hi . ho. m ^ ^LmmLm^^^imi^ STATE OF CALIFORNIA DEPARTMENT OF NATURAL RESOURCES PHYSICAL SCltNCES IIBRARY UC DAVIS \3 GEOLOGY OF THE BLUE LAKE QUADRANGLE CALIFORNIA BULLETIN 148 1950 DIVISION OF MINES FERRY BUILDING, SAN FRANCISCO STATE OF CALIFORNIA EARL WARREN. Governor DEPARTMENT OF NATURAL RESOURCES WARREN T. HANNUM, Director DIVISION OF MINES FERRY BUILDING, SAN FRANCISCO OLAF P. JENKINS, Chief SAN FRANCISCO BULLETIN 148 JULY 1950 GEOLOGY OF THE BLUE LAKE QUADRANGLE CALIFORNIA By GEORGE A. MANNING and BURDETTE A. OGLE LETTER OF TRANSMITTAL To His Excellency The Honorable Earl Warren Governor of the State of California Sir : I have the honor to transmit Bulletin 148, Geology of the Blue Lake Quadrangle, California, prepared under the direction of Olaf P. Jenkins, Chief of the Division of Mines, Department of Natural Resources. The most important part of this report is its accompanying geologic map printed as a lithograph in color. It covers an area of about 250 square miles, located in the north central part of Humboldt County. The authors, George A. Manning and Burdette A. Ogle, prepared the report after mapping the geology of the quadrangle as a project of a research program with the University of California and in connection with graduate study. Much of the area is inaccessible to ordinary travel and is generally unknown to persons in developmental or scientific work. It is hoped that the publication of this new material will stimulate a general interest in this frontier and little known region of California. Respectfully submitted, Warren T. Hannum, Director Department of Natural Resources December 2, 1949 (3) CONTENTS Page ABSTRACT 7 INTRODUCTION 7 ACKNOWLEDGMENTS 9 GEOGRAPHY AND TOPOGRAPHY 9 Accessibility and industry 9 Climate 10 Vegetation 11 Topography 11 GEOMORPHOLOGY 12 PREVIOUS LITERATURE 13 STRATIGRAPHY AND PETROGRAPHY 13 Kerr Ranch schist 13 Franciscan (Upper Jurassic) : 18 Falor formation 22 Anorthoclase trachyte of undetermined age (Tertiary?) 26 Quaternary terrace gravels 26 Alluvium 26 Landslides 26 STRUCTURE 27 Faulting 27 GEOLOGIC AND STRUCTURAL HISTORY 28 ECONOMIC GEOLOGY 29 Barite 29 Chromium 29 Clay 29 Coal (lignite), Maple Creek deposit 29 Copper 29 Limestone 30 Manganese 30 Road metal : 30 BIBLIOGRAPHY 30 INDEX 32 ILLUSTRATIONS Page Figure 1. Index map showing location of Blue Lake quadrangle 8 2. Generalized stratigraphic section, Blue Lake quadrangle 14 Plate ]. Geologic map of the Blue Lake quadrangle, California In pocket la. Economic map of Blue Lake quadrangle, California In pocket 2. Geologic structure sections across Blue Lake quadrangle, California In pocket 3. Redwood Creek Valley from Bald Mountain 16-17 4. An exposure of the Kerr Ranch schist on Bald Mountain 1(5-17 5. Franciscan pillow lava in the quarry at the top of Bald Mountain Ridge -iC^-17 6. Pecten oregonensis Howe var., left valve 16-17 7. Pecten oregonensis Howe var., right valve 16-17 8. A, Mytilus afE. M. middendorfi Grewingk, new species. B, Mytilus edulis Linnaeus var 16-17 9. A, Cardium (Cerastoderma) meekianum Gabb. B, Chione securis Shumard 16-17 10. A, Nassarius moranianus (Martin). B, Gyrineum lewisii Carson 1(>-17 11. A, Muscovite-quartz-albite schist (Kerr Ranch schist) . B, Glaucophane-chlorite-albite schist (Kerr Ranch schist) 16-17 12. A, Serai-schist (Kerr Ranch schist). jB, Quartz-glaucophane-muscovite sfhi.st, Franciscan formation 16-17 13. A, Actinolite-glaucophano-pumpellyite-muscovite-chlorite schist. B, Anorthoclase trachyte, Tertiary ( ?) 16-17 (5) GEOLOGY OF THE BLUE LAKE QUADRANGLE, CALIFORNIA f Bt George A. Manning * AND BURDETTE A. OGLE ** ABSTRACT The Blue Lake quadrangle, Humboldt County, California, is largely in the northern Coast Eanges but its eastern portion lies in the edge of the Klamath Mountain Province. Three formations were mapped. The oldest, the Kerr Ranch schist, is a series of quartz-muscovite schists, green schists and semi-schists, formed by low grade regional metamorphism of sandstones, shales, con- glomerates, cherts, interbedded volcanics and basic and ultra-basic intrusives. These rocks have been but slightly metamorphosed. The forma- tion is pre-Francisean in age and may be equivalent to the Abrams schist of the Klamath Mountains. The Franciscan formation, of Upper Jurassic (Tithonian) age, is in fault contact with the Kerr Eanch schist. Franciscan rocks are pre- dominautl.v dark gray, arkosic sandstones with interbedded volcanics, shales, conglomerates and cherts. Basic and ultra-basic rocks are intrusive into the sediments and volcanics and have locally caused metasomatic alteration. The Franciscan exposed in this area is lithologically similar to the lower part of the Francisean-KnoxA'ille group. The Falor formation, in fault contact with, the Franciscan, is com- posed of fine-grained, buff to gray sandstones, clays and minor con- glomerates. Assemblages totaling forty-five molluscan and echinoid spe- cies indicate that this formation is lower Pliocene to lower middle Plio- cene in age. The area is characterized by complex, repeated faulting. All contacts are along faults. An eastern belt of schist is thrust over Franciscan; an eastern Franciscan belt is thrust from the northeast over a western schist belt; the western schist is thrust, with later possible normal faulting, over the Franciscan ; and the Pliocene sediments occur as a down-dropped block, or blocks, in the Franciscan. Two major periods of faulting are apparent. Pre-Pliocene compressive deformation folded the Franciscan and started the thrusting. Normal faulting started at the end of the Pliocene. The general strike of the beds is northwest ; the Kerr Ranch schist is highly contorted and forms isoclinal folds, while the Falor beds show a homoclinal dip to the northeast. Mineral deposits of economic importance have not been found in this region, and there are but a few minor prospects. INTRODUCTION The Blue Lake quadrangle is located in northwestern California, in the north central part of Humboldt County. The area is bounded by lat. 40°45' on the south, and lat. 41°00' on the north, long. 123°45' on the * Geologist, Standard Oil Company of Texas. ** Lecturer, Department of Geological Sciences, University of California. t Based upon dissertations submitted in partial satisfaction of the requirements for the degree Master of Arts in geology. University of California, Berkeley, 1947. Manuscript submitted for publication June 30, 1947. (7) GEOLOGY OF THE BLUE LAKE QUADRANGLE [BllU. 148 42" rescent City ^ showing location of Blue Lake quadrangle. 1950] GEOGRAPHY AND TOPOGRAPHY 9 east, and long. 124°00' on the west. San Francisco is located about 300 miles to the south and Eureka, on Humboldt Bay, is 15 miles to the west. The quadrangle is named for the town of Blue Lake, which is situated in the west central part of the quadrangle. The area lies partly in the Coast Kanges and partly in the Klamath Mountains. Little is known of the geology of northwestern California, other than that revealed in the reconnaissance mapping of Diller, Hershey, and Lawson in the period, 1894-1911. The paucity of economic deposits and the lack of topographic base maps have retarded more detailed studies in recent years. Blue Lake quadrangle, which the authors used as a base map, was published by the IT. S. Forest Service and Corps of Engineers, U. S. Army in 1943. It has a scale of 1 :62,500 and a contour interval of 50 feet. Aerial photographs, with an approximate scale of 1 inch equals 2,000 feet, were also used by the authors. References to locations in this report apply to the standard grid coordinate system. The quadrangle was mapped in two parts : the northern half by George A. Manning and the southern half by Burdette A. Ogle. This field work was done during the 3 summer months of 1946 and laboratory studies were completed in the spring of 1947. All thin sections and rock specimens are on file at the University of California. References to thin sections are by University of California catalogue numbers. The fossil locality numbers used are those of the ITniversity of California Museum of Paleontology where the material is available for study. ACKNOWLEDGMENTS The writers are indebted to Dr. N. L. Taliaferro for encouragement and helpful guidance in the field work ; to Dr. F. J. Turner for aid in petrography", for continued encouragement and for reading the manu- script ; to Dr. C. M. Gilbert for assistance with mechanical analyses and mineral determinations ; to Dr. Leo Hertlein of the California Academy of Science who was invaluable in identifying the Pliocene fossils ; and to Dr. Howel Williams for his interest and aid. Dr. Harry D. MacGinitie of Humboldt State College encouraged the work and did great service in locating several fossil localities. The writers are grateful to all the landowners in this area, whose cooperation made the field mapping possible. The Northern Redwood Lumber Company, the California Barrel Company, Dr. and Mrs. William J. Kerr, Guy B. Kerr, Myers Gundersen, Mr. and Mrs. George Partout, Mr. and Mrs. Rudy Mora, and Mr. and Mrs. Loftus Grey, were especially helpful. Financial aid from the Research Council of the University of Cali- fornia is gratefully acknowledged. Mrs. B. A. Ogle, a constant source of encouragement, helped collect many of the fossils, and performed the arduous task of preparing the collection for identification. GEOGRAPHY AND TOPOGRAPHY Accessibility and Industry U. S. Highway 299, a good hard-surface, all-weather road, crosses the northern part of the quadrangle in a general east-west direction. 10 GEOLOGY OF THE BLUE LAKE QUADRANGLE [Bull. 148 Another paved road connects Blue Lake and Korbel. All others are graded gravel, graded dirt, or poorly maintained, dry weather dirt roads. Logging roads are abundant, but most of them are temporary and are not shown on the map. The following graded routes are usually fairly well maintained : Korbel to the Carson Ranch, via Bald Mountain ; Korbel to the Wiggins Ranch and from the Wiggins Ranch to the Archibald Ranch ; the road from U. S. 299 to the Redwood Creek Ranch ; the branch going north from Redwood Creek Ranch along Redwood Creek ; and the branch going from Redwood Creek Ranch to the Hoopa Indian Reserva- tion to the northeast. A railroad operates between Korbel and Areata, but at present carries only freight and mail. Many trails made either by man, horse, or deer cover the mountainous areas. Some, such as the Hyampom Trail which connects the Russ Ranch with Hyampom Valley in Trinity County, are maintained by the county. The region is sharply divided into two topographic subdivisions ; the bottom land, represented by the area around Blue Lake and the fertile valley to the west, and the mountains that occupy the rest of the area. The bottom land supports intensive truck farming, dairying, and the growing of grasses and alfalfa. Redwood (Sequoia sempervirens) and Douglas fir forests grow in the mountains and lumbering is tlie principal industry of this area. This industry reached its height 20 to 30 years ago when Korbel, a company town, was booming and a mill at Riverside was operating. Many camps, such as Camp 4 on the Mad River, were in full swing. Small logging rail- road lines operated on both sides of Mad River, and the farming popula- tion in the surrounding area prospered by selling produce to the lumber companies. The mill at Korbel was closed in the 1930 's and has only recently reopened. In the spring of 1947, a mill at the mouth of Boulder Creek was operating and there are many small mills running west of Blue Lake. The redwood timber south of Korbel has now been largely cut and redwood logging at present is confined to the northern part of the area. In the mountains of the central and eastern part of the quad- rangle, there is extensive cutting of Douglas fir and to a lesser extent, yellow pine. Second growth brush has rapidly covered cut over areas and many regions that were large open forests, or even old logging railroad right-of-ways, are now nearly impassable. The cutting of tan oaks for tan-bark is a minor yet important lumbering operation in this area. Cattle and sheep grazing is second in imj^ortance to lumbering in the mountainous area. Several large ranches are operated profitably and many small landowners make a comfortable living. The climate in this upland region is warm and dryer than the bottom land area in summer, and is cold with abundant rain and snow in the winter. Climate The climate is, in general, moist, and the rainfall increases coast- ward. The greatest amount of rainfall occurs from November to May. In the lowland regions and for considerable distances up many of the larger streams, fogs are persistent during the winter and throughout most of the summer months. 