STATE OF OREGON

DEPARTMENT OF GEOLOGY AND MINERAL INDUSTRIES

702 Woodlark Building

Portland 5, Oregon

Bulletin No. 40

PRELIMINARY DESCRIPTION of the GEOLOGY OF THE KERBY QUADRANGLE, OREGON

by Francis G. Wells, Preston E. Hotz, and Fred W. Cater, Jr. Geologilfl, United States Geological Survey

1949

. . . •.

Prepared in Cooperation with the United States Geological Survey

STATE GOVERNING BOARD

NIEL R. ALLEN, CHAIRMAN GRANTS PASS

E. B. MAcNAUGHTON PORTLAND

H. E. HENDRYX • BAKER

F. W. LIBBEY DIRECTOR

Prioe 85 centa STATE OF OREGON

DEPARTMENT OF GEOLOGY AND MINERAL INDUSTRIES

702 Woodlarlc Building

Portland 5, Oregon

Bulletin No. 40

. PRELIMINARY DESCRIPTION of the GEOLOGY OF THE KERBY QUADRANGLE, OREGON

by Francis G. Wells, Preston E. Hotz, and Fred W. Cater,Jr. Geologists, United States Geologlc•l Survey

1949

. . •.

Prepared In Cooperation with the United States Geological Survey

STATE GOVERNING BOARD NIEL R. ALLEN, CHAIRMAN GRANTS PASS

E. B. MAcNAUGHTON • PoRTLAND

H. E. HENDRYX • BAJC£11

F. W. LIBBEY DIREcTOR PRELIMINARY DESCRIPTION OF THE GEOLOGY OF THE KERBY QUADRANGLE, OREGON

By

Francis G. Wells, Preston E. Hotz and Fred W. Cater, Jr.*

CONTENTS

Page Page

Introduction...... 1 Hornblende diorite and related Purpose...... l rocks--Continued. Field work. • . • . • • • • . • . . . . • • • • • . . . . • • . 1 Hornblende diorite .•••...... 12 Acknowledgments...... 1 Gabbro •..•.•••••.••..•..••••• 12 Previous work...... 1 Pegmatitic hornblende Geography. • . • . • • . • . . . • • . • • • . . . • • • • • • • • • . l diorite .•.•.•.•...•.•••.••. 12 Location .••.•..•••.••..•.••••.•..•••. 1 Gneissic migmatite •.••••••..• 13 Accessibility .....••••.•.••...•••..•. 1 Granodiorite ...•.•.•...... •• 13 Topography...... 1 Structure of hornblende Culture.. . . • • . . . • • • • • . • • . • • . • . . . • . .. . 2 diorite and related rocks .• 13 Descriptive geology ...•••.•.•••...•••.•.. 2 Dacite porphyry .••••••••.....•.•. 14 General statement. • • . • • . • • . • . ... • . . .. 2 Cretaceous system •.••••..••••...•.••. 14 Amphibole gneiss (age uncertain) •••.• 2 Horsetown formation .•••.. .•••••• • 14 Triassic system .•.•••••...... 3 Tertiary system ••••••••....•••.•••.•• 15 Applegate group ••.••..•••.•...... � Arago formation •..••••••••.•• •..• 15 Metavolcanic rock...... :5 Old gravels ....••••••••••...... 15 Metasedimentary rocks •.•.•..• 3 Quaternary system ...... 16 Age and correlation...... • . • • 4 Auriferous gravels of the Jurassic system...... 4 second cycle of erosion •••••.•. 16 Gall ce formation. . . • . . . • . • . • . . . • • 4 Llano de Oro formation and Distribution and general bench gravels •••...•••...••••.• 17 character. . • . . • • • . • . . • • . . • • 4 Glacial moraine ••••••••.••.•....• 17 Volcanic member...... 1 Alluvium ••...••••...•...... •••• 17 Sedimentary member •...••.•..• 5 Structure ••••...•.••...•...... •...••.... 17 Structure...... 6 General statement...... 17 Age and correlation .•.••.•... 7 Reverse faults •.•.....•...•••••••.••. 18 Dothan forma tl on.. • • • . . • • . . • . . . • . 7 Northwest-trending structures ...... 19 Distribution.. . • . . . • . • • • • • . . • 7 Cross faults •...•..••.•..•...... •. 19 Structure...... 8 Mineral deposits ...... •.••...•..••••..... 19 Thickness...... 8 Clay ..•..••...... •••••.••.•.••...•.. 19 Stratigraphic position and Chromite •...... ••..•.••••...... •.. 19 age ...... 9 Cobalt •.••....•...••••..••.•.•...•••• 20 Late Jurassic or early Cretaceous Copper •...... •.•.•••.••.••••..•..••• 20 intrusive rocks...... g Gold •..••..••..•.•••••••••• •••.•••••• 20 Ultramaftc rocks...... g Placer •••.•••.•..••.•••••..•••.•• 20 Periodoti te...... 9 Lode •.•..•....••••••..•..••.••.•. 21 Pyroxenite •. •..••••...... 10 Manganese ..••..• ·• •••••••.•.•..•••.••• 21 Serpentine .•••.•...••••.....• 10 Nickel .••.•••.•.•.••...... •...••••••• 21 Olivine gabbro ...... 10 Platinum and allied metals ....•.•.••• 21 Metagabbroic complex ••••..••••... 11 Pyrite ..••••••••• ••.••..•••••••••...• 22 Dolerite and related dikes •.••.•. 11 �uicksil ver ..••·..••...... •• •.•.•.••.• 22 Hornblende diorite and related Silver ••.•.••••..••..•...... •••..•• 22 rocks ..•...•.••..•.••••.••••... 12 Zinc •..•..•..•....•...... •.•.•..•••.• 22 Distribution ....••••..•...... 12 Bibliography .•••.•....••..••.••• ••.•••.•. 22

