly to a cover of Red Bluff gravel, though oped along Cow Creek and its tributaries and Fagus Antipofii Abich. conglomerate has a thickness of at least. 15 feet Persea pseudo-caroliriensis Lesq. some of it has been removed by erosion. along Sacramento River, particularly from Red­ and includes material from the Triassic shales and Laurus sp. There is a typical exposure 2^ miles northeast ding to the southern margin of the quadrangle. Magnolia californica Lesq. igneous rocks against which it rests. Rhus mixta Lesq. of Buckeye, on Stillwater Creek, where the speci­ IGNEOUS EOCKS. Basin Hollow affords one of the largest exposures mens were obtained for the educational series o£ INTRODUCTION. of the upper shales, which form adobe, but there Concerning these Dr. Knowlton remarks that rocks described in Bulletin 150, page 211. are prominent ledges of sandstone and conglom­ "all of the species (with one exception), whether Thickness. In the stony plains region along the In the Redding quadrangle there is a long suc­ erates also. One bed of the latter is nearly 20 feet correctly identified or not, Come from what is eastern border of the quadrangle the tuff is 400 cession of igneous rocks, which began with the in thickness and contains some pebbles at least 4 known (in the Sierra Nevada) as the auriferous feet thick and much of the material is coarse, b^it eruption of acidic and basic volcanics before the inches in diameter. From Basin Hollow the Chico gravels. . . . There is nothing in the collection on the western border of the valley it is much finfcr middle of the Devonian and continued at inter­ extends eastward across the Copper City arch of which suggests an age as old as the Eocene." The and usually less than 25 feet in thickness. ! vals in the Carboniferous, Triassic, and Jurassic older rocks, and outcrops in patches at Oak Run, formation is accordingly considered to be of Miocene Source of material. The material of the Tuscin nearly to the end of the Mesozoic, when a variety Oak Flat, and Little Cow Creek, 3 miles east of age. tuff is all derived from the volcanoes of the Lassen of dike rocks such as quartz-augite-diorite, augite- Furnaceville, as well as at Round Mountain, 4 A mussel (Unio) has been found with the leaves Peak region. This is clearly shown by the distri­ diorite-porphyry, dacite-porphyry, and amphibolite miles beyond the eastern limit of the Redding on Little Cow Creek and indicates that the water bution of the material, not only as to size of frag­ appeared, with larger masses of quartz-hornblende- quadrangle. This is the easternmost exposure of was fresh at that point, but farther south in the ments and thickness of mass, but also as to the diorite, quartz-mica-diorite, and serpentine. Dur­ the Chico in the region. It dips to the east and Sacramento Valley, about Marysville Buttes, as kind of lava. The bulk of the finer material ing the Tertiary followed the great eruptions of disappears beneath the later formations which shown by Mr. Lindgren, the same formation con­ which appears on the western side of the Sacra­ the Cascade Range from the vicinity of Lassen underlie the lavas of the Lassen Peak district. tains marine fossils. During the lone epoch the mento Valley contains a considerable amount of Peak and Mount Shasta, which flooded the How far it extends beneath the lavas is unknown, great bay which occupied the Sacramento Valley hornblende and most likely came from the grea northeastern part of California with lava and but it may connect by way of the Great Bend of was receiving so large an influx of water by way volcano of Lassen Peak. continued with decreasing energy to the late Pit River and Mount Shasta with the Chico of of the "Lassen Strait" region as to keep its Relation to adjacent formations. The Tuscrn Quaternary. Shasta Valley. tuff in many places appears to rest conformab upper part comparatively fresh. The conditions PRE-KENNETT. Thickness. The greatest thickness of the Chico were such, however, as to favor the accumulation upon the lone, but in others, as already stated, the formation in the Redding quadrangle is at Basin of vegetation, from which small beds of coal were two formations are evidently separated by an inter­ COPLEY METAANDESITE. Hollow, where it is about 500 feet. It thickens formed at a number of localities. At the same val of erosion. A similar interval separates' the General description. The Copley metaandesite rapidly southwestward from Redding by the con­ time the ancient streams were depositing aurif­ Tuscan tuff from the Red Bluff. was named from its occurrence in the vicinity of formable addition beneath of older beds first the erous gravels over the gentle slope of the Sierra Age. During Miocene and Pliocene time the Copley, where the most important type is well Horsetown, then the Knoxville until on Elder Nevada. volcanoes of the Cascade Range were in vigorous exposed. It is generally pale green on weathered Creek, 50 miles from Redding, the Shasta-Chico Relation to adjacent formations. On the western activity. The border of the great volcanic field to surface, but darker green and compact on fresh, series of beds attains an estimated thickness of side of the Sacramento Valley the lone formation which they belong extends into the southeastern somewhat shaly fracture. Distinct porphyritic 29,000 feet. rests upon the Chico with marked unconformity, part of the Redding quadrangle, where it is rep­ structure is not common, but the rock is fre­ Fossils and age. The Chico formation is highly but along Cow Creek and Little Cow Creek on the resented by the Tuscan tuff and some overlapping quently more or less fragmental, a feature which fossiliferous and its fauna is well known. Its age eastern side of the valley the unconformity, though flows which have been mapped separately. As shows most clearly on the weathered surface. is below the middle of the Upper Cretaceous, but appreciable, is much less distinct. The movement the mass of the Tuscan tuff lies unconformably Occurrence. The Copley metaandesite includes the addition of the Horsetown and Knoxville producing this discordance must have taken place between the lone (Miocene) on the one hand and a great mass of lava made up of many separate beneath carries the succession of strata far into the about the close of the Cretaceous, and it is evident the Red Bluff (Quaternary) on the other, it is volcanic flows of considerable variety and sheets of Lower Cretaceous. that the resulting deformation was much greater chiefly Pliocene. tuffs more or less distinctly bedded but generally Relation to adjacent formations. The Chico rests in the Klamath Mountain region than about the so compressed as to develop slaty cleavage. QUATERNARY SYSTEM. with marked unconformity on the older formations, north end of the Sierra Nevada. Since that defor­ Cut by numerous joints in various directions from the Jurassic to the Devonian inclusive, around mation and upheaval the Klamath Mountains have BED BLUFF FORMATION. ; and deeply eroded and intersected by many dikes the north end of the Sacramento Valley. This remained for the most part above the sea, and the The Red Bluff formation consists chiefly of of rhyolite and quartz-augite-diorite, the Copley unconformity is the most profound interruption same may be said of the "Lassen Strait" region, gravel and sands, with a small proportion of clay. metaandesite has an aspect of greater age than among the sedimentary rocks of the Pacific coast which during the lone epoch was occupied by a It is well exposed on Sacramento River 1J miles any other area of volcanics in the Redding quad­ and can be traced over a wide area. The relation body of fresh water connecting with the sea by east of .Redding, in a prominent bluff nearly rangle. This feature is emphasized also by the of the Chico to the lone will be considered later. way of the Sacramento Valley. 100 feet in height. The exposure which gave occurrence of auriferous quartz veins, especially in The rock next younger than the lone is the name to the formation is at Red Bluff, nearly 40 the southwestern portion, where some of them are TERTIARY SYSTEM. Tuscan tuff, which rests unconformably upon its miles south of Redding. In the Redding quad­ mined. In the northern half of the area, on the MIOCENE SERIES. eroded surface; in some places, especially near Oak rangle gravel predominates largely over sand; the slopes of Bass and O'Brien mountains, the meta- IONB FORMATION. Run, the lone had been completely removed by well-rounded pebbles rarely attain a diameter of 4 andesites are less altered and the sheeted character Composition and distribution. Within the Red­ erosion before the deposition of the Tuscan tuff, inches, although there are occasional rough bowl­ and beds of tuff better preserved than farther south. ding quadrangle the lone formation is composed of which now rests directly upon the Cretaceous. ders having a diameter of over 5 feet. Farther In the tuffs, especially from Bass Mountain 7 northward, the lapilli are sometimes well pre­ : BALAKLALA RHYOLITE. don, from which, on the eastern side in McCall ophitic structure and is not clearly distinguish­ served, with crystals of fresh augite an^l feldspar General description. The Balaklala rhyolite was (jtulch, it is separated by a fault. able petrographically from the Bass Mountain in a yellowish devitrified groundmass. Many of diabase. The' two can be distinguished only named from the fact that it forms the hills about Petrographic description. Having been much affected by the lapilli and some of the flows are amygdaloidal, the Balaklala mine. Where freshest the rock is pressure, the Balaklala rjhyolite has an uneven fracture. When when it is possible to discover their relation to leaving no doubt as to the explosive character of gray, generally with distinct phenocrysts of quartz, fresh its color is light gray and the dai'k phenocrysts of the Bragdon. It is evident that since the same .quartz are distinct on the compact groundmass. Frequently, the volcanic action by which they were produced, and is often impregnated by pyrite. On the surface however, the rock has a granular appearance in the field and diorite cuts the Jurassic rocks it is much younger and though they are not common, their wide dis­ it is deeply stained with oxide of iron and is porous loses all trace of porphyHtic structure, though in thin section than the diabase. No dikes of the diorite were tribution-. shows that the whole mass with which Under a microscope it is still distinct. The irregular pheno­ found in the diabase. In the Middle and North from the decomposition of the pyrite. Flow struc­ crysts of quartz are much embayed by the groundmass and they are connected is made up of surface eruptions. ture is rarely distinct. In many cases it is frag­ broken, giving wavy extinction. The feldspar occurs in Salt Creek regions the bodies of igneous rocks of Southwest of Redding the metaandesite is gen­ mental and most frequently it is brecciated. sliarply defined crystals and also in fragments or groups of the Bragdon area are chiefly diabase, but farther fragments. The. crystals are tabular. Tho're of orthoclase erally a breccia of green fragments in a light- Occurrence.^ The Balaklala rhyolite is made up are without twinning or simply Carlsbad twins. Those of southeast, on Salt Creek, the diorite prevails, though greenish matrix. It is rarely coarse; the fragments of a succession of irregular lava flows and tuffs plagioclase have multiple twinning. It is doubtful if the it is possible that considerable masses of quartz- where largest are generally less than 4 inches in orthoclase is generally in excess of the plagioclase. It is pos- augite-diorite are included in the areas marked which have been so compressed and folded as to £ible that this rock is more closely related to dacite than to diameter.' Near the eastern border of the mass, render very Obscure the original layered arrange­ rhyolite. Bass Mountain diabase. about Olney Creek and Oregon Gulch, are some of ment of the mass. Little Backbone Creek and The groundmass is generally finely cryptocrystalline and may contain few or many microlites .of feldspar. "Where Petrographic description. Normally the Bass Mountain the best exposures of breccia. Grains of quartz Squaw -Creek cut narrow valleys in it to a depth altered, the feldspar of the groundmass yields sericite, and diabase is holocrystalline, generally with automorphic pla­ frequently appear on the weathered surface, so that of 1000 feet; Their slopes are steep and' rocky, in locally it becomes abundant. gioclase and xenomorphic augite. The fabric is ophitic or ophitic granular. Rarely, when pyroxene is abundant, there it looks like quartz-porphyry, but on closer exam­ strong contrast with the gentle relief and small CARBONIFEROUS. are poikilitic patches. Some of the vesicular flows and the ination these grains are generally found to be sec­ ledges of the main ridge about the heads of Cot- lapilli in the tuff contained originally considerable amor­ BASS MOUNTAIN DIABASE. phous matter. In this case the automorphic plagioclase is ondary in fact, to be amygdules filling ancient tonwood, Motion, and Spring creeks. The ledges long and narrow,^but in the larger masses where the diabase steam holes in the andesite. It is often difficult to in the rocky canyons are generally irregular and General description. The diabase of the south­ is normal it becomes more coarsely crystalline, the plagioclase decide in the field, where the rocks are as highly massive, rarely appearing as sheets or flows, and ern slope of Bass Mountain is generally a dark, becomes partly xenomorphic, and the structure tends toward even granular. " altered as those of Larkin and Old Digging^ yet the occurrence of tuff among the masses of somewhat greenish, compact lava which is not por- The greatest variation of the rock is in its mineral compo­ whether the quartz is primary or secondary, and nonfragmental material clearly indicates that it is phyritic, but is occasionally vesicular and more fre­ sition. Ordinarily that on the middle southeastern slope of Bass Mountain is composed of plagioclase and augite, but at it is probable, on this account, that some quartz- of volcanic origin. In the vicinity of the Uncle quently fragmental. Where fresh this lava has the base, near the road, graphic quartz intergrown with pla­ porphyries may have been included in the areas Sam mine it is usually lighter colored and is rich in darker spots of augite embedded in a lighter colored gioclase becomes common and the rock is a quartz-diabase. marked metaandesite. Here and there the meta­ larger grains of quartz, so that in the field it groundmass. Granitic quartz, but not generally graphic, is a common con­ stituent of the diabase along the road to within a mile of andesite is rotten and deeply stained by oxide of resembles granite-porphyry. Breccia is common Distribution. There are two principal areas or Newtown, and yet there are places within this large area iron. At other places it has a decided cleavage, and occasionally conspicuous. The best examples groups of areas of the Bass Mountain diabase. where it