1950] GEOGEAPHY AND TOPOGRAPHY 11 An annual rainfall of 100 inches may take place at 4000 feet as com- pared with 40 inches at sea level. U. S. Weather Bureau records ^ show the precipitation at Eureka, from 1887-1937, averaged 39.04 inches per year and the precipitation at China Flat, on the Trinity Kiver in the quadrangle to the east, averaged 43.37 inches for the same period. Both of these areas are below 500 feet elevation. Local inhabitants estimate the average annual precipitation at the eastern Kerr Ranch to have been 90 inches per year, over a period of 30 j^ears. Temperatures in the mountains, above 2000 feet, fall below freezing (10° to 20° F.), for short periods during the winter months and reach as high as 100° F. in the summer. At these higher elevations considerable snow falls during these colder periods. In the western lowland area, the temperature is mild ; the low rarely reaches freezing and the high is never above 80° F. Vegetation Variation in vegetation apparently is controlled more by differences in climate, altitude, and porosity and thickness of the soil cover than by lithologic differences in the bed rock. Grassy areas seem more common on Franciscan rocks, but are not restricted to them. Chemical weathering of all formations in the area yields similar soils. The high humidity and dense vegetation have produced a soil cover that, in many parts of the quadrangle, is 5 to 10 feet thick. Locally, where the rock is more resistant, outcrops stand out. Altitude is an important vegetation control. At the higher elevations around the Snow Camp Mountains, cedars, white fir, yellow pine and sugar pine are common. Below about the 4,000-foot elevation, Douglas fir forests are dominant. Redwood forests, with few exceptions, are confined to the valley of the North Fork of the Mad River. Their presence seems to depend on a deep soil and proximity to the fog belt. Topography The ridges and major streams of the area trend generallj^ northwest. The principal streams, from west to east, are Mad River, North Fork of the Mad River, and Redwood Creek. The Mad River provides water for Eureka, and is used for irrigation on the bottom land. The ridges are nearly continuous. The major ridge lines, from the southwest to the northeast, are Fickle Ridge, Tip Top Ridge, Snow Camp Mountain-Bald Mountain Ridge, Redwood Mountain Ridge, (the ridge east of Redwood Creek), and Indian Field Ridge. These major stream and ridge lines follow the general strike of the structure of the formations in this area. The major streams are chiefly subsequent, but portions of the North Fork of the Mad River, and Mad River appear to be superimposed. The minor streams are generally consequent or obsequent, although many follow lines of weakness produced by small cross faults. ]\Iad River is a mature stream throughout most of this region, but in localities such as that southwest of the Falor Ranch, where it cuts through resistant Franciscan volcanics, the river appears youthful. The North Fork of the Mad River, and Redwood Creek are youthful streams. The 1 U. S. Weatl\er Bureau, Annual reports, California section : 1937. Baker, P. S., Mountain climates of western United States, Ecological Mon., vol. 14, pp. 223-254, April, 1944. 12 GEOLOGY OF THE BLUE LAKE QUADRANGLE [BuU. 148 small streams form a dendritic to sub-trellis drainage pattern. Relief in the area ranges from 1000 feet near Blue Lake to 4625 feet at Snow Camp Mountain. GEOMORPHOLOGY The terrain of the Blue Lake region, as viewed from the higher peaks, shows the following prominent features : 1) Essential parallelism of all the major streams and ridges, not only in this quadrangle, but to the southwest and northeast. East of the Trinity River the drainage pattern is irregular. 2) The nearly even tops of the long parallel ridges and the general similarity of elevation of the major ridges southwest of Redwood Creek. The ridge line to the east of Redwood Creek is higher in elevation. 3) Broad, higher, older valleys and narrow, younger, inner vallej^s of the major streams (Redwood Creek and Mad River) with successive steplike breaks of slope from stream to crest. The flat-topped ridges have been explained as remnants of an old peneplain which has been subsequently elevated. A multistage elevation is shown by the shapes of the valleys. Diller ^ discussed the topographic development of the general region of northwestern California and postu- lated several stages of post-Eocene peneplanation and uplift. The ridge to the northeast of Redwood Creek, according to Diller, is a remnant of the peneplain developed in the Klamath stage which he dated as prob- ably lower Miocene. He also states, ". . . . the divide between Mad River and Redwood Creek is in the Coast Ranges and its flat crest is part of the Bellspring peneplain. ' ' He dated this peneplain as probably mid- Miocene. Lawson,^ in discussing the geomorphology of the northern Coast Ranges, (to the south of this area), mentions "... the develop- ment in Pliocene time of a great coastal peneplain with correlative accu- mulation of of marine sediments, ' ' and with later progressive uplift of this peneplain. The peneplains in this area cannot be dated accurately. The Klam- ath peneplain may be older, but the age is uncertain. The so-called Bell- spring peneplain may have developed in Pliocene time while marine sediments of the Boulder Creek formation were being deposited in a shallow trough. Though the age of some of the events is uncertain, the present fea- tures suggest the following history : 1) Formation of the Klamath peneplain in the eastern part and Bellspring peneplain in the western part of the area. The degree of flat- ness of these peneplains is not evident but they must have been old, or subdued land surfaces. 2) Several uplifts and development of the older broad valleys, the terraces of which indicate that they were cut in at least two cycles. Dur- ing this time Pliocene sediments 'were block-faulted downward. 3) Another uplift, and subsequent erosion, and cutting of the nar- row inner valleys. 2.Diller, J. S., Topographic development of the Klamath Mountains: U. S. Geol. Survey Bull. 196, 1902. 3 Lawson, A. C, The geomorphogeny of the coast of northern California : Univ. California, Dept. Geol. Scl., Bull., vol. 1, pp. 241-271, 1894. 1950] GEOMORPHOLOGY 13 4) Deposition of terrace gravels at elevations of from 50 feet to 350 feet above the present stream bed. This suggests several additional minor uplifts. The ancestral Mad River must have formerly flowed over the soft Pliocene sediments. Meanders developed, then after faulting and subse- quent uplifts and erosion, the river was superimposed on the hard Fran- ciscan rocks in the southern part of the area. The river was then deviated in various directions by the differences in hardness and resistiveness of the many rock types. Mad River, therefore, twists through the resistant Franciscan and only touches the soft Pliocene in several places before it reaches its lower valley. PREVIOUS LITERATURE Diller ^ in 1902 was the first to mention the geology of the area now included in the Blue Lake quadrangle. Near Korbel, he noted the Plio- cene beds along the Mad River, and made several geomorphologic obser- vations. Hershey, in a contemporaneous study of the Klamath Mountains, mentions parts of the quadrangle in several papers. He states that a "... belt of schist, chiefly Abrams mica schist which forms the South Fork Mountains ... is prolonged northwestward to and probably across the Klamath River. The sandstones of the Coast Range region adjoin this schist belt on the west . . . " ^ Hershey ^ later recognized this contact as a fault and proposed the name Redwood Mountain fault. Diller, who first noticed this fault along South Fork Mountain to the south, did not name it. The terraces along Mad River and Redwood Creek have also been mentioned by Hershey.'^ STRATIGRAPHY AND PETROGRAPHY Kerr Ranch Schist® The name Kerr Ranch schist is proposed by the writers for the schists that occur in two belts of nearly identical lithology. The type locality is near the Kerr Ranch in the southeastern part of the quadrangle. The rock types of the Kerr Ranch schist include muscovite-quartz- albite schists, quartz-muscovite schist, semi-schists that contain abun- dant relict sedimentary grains, slates, meta-conglomerates, green schists (actinolite schists, chlorite schists, etc.), meta-cherts, and glaueophane schists. Muscovite-quartz-albite schists comprise about 70 percent of the formation. Typically, these schists are foliated, fine-grained, light- gray to dark-gray rocks with a pearly silky sheen to the foliated surface. Other rock types are green schists of two kinds : 1 ) green platy schists derived from flows, and 2) dark-green hard massive meta-intru- sives composed of metamorphic minerals such as pumpellyite, sphene, chlorite, albite, and with some relict pyroxenes; semi schists (meta- sandstones that show the first slight orientation of the intergranular * Diller, J. S., op. cit. ^ Hershey, O. H., Metamorphic formations of northwestern California : Am. Geol., vol. 27, pp. 225-245, 1901. « Hershey, O. H., Some western Klamath stratigraphy : Am. Jour. Sci., 4th ser., vol. 21, pp. 58-63, 1906. ' Hershey, O. H., Certain river terraces of the Klamath region, California : Am. Jour. Sci., 4th ser., vol. 16, pp. 240-250, 1903. 8 The name "Redwood Creek" schist, used by the authors in unpublished masters' theses, University of California, 1947, and by B. A. Ogle in a talk before the Le Conte Club at Stanford University on December 4, 1948, is replaced by "Kerr Ranch" schist because of prior use of the term "Redwood formation." 