*Geologists, U. S. Geological Survey INTRODUCTION Anyone who lives and works in unsettled mountainous country·must depend on the Forest Purpose Service for many things, and the SUrvey parties enjoyed the liberal generosity and courtesy Knowledge of the geology of an area is extended by all of the personnel of the essential to an adequate appraisal of its Siskiyou National Forest, especially by H. c. mineral resources and to a solution of engi­ Obye, Supervisor, C. D. Cameron, Harold neering and scientific problems that are Bowerman, and Cecil Hathaway. related to bedrock, soils and surficial de­ posits. Therefore the Oregon State Depart­ Previous work ment of Geology and X1neral Industries in cooperation with the U. S. Geological Survey Xany of the mineral deposits in the quad­ is preparing geologic quadrangle maps of the rangle as well a� some of the geology have been state as rapidly. as funds and available described in published reports, a selected personnel will permit. It is the policy of bibliography of which is gi ven at the end of the State Department of Geology and Xineral this text. P. J. Shenon (14) has systemati­ Resources to release promptly information that cally mapped 33 square miles in the vicinity of is of value to the public. In line with this Takilma, and his work is incorporated in the policy this geologic map of the Kerby quad­ present map. Geologic maps of the Riddle, rangle, based on field work finished in Grants Pass and Xedford quadrangles, which lovember 1946, is being issued now before it adjoin the Kerby on the northwest and east, has been possible thoroughly to digest the and the Port Orford quadrangle to the north­ data collected and to complete laboratory west, have been published either by the U. S. studies of the materials collected. Hence, as Geological Survey or by the State Department mos� geologists will understand, the map is to of Geology and Xineral Industries in coopera­ be regarded as preliminary. The classifica­ tion with the U. S. Geological Survey. tion and description of the rocks shown on the map is largely based �n field examination GEOGRAPHY alone and is certain to be modified in some particulars by laboratory study of the speci­ Location mens collected. A final report embodying the results of this study and of other scientific The Kerby quadra�gle is in southwestern work is planned for later publication by the Oregon and is bounded by the meridians 123° 30' U. S. Geological Survey. and 124° 00' west, and by parallels 42° 00' and 42° 301 north. Its south boundary almost Field work coincides with the Oregon-California state line, and all of the quadrangle except the Geologic mapping of the quadrangle was southwestern quarter, which is in CUrry County, begun in July 1940 and continued until the end is in Josephine County. The quadrangle com­ of October; it was resumed the first week of prises 890 square miles. June 1941 and continued until the end of September. During these two seasons the pro­ Accessibility ject was under the immediate direction of Francis G. Wells of the U. S. Geological No railroad enters the quadrangle but Survey. He was assisted by Preston E. Hotz, good roads serve its eastern part. U. S. Gordon L. Bell and Harold L. James. As the Highway 199 traverses the length of the season of 1941 progressed Wells was able to Illinois Valley, and gravel·led or paved :"Oads give only supervision and review, and it lead up its broader tributary valleys to the became necessary to rece�s the project after west, such as Clear and Sucker Creeks. Dirt war was declared. Wells, ably assisted by roads, impassable in wet weather, lead short Fred W. Cater, Jr., resumed field mapping in distances up the narrow valleys and ridges. May 1945 and continued until the second week Three Forest Service roads lead westward from of September; they returned to the field late Highway 199. They are from north to sou th, in Xay 1946 and completed mapping the end of the Onion Xountain Road that goes to Ferren October. Hotz and Cater have contributed. Guard Station, the road down Illinois Canyon much to the preparation of this report, which to Oak Flat, and the older Wimer road vtl.ich has been written by Wells. goes to Sourdough Camp in the southwestern corner of the quadrangle. All are impassable Acknowledgments from la"e ��11 to late spring except th e road down lllinois Canyon. Cordial thanks are due to the many in­ habitants of southwestern Oregon and to other No road penetrates the western third of persons interested in its resources for gener­ the quadrangle. One can drive to within a ous help and cooperation. It would be impossi­ few miles of its northwestern corner by taking ble to name all those to whom the parties were the Forest Service road to about three miles thus indebted but the following persons were beyond Agnes. Otherwise, this rugged region particularly helpful� Edward Cox, Fritz is accessible only by trails, and many of Grunow, William L. Heustis, E. W. Kubli, which are in poor condition and impassible to Chester X. Zachary, and H. F. Byram of the pack trains. Rustless Steel Xining Co.; the personnel of the Oregon State Department of Geology and Topography Mineral Industries, the former Director Earl K. Hixon, the present Director F. W. Libbey, Some of the most rugged terrian in south­ and geologists of the Department stationed in western Oregon is in the Kerby quadrangle. Grants Pass--Ray C. Treasher, Elton Youngberg Except for 60 square miles of rolling hills and ancl Hollis Dole. flats in the Illinois Valley, the region is a