practically disappears. Hornblende is another of the variable minerals. In many like slate, and has lost its general resemblance observed are on the slope north of Squaw Creek, One on the southern slope of Bass Mountain places there is no trace of it; in others there is a small amount to lava, but in thin section under a microscope where some of ,the fragments are over a foot in extends southward to the border of the newer of light-brown hornblende, increasing in quantity until it traces of its original igneous structure may still diameter. Finer breccia occurs on the railroad rocks about Sacramento Valley as an irregular area equals or exceeds that of the augite. Sometimes it is in par­ allel intergrowth with the augite, but generally it is inde­ be seen. near the mouth of Squaw Creek and on the over 6 miles in length and 4 miles in width, with pendent, yet holds essentially the same relation as the augite Relation to adjacent rocks. The oldest rocks divide near the, trail between the heads of Cot­ several included tracts of Kennett and Chico; the to the rock fabric. The quartz and hornblende vary without reference to each other, and both occur at intervals in both with which the Copley metaandesite comes in ton wood and 'Motion creeks, as well as beneath other consists of four or more small parallel strips areas that is, among the interbedded sheets of the Bragdon contact are those of Devonian age. Their rela­ the limestone on the Quarry road 1£ miles north­ 1 to 3 miles in length extending northwest and formation along North Salt Creek, as well as in the area tion may be seen to greatest advantage in the east of Kennett. The fragments are generally southeast in the region of Middle Salt Creek. northeast of Newtown. In many places the rock is highly altered, the feldspars are Kennett region, where Devonian rocks clearly rhyolitic, but in some cases, decidedly andesitic, Occurrence. The best exposures are about the kaolinized, and the augite is completely replaced by chlorite overlie the ancient rhyolites and andesites. like the Copley metaandesite. head of Rancheria Creek, on the lower slopes of and calcite. Green hornblende, which is secondary, gener­ ally after augite, is rarely abundant and less widely dis­ Masses of shale occur in the O'Brien Mountain The Balaklala rhyolite is everywhere cut by Bass Mountain, where the ledges are made up of tributed than the brown hornblende. and Larkin areas of the Copley metaandesite, and numerous joints running in many directions, but irregular masses of tuff and sheets of lava which in places they contain beds of tuff. They are usu­ those having a northeast-southwest trend appear to are locally vesicular. Fragmental material is much QUARTZ-LATITE. ally long, narrow belts, folded or faulted down into be most common and are sometimes accompanied the more abundant on the mountain slopes, but In the Nosoni formation are several small masses the volcanics upon which they rest. The shales by shearing. In some places, especially about less so farther south, though in places clearly made of somewhat rhyolitic rock, on the southwest spurs are associated with fossiliferous limestones of Devo­ Balaklala Hill, the shearing was so great as to up of small cellular lapilli such as commonly result of Bollibokka and Horse mountains. At the latter nian age, and show that the Copley. metaandesites render the rock fissile, like shale, but the grains of from explosive eruptions in connection with the locality only tuffs were seen interbedded with fos­ are older than the middle Devonian. This relation quartz are generally preserved. volcanic effusion of this type of lava. The rock siliferous shales, but at the former, about 1£ miles is also emphasized by the fact, set forth more fully Relation and age. The Balaklala rhyolite, with is generally well jointed, but not slaty, and yields a little east of north from the mouth of Nosoni in the description of the Kennett formation, that its associated tuffs, clearly underlies the Kennett a deep-red soil. Creek, a well-defined sheet of lava of rhyolitic the Devonian* sediments are derived in part from limestone and shale which form the crest of the Rocks of essentially the same character as the aspect occurs, but is not separately mapped. It is the Copley metaandesite. The Bragdon, like the ridges between "Squaw Creek and Backbone Creek. diabase of the southern slope of Bass Mountain about 75 feet in thickness, and, like the tuffs below Kennett, rests upon the metaandesite and contains The Devonian sandstones on Backbone Creek con­ occur within the Bragdon area in the vicinity of and the tuffs and fossiliferous shales above, strikes much sediment derived from it. tain rhyolitic material like that of the Balaklala, Middle Salt Creek and apparently throw light nearly north and south and dips eastward into The Copley metaandesite is clearly cut by dikes and afford conclusive evidence that the Balaklala upon the general relations of the larger mass Bollibokka Mountain. A prominent ledge of this of the adjoining Balaklala rhyolite, as well as of all rhyolite is older than the middle Devonian. south of Bass Mountain. On Middle Salt Creek reddish rock is locally banded and has cavities sug­ the younger eruptives, the most abundant of which The rhyolite penetrates and overlies the Copley the diabase occurs as interbedded flows. The gesting lithophysee. The rock has a few long pla­ are quartz-augite-diorite and dacite-porphyry. metaandesite. The mass of the metaandesite sheets, are not only conformable between the gioclase twins with symmetric extinction angles up Distribution. The principal area of the Copley was erupted before that of the rhyolite, but their layers of the Bragdon sediments, but are occa­ to 30°, indicating labradorite. They are inclosed metaandesite is that of O'Brien Mountain, extend­ eruptions appear to some extent to have alter­ sionally associated with beds of volcanic sand in a microgranitic groundmass of quartz and feld­ ing south through Bass Mountain and the hills nated, and it has not been possible in all cases to whose origin is connected with the eruption of spar, of which a few of the grains show lamellar about' 1 the National mine to Copley and Old separate them. the diabase. These tuffaceous sandstones are com­ twinning. Notwithstanding the rhyolitic aspect Diggings. Pit River crosses the northern portion It is not certain that all the dikes of rhyolite west posed of the same, minerals as the diabase and con­ of the rock, the absence of orthoclase, with the and the Little Sacramento and Sacramento follow of the Sacramento are Balaklala and older than the tain occasional fragments of the underlying shale. prevalence of labradorite and the presence of free the general course of the northwestern border. middle Devonian. There were extensive eruptions The whole association indicates contemporaneous quartz, places it among the quartz-latites. The rocky banks of the latter afford particularly of rhyolite early in the Triassic and it is possible volcanic activity at intervals in the later portion of TRIASSIC. good exposures. that some of the dikes west of the Sacramento may the Bragdon epoch, and it is believed that the Bass D'EKKAS ANDEJSITE. ' Another area of Copley metaandesite lies south­ have been formed at that time. The dike-like Mountain diabase belongs to that horizon, though ' « . . V 4 west of Redding and is in line with that of O'Brien masses on the slope west of Copley are very fresh the evidence is not altogether satisfactory. General description. The Dekkas andesite is and Bass mountains, though separated from it by and may belong to this class. At several points Relation to adjacent formations. The relation of generally a dark-gray lava that is more or less a mass of rhyolite. also, but more particularly on the east slope of the diabase on Middle Salt Creek to the Bragdon is porphyritic, but not conspicuously so to the naked Two small areas of Copley metaandesite occur Backbone Creek, over 4 miles above Kennett, a clearly that of contemporaneous interbedded flows. eye. It takes its name from Dekkas Creek, along in the northwest corner of the Redding quadran­ peculiar breccia of shale fragments, apparently In the case of the masses, south of Bass Mountain, which the rock is well exposed. It includes a gle, one on Dog Creek and the other at Portuguese cemented by igneous material, was found along which are supposed to be of the same age, the rela­ great mass of lava made up of many separate over­ Flat. These areas are completely surrounded by the contact of the rhyolite and the Devonian tions are different. The diabase appears to rest lapping volcanic flows and sheets of tuff more or rocks of later age and it is probable that the vol­ shale, indicating that the rhyolite is younger than directly upon the eroded surface of the Copley less distinctly bedded, irregularly conformable, and canic rocks occupy a large area beneath the Bragdon. the shale and presumably of Triassic age, but this metaandesite and of the Kennett formation. The dipping eastward. Petrographic description. The Copley metaandesite is is not separated on the map from the Balaklala absence of the Bragdon beneath is evidence that Occurrence. Its best exposures are on the well exposed along the river in the vicinity of Copley, where rhyolite. Some of the tuffs underlying the lime­ the eruption took place on land, but its presence western slope of the ridge from Horse Mountain it is decidedly, green and compact, though in places clearly fragmental. In thin section under a microscope it is found stones contain dark fragments of shale which is above shows that after the eruptions from the sev­ to Bollibokka Mountain, where the hard layers of to be composed chiefly of plagioclase (apparently andesine) probably older than the Kennett. eral centers south of Bass Mountain the district tuff and lava make a succession of bold bluffs and and chlorite with variable amounts of epidote, fibrous green Distribution. The principal area is that of subsided, was covered by the Bragdon sea, and show better than elsewhere their general character hornblende, magnetite, and calcite, sometimes also quartz* The plagioclase is most abundant, generally much altered, which Balaklala Hill is a part, extending from received the upper beds of the Bragdon formation. and position. That the sheets of lava were flows but sometimes fresh, in well-defined elongated crystals, with Backbone Creek south westward across the west­ The large patches of Kennett within the Bass upon the surface is shown by the vesicular char­ irregular patches of chlorite apparently derived from augite acter of the upper portion, which has since been filling the spaces between them. Epidote is generally present ern border of the Redding quadrangle .to Iron Mountain diabase area may have been laid bare by and often abundant and varies inversely with the amount of Mountain, and forming the country rock of the recent erosion, but it is evident that the diabase converted into amygdaloid, and by their associa­ calcite present. Magnetite is less abundant, in some places copper deposits of that region. cover is ,not very thick and that the Devonian was tion with layers of volcanic ejecta. rare. The regular intersertal structure is often modified by the parallel, stream-like arrangement of the feldspars. The An area of rhyolite lies along the eastern side not completely covered by it, for the Bragdon at On the western slope of Town Mountain the rock, though generally holocrystalline, is often hypocrystal- of the Sacramento from Keswiek to Waugh and one point appears to rest ^directly on the Kennett. sheets of lava are more prominent than*-those of line and yanges jn structure from pilotaxitic and intersertal fragmental material. Near the ; summit,Ja|6,ve the,f to granular in which only the feldspar shows traces of crys- has been cut down to the level of the plain about Relation to the quartz-augite-diorite. In the Mid­ tallbgraphic boundaries. the north end of the Sacramento Valley. Another dle Salt Creek region, to a limited extent, the bulk of the altered andesites, are prominent^cliis'1 Originally jthe rock was some form of pyroxene-andesite, small area occurs on Dog Creek, 3 miles west of Bragdon is cut by dikes and intruded sheets of formed by several sheets of a/fine gr'a'riiilal^ro'ck 1' but in view of the degree of alteration it may be more appropriately designated metaandesite. Delta; it is here partially surrounded by the Brag­ quartz-augite-diojite, which frequently has an (quartz-augite-diorite) like that which .so exten- Redding. 8 sively cuts the McGloud limestone, while the wholly from the alteration of augite. No djstinet traces of clastic material occurs in the Pit-River area, but .The feldspar is deeply kaolinized, .but in polarized "light summit of the mountain is made up chiefly of original .hornblende or mica, such as occur in the augite- lava flows are almost equally abundant. Pit much of it shows the lamellar twinning of plagioclase. Their diorite, could be found, though in several cases small amounts absence in a few cases may possibly indicate the presence of fine tuffs and shales locally containing red chert. of secondary hornblende were present. River cuts a deep canyon. across the area, expos­ orthoclase. Grains of epidote are common among the prod­ On the western slope of Minnesota and Salt ing in the steep slope opposite the mouth of ucts of alteration in some grains, while scales of sericite pre­ BULLY HILL BHTOLTTE. vail in others. The hornblende occurs in small grains and Creek mountains fragmental volcanic rocks are Potem Creek great sheets of lava and tuff dip­ shreds. It is in most cases light brown, but often green and most prominent, but, as elsewhere, the fragments General description. This rhyolite takes its ping to the northeast. In some places these rocks occasionally changed to chlorite A small amount of mag­ are not coarse, being rarely over an inch in diam­ name from Bully Hill, famous for its mines, have a distinct cleavage, but its production has netite is present, and occasionally also, as at the falls of Clover Creek, leucoxene and traces of pyroxene. eter and never much larger. This indicates a where, though much altered, the rhyolite is well not been accompanied by any considerable degree Near the boundaries of the areas the rock becomes finer considerable distance from the volcano whence exposed. On a fresh fracture it is gray, contain­ of metamorphism nor even by deformation of grained, but generally has an even granitic structure. In other places, especially east of Larkin, it is porphyritic. The they issued, and yet the distance can not have ing distinct phenocrysts of quartz in a compact fossils. feldspar in part and rarely the quartz appear as phenocrysts been great, for layers composed wholly of very groundmass. On the surface it' is usually porous Relation. Both areas of the Bagley andesite in a granitic groundmass, and the dike-like extension from fine material, such as volcanic dust, are equally and deeply stained reddish from the oxidation of lie practically on the border between the Potem this mass resembles