14 GEOLOGY OF THE BLUE LAKE QUADRANGLE [Bull. 148 AGE FORMATION COLUMN THIGK- INESS FT DESCRIPTION RECENT TERRACES ALLUVIUM Gravel, sand and silt. PLIOCENE FALOR FORMATION FAULT CONTACT UPPER FRANCI S CAN JURASSIC GROUP 10,000- 12,000 FAULT CONTACT PRE- FRANCISCAN KERR RANCH SCHIST Poorly consolidated marine sandstones, clays^ silts and conglomerates. Contains some fossils and abundant plant debris. Upper 200 feet ore red beds. Dork-colored, well- indurated, orkosic sand stones. Dark- colored stioles. Minor lenses of radiolorian chert, con- glomerate and lime- stone. Basic volconics. Basic and ultra- basic intrusives wtiich have locally con- verted the sediments to gloucophone, chlorite and actinolite schists near their contacts. Quartz-muscovite schists with subordi- nate semi-schists, slates, meto-conglomer- ates, green-schists and meto-cherts. Fig. 2. Generalized stratigraphic section, Blue Lake quadrangle. 1950] STRATIGRAPHY AND PETROGRAPHY 15 micaceous material), glossy dark-gray slates, and metaconglomerates. These schists are products of regional metamorphism of a low grade, equivalent to the green schist facies of Eskola.^'^ A few schists are found whose origin is not clear. These include glaucophane-chlorite-albite, glau- cophane-chlorite-sphene-garnet (relict), and lawsonite-chlorite-albite- talc-aetinolite schists. They outcrop near meta-intrusives and may be the result of some metasomatism. Due to the fine-grained character of these rocks a petrographic examination was necessary for their study. Usually the micaceous schists are highly contorted, banded with alternating quartz-albite and micaceous -(muscovite-chlorite-graphite?) bands, and often veined with quartz. The original rocks from which the Kerr Ranch schists were meta- morphosed include sandstones, shales, chert, volcanics, and basic and ultra-basic intrusives. Muscovite-quartz schist outcrops throughout the eastern belt and over most of the western belt except along Redwood Creek where semi- schists and slates are prevalent. The muscovite-quartz schist does not usually form prominent outcrops except where characterized by a high percentage of quartz which may occur either as granular bands or as veins that cut across the schistosity. StraUgrapliic Correlation. Previously mapped schists in north- western California and southwestern Oregon either do not correspond in grade of metamorphism to the Kerr Ranch schist, are not contiguous, or are poorly defined and described. The authors, therefore, propose the new formation name. No fossils have been found in the formation and any correlation must necessarily be on lithologic similarity, geographic location, or stratigraphic position. In many respects the Kerr Ranch schist resembles the Abrams schist in Trinity County as described and named by 0. H. Hershey.^ His description follows : "It is composed of thin folia of muscovite of dull colors, such as gray, light brown, yellow and dull red, separated by irregular layers of white quartz, representing the original laminae. Throughout it is very highly siliceous and doubtless portions of it would be called a micaceous quartz schist. In certain belts the silica predominates to such an extent as to cause it to outcrop like great veins of very glassy white and dark blue quartz." The Abrams schist, he concludes, "is undoubtedly a highly meta- morphosed sedimentary, ' ' probably of Algonkian age. N. E. A. Hinds,^° in a more recent study of the Klamath region, states that : "The Abrams formation consists for the most part of highly micaceous, white, pale gray, or dark gray schists, generally pink or red on weathered surfaces, and com- posed of colorless or black mica and varying amounts of quartz. In places the mica is green and gives to the rocks a blue-green or dark green color. These schists were appar- ently derived from clays and shales, much of which contained more or less quartz, and from shaly sandstones. These rocks are transitional into micaceous quartzites and pure quartzites, which were originally slightly impure standstone and almost pure quartz sandstone. There are also some beds of highly metamorphosed conglomerate, and numerous lenses of coarsely crystalline limestone and marble. Hornblende schists in zones ranging from a few inches to several hundred feet in thickness are present at many horizons." 8a Eskola, Pentti, Die metamorphen Gesteine, in Barth, T.F.W., Correns, Carl W., and Eskola, Pentti: Die Enstehung der Gesteine, pp. 357-359, Berlin, Julius Springer, 1939. » Hershey, O. H., Metamorphic formations of northwestern California : Am. Geol., vol. 27, pp. 225-245, 1901. 10 Hinds, N. E. A., Geologic formations of Redding, Weaverville district, California : California Div. Mines Rept. 29, pp. 77-122, 1933. 16 GEOLOGY OF THE BLUE LAKE QUADRANGLE [Bull. 148 "Rocks of the Abrams, " Hinds states, "are thoroughly reerystallized so that none of the original sedimentary types remain. . . . The sehistosity in general parallels the original bedding of the sediments so that initial metamorphism was accomplished without much deformation and prob- ably was of the load type." The Abrams, Hinds believes, is definitely pre-Devonian and probably pre-Silurian. Thin sections collected by Hinds have been studied by the authors who conclude that the Abrams rocks range from Eskola's,^^ green-schist facies to the lower part of his amphibolite facies. The schists are crystal- line, some rather coarsely so, and range from platy to nearly granulose in the higher grade amphibolite schists. Typical mineral assemblages are : albite - chlorite - epidote - calcite - quartz, muscovite - biotite - albite - quartz, oligoclase - muscovite - epidote, muscovite - garnet - oligoclase - epidote, and actinolite-oligoclase-garnet. These assemblages represent a higher grade of metamorphism than any observed in the Kerr Ranch schist, in which no brown biotite has been found by the writers. No glaucophane has been reported from the Abrams formation; but it is present in several specimens of the Kerr Ranch schist collected by the writers. Except for these differences the two schists are similar, both have been regionally metamorphosed, and the original rocks were also similar. The original rocks, however, were as much like the present unmetamorphosed Franciscan of the Coast Ranges as they were like one another. In fact, the types represented are common the world over in rocks of widely different ages. Neither of the schist belts within this area have been reported as contiguous with any of the Abrams schists in the vicinity of the Weaver- ville quadrangle or other parts of the Klamath mountains. Hershey ^^ describes the schists of South Fork Mountains to the south as " . . . another belt of schist, chiefly Abrams mica schist, which forms South Fork Mountain and is prolonged northwestward to and probably across the IClamath River near Wichiper (Weitchpec) . The sandstones of the Coast Range Region adjoin this schist belt on the west." Diller ^^ describes these rocks more fully : ". . . The priucipal rock of South Fork Mountain is a gray or greenish-gray, more or less silky, mica-schist in which the mica is sericite. Although in well defined folia and fibres giving the mass a decided schistose structure, the mica is not well crystallized in distinct scales. The quartz is generally in excess of the mica and the mass is full of quartz veins. Another type occurs along lower South Fork Mountain. The rock is greenish, more or less schistose and composed chiefly of quartz aud epidote. The occasional presence of blue hornblende in this rock suggests that it may be the result of contact metamorphism, but the field relations as far as known are not decisive." Hershey ^^ studied the mica schists at Weitchpec and named them the Weitchpec schist. He stated : "The schistose slates of the Paleozoic formations have been converted into dis- tinct micaceous schists. These differ from the more ancient schists of the Abrams for- mation in that the bedding planes are totally destroyed and the texture is finer. The Abrams formation was crystallized by thermo-metamorphism and these Paleozoic schists were altered by shearing. They are strongly developed along the trail between Hoopa Valley and Weitchpec at the mouth of the Trinity River." " Eskola, Pentti, op. ciL ^ Hershey, O. H., Metamorphic formations of northwestern California : Am. Geol., vol. 27, pp. 225-245, 1901. " Diller, J. S., Klamath Mountain section, California : Am. Jour. Sci., 4th ser., vol. 15, pp. 342-362, 1903. "Hershey, O. H., The Bragdon formation in northwestern California: Am. Geol., vol. 33, p. 357,1904. DIVISION OP MINES BULLETIN 148, PLATE 3 REDWOOD CREEK VALLEY FROM BALD MOUNTAIN The flat-topped ridges are remnants of old land surfaces. 2— 34S9 DIVISION OF MINES BULLETIN 148, PLATE 4 AN EXPOSURE OF THE KERR RANCH SCHIST ON BALD MOUNTAIN DIVISIOX OF MINES BULLETIN 14S, PLATE 5 FRANCISCAN PILLOW LAVA IN THE QUARRY AT THE TOP OF BALD MOUNTAIN RIDGE On U. S. Highway 299 (pick handle approximately IS in.). DIVISION OF MINES BULLETIN 148, PLATE 6 PECTEX OREGOXEXSIS HOWE VAR., LEFT VALVE Loc. A4233, No. 1. This specimen resembles P. oregonensis closely, but the left valve has the prominent lamellar frills characteristic of P. dilleri. Dr. Hertlein suggests listing it as a variety of P. orecjonoisis. Howe, (1922), described only the right valve of his P. oreoonensis, and it may be that they have close affinities. The shell is medium sized, of nearly circular outline. It has valves of low convexity, the right valve being moderately arched. Ribs on this specimen total 21 on the right valve, and 18 on the left valve. Ribs on the right valve are square and wider than the interspaces, sometimes showing a medial sulcvis, growth lines are prominent ; on the left valve the ribs are squarish with prominent lamellar frills. Ears are nearly equal in length, practically without scupture : byssal notch moderately deep. Dimensions: altitude, Slmm. ; length, 89mm.; length of hinge, 29min. ; diameter of the two valves, 5inm. DIVISION OF MINES BUI.LETIX 148, PLATE 7 PECTEX OREGOXEXSIS HOWE VAR., RIGHT VALVE Loc. A4233, Xo. 1. 3— 34S9 DIVISION OF .UIXKS BULLETIX 14S, PLATE 8 A, MYTILUS AFF. M. MIDDENDORFI GREWIXGK, NEW SPECIES (NATURAL SIZE) Loc. A4234, No. 3. This specimen may be similar to '•Mytihis condoni Dall" which was mentioned in an early publication of the Nautilus, (1911?), by Dall as occurring in Oregon. No description or figures of '"J/, condoni'' are available : thus the name remains a nonien nudum. It has affinities to J/, midden- dorfi which has been found in Alaska. It differs from other Tertiary and Quarternary species in having plications on the distal portion of the valves. The shell is curved, thick, and the beaks are pointed. Dimensions: length, 54nim. ; width, 22mm. ; diameter of one valve, 19mni. B, MYTILUS EDVLIS LINNAECS VAR. Loc. A4233, No. 2. This specimen appears to be similar to M. ednlis except for the huge size of this variety. All fossils found were of this same general size : thus the appearance of the young of this variety is unknown. 31. edulis is the common mussel found along the Pacific Coast at present and is too well known to need a full description, the concentric undulations and dark color being particularly noted. Dimensions : length, 23omm. ; width, 100mm. ; diameter of both valves, 63nim. DIVISION OF MIXES BULLETIN 14S, PLATE 9 A, CARDIUM (CERASTODERMA) MEEKIANUM GABB (NATURAL size) Loc. A4234. %. B, CHIOKE SECURIS SHUMARD (NATUKAL SIZK) Loc. A4233. DIVISION OF MINES BULLETIN 14S, PLATE 10 A, NASSARIUS MORANIAXUS (MARTIN) (NATURAL SIZE) Loc. A4233. B. GYRINEUM LEWISII CARSON (NATURAL SIZE) Loc. A4233. DIVISION OF MINES BULLETIN 14S, PLATE 11 A, Muscovite-qiiartz-albite schist (Kerr Ranch schist). Note alternating- bands of quartz and muscovite-chlorite- graphite ( ?). Under crossed nicols, x50. B, Glaucophane-chlorite-albite schist (Kerr Ranch schist). Bands of glaiicophane prisms alternate with chlo- rite-graphite ( ?) -albite. Under crossed nicols, x50. DIVISIOX OF MIXES BULLETIN 14S, PLATE 12 -4, Semi-schist (Kerr Ranch schist). Clastic grains of oligociase, quartz, etc. with tiny schistose intergranular flakes of muscovite, chlorite, and carbonaceous material. Under crossed nicols, x50. '.^< ,/ r- B. Quartz-giaucophane-muscovite schist, Franciscan formation. Large prisms of glaucophane, irregular quartz grains and minor magnetite. Under crossed nicols, x50. DIVISION OF MINES BULLETIN 148, PLATE 13 A. Actinolite-glaucophane-pumpellyite-muscovite-chlo- rite schist (Franciscan formation). Note large piunpellyite crystal in center ; other minerals are quartz, and chlorite, actinolite, glaucophane and muscovite in the indistinguish- able background. Ordinary light, x50. B, Anorthoclase trachyte. Tertiary (?). Large pheno- cry.sts of anorthoclase and basaltic hornblende are set in a trachytic groundmass of anorthoclase laths, tiny biotites, amphiboles, ami iron ores. Under crossed nicols, x'>0. 1950] STRATIGRAPHY AND PETROGRAPHY 17 He further states that ' ' the Weitchpec schists resemble the most highly- metamorphosed Calaveras schists. ' ' In 1911, Hershey ^^ on a reconnaissance map of Del Norte County and a small portion of northern Humboldt County, shows the Weitchpec schists in contact with the Franciscan on the west along the Redwood Mountain fault. He had earlier described the Redwood Mountain fault as the thrust fault running from South Fork Mountain along Redwood Mountain and extending northward to the Klamath River. To the east he shows a belt of serpentine and metagabbro, then a belt of the Galice formation (slates) equivalent to Mariposa, Upper Jurassic. The Weitch- pec schists, Hershej^ concludes, are mainly highly metamorphosed por- tions of the Galice formation. Maxson ^^ in mapping the northern and central part of Del Norte County notes quartz mica schist and implies it is equivalent to the Abrams schist. Herghey mapped the same formation in 1911 as Weitchpec schist. Maxson 's description noted that : " . . . quartz mica schist is subordinate to interbedded phyllite and slate," and that "the formation represents a dynamometamorphosed series of shales and argillaceous sandstones. ' ' Diller, in 1903, described and named the Colebrooke schist. ^'^ His description follows : "The rocks are in part mica-schists intermingled with slates in which the cleavage is highly developed but without definite crystalline structure visible to the unaided eye. The rocks are always fine grained, with decided schistose structure, and where most highly metamorphosed have much fine silky mica (sericite) on the foliated surface, so that they may be more definitely designated sericite-schists, or phyllites. They are much folded and crumpled. The schistose structure varies a great deal in direction, but the strike usually lies between north and west, with a vertical dip. On the .south end of Brushy Bald Mountain the phyllite is so fine that its micaceous nature can be dis- covered only under the microscope. It looks in places like roofing slate and is composed chiefly of sericite and quartz, the former containing a multitude of minute rutile needles. Farther north on Brushy Bald Mountain it becomes coarser and fragmental, indicating its origin in sedimentary rocks. Quartz is the chief constituent, but there is some plagioclase feldspar and much sericite. On the summit of Brushy Bald Mountain the schist is coarser and the schistosity is so wavy as to apparently give a rough fibrous structure to the mass. Fine granular quartz largely predominates over the sericite which marks the structure, and is most prominent on the cleavage faces. . . . On Lobster Creek, a few miles below the trail crossing, black glossy slates (phyllites) are common. They contain much sericite, with fine granular quartz, and a large amount of dark carbonaceous matter which gives color to the mass. They are decidedly crumpled, giving the cleavage face a decidedly wavy profile. The rocks contain many small veins of quartz, which on weathering yield numerous fragments of quartz, to the soil. As to the geologic age of these rocks, we have no decisive evidence in the Port Orford Quadrangle, except that they are pre-Cretaceous. Elsewhere in the Klamath Mountains, however, there is evidence that the Colebrooke schist is possibly of pre- Devonian age." This quotation is given because it describes rocks that are similar to the Kerr Ranch schist. From the foregoing descriptions, it is apparent that the earlier writers believed that the schists in the western Klamath Mountains were of a lower metamorphic grade than the eastern type section of Abrams schists. Hershey believed that the degree of metamorphism was an indi- cation of age, and stated that the Abrams schist was probably Algon- 15 Hershey, O. H., Del Norte County geology : Min. Sci. Press, vol. 102, p. 468, 1911. w Maxson, J. H., Economic geology of portions of Del Norte and Siskiyou Counties, northwestern California: California Jour. Mines and Geology, vol. 29, nos. 1, 2, pp. 123- 160, January and April, 1933. " Diller, J. S., U. S. Geol. Survey Geol. Atlas, Port Orford folio, (no. 89), 1903. 4 — 3489 18 GEOLOGY OF THE BLUE LAKE QUADRANGLE [Bllll. 148 kian/^ and later thought the Weitehpec schist Avas Galice age (Upper Jurassic) . Though Diller 's description of the schists indicates a low grade metamorphism he followed Hershey's original designation and included them in the Abrams. Hershey believed the Redwood Mountain fault separated Francis- can on the west from schist on the east in the area from South Fork Moun- tain to southern Del Norte County. The schist, therefore, by his descrip- tion, would be Algonkian at South Fork Mountain ^^ and Upper Jurassic at Weitehpec.-^ Hershey 's papers were often written while in the field and he was probably unable to check his previously published statements. The writers believe that this belt of schist, east of the Redwood Moun- tain fault, may be continuous from South Fork Mountain to at least south- ern Del Norte County and possibly farther north. Large gaps between South Fork Mountain, the Blue Lake quadrangle, and the Weitehpec locality together with the confused state of nomenclature seems to neces- sitate the introduction of the name Kerr Ranch schist. Future work may prove either that all of the northwestern California-southwestern Oregon mica schists are the same formation with varying degrees of metamor- phism, or that there are several formations of different ages which have been metamorphosed to somewhat similar grades. The writers conclude that the Kerr Ranch schist must be older than the Franciscan, an opinion based on the lack of regional metamorphic effects in the Franciscan and absence of gradational contacts between the rock types of the two formations. If the Kerr Ranch is a lower grade equivalent of the Abrams, it is pre-Devonian. Franciscan (Upper Jurassic) The Franciscan, long a subject of controversy, has been variously placed anywhere from Permian to Cretaceous in age. Taliaferro has placed the Franciscan and the overlying Knoxville in the uppermost Upper Jurassic ^^ and has related the Franciscan to other Jurassic forma- tions of California and Oregon.-- He has treated the Franciscan and Knoxville as lithologic units, and has found that the Knoxville of any area always lies above the Franciscan of that same area but that it may be contemporaneous with a part of the upper Franciscan elsewhere. A Franciscan designation has been given the rocks west and east of the Pliocene sediments, and between the two belts of Kerr Ranch schist. These rocks are lithologically similar to each other and to Franciscan rocks of other parts of the state. All contacts between this formation and either the Falor formation or the Kerr Ranch schist are faults. The Kerr Ranch schist has been regionally metamorphosed, while the Franciscan rocks are unmetamorphosed except for pronounced compaction, local strong deformation, and some metasomatism. There is no evidence of a a gradation from normal Franciscan sediments to Kerr Ranch schist. No fossils were found in the Franciscan of Blue Lake quadrangle. Dr. H. D. MacGinitie of Humboldt State College, however, has found a 18 Her.shey, O. H., Metamorphic formations of northwestern California : Am. Geol., vol. 27, pp. 225-245, 1901. 1" Hershey, O. H., Metamorphic formations of northwestern California: Am. Geol., vol. 27, pp. 225-245, 1901. 2u Hershey, O. H., Del Norte Coimty geology: Min. and Sci. Press, vol. 102, p. 468, 1911. =1 Taliaferro, N. L., The Franciscan-Knoxville problem: Am. Assoc. Petroleum Geolofjists Bull., vol. 27, pt. 1, pp. 109-219, 1943. 22 Taliaferro, N. L., Geologic correlation of the Jurassic of southwestern Oregon and California : Geol. Soc. America Bull., vol. 53, pp. 71-112, 19 42. 1950] STRATIORAPIIY AND PETROGRAPHY 19 f ossilif erous limestone in a belt of Franciscan rocks in the Trinidad qnad- rangle. This belt of Franciscan can be traced into the Blue Lake quadran- gle. The most distinctive species in this limestone is Aucella pioche, a Tithonian (Upper Jurassic) form common in the Knoxville. It is prob- able that this form is also characteristic well down into the Franciscan. Taliaferro -^ described four stages of the Franciscan-Knoxville group, based mainly on varying conditions of depositions and igneous activity. Franciscan of the Blue Lake area, consists principally of sand- stones with minor shales and some basaltic flows and plugs. This lithology corresponds most closelj' with all of the first and part of the second stage (lower Franciscan, and lower upper Franciscan) as recognized by Talia- ferro. The thickness of the Franciscan, though not measured accurately because of the lack of exposures, probably exceeds 12,000 feet in the western part of the area. The Franciscan of the Blue Lake quadrangle is composed of arkosic sandstones (including graywackes), dark sandy shales, dark-gray clay shales, pebbly conglomerates, dark-gray limestone (very minor), red, green and gray chert, pillow lavas, vesicular basalts, minor agglomerates, and tuffs. These are intruded by basaltic plugs, ultra-basic intrusives, (often converted into serpentine), and gabbroic intrusives. Associated with the ultra-basic intrusives are the products of metasomatism -. glauco- phane and actinolite schists, and in some cases the steatitization of the intrusives themselves. Sandstone. This is the predominate rock type, composing well over 50 percent of the formation. It is a massive, dark greenish gray to dark gray, arkosic sandstone or graywacke which weathers to light gray, red- dish brown or buff. This rock is composed of fine to coarse, angular to subangular grains. It is usually very hard, well indurated and well cemented with a siliceous or, less commonly, calcareous or argillaceous cement. Dark-gray shale fragments, some of which are quite large, are common. These shale particles are largely responsible for the dark color of the sandstone. Volcanic material is locally sufficiently abundant to pro- duce a tuffaceous sandstone or sandy tuff. Thin section studies and mechanical analysis of a series of grab sam- ples indicate that the sandstone, in general, is composed of 85 to 90 percent light minerals and 1 to 2 percent heavy minerals, the remainder being rock fragments. The lights are about 50 percent quartz, 45 percent feldspar and 5 percent museovite. Most of the feldspars are too badly sericitized to determine. Those identified range from intermediate oligo- clase to intermediate andesine with some microcline. Sericitization is considerably more extensive than in most specimens of Franciscan the writers have seen from other areas. Of the heavy minerals apatite, biotite, chlorite, epidote, hornblende and iron ores are the most abundant, tourmaline is less common, and allanite ( ?) and brookite are rare. The rock fragments are volcanics, chert, and shale. No Kerr Ranch schist fragments could be definitely recognized. A very light gray to white, fine-grained arkosic sandstone inter- bedded with thin, dark-gray, slaty shale occurs near the Christie Ranch. Some of these rocks have dark laminae parallel with the bedding; these 23 Taliaferro, N. L.., The Franci.