the dacite porphyries in texture. uncommon. pyrite. and Modin formations, but do not necessarily Relation and age. The age of the quartz-horn­ This belt is remarkable for tjie numerous layers Occurrence and relations. In the Bully Hill indicate an unconformity. These areas represent blende-diorite can not be closely determined jn the of fossiliferous, more or less tuffaceous shale which region the rhyolite is arranged in flows alternating centers of greater accumulation of volcanic mate­ Redding quadrangle. The youngest rock it cuts in it contains interbedded with the lavas and tuffs. with tuffs dipping southeastward beneath the Pit rial near points of eruption during the beginning that region is the Bully Hill rhyolite of early Tri­ As the shales inclose many microscopic fossils of shales, but in places, as for example on Baxter of the Potem epoch. Between the two points the assic age. On the other hand, it is older than the marine origin similar to those of the Pit shales to Creek near Copper City, it cuts the lower portion contemporaneous sediments contain some detritus dikes of quartz-augite-diorite and hornblendite, the east, the volcanic products must have spread of the Pit shales and envelops its fragments. The from both centers, but apparently the greater por­ which are younger than the Potem and were out upon the sea floor. long, narrow belts running from Bully Hill toward tion comes from a different source. For this rea­ erupted about the close of the Jurassic. While Relation. The Town Mountain belt of Dekkas the Afterthought district are for the most part along son the intermediate sediments were included in it is certain that the quartz-hornblende-diorite is "andesite from one end to the other is bounded on the crest of an arch running from the Klamath the Potem. - of .Mesozoic age, its eruption most likely occurred the west by the Carboniferous and on the east Mountains southeast toward the Sierra Nevada. late in the Jurassic. PetrograpMc description. The prevailing type of Bagley chiefly by the Triassic, and its sheets of lava and It is flanked on both sides by the Pit shales, with andesite in the deep canyon of Potem Creek near its mouth QUARTZ-MICA-DIORITE. tuff, like the rocks of both adjoining systems, dip anticlinal dips, but part of the area, not readily is darker and generally fresher than elsewhere, but not so to the east between them so as to approximately porphyritic. In thin section the numerous irregular pheno­ General description. The quartz-mica-diorite separable, is occupied by a somewhat later rhyolite, crysts of plagioclase lie in a fine granular, apparently holo­ fix the general horizon of the volcanic activity which, on Cedar Creek and in a number of small crystalline groundmass of well-defined plagioclase crystals found in this quadrangle is a, gray rock of gran­ which it represents. Along the eastern border occurrences north of Pit River, cuts through the and grains of augite. Along Pit River it is less microporphy- itic habit, composed essentially of quartz, plagio­ ritic and there is considerable dark-brown glass present in these flows of volcanic rocks are overlain conform­ Pit shales to the Hosselkus limestone. For con­ place of the augite. The glass is for the most part altered, clase feldspar (generally andesine), and a black ably by, and to a small extent are interbedded with, venience, all the rhyolites erupted in the Redding yielding much carbonate of lime. mica (biotite). It frequently contains a small the bottom part of the Pit shales. On the western In the Bagley Mountain area a small portion of the lava amount of orthoclase, showing its close relation quadrangle during the deposition of the Pit shales contains phenocrysts of hypersthene, possibly also of horn­ side the relation to the Nosoni formation as out­ are included under the term Bully Hill rhyolite, blende and rarely of augite, with those of plagioclase. The to granodiorite. lined is equally clear. The outcrops of the Dekkas though they represent a considerable range of time. hypersthene is replaced by oxide of iron or by a dark-green Distribution. There is only one small area of pleochroic, chloritic mineral, but the augite is fresh. The andesite and Nosoni formation are approximately Bedded tuffs, composed largely of crystal fragments groundmass in this type is less crystalline than in the other quartz-mica-diorite in the Redding quadrangle, in parallel for over 20 miles, but the Nosoni belt nar­ of quartz and feldspar, with a smaller proportion and is full of feldspar microlites, with much yellowish-green the southwest corner, a mile from Larkin. This rows to the south, and on Campbell Creek, as well of glass and pumice particles replaced by quartz, chlorite. occurrence is .a small stock, but there are larger as near Lilienthal, it is un conformably overlapped are common among the Pit shales and are locally LATE JURASSIC OR EARLY CRETACEOUS. masses, possibly batholiths, farther west. The rock by the andesitic flows, which extend westward a associated with sheets of rhyolite. is bright and fresh, forming prominent ledges close QUARTZ-HORNBLENDE-DIORITE. short distance beyond the McCloud limestone. Distribution. The area is extremely irregular to the edge of tjie plain, where it is quarried to.# The stratigraphic position of the great body of and roughly T-shaped, with Bully Hill at the General description. At several points in the small extent for curbing and tombstones. volcanic rocks made up of the Dekkas andesite and radial center. The top part lies along the south­ quadrangle there are areas of holocrystalline, even- PetrograpMc description. The medium-grained holocrys­ the Bully Hill rhyolite, conformably under the Tri­ eastern base of the prominent ridge formed by granular rock, like granite in appearance, com­ talline aggregate contains quartz and plagioclase in about posed essentially of quartz, plagioclase, and horn­ equal proportions, with irregular scales of brown biotite form­ assic and unconformably upon the upper Carbon­ Horse and Town mountains, and extends from ing about one-tenth of the mass. The feldspar is generally iferous, fixes the horizon of great volcanic activity Pit River northeastward, forming many promi­ blende. These form stocks and cut rocks as young unaltered and xenonibrphic, and zonal structure is common. at the beginning of the Mesozoic. Although the nent ledges, to the slopes of Didallas Creek. as the Triassic rhyolites, A few grains of magnetite are present and minute crystals of zircon are rarely included in the quartz and feldspar. A greatest volume of volcanic products occurs at this From Bully Hill the stem part of the area Occurrence. In the Redding region generally small trace of calciteis present, probably from incipient alter­ .horizon, it must be remembered that there was extends southeastward to the Afterthought region this rock is covered by residual material, except in ation of feldspar, and a small quantity of the biotite has vigorous volcanic activity in the same region dur­ along Cow Creek, where it spreads and disappears the rocky canyons of vigorous streams like Spring changed to chlorite. ing the later Carboniferous, and that it continued beneath the cover of lavas from Lassen Peak. Creek, where it is well exposed. The light-gray . The rock, though exposed un

just beyond the northeastern limit of the Red­ Devonian and give evidence not only of extensive igneous masses penetrating and overflowing the but isolated patches of Cretaceous strata occur at ding quadrangle, and is composed largely of Car­ sedimentation, but also of an epoch of metamor- sediments of greater age. a number of points in these mountains, so that boniferous strata. The eastern extremity of this phism which antedates the earliest records in the the evidence is conclusive that a large part if not TRIASSIC. arch passes beneath the lone formation and the Redding quadrangle. the whole of this region was beneath the sea at the lavas of the Cascade Range, and both of these ter- The first events chronicled in the rocks of the The vigorous volcanic activity begun in the late close of the epoch of Cretaceous subsidence. The ranes have been uplifted, showing that there has quadrangle consist of extensive, vigorous, and Carboniferous was accompanied, as already indi­ same is true also of the foundations of the Cascade been movement along the arch possibly as late as long-continued volcanic activity, beginning with cated, in part of the Klamath Mountains, at the Range, and the fineness of the later Cretaceous the Pleistocene. the effusion of a great mass of andesitic lavas close of the Paleozoic, by a short interval of sediments in the Sacramento Valley indicates that Near the head of Chatterdowen Creek, where (Copley metaandesite) and closing with the upheaval and erosion and was then followed by the Sierra Nevada region was reduced by long- the Hosselkus limestone and Brock shale are Balaklala rhyolite. The eruptions, as far as con­ extensive and long-continued volcanic eruptions continued erosion to one of low relief. turned eastward by the Grizzly arch, a narrow cerns the Redding quadrangle, appear to have of the Dekkas andesite and the Bully Hill rhy­ The Cretaceous subsidence of the land and syncline extends northwest beyond the quad­ taken place on land, for no marine beds have been olite of early Triassic time. It was one of the advance of the sea were not without interruption, rangle boundary to the upper portion of Clai- found among the lavas, though some of the tuffs most extensive and prolific volcanic epochs in the for at some time during the Cretaceous, probably borne Creek, where the structure is well exposed. are stratified. geologic history of northern California and stands near its close, there were intrusions of peridotite, The syncline of the Great Bend of Pit River DEVONIAN. nearly midway between the other great volcanic which by alteration have given rise to great and that of the Sacramento Valley lie close epochs, one in the early Paleozoic and the other masses of serpentine. Some gabbros were intruded together, end to end, and are separated, if at all, Over the whole of the Klamath Mountain region in the Tertiary. about this time, and there were such oscillations of only by the low arch running southeastward during middle Devonian time deep-sea conditions During the entire period of volcanic activity the land as to change the succession of strata at from Copper City. They represent the great prevailed, and fine sediments, chiefly shales, often embracing the close of the Paleozoic and the many points from what it would have been had depression in the pre-Cretaceous rocks between siliceous and full of microscopic shells, were depos­ beginning of the Mesozoic the eruptions of the the subsidence been regular and continuous. the Klamath Mountains and the north end of the ited, with occasional lenses of limestone in which Redding quadrangle were submarine, burying lay­ At the close of the Cretaceous period the Kla-^ Sierra Nevada, a depression which has been filled corals and some other forms of marine life are espe­ ers of characteristic fossiliferous shale. As the math Mountains were again uplifted and the Cre­ with the Chico and lone formations, the Tuscan cially abundant. The few sandstones found are eruptions decreased at the close of the volcanic taceous strata in places were greatly crushed, but tuff, and the great lava mass of the Lassen Peak made up of sediment derived from the earlier epoch, shales and sandstones began to predomi­ not so within the Redding quadrangle. region, thus forming mountains out of later mate­ volcanics. nate, with an occasional layer of lava and tuff in rial, so that the Klamath Mountains appear to be The middle Devonian epoch of deposition was the Pit formation. Another epoch of quiescence TERTIARY .AND QUATERNARY. continuous with the Sierra Nevada. During at closed by an uplift that exposed the consolidated followed, during which the Hosselkus limestone The Tertiary period opened with the Klamath least a portion of later Cretaceous time the Lassen beds of sandstone, shale, and limestone to vigorous and the overlying Brock shale were formed. Mountains above the sea, and they have remained depression was occupied by an arm of the sea, but erosion, which completely swept away large tracts above ever since. During the Tertiary and the JURASSIC. during the Miocene the water was fresh. of the Devonian sediments, exposing the under­ Pleistocene there were many oscillations of the lying volcanics and paving the way, as it were, The quiet of the closing Triassic was broken land, alternating with long or short epochs when AREAL DISTRIBUTION. for the unconformity between the Devonian and and the Jurassic initiated by volcanism which it was comparatively stable. These movements The structural features determine the areal dis­ Carboniferous. is represented in the extensive tuffaceous con­ are registered for the most part in the topographic tribution of the formations. The uplifts bring the glomerate at the base of the Modin, a conglom­ forms sculptured by erosion and may be most con­ CARBONIFEROUS. . older rocks to the surface and the depressions or erate which contains, besides volcanic material, veniently considered under the heading "physio­ synclines are filled with the newer formations. In Subsidence in the Redding quadrangle initiated fragments of fossiliferous Triassic limestone. The graphic record." the Redding quadrangle the Klamath uplift more the early part of the Carboniferous and the deposi­ slight unconformity of the Modin conglomerate than any other feature is expressed in the areal tion of the Bragdon, with marked erosional dis­ on the Brock shale is due to changes of eleva­ PHYSIOGRAPHIC RECORD. distribution. The general strike of the formations cordance, upon the Devonian and earlier volcanics. tion in connection with the volcanic activity, but Topographic provinces. The three topographic is north and south and the dip toward the east. The uplift and subsidence about the close of the unaccompanied by rock folding. The source of provinces represented in the Redding quadrangle The older formations outcrop in the western por­ Devonian were not accompanied in this quadrangle the volcanic material was not discovered. It was differ widely in origin. The plain of the Sacra­ tion of the quadrangle, and the rocks are suc­ by any rock folding, for the bedding in the Brag­ of short duration and the succeeding strata were mento Valley is purely constructional, being due cessively newer toward the east up through the don and Kennett formations at their contact is formed of finer sediments locally rich in fossils. to valley filling leveled by the floods of the Sac­ Paleozoic and Mesozoic to the Tertiary and Qua­ apparently parallel. The fossils show that marine At the beginning of the Potem epoch there were ramento. The Piedmont Plain bordering the ternary. conditions prevailed during the Bragdon, and that andesitic eruptions of importance, chiefly at two Cascade province is also constructional, being due The most ancient rocks of the quadrangle are the water was shallow is indicated by the fact