«can-Knoxville problem : Am. Assoc. Petroleum Geologists Bull., vol. 27, pt. 1, pp. 109-219, 1943. 20 GEOLOGY OF THE BLUE LAKE QUADRANGLE [BuU. 148 are very small compared with the white layers. The dark laminae are formed by concentrations of biotite and other ferromagnesian minerals. There are no shale chips or volcanic debris in these sandstones. These sandstones have angular to sub-angular fragments, are fairly well sorted and are hard, compact, and well cemented. They commonly weather to a buff or light brown, and are more resistant than the gray- green sandstone. The white sandstones are locally interbedded with cherts, and are underlain and overlain by the gray-green sandstone. Taliaferro ^^ states that the Franciscan sediments were derived from a high, rugged landmass under rigorous climatic conditions and were deposited in shallow marine waters in a slowly sinking basin. The sediments, he believes, were carried down by great rivers with high gradients. He also states that the source of most of the detritus was a land mass to the west which contained granodiorite, crystalline schists, quartz- ites, re-crystallized chert, and much intrusive quartz-feldspar porphyry. Part of the Franciscan debris is reworked Franciscan locally upwarped at the borders of the geosyncline. Nothing to dispute Taliaferro 's general concept was found in the Blue Lake quadrangle. Some of the material, however, may have come from Kerr Ranch or Abrams schist, granodio- rites or slates of the Klamath Mountains. A quartz-albite schist may have been a source rock of the white sandstone. The volcanic debris in the tuffaceous varieties indicates contemporaneous volcanism. Conglomerates. These, though not plentiful, are widespread as com- paratively thin lenses that apparently occur throughout the section. Conglomerates seem to be more extensive in the most easterly belt of Franciscan. In the northeast corner of the area, along the Horse Moun- tain road, striking bold outcrops of fine grit to pebble conglomerates grade into coarse sandstones. The pebbles are similar in all exposures. The most abundant pebbles are pink to gray to white quartzites, black cherts, and quartz porphyries; minor types are old volcanics, granitic rocks, quartz, and limestone. The fragments range in size from grits to small cobbles, with diameters of about ^-1 inch the most abundant. They are sub-angular to angular, and occasionally well-rounded. None seem to have been derived from the Kerr Ranch schist or other schists. These foliated and micaceous formations, however, disintegrate into small frag- ments which would only be noticed in the finer sediments. Shales. The shales interbedded with sandstones are dark gray or dark brown and weather buff or gray ; some of the shales are interbedded with chert and are either green or red. They are quite hard and are locally slaty. Composition ranges from fine clay to rather coarse silts, the more silty shales being most common. Near chert or limestone lenses they may be siliceous or limy. Carbonized plant fragments are plentiful but they are too small and poorly preserved to identify. The distribution of these shales is wide but their relative percentage is small. They occur mainly as occasional thin beds in the massive sand- stone. Where interbedded with the white sandstone, as in exposures along Mad River and near Christie Ranch, they form an appreciable percent- age of the section. Cherts. Cherts are not abundant. There are red, very pale green, and some variegated yellow, green, and red types. Usually the cherts occur in beds an inch or two in thickness and are interbedded with thin -* Taliaferro, H. L., The Franciscan-Knoxville problem : Am. Assoc. Petroleum Geolog-ists Bull., vol. 27, pt. 1, pp. 109-219, 1943. 1950] STRATIGRAPHY AXD PETROGRAPHY 21 red or green shales. Lensing is common and the beds are often quite con- torted. Quartz veins produce a network of welts on the cleaved surfaces of many of the cherts. ]\Ianganiferous cherts a few feet in thickness, occur locally along Fickle Ridge. Radiolaria are a minor constituent of both the red and green cherts. The petrography' and origin of chert have been discussed by Davis -^ and Taliaferro.^^ Limestone. A few very small lenses of thoroughly recrystallized, hard, dense, dark gray limestone occur in the Franciscan. Volcanics. Volcanics are next to sandstones in the order of abun- dance. They include pillow basalts, vesicular (often amygdaloidal) basalts, spilitic basalts, tuffs that contain an appreciable amount of clastic materials, some rocks that are probably altered olivine basalts, and some andesites. The feldspars are usually too badly altered for accurate identification. The most common type is the vesicular basalt. It is deep greenish- black and highly fractured ; all fracture surfaces weather to a purplish- red brown. The individual fragments are very hard and angular. This rock commonly is amygdaloidal, the amj^gdules consisting of chlorite, quartz, and calcite. The rocks classed as tuffs are interbedded with normal clastic sand- stones, and in all cases contain up to 10 per cent clastic grains. They grade into the tuffaceous sandstones. Microscopic examination of a typi- cal thin section of tuff reveals a heterogeneous assortment of tiny plagio- clase laths, large well-formed plagioelase crystals, volcanic rock frag- ments, and sand grains of quartz, feldspar, and opaque minerals. Irregular masses of chlorite are abundant throughout the rock and there is some sphene and ilmenite-leucoxene. There are many quartz and cal- cite veins, and some openings filled with chlorite, quartz, and calcite. The plagioelase is altered but appears to range from oligoclase to andesine. Basic and Ultra-Basic Intrusives. Throughout the Franciscan in this area there are numerous basic and ultra-basic intrusives that appear to be mostly plugs and dike-like bodies. Near the Beckstine Ranch, at peak 1706, and near Canon Creek these intrusives form prominent bold outcrops and often stand as great pillar rocks above the surrounding countryside. The intrusives range in composition from basic basalt plugs, through gabbroie types to serpentinized ultra-basics. Many have been metamorphosed. In some cases, as at peak 1706, the serpentine and gabbro are closely associated and apparently have no sharp boundary. The writers believe the gabbro is a differentiation product. Gabbroie bodies were not seen cutting the ultra-basics. xVlong the west contact of the eastern belt of Franciscan with the Kerr Ranch schist several intrusives appear to be part of the schist formation, and are mapped as such. They may be altered Franciscan ultra-basics, however. From evidence in other parts of California, Taliaferro ^^ has shown that similar intrusives were confined to late Upper Jurassic. -^ Davis, E. F., Radiolarian cherts of the Franciscan group : Univ. California, Dept. CJeol. Sci., Bull., vol. 2, pp. 235-432, 191S. 2« Taliaferro, X. L., Relation of volcanism to diatomaceous and associated siliceous sediments : Univ. California, Dept. Geol. Sci., Bull., vol. 23, pp. 4S-49, 1933. -' Taliaferro, N. L., The Franciscan-Knoxville problem : Am. Assoc. Petroleum Geologists Bull., vol. 27, pt. 1, pp. 109-219, 1943. 5 — 3489 22 GEOLOGY OF THE BLUE LAKE QUADRANGLE [Bull. 148 Schists. In the following section the term schist includes metamor- phosed rocks which do not have a schistose structure but which are com- posed of metamorphic minerals. None of these rocks is extensivelj^ exposed and all seem to have been affected by metasomatism. Ultra-basic igneous rocks are closely associated with each, a condition common in the glauco- phane schists of California. Fluids causing metasomatism probably originate in the late magmatic emanations of the ultra-basic magmas. Taliaferro ^^ has discussed the formation of these schists. They are inter- bedded or associated with unmetamorphosed sediments and igneous rocks, and all the metamorphic minerals are low temperature, low pressure types that fall within the green-schist facies. Some rocks have been locally sheared. Minerals in the schists include actinolite, albite, relict grains of stilpnomelane, augite, chlorite, chloromelanite, clinozoisite, epidote, glaucophane, muscovite, quartz, pumpellyite, talc, and zoisite. Falor^ Formation The name Falor formation is proposed for Pliocene beds composed of poorly cemented gray to buff sandstone, gray to tan clay, lenticular limestone, thin red beds, and pebbly conglomerate. The type locality is the section along Maple Creek near the Falor Ranch (733.5-2039.0). It is exposed in an area that extends from near Blue Lake, along the eastern slopes of the Mad Eiver basin, south through the Falor Ranch to the southern border of the quadrangle near Boulder Creek where it continues to the south. Along Boulder Creek, near the Wiggins Ranch, this forma- tion contains an abundant molluscan fauna. The beds are marine with the possible exception of the upper 200 feet of red-brown clays and gravels exposed northwest of Korbel; these may be continental. The clays, sandstones, and conglomerates lense rapidly and grade into each other, and no members were mapped. The sandstones are characteristically fine-grained, usually gray to buff, poorly cemented and compacted, and well sorted. Size analyses indicate that approximately 70 percent of the grains have diameters between ^ mm. and j"^ mm. Cementing material is dominantly argilla- ceous, but calcareous cement is also common. Plagioclase commonly composes 60 percent of the light minerals, but quartz, orthoclase, and chlorite are also present. The hea^^y mineral percentage varies greatly ; the most abundant are hornblende, actinolite, tremolite, epidote, sphene and magnetite. Ilmenite-leucoxene, augite, clinozoisite, garnet, rutile, hypersthene, zircon, zoisite, tourmaline, glau- cophane and basaltic hornblende were also identified. Faunal evidence indicates that these beds are equivalent to a part of the Wildcat Series as described by Lawson.