that places, Bagley Mountain and a point about 10 to volcanic floods from local vents or from larger volcanic, including the Copley metaandesite and conglomerates are common in which the pebbles miles to the south. They were submarine and volcanoes in the main ridge streaming and spread­ the Balaklala rhyolite, which form a large area were derived largely from Devonian sediments, furnished much tuffaceous material for the Potem ing in a plain toward the Sacramento Valley. The and several smaller ones near the western border with some from the older lavas. Toward the close formation. Klamath Mountains, on the other hand, are not of the quadrangle. Upon these rests the Kennett of the Bragdon epoch there were eruptions of dia­ Between the Potem and the Chico is a con­ built up like the other two, but are lifted up, and formation, which once formed a continuous cover, base, and beds of volcanic sand, associated with spicuous unconformity which represents a long the special surface features are degradational, the but by erosion and the eruption of later igneous contemporaneous flows, occur at various places. interval, in part Jurassic but chiefly Cretaceous, result of erosion, chiefly stream carving, and will rocks it has been reduced to a number of isolated In the Bass Mountain region, however, the erup­ and during that interval the geologic changes were be considered chronologically in connection with patches; in the northwestern part of the quad­ tions appear to have been on land and not directly more profound than at any other time. The the contemporary sedimentary and igneous record. rangle these are covered by the large area of Brag- associated with marine deposits. Jurassic part of the interval is represented else­ EOCENE, OLIGOCENE, AND MIOCENE. don, but the Kennett reappears just beyond the Between the Bragdon and Baird epochs, both of where in California by the Mariposa beds on northern border of the quadrangle. Next above which are early Carboniferous, there was contin­ the eastern side of the Sacramento Valley, while During Eocene time California north of the the Bragdon is the Baird, whose outcrop, like that uous sedimentation without definite interruption. the Cretaceous part is represented by the Knox- fortieth parallel was wholly above sea level and of the McCloud, the Nosoni, and the Pit forma­ Volcanic activity became more general. The lavas ville beds on the western side of the same valley. received no marine deposits, though such extend tions, as well as the included volcanic horizons of came from different centers and were more andes­ They are supposed to be unconformable, but they north in the Sacramento Valley to Marysville the Dekkas andesite and the Bully Hill rhyolite, itic. Toward the close of Baird time, however, vol­ have not yet been found together in California. Buttes and south along the coast of Oregon to forms more definite north-south belts. The expo­ canic activity ceased, and the long quiet succeeded At the close of the Jurassic period came one of Rogue River. sure of the Pit formation is widened by the Copper during which the 2000 feet of McCloud limestone the great mountain-building epochs of the Pacific The Eocene was closed by a disturbance which City arch and the syncline to the west, which of the middle Carboniferous was deposited. coast of the United States. The rocks were greatly folded the strata before the deposition of the Mio­ catches the Hosselkus limestone and part of the Oscillations began and the McCloud limestone folded, faulted, and crushed, and uplifted, giving cene, producing slight changes in the form and Modin formation in the Bear Mountain syncline. was succeeded during the Nosoni epoch, of late Car­ to the Sierra Nevada and the Klamath Mountains size of the land areas. An arm of the sea filled In the northeast corner of the quadrangle the dis­ boniferous age, by shales and sandstones, with an much greater altitude and extent than they had the Sacramento Valley, but at its north end the tribution of the Hosselkus limestone, Brock shale, increasing amount of tuff. Pyroclastic rocks, with before. They probably extended northwestward water was comparatively fresh. It extended north­ and Modin and Potem formations is determined by occasional sheets of basalt or basaltic andesite and beyond the present coast line so as to occupy a east through the Lassen depression and received the synclinal corner of the Great Bend of Pit River. rarely also fossiliferous shales, accumulated to a portion of what is now the Pacific Ocean. In the thick deposit of fine sediments that make up The later formations, Cretaceous to Quaternary greater and greater thickness northward, indicat­ connection with the intense dynamic action which the lone formation. inclusive, are limited in their distribution to the ing that the volcanic source was in that direction formed the mountains, there was vigorous igneous Klamath peneplain. The long-continued ero­ Sacramento Valley and the great depression filled beyond Nawtawakit Mountain. intrusion, for all the beds older than the Creta­ sion of the Eocene, Oligocene, and Miocene reduced mainly by the lavas of the Lassen Peak region About the close of the Carboniferous and before ceous are intersected by batholiths or dikes of the Klamath Mountains and the Sierra Nevada which appear in the southeast corner of the quad­ the deposition of the Triassic there was extensive granitic, porphyritic, and aphanitic rocks, whose region to a peneplain, which in the region first rangle. movement, resulting in mountain uplifts by which eruption must have taken place before the depo­ named is known as the Klamath peneplain. The portions of the Sierra Nevada and of the Klamath sition of the Cretaceous in that region. low relief is indicated not only by the fine char­ HISTORICAL GEOLOGY. Mountain region appeared above the sea, restrict­ acter of the sediment in the lone, but also by the CRETACEOUS. SEDIMENTARY AND IGNEOUS RECORD. ing the area over which the marine sediments of character of its fossil flora, which is that of a flat the succeeding period were laid down. So far as The epoch of mountain building and igneous coastal region whose climatic conditions were similar PRE-DEVONIAN. yet known the strata of Jurassic and Triassic age activity closed with the Pacific coast of northern to those of Florida. California farther west than it is now. The land The geologic history recorded in the terranes of are limited to the southeastern portion of the Kla­ PLIOCENE. the Redding quadrangle should be prefaced by a math Mountains, east of Sacramento River. While began to subside more or less continuously and the statement concerning earlier events recorded in it is possible that these strata once covered the Kla­ sea to advance, with interruptions, upon the land, The volcanic eruptions which contributed to the other portions of the Klamath Mountains, where math region and have been wholly or partially until toward the close of the Cretaceous the waves Tuscan tuff took place chiefly in the Pliocene and there is exposed a series of schists, for the most removed by subsequent erosion, the evidence is of the ocean beat against the western base of the were subsequent to an upheaval which led to the part mica-schists, derived by regional metamor- not yet conclusive and the determination of this Sierra Nevada in California and of the Blue erosion of the lone in the Redding quadrangle phism from sedimentary rocks. No fossils have point must await further investigation; but there Mountains in Oregon. The Klamath Mountains before the Tuscan tuff was deposited. The great been found in them and it seems probable that the is evidence in the unequal distribution already were chiefly, if not completely, covered by the volume of volcanics completely filled the Lassen schists are older than the Silurian, which is well known that an uplift of the region occurred about advancing Cretaceous sea. This is indicated by depression, covering the lone formation and many preserved at one point in the north end of the the close- of the Carboniferous and that it was the fact that not only are the Klamath Mountains of the ancient streams of auriferous gravel on the Sierra Nevada. They are certainly older than the accompanied by extensive volcanic activity, the practically surrounded by Cretaceous sediments, western slope of the Sierra Nevada and, north of 11

the fortieth parallel, "forming the Piedmont Plain its' source, in three' parts": (1) Placer gold, (2) series of 'igneous rocks,' andesites and rhyolites^f which characterizes such' bodies removes the toward the Sacramento. gold from quartz veins, and (3) gold from copper so allerljcTTby pressure in many cases as to copper, but leaves most of the iron in the form mines. closely resemble slate. Although most of the of linionite, and with it the bulk of the gold and QUATERNARY. Placer mining. Placer gold was discovered in mines are shallow, some of them, especially at silver, so that in the early days the mines were Differential uplift began near the close of the California by James W. Marshall in 1848, and Old Diggings and farther northwest on Squaw opened and worked for gold and silver only, and Miocene and continued at intervals, with long the wave of prospectors early reached the Shasta Creek, have reached a depth of 500 feet and it was not recognized until later that large bodies halts and occasional subsidences, through the Plio­ region. At first mining was confined to the beds indicate a considerable degree of continuity. of copper ore were lying below. The presence of a cene and Quaternary, until some parts of the Klam- and bars of present streams, and until 1854 nearly Most of the mines about Old Diggings, espe­ small amount of the precious metals makes it pos­ ath peneplain reached an elevation of nearly 7000 all the gold produced in California came from this cially the Central, Evening Star, Mammoth, and sible to mine a comparatively low-grade copper ore feet above the sea. This peneplain is also bordered source. The maximum production of gold in Cal­ Spanish, are working to a greater or less extent. at a profit. by other similar but later plains of erosion whose ifornia was nearly $68,000,000 in 1853, but as the All are on rather irregular but nearly parallel SILVEK. relations have not yet been fully traced out. The shallow placers were worked out the higher gravels quartz veins, whose general course is a few degrees uplift, which was slow but intermittent, greatly of the ancient streams were attacked by the more east of north (dip about 85° SE.), and have been With the mining of copper in the Redding invigorated erosion, and the streams carved out expensive hydraulic methods, and the yield of worked in that direction as far as the National region in 1897 the associated silver product of their valleys wider or narrower in response to the placer gold was kept up for many years, though on mine. The veins range in thickness from a few Shasta County greatly increased, and since then grade imposed by the differential changes of level. a reduced scale. The restrictions placed on hydrau­ inches to 18 feet and carry disseminated pyrite Shasta County has yielded more silver annually One of the early stages recorded in the Redding lic mining within the Sacramento drainage, which and chalcopyrite. The Central mine is at present than any other county of the State. The product region produced- the wide elevated valleys illus­ includes the Redding quadrangle, have materially the largest producer of the Old Diggings vicinity within the quadrangle is now derived wholly from trated by the earlier valley of Pit River. This is reduced the annual yield in that region. Of the and furnishes the bucket tramway over which the the copper mines. closely related in level to the Potter Creek cave, thirteen placer mines reported by the State mining other mines ship their ore across Sacramento River COPPEK. concerning whose fauna Mr. Sinclair remarks: bureau in March, 1902, in Shasta'County, twelve to the Southern Pacific Railroad. "Associated with mountain and-forest types like are in the Redding quadrangle, "one each" near A group of veins about Quartz Hill have been Within a decade California has come into prom­ Haploeerm and the deer are plains species the Slatonis, Copley, Redding, and Delamar, three worked and have furnished some ore for the inence as a copper-producing State and at present horse, camel, bison, and elephant," a combination near Delta, on Dog Creek, and five near Copper Keswick smelter. The largest vein of the hill is fifth in rank. This advance has brought Shasta which > accords with the gentle relief with which it City, but-their combined yield is-hot- over a few is not less than 40 feet in thickness, with a strike County to first rank in the State as a source of is associated on the border of a great river valley. thousand dollars. They are chiefly on low stream of N. 45° E. and a dip of 65° SE., but only the mineral wealth, the greater part of which comes According to Mr. Sinclair, "the types present, as terraces and are worked during the rainy winter central portion has been removed. The north­ from the Redding quadrangle or from very close well-as the proportion of living and extinct species, and spring, but in1 some cases on present stream eastern extension of the veins of this region to its borders. The total copper product of Cal­ indicate that we are dealing with an assemblage of beds the mines are worked at low water during the has furnished the gold for the early rich placers ifornia for 1904 was valued at $3,786,022, of which forms of later Quaternary age/' summer. of the Buckeye region and may yet be the scene Shasta County yielded $3,402,517, an increase for - The earlier-valley interval was closed by an uplift In the Redding quadrangle there were three of greater activity. the county of $1,231,020 over the product of 1903. which changed the grade" of the streams, causing localities in the early days where placer mining A short distance southeast of the Old Spanish Although mines now operated for copper were them to wear away their beds and cut the narrow, was especially active and productive in the vicin­ mine, about 3 miles west of Redding, the Crown located as early as 1862 near Copper City for gold canyon-like' valleys which have been designated ity of Shasta, about Buckeye, and between these Deep and Bracket mines were active in the sum­ and silver and their copper contents were- noted, the later valleys. The uplift was long continued, two localities at Old Diggings, near Sacramento mer of 1903, and were shipping ore to Keswick. the real exploitation for copper in the Redding' with intervals of stability which- permitted the River. ' ; The veins of these mines are less regular than region began in 1895, at Iron Mountain, when streams under favoring conditions to widen their The Buckeye district embraced : only shallow those of the other regions and generally strike N. that property came into the possession of a London valleys slightly; as at Keswick arid around the gravels and residual material of that portion of 12"-40° W., though at the Old Spanish mine the syndicate.