^^ The type section is located near Ferndale about 30 miles to the southwest. The portion of the Wildcat to which these beds are equivalent has not been definitely deter- mined. Hertlein believes the fauna most resembles that of the upper Wildcat as described by Martin.^^ Hertlein believes further that the 28 Taliaferro, N. L., The Franciscan-Knoxville problem : Am. Assoc. Petroleum Geologists Bull., vol. 27, pt. 1, pp. 109-219, 1943. 2» The name "Boulder Creek" formation, used by the authors in unpublished masters' theses, University of California, 1947, is replaced by "Falor" formation because of prior use of the term "Boulder formation." ™ Lawson, A. C, The geomorphogeny of the coast of northern California: Univ. California, Dept. Geol. Sci., Bull., vol. 1, pp. 241-271, 1894. ^ Martin, Bruce, Descriptions of new species of fossil mollusca from the later marine Neocene of California : Univ. California, Dept Geol. Sci., Bull., vol. 8, pp. 181-202, 1914. 1950] STRATIGRAPHY AND PETROGRAPHY 23 Falor beds are probably upper 'lower Pliocene and extend into lower middle Pliocene. Faunal similarities also indicate a correlation with part of the Empire formation near Coos Bay, and part of the Merced near San Francisco Bay. The contacts with the Franciscan on both sides of the formation are along faults, thus it is difficult to tell how much of the section has been faulted out. The beds have a fairly constant strike of approximately N. 40° W., and dip homoclinally about 20° to the northeast. A section measured near Maple Creek shows an exposed thickness of 2000 feet ; a section measured from map coordinates 731-2042.5 to 732.5-2043.5 32 shows a thickness of 2460 feet. The section north of Korbel is only about 750 feet thick. A faunal assemblage of 44 species was collected in this formation. Four localities yielded recognizable species. Unidentifiable broken shell fragments and soft crumbly shells occur in many other localities. Most of the fossils collected were found in limey concretionary portions of a fine-grained, poorly compacted and cemented, buff to gray arkosic sand- stone. The formation is not fossiliferous throughout, and faulting has made the localities difficult to locate stratigraphically. Not enough forms were found at each locality to allow zoning of the beds. The fossils in the following assemblages are listed by localities and were determined by Dr. Leo G. Hertlein and B. A. Ogle : Locality A4233 : near the bridge crossing Boulder Creek, adjacent to the Wiggins Ranch, (approximately 739.3-2036.2). The fossils are found in the stream banks for a distance of 300 yards along Boulder Creek. Part of this locality has since been submerged in a mill pond. Echinoidea Anorthoscutum oregonense quaylei Grant and Hertlein Pelecypoda Anadara trilineata (Conrad) Cardium (Cerastoderma) meekianum Gabb Chione securis (Shumard) Hinnites sp. Macoma sp. Mytilus edulis, new variety Panope generosa Gould Pecten caurinus Gould oregonensis Howe var. sp. Schizothaerus nuttallii (Conrad) Solen sicarius Gould Spisula albaria (Conrad) brevirostrata Packard catilliformis Conrad voyi (Gabb) sp. Yoldia scissurata var. strigata Dall Gastropoda Calyptraea mamillaris Broderip Crepidula princeps Conrad Gyrineum Icwisii Carson Nassarius moranianus (Martin) Natica russa Gould Neptunea eurekaensis (Martin) recur va Gabb Olivella biplicata (Sowerby) Turris perversa (Gabb) 32 See plate 1. 24 GEOLOGY OF THE BLUE LAKE QUADRANGLE [Bull. 148 Cirripedia Balaiiiis cf. B. tiutinnabiiliim var. coosensis Dall Locality A4234, on the Mad Kiver road, near the mouth of Cauou Creek. The fossils are in high, vertical, sandstone bluffs. (729-2045.3). Pelecypoda Cardium (Cerastoderma) coosense Dall (Cerastoderma) meekiauum Gabb (Clinocardium) nuttallii Conrad Luciua cf. excavata Carpenter Macoma astori Dall inquinata (Deshayes) uasuta (Conrad) secta (Conrad) Mya japonica Jay Mytilus highoohiae Mandra Sanguinolaria nuttallii Conrad Saxidomus uuttalli Conrad Semele cf. S. sylviaensis Weaver Thracia sp. Locality A4235, on a tributary of Boulder Creek, (736.6-2035.7), Pelecypoda Scliizothaerus nuttallii (Conrad) Gastropoda Thais lamellosa (Gmelin) ostrina (Gould) Locality A4236, along road to Garner Ranch, at (731.2-2044). Pelecypoda Macoma inquinata (Deshayes) All of these forms have been previously described or figured except Pecten oregonensis Howe var., Mytilus edulis new variety, and Mytilus new species, t The environment ranges from depths of about 50 fathoms to shore- line conditions. Hertlein states,^^ ' ' This is a cool water fauna similar to that living off the coast of Humboldt County today. ' ' He further states, "These are shallow water forms that probably lived in an embayment which was fairly open to the sea. There are no great number of bay forms and no brackish water forms to indicate estuarine conditions. Instead, the fauna indicates that marine conditions existed. ' ' Plant remains occur in mau}^ of the sandstones and clays. These are usually small fragments, poorly preserved, which, according to H. D. MacGinitie, and R. W. Chaney are unidentifiable. Small conifer cones tentatively identified by MacGinitie as spruce cones ^"* were found on Maple Creek Road near B.M. 999. Fairly well preserved leaves in poorly fissile clayey shales were found east of the post office at Korbel. At 732.7- 2040.2, on Mad River, are abundant chunks of carbonized wood imbedded in the gray claj' beds. Some of these are 4 feet long and 2 feet in diameter, and some have the appearance of being stumps which include part of the larger roots. "Where exposed to weathering, the outer surfaces are friable. On a fresh-broken surface, the wood is a glittering black, with a suggestion of wood growth rings. Lignite from a small abandoned coal mine on Maple Creek near B.M. 456 is reported to have commonly had wood structure. Many freshly exposed claj^s and silts in this formation t Ed. note : Since this paper was written, Mytilus n. sp. has been described as Mytilus highoohiae by York T. Mandra in J. Paleontology, January, 1949. ■^ Hertlein, Leo, Oral communication, March, 1947. 31 MacGinitie, H. D., Oral communication, July, 1946. 1950] STRATIGRAPHY AND PETROGRAPHY 25 have a characteristic fetid, swampy odor. The abundant plant remains suggest a rapid, near-shore deposition and a moist climate. The greater part of this formation is marine, but the upper portion, best exposed north of Korbel, may be in part continental. The basin of deposition must have been relatively narrow and long. It was fairly shallow, though deep and wide enough at the open sea end to support typical marine instead of estuarine life. Conglomerates are less abundant than either clays or sandstones. They usually occur as thin lenses and beds but near 735.5-2037.2 they reach thicknesses of from 30 to 50 feet and grade into interbedded pebbly sandstone. These conglomerates are usually well cemented and resistant. The conglomerate pebbles are set in a matrix of fine-grained buff sand- stone. Most of the conglomerate material is of pebble size but some range to cobbles and boulders. The pebbles are poorly sorted and sub-angular to sub-rounded. The average pebble is about .5 to 1 inch in diameter. Franciscan debris, the most abundant material, includes, in order of abundance, sandstone, red chert, basalt, dark-green serpentine, and green chert. Pebbles of Kerr Kanch muscovite-quartz schist follow the Fran- ciscan sandstone and chert in relative abundance. Minor constituents include well-rounded pebbles of quartz porphyr}'-, black quartzite, white quartzite and dark igneous rocks, probably reworked from the Fran- ciscan. At 733-2040.2 the mica schist is the most common pebble, in con- trast to all other locations noted. At fossil locality A-4235, some of the fossils are in pebble conglomerate. The conglomerates must have been deposited in a shallow water environment. The local variation of grade and material is probably due to deposition from different drainage sources into a somewhat restricted basin. The clays, second in abundance to the sand.stones, are light graj^ to buff and grade to fine siltstones. Only locally, where filled with abun- dant leafy remains, are they shaly. They are interbedded and lens into the sandstones. A mineral and chemical analysis of these clays should be made to investigate possible economic use. The continental beds are well exposed northwest of Korbel along U. S. Highway 299, but elsewhere their extent is concealed by dense vegetation and terrace gravels. They are composed of reddish-brown soft clays, poorly sorted "rotten" pebble conglomerates, and small lenses of reddish silt-stones. Sorting is poor and all rock types grade into each other rapidly. They may be as thick as 200 feet and are stratigraphically higher than the definite marine beds to the south. No evidence of conti- nental origin has been found. The source of the sediments is certainly fairly local. The pebbles and sand minerals suggest that the Franciscan formation and Kerr Eanch schist were the principal source rocks. The altered feldspars and the floral remains indicate a moist seasonal climate similar to that of coastal Humboldt County today. Chemical weathering Avas probably pronounced. The fine-grained material suggests an area of moderately low relief. Sedimentation must have been rapid to preserve the plant remains. These sediments probabl.v had their source in positive areas both to the northeast and southwest. Local differences in deposi- tional conditions favored rapid lateral variation of the sediments. Many of the clays were possibly laid down as shallow nuid flats in which stumps of trees were buried. Finally, there may have been a gradual recession of the sea in the northwestern part of the basin, possibly due to a slight uplift, followed by continental deposition. 