northern border of the Sacramento Valley, where the peneplain about the head of Buckeye Creek strike is usually N. 12°-35° E. At the Bracket COPPER DISTRICTS. the Redding quadrangle laps over upon a border­ and its tributaries, and could be worked only in and Crown Deep mines the veins ;are crushed in ing peneplain. The final valley filling or aggrad­ the - wet season. In 1881 $14,000 was reported places and the intermingled vein material appears The copper region of Shasta County, about 30 ing !of the north end of the Sacramento Valley from this district, but in late years the output has to be of several ages. miles in length and scarcely half as wide, extends with the Red Bluff formation was completed at been very small-. The gold is evidently derived The auriferous quartz veins of the Old Spanish nearly east and west across the middle of the Red­ this time, though the deposition of the older por­ from the auriferous quartz veins which intersect mine and Shasta region are in granodiorite, though- ding quadrangle and embraces two actively pro­ tion of the Red Bluff on the valley bottom began the ancient igneous rocks of the region. The long they too belong to the same system as those already ducing districts, Iron Mountain and Bully Hill, long before, at the time when the later-valley cut­ period of degradation incident to the development referred to; but thus far none of those in the gran­ which are separated by a dozen miles of country ting was initiated. Another uplift at the close of of the peneplain about Buckeye has greatly favored ite have proved more durable than those in the where as yet no large bodies of copper ore have the Red Bluff epoch increased the bottom cutting the concentration of placer gold in the vicinity. other igneous rocks. been found. once more, and the streams carved out the narrow The group of placer mines near Shasta was most The quartz mines of Squaw Creek west of Ken- The Iron Mountain district is the largest and by valleys in which we now find them. The uplift active in the early days and, according to the cen­ nett are of .interest as being among the oldest and far the most important of the region. Iron Moun­ was circumferential about the northern part of the sus reports, yielded $25,920 in 1881. This, of most extensively worked of the region. The Uncle tain lies just outside of the border of the Redding Sacramento Valley, but greatest on the east, less on course, is small, compared with their original Sam ran ten or more stamps for about a dozen quadrangle, northwest of Keswick, and from this the north,-and least on the west, as evidenced by annual production, and they are now practically years with a chlorination plant, and drifted on the locality the district extends nearly northeast for 25 the various canyons and alluvial plains developed. exhausted. Interest at present centers in rock vein for 1500 feet at a level about 500 feet beneath miles, to beyond the Mammoth mine, and has a mining, from which the bulk of the precious the cropping. An incline was sunk on the vein width of scarcely 2 miles. It comprises the hold­ ECONOMIC GEOLOGY. metals is obtained. from the main level to 1040 feet beneath the sur­ ings of the Mountain Copper,Company, Balaklala, .,,.. MINERAL RESOURCES.. . During the summers from 1902 to 1905 a suc­ face. Two veins which combine strike nearly Trinity Copper Company, Mammoth, Summit, and Metalliferous Deposits. , tion dredger was used in Sacramento River near northwest and southeast and dip northeast, with a number of other companies. ' Shasta County has long been celebrated for its Middle Creek, above Redding. This work has a thickness ranging over 4 feet for much of their The Bully Hill district,.an area scarcely 3 miles mineral products, and for five years was the banner been carried on in a small way more or less extent. The quartz contains locally disseminated north and south by 2 miles east and west; includes county of the State. Gold, silver, and copper are irregularly for a number of years, with varying pyrite, chalcopyrite, and occasional traces of free the Bully Hill and Copper City tracts, besides a its principal products, and to copper it owes its pre­ results. < ' '. ., ' gold. The greater values were found in the upper number of prospected claims on the slope south eminence. The value of its products rose from a Qn Clear Creek below Horsetown, near the part of the eastern portion of the mine, about a and southwest of Horse Mountain. total in 1897 of $2)224,706 to $6,737,571 in 1901, southwest corner of the quadrangle, a chain- dike of andesite-porphyry which probably effected The Afterthought, at the east end of the copper but owing to-a decline in the price of copper and bucket dredger was installed in 1903 on ground the enrichment of the vein. The mine was recently region, has recently become a producer. The the occurrence of miners' strikes' the total output which, judged from the early yield of that region, bonded and thoroughly prospected by the Trinity Black Diamond, though not a producer, deserves was reduced in 1902 to $3,730,04.9 and in 1903 to should be rich. Difficulties were encountered and Copper Company. consideration on account of the exceptional mode $3,201,680, but in 1904 it rose again to $3,402,517. the dredger was burned, but it has been rebuilt and The group of quartz veins about the Uncle Sam, of occurrence of its deposits. Although ' Shasta County embraces almost four operations continued. - extending from the Riley and Bliss to .beyond the The country rock of the copper deposits is essen­ times the area of the included Redding quad­ Vein mining. With the decline of placer mining Clipper, are at an elevation of 2000 feet or more tially the same throughout, though not all of the rangle, the greater part of the mineral values of the- source of the placer gold was sought farther up on North Fork of Squaw Creek, and are conven­ same age. It is chiefly rhyolite, with a smaller the county now comes from within'the quadrangle the same streams, and many claims were filed on iently located to furnish siliceous ores which may proportion of metaandesite and tuff and here and or from very close to its borders. The following quartz veins' containing free gold and sulphides. be needed at the Mammoth smelter in treating the there a trace of included sediments. The copper- table, compiled chiefly from data secured by Mr. Some of these veins have been worked with limited large bodies of copper ores of the same region. ore deposits are limited to lines or zones' of dis­ Charles G. Yale, ~of the United States Geological success, but on the whole they have been of too low These veins generally strike about N. 50° W., but turbance in which the country rock is crushed and Survey, gives a nummary of the mineral produc­ grade for even moderate results unless worked there are exceptional cases where they strike nearly sheared, thus preparing the way for circulating tion of Shasta County for 1904: under the most auspicious circumstances. Such east and west. waters and greatly enhancing the possibilities of '' ' Mineral'produciion of Shasta County in 1904. a favorable opportunity occurred in supplying On Dog Creek, about 4 miles southwest of mineral solution and deposition. . Gold: 1 '-" : ' ; ":' '» ' "' . ' ' '.. " the demand of the Keswick smelter for siliceous Delta, a mass of rhyolitic rock occurs, locally FISSURE SYSTEMS. From) placers...... ^.. §21,082 ores to flux the copper and iron sulphides, and impregnated with sulphides and traversed occa­ From siliceous ores...... 641,272 The rocks of the copper region have experienced" From copper ores.... 1'...... 369,813 for several years a number of the mines in that sionally by quartz veins. Half a dozen groups /iv.1- ' ! '" $1;032,167 vicinity, especially near Old Diggings, have be^h 1 of claims have been located at this place in the disturbances at many periods extending over a Silver, ...... 399,686 wide range-of time. These have doubtless varied Copper ...... I...... *...... I!..-...'.. 3,402,517 worked for this purpose, but With a total shipment, Redding quadrangle, but none are now working. Lime .v.... 10,800 in large part of carefully selected and graded ores, The only mine in the region now shipping ore is greatly in intensity from time to time, but each is Limestone. 5,400 amounting to not over 500 tons per month during the Inca. ' A tuiinel follows the small decomposed recorded in corresponding flexures and fractures of Chroinite. 2,250 Pyrite .... 5,500 the summer of 1903. This amount must have quartz vein N. 65° W., and only the carefully its own, producing a very complex aggregate, in Macadam., 1,500 been greatly increased during; the last two years to assorted ore is shipped in bags. which it is not only difficult.-"but practically impos­ Brick. .... 17,500 Gold" associated with copper. In the table already, sible to assign with certainty every effect to, its The silver is obtained chiefly from copper ores. meet the demands of two new 'smelters. The country rock of the auriferous quartz veins given it will be seen, that a large part of the gold period. The matter may be rendered clearer GOLD.. throughout, with the exception of the Shasta product of(the Redding quadrangle comes from the by considering the fissures in three groups (I) The gold obtained in the Redding quadrangle region, is essentially the same as that of the copper mines. The leaching of the pyritiferous earlier fissures filled, at least in part, by igneous, may be conveniently considered, according to copper-ore bodies and Consists of an ancient copper ores near the surface to form the gossan rocks of pre-Cretaceous eruption, (2) fissures bear- Redding. 12 ing ore deposits, and (3) fissures of late Cretaceous tion of .the ore bodies is due to recent faulting, a originated in the alteration of pyrite. It is prob­ the bulk of the gossan, which is often cavernous, or post-Cretaceous age. large part is attributable to lack of regularity in able that the same is true at Bully Hill, where the with beautiful, iridescent, stalactitic, and botry- Earliest fissures. These fissures, including a the original deposits. bornite appears to penetrate the pyrite and chalco­ oidal lining. It results from the oxidation of the very large group through which from the earth's pyrite along the fissures, but the matter could pyrite and chalcopyrite, and is limited to the zone interior the numerous igneous rocks of the Red­ DISTRIBUTION OF ORBS. not be definitely settled from the thin sections of oxidation near the surface. ding quadrangle at various times reached the sur­ So far as yet known ore bodies of economic examined. Barite (BaSO 4) is the most abundant gangue min­ face, are of earlier date than those which contain value have been found only in the Balaklala and Chalcocite (copper glance, Cu 2S) occurs, gener* eral. It is distributed throughout the ores of the the ore deposits under consideration, for the ores Bully Hill rhyelites. At a number of points they ally in the form of nodules, but sometimes as a Bully Hill and Afterthought districts, but is always are found in the igneous rocks which fill the earlier occur near the contact with sedimentary rocks, but fine black powder, at Bully Hill, chiefly just disseminated in fine particles, so small in amount fissures. It is possible that there, were ore deposits not within them. However, it is not improbable beneath the zone of complete oxidation. It is compared with the ore minerals as to be scarcely of importance antedating the Town Mountain series that such may yet be found, for similar deposits often associated with green or rarely blue copper visible to the naked eye. In the eastern districts of igneous rocks or those of later Jurassic age and are known at Rio Tinto, Spain, in slates. carbonates (malachite and azurite) at the bottom of it occurs from the surface to the greatest depths yet that they were modified or completely removed by The Balaklala and Bully Hill eruptives, made the gossan, or in the sheared borders of the ore attained and appears to be one of the primary min­ subsequent erosion, but of such deposits distinct up chiefly of ancient rhyolites, with andesites and body to a depth generally of a few hundred feet. erals of the ore bodies. Rarely it occurs in cavities evidence has not been found. tuffs and small masses of included sediments, the In November, 1903, it was found with bornite on as small tabular crystals, and at Copper City it has Ore-bearing fissures. The fissures which gave whole intersected by various dikes, afford a wide the 570-foot level at Bully Hill, much deeper than been found in small veins cutting the ore. There access to mineral-bearing solutions and. thus per­ range in the chemical composition and physical ever before in that locality.. It has a dull blackish appear to be at least two generations of barite. In mitted the formation of deposits of copper and condition of the country rock. The copper-ore lead-gray color and is massive rather than distinctly the Iron Mountain district, where quartz is the auriferous quartz originated chiefly during the bodies are usually found in the rhyolitic rocks, but crystalline. As a source of copper thus far, even principal gangue, barite was found locally by epoch of rock crushing and mountain making occur also in the more basic forms or on the con­ where it is most abundant, it is of much less impor­ Mr. A. H. Brown in the Golinsky mine, and about the close of the Jurassic. This is indicated tact between the two. The limited general exam­ tance than chalcopyrite, on account of the small traces were seen elsewhere north of Squaw Creek. by the fact that the fissures bearing ore have been inations of the mines made thus far do not disclose size of the masses. , Small veins of chalcocite occur Barite is most common among copper and lead found in Jurassic rocks, but not in the Cretaceous. marked variation in deposit values due to variation in pyrite and chalcopyrite, and it is evidently of ores, while quartz is associated with pyrite. As the All the important ore-bearing fissures-in any dis­ in the country rock, and yet there are suggestions later origin than either of the others. It pene­ feldspar of the rhyolite in Bully Hill contains trict have been generally supposed to be approxi­ in the Bully Hill and Iron- Mountain districts that trates and envelops chalcopyrite in such a way barium, the barite may come from its alteration. mately parallel, while those of different districts are such may be the case in the neighborhood of dikes. as to suggest its derivation, at least in part, from Quartz (SiO 2 ) is the usual gangue mineral of more or less oblique. This is true of the smaller The ore bodies are found in irregular fissures chalcopyrite. the copper ores in the Iron Mountain district, as districts only, and the discordance is apparent only along which there has been much shearing, so that Tetrahedrite (gray copper ore, Cu 8Sb 2S7 ) is barite is in the Bully Hill and Afterthought when we compare the general direction of the whole a narrow zone of the adjacent rock is often;ren­ reported by Mr. Keating and is possibly present districts. It is even more finely disseminated than region with that of the separate districts. The dered fissile. The form of the ore body is as a locally in the ore of Bully Hill, for some antimony barite, though occasionally it is visible to the greatest extension of the copper Tegion is in a rule irregularly lenticular, of unequal planar diam­ has been found by the assayers. naked eye. Nowhere is it so abundant as to form direction about N. 80° E., while that of the eters in the shear zone. Its extent along the strike Cuprite (red oxide of copper, Cu 2 O), in a nodule a conspicuous part of the ore bodies, or to suggest several districts ranges from N. 50° W. to N. 32° E. is usually less than that along the dip. Its direc­ of considerable size, was observed and a specimen that these are quartz veins. At Bully Hill it is not The general trend of the Iron Mountain district tion of greatest extent often makes a small angle to collected by Mr. Oxam, mine superintendent (1902), common, but was seen disseminated with pyrite on is N. 32° E., but the strike of its ore-bearing fis­ the dip and lies in the "rake" or pitch of the ore in the clay selvage at Bully Hill, about 6 feet from the 570-foot level, while near by barite occurs in sures rarely conforms to this general direction. body. In size these lenticular bodies range from a the ore body and 150 feet from the surface. the portion of the ore body richer in chalcopyrite Perhaps the closest approach is in the southwest­ fraction of an inch to hundreds of feet in diameter. Malachite (green carbonate of copper, Cu 2 Co4 + and other copper minerals. Quartz was seen with ern part of the district, where the general course of They succeed one another in the same irregular, H 2 O) forms a green stain, small streaks, and nod­ pyrite nearer the surface in the north and else­ the bodies is nearly northeast. In the middle por­ more or less continuous shear zone, or they may ules on the sheared border of the ore bodies at where about Bully Hill to a very limited extent. tion of the field, about the head of Motion and be in adjacent parallel shear zones. The greatest Bully Hill, just below the gossan, with chalcocite, The quartz intermingled with primary pyrite is Spring creeks, the strike of the ore-bearing fissures distance to which any closely related but discon­ very rarely azurite, and a larger amount of second­ regarded of essentially the same age, but it also varies, but the principal- ones usually run about nected series of ore bodies in the same shear belt ary quartz. occurs secondary as veinlets and irregular masses N. 70° W., while in the north slope of Balaklala has been traced is not over a mile. Azurite (blue carbonate of copper, Cu 3 C2 O 7 + of small size with the carbonates in the zone Mountain and beyond Squaw Creek their general Concerning the depths of ore deposits compara­ H2O) is rare at Bully Hill, occurring with mala­ of oxidation. course is more nearly N. 70° E., though locally tively little can be said. The deepest mine is less chite. Calcite (CaCO 3 ) occurs locally as gangue in diverted. The rocks are much sheared, and in all than 1000 feet deep; another within the Redding Native copper (Cu) occurs sparingly at many bands of chalcopyrite in the Afterthought, and parts of the district the fissures containing the ore quadrangle has not been followed more than 700 places in the joint planes of the zone of oxidation rarely also elsewhere in the lower portion of the deposits are usually those that show the greatest feet beneath the surface. The present character of or commingled with the oxidation products. zone of oxidation. shearing. the ore, however, indicates rather an increase than Chalcanthite (blue vitriol, CuSO4 + 5H 2 O) is LODES AND PROSPECTS. In the Bully Hill district the principal ore- a decrease in its essential values with increasing common in the oxidizing portion of nearly all bearing fissures course about N. 10° E., parallel depth. mines along water seepage and damp places, but The term lode is here used to include all the ore with the greatest extent of the producing dis­ is generally associated with melanterite (green vit­ bodies in essentially the same shear zone. Rarely trict, though there are local variations of minor ORE AND GANGUE MINERALS AND THEIR RELATIONS. riol or copperas, FeSO4 +7H2O). Some bluish- they are 100 feet in width and a mile in length, importance. Pyrite (FeS 2 ) is generally by far the most com­ green vitriol in the mine tested yielded much iron and several may occur in each ore-bearing tract In the Afterthought district the principal fis­ mon and abundant mineral of the ore deposits, and only a trace of copper. within a district. sures range from N.. 50°-60° W., parallel to the sometimes occurring alone in relatively pure Sphalerite (zinc blende, ZnS) is widely but not Bully Hill. The Bully Hill district has two greatest extension of the district and also to the masses, but more frequently carrying a mixture uniformly distributed, occurring apparently in all ore-bearing tracts, Bully Hill and Copper City, axis of an arch in the rocks, which stretches from of chalcopyrite and sphalerite. Not infrequently the ore bodies with pyrite, chalcopyrite, and galena. besides a number of prospects which have not the Klamath Mountains toward the Sierra Nevada. in such mixtures the ore has a decidedly schistose Like the chalcopyrite, it is generally disseminated, yet revealed important ore bodies. At Bully Hill The wide range in the direction of. the ore- structure, the darker bands being formed chiefly of but occasionally forms unsymmetrical masses of there are two lodes which are being worked the bearing fissures of the copper region is due to sphalerite. Pyrite occurs also locally disseminated considerable size in which there is little else. eastern or Delamar lode in the Bully Hill mine, the fact that, as the region lies near the borders through the country rock adjoining the ore bodies Locally it occurs with pyrite and chalcopyrite in and the western or Anchor lode in the Rising Sun of the irregular Klamath Mountains, next to the and elsewhere. The bulk of the pyrite is one of streaks, giving the mass a decided schistose struc­ mine. Sierra Nevada, it has experienced earth strains of the primary minerals, but it occurs also to some ture. Although crystalline in structure, it has no The Delamar lode was early opened on the an especially wide range in direction. extent among the minerals of later date, especially crystal outlines, even when, like pyrite and chal­ southern slope of the hill, but the deeper workings In dip the ore-bearing fissures 'are usually verti­ where it forms drusy linings on joint planes cutting copyrite, it is scattered through the country rock. are somewhat farther north. The general course cal or at a high angle, but several prominent vari­ the ore bodies. The occurrence of sphalerite, chalcopyrite, and of the lode is about N. 10° E. and the dip approx­ ations from this general rule occur in the northern Chalcopyrite (CuFeS2 ) is the chief source of the galena in the.unaltered ore bodies indicates that imately vertical. Including interruptions, it has portion of the Iron Mountain district, at the Shasta copper mined, and, though occurring as rather pure sphalerite is one of the primary minerals of the ore been traced less than half a mile, with a width King and Mammoth mines, where the.dip west­ irregular masses within the ore body, it is gener­ deposits. varying from a few feet to nearly a score and a ward flattens and locally may be even reversed. ally disseminated with sphalerite through the Galena (PbS), like bornite and chalcocite, was depth of about 800 feet (elevation, 1180 feet). Fissures of late Cretaceous or post-Cretaceous pyrite. It so grades into the pyrite in color observed only at Bully Hill, where it occurs in The shear zone is more or less distinct throughout o^. The ore bodies are traversed by occasional that it is very difficult to estimate the relative places rather abundantly in some of the ore bodies and con tains-irregularly lenticular ore bodies, some fissures which must be of later origin than the ore proportions of the two minerals. In the copper near the zone of oxidation as well as at the bottom of which have been very rich. A dike of basaltic itself. Movements have occurred along these fis­ region of California the chalcopyrite and pyrite of the mine (elevation, 1180 feet). It occurs also rock (the so-called porphyry), greatly altered, cuts sures, faulting the ore. Rarely the ore, body is appear to be of the same age and generally pri­ sparsely disseminated through the ores and coun­ through other igneous rocks and slates of the east­ sheared and schistose like the adjacent country mary, except in the zone of enrichment beneath try rock locally, but most commonly in connection ern slope of the hill, and the shear zone follows rock, and occasionally the shearing involves, .the the gossan, where the former is occasionally found with chalcopyrite, bornite, and sphalerite, and is approximately the general course of the dike, bornite as well as the pyrite. Generally, however, in joint planes cutting the ore body and is undoubt­ the primary ore mineral that may carry the silver either cutting the dike or on the contact between the ore body is contrasted with the country rock edly secondary, values. it and the rhyolite (Bully Hill quartzite), but, so by the absence of fissuring. Bornite ("horse-flesh ore" or "peacock ore," Native silver (Ag) is of the same occurrence as far as yet observed, the shear zone of the Delamar By far the greater part of the fissuring and Cu 3 FeS 3 ) has been observed locally in the Bully native copper, but rarer. lode does not enter the rhyolite. The walls are movement affecting the ore bodies has probably Hill mine, where it occurs at one point near the Wad (impure hydrated oxide of manganese) is sometimes sharp, but in many places indistinct, taken place along their borders, which are some­ zone of oxidation and from there downward at found in relatively small quantities, limited to the grading into the material of the shear zone. The times polished (as in the Hornet mine), while the intervals, intermingled with pyrite, chalcopyrite, zone of oxidation at Copper City and possibly ore is, however, almost always easily separable country rock is sheared and altered to a,whitish galena, barite, and sphalerite, to the bottom of elsewhere. It occurs as nodules in the gossan or from the country rock. gouge or selvage consisting generally of a mixture the mine, or the 570-foot level (October, 1903) in the sheared country rock bordering the upper The ore bodies of the lode are very irregularly of clay and sericite. The fissures of later origin about 820 feet below the summit of Bully Hill and part of the ore body. Its brownish-black color distributed in the shear zone in overlapping, en within or near the ore bodies sometimes contain 1180 feet above sea level. On a fresh fracture it and very light weight are features which readily echelon, or linear-discontinuous arrangement, secondary ores such as chalcocite, malachite, azur- generally has a peculiar reddish-brown color which distinguish it from the black powdery form of usually connected by small stringers. They vary ite, native copper, or quartz. While it is certain tarnishes on exposure and becomes iridescent pur- chalcocite. in size from lenticular or sheet-like nodules a few. that some of the irregularity of form and distribu-? plish blue. In-the ore deposits at Butte bornite Limonite (brown hematite, Fe2 O 3 +3H 2 O) forms inches wide up to bodies'hundreds of feet in length 13