26 GEOLOGY OF THE BLUE LAKE QUADRANGLE [Bull. 148 Anorthoclase Trachyte of Undetermined Age (Tertiary?) A pale buff to nearly white porphyritic anorthoclase trachyte is exposed in a single, small outcrop in the northwestern part of the area at 723.5-2048.4. To the west, in the Eureka Quadrangle, this rock forms several prominent knobs, on one of which it has been quarried for fills and road metal. The shape of the outcrop suggests a plug-like intrusive into Franciscan rocks. It apparenth^ does not cut the Falor beds at the one locality where the two are in contact. The rock is much fresher and less fractured than typical Franciscan volcanic rocks, and no rocks of this type have been described from the Franciscan. A pre-Pliocene and post-Franciscan age is probable. Emplacement was possibly contempo- raneous with Miocene volcanism of the Coast Eanges farther south. In the hand specimen, the rock is buff to nearly white, has pheno- crysts of feldspar and amphibole as large as eight mm. in length, is hard, rough to the touch, and has some tiny openings. Microscopic examination reveals abundant anorthoclase and minor basaltic hornblende phenocrysts that average about one mm. in diameter. These are set in an intergranular groundmass of small feldspar laths, and tiny biotite and amphibole crystals. Anorthoclase phenocrysts which compose approximately 85 percent of the rocks, often show a faint ghost twinning and some zoning. Quaternary Terrace Gravels Terrace gravels have been deposited at several levels along Mad River, Maple Creek, Boulder Creek and to a lesser degree along Redwood Creek. They are usually unsorted gravels, sands, boulders and finer debris. They range in thickness from a few feet to as much as 50 feet. Their most striking occurrence is along the Pacific Gas and Electric Company power line, east of Christie Ranch. Here, between Mad River and Maple Creek, there are three principal terrace levels: two on the ]\Iad River slope, one at the crest of the small divide, and two corre- sponding ones on the Maple Creek slope. The lowest level is 100 feet above the stream, the second is 150 feet, and the crest terrace is 300 feet. The age of these terrace gravels is indeterminate ; but they are fairly flat, lying over all older rocks and post-date the faulting. Alluvium The only alluvium, mapped as such, is the stream bed material. The present channel of the Mad River is about 10 feet below the general land surface. Many of the streams, especially Mad River, have broad gravel and sand covered stream channels which are filled only during exceed- ingly high water. Landslides Landslides, though not mapped, are common. Franciscan rocks, especially serpentine areas, are commonly slumped. Along the steeper parts of Redwood Creek Canyon, there are many slides of Kerr Ranch schist. Water soaked clays and soft sands of the Falor formation give way readily and produce great slumps and slides, an example of which occurs north of the Falor Ranch. 1950] STRUCTURE 27 STRUCTURE This region is characterized by a complex fault sj^stem and strong, early folding. The metamorphic rocks of the Kerr Ranch schist show the evidence of strong directed stress, but structures are difficult to detect. Along Redwood Creek the principal schistosity parallels the original bed- ding. Elsewhere the attitudes were taken on what seemed to be the prin- cipal plane of schistosity and the relation of original bedding to present schistosity was not determined. Two steep-flanked anticlinal structures in the schist, one along Redwood Creek, and one running through High Prairie, have been mapped. Other folds could not be delineated due to poor exposures. However, it is possible that isoclinal folding may char- acterize structure in the Kerr Ranch schist. The Franciscan rocks have been folded and faulted, probably in several cycles ; dips and strikes often vary widely in local areas. Part of the local contortions are due to faulting, and part are probably due to folding of sediments against more rigid intrusives which act as buttresses. Though accurate attitudes were difficult to obtain, the central belt seems to be a large syncline, and the eastern belt apparently is the eastern limb of a faulted anticline. Kerr Ranch schist forms the upwarped core of this structure. The Falor formation has been down-faulted and uniformly tilted to the northeast with a dip of from 15° to 20°. Locally, near faults, this general attitude is changed. Faulting Seven major faults occur in this area. In some places their traces have been offset by cross faulting. The normal faults, from west to east, are the Falor, Blue Lake, Crawford and Korbel faults. These bound down-dropped blocks of the Falor formation. The Bald Mountain fault probably was originally a thrust along which there has been later move- ment. The Crogan fault thrusts Franciscan westward over Kerr Ranch schist. The Redwood Mountain fault barely enters the quadrangle, but extends both northwest and southeast for great distances. Hershey ^^ named the Redwood Mountain fault and listed it as one of the four important members of the thrust faulting system of the Klamath Moun- tains. He also noted the fault at Bald Mountain but did not describe or name it. The innumerable cross-faults which offset the main faults are difficult to explain. They seem to be later than the main faults and are possibly tensional effects, or are a response to stress in a direction oblique to the original compressive forces.* Small streams usually mark their trace. At many places, as at 736.7-2036.2, there is abundant fault gouge and a badly fractured zone. A sandstone from this locality is thoroughly mashed and brecciated and recemented with calcite. Faults bound several Franciscan masses around which Falor beds have dropped. In each case, the main mass of the "island" is made up of 35 Hershey, O. H., Some western Klamath stratigraphy, Am. Jour. Sci., 4th ser., vol. 21, pp. 58-63, 1906. * Since this paper was written, B. A. Ogle has found from field work in the Hum- boldt Bay-Eel River Tertiary-Quaternary basin, immediately to the west, that late structures have a general eastward trend. At least one major fault thrusts Pliocene beds over Pleistocene gravels. It is probable that the late cross-faults of this area are of a similar age and may be the dying-out of the major diastrophism to the west. 28 GEOLOGY OF THE BLUE LAKE QUADRANGLE [Bull. 148 Franeiscau igneous rocks and schists. Apparently the faults were gov- erned by the location of intrusive bodies in the heterogeneous Franciscan mass. GEOLOGIC AND STRUCTURAL HISTORY The Kerr Ranch sediments were deposited in a sinking basin prior to late Upper Jurassic, possibly in pre-Cambrian time. Contemporaneous volcanism contributed the interbedded basic volcanics. Prior to metamor- phism and possibly during deposition, the sediments and volcanics were intruded bj^ basic and ultra-basic igneous rocks. Conglomerates and coarse clastic grains in the semi-schists suggest a relatively close source area of moderate relief. Following deposition but apparentlj^ before formation of the Fran- ciscan basin, this series was folded and subjected to regional metamor- phism. The recrystallized Kerr Ranch and unaltered Franciscan are in sharp contrast, though the rocks, as originally deposited, were similar. Uplift and erosion followed metamorphism and overlying unmetamor- phosed material, if present, was stripped off. The area was again submerged in late Upper Jurassic. The great Franciscan geos^-ncline was initiated as a result of the Nevadan oro- geny.36 Franciscan deposition resulted in a section of at least ten thou- sand feet of shallow water sediments and submarine volcanics. Rarity of fossils may have been due to the rapid rate of deposition. Introduction of the basic and ultra-basic intrusives accompanied part of the sedimen- tation, and the sediments and volcanics were metasomatized to glauco- phane and associated schists in the neighborhood of the contacts. The coarseness and predominance of the clastic material at the base suggests a source area of rather high relief not far from the basin of deposition. The abundance of organic material indicates that this high- land was well wooded. Taliaferro's reference to a western source is, in general, borne out. but at least a small amount of material must have come from Kerr Ranch exposures to the east. The much greater abun- dance of shale and chemical sediments near the top of the formation suggests reduction in relief of the source areas. Franciscan deposition was followed by folding and faulting, prob- ably in several stages, and the Redwood Mountain fault, the Crogan fault and probably the Bald Mountain fault were initiated. The area was uplifted and eroded to expose the Kerr Ranch schist which with the Franciscan furnished sediments for the Falor formation. The minor, local volcanism in the western part of the area belongs in this period, possibly in the Miocene. In the upper lower Pliocene the area subsided, an arm of the sea entered the wide ancestral Mad River valley, and sediments from the near-by, heavily wooded land area were deposited. A molluscan shallow- Avater fauna flourished. The uppermost beds may represent continental deposition. The end of the Pliocene was marked by uplift and normal faulting, followed by strong cross faulting and recurrent movement along old faults. There may also have been some compressional stress at an oblique angle to early stresses. During Quaternary time faulting continued and 5* Taliaferro. N. L., Geologic correlation of the Jurassic of southwestern Oregon and California: Geol. Soc. America Bull., vol. 53, pp. 71-112, 1942. 1950] ECONOMIC GEOLOGY 29 the present topography was formed. Several Quaternary uplifts are indicated by terraces and by narrow lower stream valleys that contrast with the broad upper valleys. ECONOMIC GEOLOGY No mineral deposits are currently exploited in the area. There are a few minor prospects that have been worked from time to time. One property, the Horse Mountain Copper mine, to the east of the east boundary of the quadrangle, has yielded copper, and at one time employed several hundred men. The following data were obtained prin- cipally from a report of the California Division of Mines.^'^ Barite A small vein of barite occurs in Franciscan sandstone on the Ford Ranch at Liscombe Hill. At present this vein is covered by soil, but float is abundant for about one-half mile along the strike. It is reported to be about 10 inches thick and parallel with the attitude of the sandstone. Chromium Several hundred tons of chromite were removed from the Horse Mountain Copper mine during World War I. It occurred in an ultra- basic igneous intrusive altered to serpentine. There may well be chromite in the ultra-basics of the Blue Lake quadrangle, but none was observed. Clay Near Hungry Hollow, section 20 ( ?), T. 6 N., R. 3 E ; on this map, 731.2-2049, some small lots of clay usable for pottery making have been obtained by R. H. Jenkins for pottery making in his classes at Humboldt State College, Areata. This clay is in the Franciscan formation and is a very small local deposit which was being worked in the summer of 1946, Avhen the writers visited it. The clays in the Falor formation may be of value but no data are -available. Coal (Lignite), Maple Creek Deposit An early patent for coal was granted for 80 acres in sections 20 and 29, T. 5 N., R. 3 E., H. M., on Maple Creek; on this map 734.6-2038.8. A seam of tough brownish-black lignite is reported to dip 45° NE. The width is not known, but it is thought to be 8 to 4 feet. In 1946, the mine area was completely overgrown. Mr. Myers Gundersen, an old resident, states that coal was dug about 30 years ago, but that it did not burn well. Copper Two miles to the east of the northeastern part of this area (sections 33 and 34, T. 6 N.. R. 4 E., IT. M.), there is an economic deposit of copper ore. There are 60 unpatented claims here under the group name of Horse Mountain Copper Glance Consolidated (Horse Mountain Copper Com- pany). The last work was done in 1929; production was small and the property has since been abandoned. The country rock is serpentine and 3" Averill, C. V., Mineral resources of Humboldt County : California Div. Mines Rept, vol. 37, pp. 499-527, 1941. 