and nearly a score of feet in thickness. The great­ activity nearly ceased. Recently the property has The ore is associated with contact minerals, borders are sheared and sometimes polished by est extent of the ore bodies appears to be in a nearly been developed, in connection with that of Bully hedenbergite and garnet, resulting from the inter­ movements since the ore was formed. In dip it is vertical direction, pitching steeply to the north. Hill, to a depth of several hundred feet. The action between the intruded igneous material and vertical, with pitch apparently at a high angle to The crushed rock of the shear zone is not always shear zone in which the lode occurs traverses the limestone. These contact minerals may there­ the northeast. mineralized, but it is generally more or less richly rhyolite like that of Bully Hill and locally gives fore be regarded as the gangue of the ore. Heden­ The annual average of copper in the Iron Moun­ impregnated with ores and sometimes completely to it a decidedly slaty structure. In the main bergite is a pyroxene rich in lime and iron. It is tain lode, judging from the reports of the company, replaced. tunnel east of the lode the rhyolite clearly cuts the most striking mineral of the contact, occurring thus far has ranged from less than 5 to over 7 per The zone of complete oxidation in the Delamar the slates and includes slate fragments. Although in coarse, crystalline, green, fibrous masses, with cent, with an average value of precious metals of lode consists largely of limonite, but is frequently ore bodies were seen close to the slates none were the fibers arranged perpendicular to the contact less than $1 in gold and a little more in silver to a breccia in which limonite is the cement binding found in them. The shear zones of the Bully between the limestone and the diorite. Heden­ the ton. Up to the end of 1902 the mine had the fragments of the country rock. Rarely the Hill and Copper City tracts may traverse the bergite readily alters under the influence of the yielded approximately 62,000 tons of fine copper. limonite forms small iridescent cavities lined with slates between them, but important mineralization weather, and as it is rich in iron its decomposition Some years ago the Mountain Copper Company stalactites. It results from the oxidation of the appears to have taken place only in the igneous yields much limonite. Magnetite, too, oxidizes prospected under bond with diamond drills a num­ ores by circulating waters, which carry away the rocks. readily and gives rise to limonite, so that from ber of the lodes northeast of its own. copper, zinc, and lead, leaving most of the gold The general course of the lode, where recently both these sources the contact region becomes Proceeding northeast from the Iron Mountain and silver behind with the iron. Some of the dis­ worked by the Bully Hill Company, is N. 50° E., deeply stained reddish yellow with hydrous oxide lode, which is closely in line with the workings at solved metals may have been entirely removed, and the dip is vertical. The ore is pyrite and of iron. Sugarloaf, one enters the Redding quadrangle and but a large part of the copper found its way down­ sphalerite, with chalcopyrite in varying propor­ One of the best exposures of the contact phe­ finds the King Copper, Spread Eagle, and Loraine ward and was added to the ore body, greatly enrich­ tions and barite as gangue. In 1902 this lode nomena is on the crest of the limestone ridge Gray lodes in the same course. All have been pros­ ing the lode below the gossan. The lower limit of was worked in connection with the Bully Hill Rocks, where it is cut across by a number of dio­ pected, but the most extensive workings are at the gossan descends irregularly, deep into the ore mine, but in 1903 activity in the Copper City rite dikes running east and west and ranging from Spread Eagle, where there is a large mass of body along fissures, but the contact is usually tract was confined chiefly to the Arps and Tarn- 5 to 100 feet in width. Along the edges of these gossan on the steep slopes at the head of Motion abrupt and marked by more or less black powdery rack prospects. dikes, in contact with the limestone at many Creek. This has been penetrated by tunnels, which ore. West of the Bully Hill district, near the summit points, pits have been dug into the iron-stained have cut a mass of sulphide ore that appears to In the upper part of the enriched zone the ore is of Horse Mountain, is an interesting occurrence of fibrous mass of pyroxene, which is mixed occa­ strike N. 70°-80° W. and to dip 75° SW. This usually black from the presence of chalcocite and native copper, very small particles of which are sionally with garnet, another mineral resembling is traversed by sheared fissures, some nearly paral­ galena, but at greater depths, with some exceptions, sparsely scattered through a mass of altered vesuvianite, and traces of the ores. lel to the strike and others transverse. The pyrite pyrite and chalcopyrite generally give their color igneous material, chiefly of volcanic breccia or ore beneath the gossan is generally wet, soft, and to the ore. In the upper ores of the zone of conglomerate of siliceous lavas. Farther sOuth- incoherent, and in places it is cemented by quartz enrichment, mined some time ago from the Dela­ west, near the head of Potter Creek, a number gangue in varying proportions. In the lower tun­ mar lode, the proportion of copper was so high of prospects show distinct traces of copper ores, nel some small masses of chalcopyrite are seen. that an iron flux had to be added in smelting; but but as yet no considerable ore bodies have been The general trend of the small ore body of the in those below, which are now being removed, disclosed. King Copper, on the slope of Spring Creek, is there is a greater percentage of pyrite, and no iron Afterthought. The Copper Hill lode, in the N. 70°-76° W. It dips 84° SW. and apparently flux is necessary. Near the gossan copper carbon­ Afterthought district, was worked years ago and agrees quite closely with the position of the Spread ates occur, with chalcocite and rarely cuprite and has lately been revived and become a producer. It Eagle ore body, transverse to the general direction native copper on the sheared borders of the lode. consists, so far as known at present, of two short, of the Iron Mountain lode. The body of the lode is composed of pyrite, chal­ nearly vertical ore bodies which strike about N. The Balaklala lode is one of the most prominent copyrite, chalcocite, bornite, sphalerite, and galena 55° W., parallel to the Copper City arch. The in the Iron Mountain district. It is well marked in varying proportions. Pyrite is generally most two bodies are nearly parallel and stand en in places by heavy gossan and has been traced abundant, but locally it may be surpassed by an echelon, approximately 350 feet apart. One of more or less continuously for over half a mile. It increase in one or more of the other ores. Chalco­ them in 1903 had been prospected to a depth lies in and nearly parallel with the slope of South cite is generally limited to within a hundred feet of over 100 feet. They lie close to the contact Fork of Squaw Creek, and strikes about N. 70° E., of the gossan, but has lately (November 16, 1903) in rhyolite that incloses fragments of slate. Like with a northwesterly dip somewhat steeper than been reported by Mr. Keating to occur with born­ those of the other districts, they are composed the slope on which it occurs. The principal ore ite on the 570-foot level, where its occurrence is of largely of pyrite, sphalerite, chalcopyrite, and body yet known in this lode, the Windy Camp especial interest as lowering the probable extent of galena, with local traces of bornite. The gangue, body, has been followed along the strike for nearly the zone of enrichment. which forms less than 5 per cent of the ore, is 1000 feet and on the dip for over 500 feet. It has The Anchor lode is approximately parallel with barite, with a trace of calcite. an irregular thickness ranging from a few feet to the Delamar and lies over 200 yards to the west, Several years ago this property was purchased over a score, and appears to pitch to the northeast. with a known length of about one-fourth mile. by the Great Western Gold Company. Develop­ The rocks on the borders of the ore body are gen­ It is wholly within the rhyolite locally known as ment has since gone far beyond the limit of 1903. erally sheared, with but little clay, and are not the "Bully Hill quartzite." It has been traced A smelter has been erected and is now said to be much impregnated by sulphides. The ores are farther south than the Delamar lode and opened shipping matte to an eastern refinery. chiefly pyrite, with more or less chalcopyrite, but by a tunnel and shaft in the Rising Star mine to a The Donkey mine is on the strike of the Copper are generally of low grade. Quartz is the only depth of about 200 feet from the surface, or to an Hill lode, a mile farther southeast and in the same FIG. 1 Sketch map showing relation of Iron Mountain lode gangue mineral, and forms a larger percentage of elevation of about 1300 feet above the sea. The rocks, but the workings were water filled in 1903, to other lodes of the same district. the ore than at Iron Mountain. At the north gossan scarcely reached the surface at the Rising and an examination of the ore in place was there­ Iron Mountain. The Iron Mountain lode, as end of the lode, where the great masses of gossan Star, but is well developed beneath. In the irreg­ fore impracticable. shown on the sketch map (fig. 1), lies wholly occur, comparatively little is known of the unal­ ular ore body pyrite, chalcopyrite, sphalerite, and Black Diamond. The Black Diamond district outside the Redding quadrangle, but close to its tered ore bodies. chalcocite vary greatly in relative proportions. is near the center of the copper region, about 14 western border. On account of its great economic The Shasta King ore body lies on the west slope Chalcocite penetrates the ore body in veins and miles northeast of Redding. Its ore bodies are importance and close relation to the other lodes of of South Fork of Squaw Creek, nearly opposite the is clearly secondary. Locally sphalerite is abun­ contact deposits and therefore decidedly unlike the same district within the quadrangle, it may be Windy Camp ore body and at a lower level. As dant, and near it chalcopyrite may prevail. those of other portions of the copper region. mentioned here. It has been traced from the head the general dip of the Windy Camp body is toward Farther north on the same lode, where reached The country rocks are limestone and quartz- of Slick Rock Creek northeast to beyond Boulder the Shasta King, they have been regarded as belong­ by tunnels 4 and 7, galena appears, as in the augite-diorite. The former is the McCloud lime­ Creek, a distance of fully a mile, and embraces a ing to the same shear zone. This view is strength­ Delamar lode. The surface of the Anchor lode stone, of Carboniferous age, and is cut to pieces by number of approximately parallel ore bodies, two ened by the occurrence of smaller ore bodies on the has been traced into the summit of Bully Hill, the fine-grained quartz-augite-diorite. Both rocks of which are much larger than the others. The steep slope between them, suggesting a former con­ where granular pyrite prevails in old openings. extend from the end of the Sacramento Valley large and prominent gossan, which in places nection which has been severed by the erosion of Locally in this lode, as in the Delamar, quartz is northward across the quadrangle, and along their extends to a depth of 100 feet, but is practically Squaw Creek; but the relations are not yet clearly the very sparse gangue of pyrite, while barite, very irregular contact at a number of points masses absent at some points, early attracted attention and understood and can not be fully worked out until somewhat more abundant, is the gangue of the of ore have been found, of which three will be was worked for silver and gold. Since 1895, when the deeper parts of the Windy Camp body are richer copper ores. Generally in this district the described. The first of these is in the Black Dia­ the great bodies of sulphide ore were discovered disclosed in detail. greater values are found with barite. Little is mond district and is largely copper ore, but the beneath the gossan, it has been worked mainly for The Shasta King body is somewhat irregularly known of the northern part of the Anchor lode last two, one 1^ miles southeast of Baird and the copper. The principal ore body is said to have basin shaped. It is some hundreds of feet in in depth, but the persistence of the Delamar sug­ other near Johns camp, about 10 miles farther up been 800 feet long, 100 to 400 feet wide, and was width, with a longer axis running nearly north gests interesting possibilities. McCloud River, are ores of iron and will be noted traced to a depth of 600 feet. It consists predom­ and south and rising somewhat to the north. It is Ore bodies of comparatively small size have under the appropriate heading. inantly of pyrite, with chalcopyrite and sphaler­ limited for the most part by fissures, along which been found in the North Star, Ydalpom, and The ore bodies thus far discovered in the Black ite in varying proportions and scarcely a trace of there has been decided shearing. Exceptions are other openings in the rhyolite on the west slope Diamond region are small, rarely over a few inches gangue minerals. Chalcocite and bornite also have found in places on the upper surface of the ore of Bully Hill. They apparently belong to a third in diameter, irregular in form, and scattered locally been reported. Calcite is occasionally found in body where it is solidly "frozen" to the country zone west of the Anchor lode. Pyrite, chalcopy­ throughout the gangue. The ore consists of chal­ chalcopyrite, and quartz in pyrite, but barite was rock. The ore is like that of Balaklala. The rite, and other ores were observed, with a larger copyrite, pyrite, pyrrhotite, or magnetite, occurring not observed. region is one of much disturbance, and the ore amount of quartz gangue and some calcite. separately or in aggregates. The pyrrhotite was The ore is occasionally schistose and affected by bodies appear to