30 GEOLOGY OF THE BLUE LAKE QUADRANGLE [BuU. 148 there are numerous hornblende gabbro pegmatite veins adjacent, some having crystals of plagioclase and hornblende 3 inches in diameter. A sample of ore obtained from a dump showed chalcocite, pyrrhotite, and chalcopyrite, in polished section. Limestone The few very small lenses of limestone in the Franciscan are not of commercial importance. Manganese Manganese stains Franciscan chert that is exposed near the AUard Ranch. Further investigation of this region may lead to the discovery of a commercial quantity of manganese. Road Metal Small quarries in which Franciscan basalt is being obtained for road metal are located along the Maple Creek Road, near the Barr Ranch, and on U. S. Highway 299 at the crest of Bald Mountain-Snow Camp Mountain Ridge. The rock, a brownish green, hard, and highly fractured variety, is loaded with a steam shovel and hauled by truck to roads in the vicinity. Some gravel, obtained along accessible reaches of Mad River, is used for concrete work or road metal. BIBLIOGRAPHY Averill, C. V. Mineral resources of Humboldt County : California Div. Mines Rept., vol 37, pp. 499-527, 1941. Baker, F. S. Mountain climates of western United States : Ecological Mon., vol. 14, pp. 223- 254, Apr. 1944. Barth, F. W. (vrith Correns, Carl W., and Eskola, Pentti), Die Enstehung der Gesteine, 422 pp., Berlin, Julius Springer, 1939. Davis, E. F. Radiolarian cherts of the Franciscan group : Univ. California, Dept. Geol. Sci. Bull., vol. 2, pp. 235-432, 1918. Diller, J. S. Topographic development of the Klamath Mountains : U. S. Geol. Survey Bull. 196, 1902. U. S. Geol. Survey Geol. Atlas, Port Orford folio (no. 89), 1903. Klamath Mountain section, California : Am. Jour. Sci., 4th ser., vol. 15, pp. 342-362, 1903. Hershey, O. H. Metamorphic formations of northwestern California : Am. Geol., vol. 27, pp. 225-245, 1901. Certain river terraces of the Klamath region, California : Am. Jour. Sci., 4th ser., vol. 16, pp. 240-250, 1903. The Bragdon formation in northwestern California : Am. Geol., vol. 33, p. 357, 1904. Some western Klamath stratigraphy : Am. Jour. Sci., 4th ser., vol. 21, pp. 58-63, 1906. Del Norte County geology : Min. Sci. Press, vol. 102, p. 468, 1911. Hinds, N. E. A. Geologic formations of Redding-Weaverville district, California : California Div. Mines Rept. 29, pp. 77-122, 1933. Lawson, A. C. The geomorphogeny of the coast of northern California : Univ. California, Dept. Geol. Sci. Bull., vol. 1, pp. 241-271, 1894. 1950] BIBLIOGRAPHY 31 Martin, Bruce Descriptions of new species of fossil mollusca from the later marine Neocene of California : Univ. California, Dept. Geol. Sci. Bull., vol. 8, pp. 181-202, 1914. Maxson, J. H. Economic geology of portions of Del Norte and Siskiyou Counties, northwestern California : California Jour. Mines and Geology, vol. 29, nos. 1, 2, pp. 123-160, January and April, 1933. Taliaferro, N. L. Relation of volcani.sm to diatomaceous and associated siliceous sediments : Univ. California, Dept. Geol. Sci. Bull., vol. 23, pp. 48-49, 1933. Geologic correlation of the .Jurassic of southwestern Oregon and California : Geol. Soc. America Bull., vol. 53, pp. 71-112, 1942. The Franciscan-Knoxville problem : Am. Assoc. Petroleum Geologists Bull., vol. 27, pt. 1, pp. 109-219, 1943. U. S. Weather Bureau Annual Reports, California Section, 1937. 1950] INDEX 33 INDEX * A Abrams schist, 7, 15-16, 20 Accessibility and industry, 9-10 Actinolite-glaucophane-pumpellyite-muscovite-chloritc schist, i)hoto, pi. IHA AUard Ranch vicinity, manganese from, 30 Alluvium, 26 Anadara triliueata (Conrad) , Boulder Creek, 23 Anorthoclase trachyte, Tertiary (?), 26; photo, pi. 13B Anorthoscutuni oregonense quaylei Grant and Hertlein. RouhhM- Creek, 23 Apatite, 19 B Balanus cf. B. tintinnabulum var. coosensis Uall, Boulder Creek, 24 Bald Mountain fault, 27, 28 , Kerr Ranch schist on, photo, pi. 4 , photo of Redwood Creek Valley from, pi. 3 Ridge, Franciscan pillow lava, photo, pi. 5 -Snow Camp Mountain Ridge, road metal from, 30 Barite, 29 Barr Ranch vicinity, road metal from, 30 Basic and ultra-basic intrusives, 21, 14 Beckstine Ranch area, basic and ultra-basic intrusives, 21 Bellspring peneplain, 12 Bibliography, 30-31 Biotite, 19, 20 Blue Lake fault, 27 Boulder Creek, Falor formation, 22 , fossils, 23, 24 ; pis. 6-10 , Quaternary terrace gravels, 20 Calyptraea mamillaris Broderip, Boulder Creek, 23 Canon Creek vicinity, basic and ultra-basic intrusives, 21 ; fossils, 24 Cardium (Cerastoderma) coosense Dall, Canon Creek, 24 meekianum Gabb, Canon and Boulder Creeks, 23, 24 ; photo, pi. 9A (Clinocardium) nuttallii Conrad, Canon Creek, 24 Cherts, 20-21, 14 Chione securis Shumard, Boulder Creek, 23 ; photo, pi. 9B Chlorite, 19, 14 Christie Ranch vicinity, Quaternary terrace gravels, 26 , shales, 20 Chromium, 29 Cirripedia, Boulder Creek, 24 Clay, 7, 14, 25, 29 Climate, 10-11 Coal (lignite) , Maple Creek deposit, 29 Coast Ranges, 7, 9, 12, 13, 16, 26 Conglomerates, 20, 7, 14, 28 Copper, 29-30 Crawford fault, 27 Crepidula princeps Conrad, Boulder Creek, 23 Crogan fault, 27, 28 E Echinoidea, Boulder Creek, 23 Economic geology, 29-30 Empire formation, Coos Bay vicinity, 23 Epidote, 19 Eureka quadrangle, anorthoclase trachyte. 26 * Prepared by Beth Collins 34 GEOLOGY OF THE BLUE LAKE QUADRANGLE [Bull. 148 F Falor fault, 7, 27 formation, 22-25, 7, 14, 26, 27, 28, 29 Ranch vicinity, Falor formation, 22, 26 Faulting, 7, 14, 27-28 Fickle Ridge, cherts along, 21 Ford Ranch, barite on, 29 Franciscan group, 18-22, 14, 25, 26, 27, 28, 29 ; photo, pi. 12P. Franciscan-Kuoxville group, 19, 20 pillow lava. Bald Mountain Ridge, photo, pi. 5 schist, photo, pi. 12B volcanics, 11 G Garner Ranch, fossils along road to, 24 Gastropoda, 23, 24 ; photo, pi. 10 Geography and topography, 9-12 Geologic and structural history, 28-29 structure sections, pi. 2 Geology, economic, 29-30 Geomorphology, 12-13 Gilbert, C. M., cited, 9 Glaucophane-chlorite-albite schist, Kerr Ranch, 15 ; photo, pi. IIB Gyrineum lewisii Carson, Boulder Creek, 23 ; photo, pi. lOB H Hertleiu, Leo, identifications of Pliocene fossil.s, 9, 22-24 High Prairie, structure, 27 Hinnites sp., Boulder Creek, 23 History, geologic and structural, 28-29 Hornblende, 19 Horse Mountain Copper Glance Cons. — see chromium, and copper, 29 road, conglomerate along, 20 Humboldt County, 7, 8 Hungry Hollow vicinity, clay production, 29 Industry, accessibility and, 9-10 Introduction, 7-9 Intrusives, basic and ultra-basic, 21, 14 Iron ores, 19 J Jenkins, R. H., clay production, 29 Jurassic, 18-22, 14, pi. 12B K Kerr Ranch schist, 13-18, 7, 25, 26, 27 ; photos, pis. 4, llA-B, 12A sediments, 28 Klamath Mountain Province, 7, 9, 17, 20 , faults, 27 peneplain, 12 Knoxville formation, 18-19 Korbel fault, 27 post office vicinity, Falor formation, 24, 25 L Landslides, 26 Lignite, 29, 24 Limestone, 14, 21, 30 Liscombe Hill, barite on, 29 Literature, previous, on Blue Lake quadrangle, 13 Lucina cf. excavata Carpenter, Canon Creek, 24 MacGinitie, Harry D., fossil area discoveries, 9, 18, 24 1950] INDEX 35 Macoma astori Dall, Boulder Creek, 24 inquinata (Deshayes), Canon Creek, 24 nasuta (Conrad), Canon Creek, 24 secta (Conrad), Canon Creek, 24 sp., Boulder Creek, 23 Mad River, alluvium in, 26 area : geology, 13, topography, 11 basin, Falor formation, 22 road, fossils along, 24 , road metal from reaches of, 30 , shales, 20 Valley, sedimentation, 28 M Manganese, 30 Manning, George A., Blue Lake quadrangle map. northern half by, 9, pi. 1 Map, index, showing Blue Lake quadrangle location, 8 , economic. Blue Lake quadrangle, pi. la , geologic. Blue Lake quadrangle, pi. 1 Maple Creek coal deposit, 29, 24 , Falor formation, 22, 23 , Quaternary terrace gravels, 26 road, fossils along, 24 , road metal from, 30 Merced formation, San Francisco Bay vicinity, 23 Miocene, 26 Muscovite-quartz-albite schist, Kerr Ranch, 13 ; photo, pi. IIA Mya japonica Jay, Canon Creek, 24 Mytilus aff. M. middenorfi Grewingk, photo, pi. 8A edulis Linnaeus var., Boulder Creek, 23 ; photo, pi. 8B highoohiae Mandra, Canon Creek, 24 N Nassarius moranianus (Martin), Boulder Creek, 23 ; photo, pi. lOA Natica russa Gould, Boulder Creek, 23 Neptunea eurekaensis (Martin) , Boulder Creek, 23 recurva Gabb, Boulder Creek, 23 Ogle, Burdette A., Blue Lake quadi-angle map, southern half by, 9, pi. 1 , Mrs. B. A., cited, 9 Olivella biplicata (Sowerby) , Boulder Creek, 23 Panope generosa Gould, Boulder Creek, 23 . Pecten caurinus Gould, Boulder Creek, 23 oregonensis Howe var., Boulder Creek, 23 ; photos, pis. 6-7 Pelecypods, Boulder and Canyon Creeks, 23, 24 ; photos, pis. 8-9 Peneplains, 12 Petrography, stratigraphv and, 13-26 Plagioclase, 21, 22 Pliocene, 7, 12, 22, 23, 28 Post Franciscan, 26 Pre-Cambrian, 28 -Franciscan, 7, 14 -Pliocine, 7, 26 Q Quartz-glaucophane-muscovite schist, Franciscan formation, photo, pi. 12B Quaternary, 28-29 ; terrace gravels, 26 36 GEOLOGY OF THE BLUE LAKE QUADRANGLE [Bull. 148 Recent gravel, sand and silt, 14 Redwood Creek Canvon, landslides, 26 Mountain fault, 13, 17, IS, 27, 28 , Quaternary terrace gravels, 26 , structure, 27 Valley, photo from Bald ^Mountain, pi. 3 Road metal, 30 Rock specimens, 9 S Sandstone, 7, 14, 19-20 Sauguinolaria nuttallii Conrad, Canon Creek, 24 Haxidomus nuttalli, Conrad, Canon Creek, 24 Schist, semi-, Kerr Ranch, photo, pi. 12A Schists, 14, 22 Schizothaerus nuttallii (Conrad), Boulder Creek, 23, 24 Semele cf. s. sylviaensis Weaver, Canon Creek, 24 Shales, 20, 14 Snow Camp Mountain-Bald Mountain Ridge, 11 Mountains, vegetation on, 11 Solen sicarius Gould. Boulder Creek, 23 South Fork Mountain, fault along, 13 Spi.sula albaria (Conrad) , Boulder Creek, 23 brevirostrata Packard, Boulder Creek, 23 catilliformis Conrad, Boulder Creek, 23 voyi (Gabb), Boulder Creek, 23 Stratigraphic correlation, 15-18 section, generalized, 14 Stratigraphy and petrography, 13-26 Structural and geologic history, 28-29 Structure, 27-28 sections, geologic, across Blue Lake quadrangle, pi. 2 T Taliaferro, N. L., cited, 9, 19 Terraces, alluvium, 14, 26 Tertiary ( ?), anorthoclase trachyte, 26 ; photo, pi. 13B Thais lamellosa (Gmelin) , Boulder Creek tributary, 24 ostrina (Gould), Boulder Creek tributary, 24 Thin sections, 9 Thracia sp.. Canon Creek, 24 Tip Top Ridge, 11 Tithonian age, 7 Topography, 11-12 Tourmaline, 19 TufPs, 21 Turner, F. J., cited, 9 Turris perversa (Gabb), Boulder Creek, 23 U U. S. Forest Service and Corps of Engineers, Blue linke (piadrangle map by, 9, pi. 1 V Vegetation, 11 Vesicular basalt, 21 Volcanics, 21, 14 W AVeitchpec schist, 16-17 Wiggins Ranch vicinity, Falor formation, 22 , fossils, 23 Wildcat series, 22 Williams, Howe], cited, 9 Y Yolinda scissurata var. strigata Dall, Boulder Creek, 23 O 3489 2-49 IM DIVISION OF MINES OLAF P JENKINS, CHIEF STATE OF CALIFORNIA DEPARTMENT OF NATURAL RESOURCES BULLETIN 148 PLATE 2 ^ \jf/ STATE OF CALIFORNIA DEPARTMENT OF NATURAL RESOURCES DIVISION OF MINES GEOLOGIC STRUCTURE SECTIONS ACROSS BLUE LAKE QUADRANGLE, CALIFORNIA ACCOMPANYING REPORT BY G. A. MANNING AND B. A. OGLE SCALE 1 2 3 4 5 MILES H I W I ^ ^ ^ ^ I I i If 5 I i I III I » II II , I I I I P ' la S J rn ■! r-' |i ^ 5||l :-] til g r^j 5^ a I = i 1 I I .|U L.|j|L_||^ .^ ^j » III III II - II ill ll il \ ^\\