have suffered greater deformation The Copper City lode has a known length of examined for nickel, but there is none present. small transverse faults. The pyritous ore comes than the adjacent quartz veins. less than one-fourth mile and a width locally up To a very limited extent the ores have been immediately in contact with the bottom of the The Mammoth lode, exposed in the Mammoth to about 5 feet. It was discovered and mined as observed locally disseminated in the adjacent gossan, but in some places is disintegrated, form­ mine, has an apparent course N. 80° E., and has early as 1862, when some of the ore was shipped limestone. The existence of large bodies of mag­ ing a fine, brassy-yellow powder. The Hornet ore been traced less than half a mile. Thus far only to Swansea, Wales, for reduction. Later, mills netite along the contact at the two localities referred body, which forms the north end of the lode and one ore body has been extensively prospected, were erected to work the decomposed material of to above suggests the possibility of the occurrence has been fully prospected but not yet mined, is showing a length of over 300 feet and a depth the zone of oxidation, but when the sulphide of similar bodies of copper -ore, but none have yet perhaps longer than the Iron Mountain ore body, at least 200 feet from the upper gossan croppings. bodies were reached the project failed and mining been found. but is not so thick nor of so high-grade ore. Its On the principal level it dips 30° NW., and cross- Redding. cut tunnels show an extensive development in that augite-diorite. Although not mined, it occurs at rock shipped chiefly to the Keswick smelter. It the upland plain of the Sacramento Valley is for direction, which may be accounted for, in part, at two points in quantities well worth noting. The is used also by the Mammoth smelter, at Kennett. the most part gravelly and in general so dry as to least, by a change to gentler dip. The ore, com­ first is \\ miles southeast of Baird, and the second Exact chemical analyses are not available, but it require irrigation for successful farming. The dry, posed chiefly of pyrite, is locally rich in chalcopy- on the northeast slope of Hirz Mountain, near is said to make excellent lime and to serve well for rocky plains of the Piedmont are sterile, but the rite and carries considerable sphalerite. Quartz is McCloud River. The ore in both cases is chiefly flux. Isolated masses of the limestone south of basalt flows, where decomposed, make good soils. the gangue mineral, but in much of the ore there magnetite, with abundant limonite on the surface. Larkin and east of Newton have been used for Although this quadrangle is richer in limestone is scarcely a trace of it. This lode supplies the At the first locality the material was formerly lime, but they are too far from the railroad to than any other of the same size in.California, these ore for the Mammoth smelter, recently erected at (1901-2) quarried for flux at Bully Hill. The compete with that near Keunett. rocks occur on steep mountain slopes not suited to Kennett. occasional presence of small bands of garnet and agriculture. Irrigation is practiced to a consider­ About a mile northeast of the Mammoth mine traces of other related minerals locally in the mag­ CLAY. able extent, but in a small way by individuals. is the Golinsky, which contains an ore body that netite indicate that it is a contact phenomenon Clays of two sorts, occurring under entirely It is evident, however, that with proper irrigation extends over 150 feet N. 70° E. and to a depth, so similar to that in the Black Diamond region. unlike conditions, have been used in the Red­ the soil would generally be productive, and it is far as known, of not over 100 feet. It is approx­ The ore body has been opened to a width of 40 ding quadrangle. In the copper region clay sel­ gratifying to know that steps are being taken in imately parallel to the Mammoth ore body, and feet without exposing its limits. It appears to vage to the ore bodies is never very abundant, but that direction. though the ore is more variable the two may be be nearly vertical, and its occurrence on the north in some of the upper workings of the Bully Hill WATEE SUPPLY. closely related. Recently the Golinsky has been slope of the hill suggests an ore body of consider­ mine there is enough for local use in the smelter as bonded and extensively prospected by the Trinity able size. According to Mr. J. B. Keating, gen­ lining for converters. Irrigation. The Sacramento, where it enters the Copper Company. eral superintendent at Bully Hill, it contains about Bricks were made several years ago from the Sacramento Valley above Redding, has a large and The Friday and Lowden prospect is a mile 70 per cent of iron, 1 or 2 per cent of insoluble sandy alluvial clay in the flood plain of Sacra­ regular volume of water, even at its lowest stage southwest of the Mammoth and is approximately material, and only a trace of sulphur. mento River several miles south of Redding, where during the dry summer seasons and early autumn, in line with the Balaklala and Golinsky mines. On the northeastern slope of Hirz Mountain the there is a large deposit; and a few miles farther when water is needed for irrigation. Much development in richly impregnated rock has iron ore has a somewhat wider distribution, but down the valley, beyond Clear Creek and near There is an extensive area of land in the north revealed at least one ore body, whose principal this may be due to the gentle dip to the east, Anderson, there is a brickyard in more contin­ end of the Sacramento Valley where the surface dimension, though small, appears to lie N. 40° W., parallel to the slope of the limestone. It has uous operation, which supplies much of the trade streams fail during the dry season and the ground or nearly transverse to the general course of the been prospected by a number of open cuts, and, of the Sacramento Valley. water lies 20 feet or more beneath the surface, so principal deposits of this part of the copper dis­ as in the other case, is generally a contact deposit that irrigation is required for the most successful BUILDING STONE. trict, but nearly parallel to a number of more or on the borders of the limestone and diorite, but in farming. The large supply of water in the Sacra­ less prominent auriferous quartz veins in the places appears to penetrate the diorite. Stone of several varieties has been used locally mento affords the opportunity to meet the demand, vicinity. Some of the ore rich in chalcopyrite In both cases the bodies of magnetic iron ore for structural purposes, but scarcely any is shipped but the river in this vicinity flows in a narrow is very heavy, suggesting the presence of barite, are large, but follow contacts of great irregularity. from the quadrangle. The Chico sandstone from valley 150 feet below the general level, and to which is known thus far to occur locally in at Each contains an element of promise of other ore Sand Flat and from Clear Creek near Texas render the water available for irrigating the higher least one other of the mines in the northern por­ bodies, for at the Black Diamond mine, on the Springs was formerly used for some of the rail­ plains would require works of great magnitude. tion of the district. same contact, the magnetite is associated with chal­ road culverts, and furnished trimmings for several Ar.tesian water. The problem of obtaining arte­ The northernmost openings of the district are copyrite and pyrrhotite. buildings in Redding. It is soft, grayish red or sian water in the north end of the Sacramento Val­ bluish, and is easily worked, but is occasionally ley has not been solved. No deep wells have been near the head of Little Backbone Creek, where the Nonmetalliferous Deposits. Summit mine tunnels show much impregnated marred by mud spots. made, though there are structural features suggest­ rhyolite with included slate and small, indistinctly LIMESTONE. A granodiorite of lively gray color forms a hill ing that some of the ground water of that region banded veins in which chalcopyrite is most prom­ The Redding quadrangle contains a larger at the southwest corner of the quadrangle and is may be under sufficient pressure to bring it to the inent, with smaller amounts of quartz and pyrite. amount of limestone than any other quadrangle locally used to a limited extent for tombstones, surface. This end of the Sacramento Valley is of the same size on our Pacific coast. Three for street curbing in Redding, and for doorsteps. part of a basin which is filled with formations MINOR METALLIFEROUS DEPOSITS. horizons of limestone, Devonian, Carboniferous, The granitic rock weathers gray, with slight dis­ younger-than the Cretaceous. Below is the lone, Chromite. Chromite is mined on Shotgun and Triassic, are shown upon the map. The coloration from the decomposition of the ferromag- overlain by the Tuscan tuff, and this in turn is

Creek, but the serpentine in which it occurs McCloud and Hosselkus limestones have been nesian minerals. It is only 6 miles from the covered by«/ the Reddinsro ogravels, * which form the reaches as far south as Slate Creek, and it is used to a limited extent for lime at a number railroad, with an easy grade, and deserves consid­ surface in the middle portion. The Tuscan tuff not improbable from the trend of the chromite of places, but more extensively for fluxing cop­ eration for any large structure in the northern part and lone, cropping out more or less continuously bodies that some may yet be discovered within per ores at Bully Hill. The average partial of the Sacramento Valley. only around the border of the valley and dipping the northwestern portion of. the Redding quad­ analyses given below were furnished by Mr. The Tuscan tuff stands fire well and, being soft, generally toward the middle portion, form a basin, rangle. At the forks of Shotgun Creek, about Keating, of Bully Hill: is easily hewn to any shape. It is commonly used except toward the south. a mile from the Southern Pacific Railroad, a Analyses of IfvCloud and Hosselkus limestones. for chimneys and fire places, and nTthe vicinity of The lone, owing to the sand and gravel which series of lenticular chromite bodies occurs in a Millville a small church and several smokehouses make up its bulk, is porous and capable of hold­ somewhat indefinite shear zone which is vertical are made of it. The Tuscan tuff is similar to the ing much water entering through the outcropping McCloud. Hosselkus. and courses S. 40° W., through the serpentine. trass of the Rhine Valley, which is so extensively edges. On the other hand, the overlying Tuscan Five bodies, ranging from 200 to 1500 tons each, used in the manufacture of puzzolan cement, and tuff, as shown by the fact that it brings the water connected by more or less distinct vein-like leaders, there appears to be no good reason why it might of the Red Bluff gravels to the surface, though have been mined to a depth of not over 40 feet CaO ...... 52.5 51.0 not be used in the Redding region for the same somewhat porous, is practically impervious to the within a distance of 250 yards. Except for these Fe8 O 3 ) 1.5 1.5 purpose, especially since the necessary lime for water in the lone and may hold it under pressure. leaders the ore masses have nothing in them Ala 0 3 } admixture is abundant. If this be true, deep borings reaching through the resembling vein structure. Generally the ore 2.0 4.0 tuff would tap the water in the lone sands and COAL, separates easily from the serpentine, but in some gravels and allow it to rise in favorable situations, cases it is "frozen" firmly to it. Other parallel The McCloud limestone contains nearly 94 per Traces of coal occur in the lone formation at a possibly as far as the surface. but as yet less productive zones have been found cent of carbonate of lime, while the Hosselkus number of places, but more particularly in sec. 12, Around the northwest corner of the valley, in the same region. A partial analysis by Dr. E. contains less than 93 per cent, but both are good T. 33 N., R. 2 W., about 2 miles southeast of the where Sacramento River enters, the Tuscan tuff T. Alien of an average sample of the chromite for the purposes used. The intrusion of igneous Afterthought mine, where it has been pretty thor­ was worn away and, by affording an outlet, relieved selected in the mine gave the following results: rocks into the McCloud limestone usually makes oughly prospected and found to be of little value. the pressure at all points higher than 500 feet above Cr2 O 3 , 43.87 per cent; FeO, 15.86 per cent (total it more difficult to quarry than the Hosselkus, sea level. To the south, also, the water is not con­ SOILS. iron reckoned as FeO); platinum, gold, and silver, which now supplies the Bully Hill and After­ fined. It may flow to the sea, and, unless the fric­ none. The ore is used for furnace linings, and thought smelters. The cultivated soils of the Redding quadrangle tion of flow is so great as to give rise to pressure, 315 tons were shipped in 1903. The Devonian limestone near Kennett is the are almost wholly alluvial, resulting from stream the ground water of the lone could not reasonably, Iron. Iron ore (magnetite) occurs in the Red­ only one extensively quarried, and furnished the transportation and deposition of fine material on be expected to be under artesian conditions. ding quadrangle at many places on the contact material from which 18,500 barrels of lime were the flood plains, where at least three-fourths of the between the McCloud limestone and the quartz- burned in 1902 at Kennett, besides 3500 tons of farming of the region is carried on. The soil of April, 1905.