1 wilderness of narrow ridges and steep canyons, Amphibole gneiss (age uncertain) Slopes that have an average grade of 30° or more, through a range of 2,000 to 4,000 feet Gneissic and schistose rocks are exposed are common. Box canyons 100 or more feet in several areas in the Kerby · quadrangle. The deep wall in many of the streams in the north largest mass extends from the northern boundary and west. of the qu adrangle 10 miles south by west, a second area is in. the valley of the Chetco and The peaks in the southeastern corner of Little Chetco Rivers, and the third crops out the quadrangle are over 5,200 feet above sea along the ridge dominated by Chetco Peak. level. Pearsall Peak near the center of the Scattered between these large areas of gneiss quadrangle has ap altitude of 5,091 feet, and are a few smaller bodies, each occupying a few in general the ridges and summits are above acres or less, which occur as roof pendants in 4,000 feet. The lowest point in the area is the peridotitic and granitic rocks. on the Illino is River in the northwestern corner of the quadrangle with an altitude of The gneiss and schist in all the areas between 100 and 200 feet. Many of the-stream are alike in lithology �d in the degree of beds lie below 1,500 feet. metamorphism which they exhibit, In general, the rocks are dark- to light-gray, banded, Three independent river systems, the medium-grai ned rocks which on closer inspection Illinois, Chetco and Smith, drain the quad­ are seen to consist of alternating light- and rangle, except for the northeastern corner dark-colored folia, usually a few millimeters which is drained by Rogue River. thick, On a large·r scale these folia are grouped to form light-colored predominantly Culture quartz-rich layers up to 8 feet in thickness and dark-colored layers ten or even hundreds The high precipitation of the region-- of feet thick, 51,5 inches per year at Waldo--gives it a dense covering of vegetation, much of which Br oadly speaking, the rocks may be di­ is underbrush. Mixed forests, predominantly vided into two general types that grade into coniferous, cover most of the area. Large each other. The mor e abundant of the two portions of the wooded tracks are of little types are rocks composed of different amounts use, but there are large stands of good timber of hornblende, plagioclase, epidote, clino­ and the accessible stands of these have yield­ zoisite, quartz, and minor quantities of mag­ ed much lumber. A little farming and some netite. Sphene in minor but noteworthy amounts , stock raising are carried on in the Illinois is usually present. The composition of the and its broader tributary valleys and the plagioclase ranges from albite to anorthite, adjacent slopes. All but about a dozen of the but albite is most common. Where anorthite is 3,800 people who live in the quadrangle are present, the associated amphibole is the calcic settled in these valleys. Cave Junction is amphibole, pargasite; and in the gneisses ex­ the largest community with a population of posed along the Chetco River and in the Carter about 1,000 in 1940. Although mining has Creek-Little Chetco River area, the amphibole been carried on actively in the past, very is in some places actinolite rather than horn­ little was going on in 1945 and 1946, blende. As a rule these rocks are distinctly foliated with hornblende-rich folia alter ­ DESCRIPTIVE GEOLOGY nating with folia in which plagioclase and quartz or clinozoisite and epidote are pre­ General statement dominant. In some rocks hornblende is the principal constituent and any or all of the The general distribution of the la rger above listed minerals may be absent. Minerals rock units in the Kerby quadrangle is simple, of th e clinozoisite-epidote group are also Bands of sedimentary, volcanic, and intrusive common in most of th ese rocks, and constitute rocks--metamorphosed to various degrees--trend more than half of some thin sections examined, across the quadrangle in a north-northeast direction. From east to west they are: Less abundant �re the rocks of the second metavolcanic and metasedimentary rocks of the type, which are composed of quartz, biotite, Applegate group of Triassic(?) age; slates, and plagioclase, with variable though generally sandstones and metavolcanic rocks, of the minor quantities of garnet and magnetite, and Galice formation of Upper Jurassic age; in­ less commonly chlorite and muscovite. No trusive peridotites of late Mesozoic age; a sphene was identified in them, With increases complex of other Mesozoic intrusive rocks; and in quartz these rocks grade into quartzites a band of massive sandstones, shales and flows containing accessory biotite and in places of the Dothan formation of Upper Jurassic age, some plagioclase. Garnet occurs as an accesso­ At various places within these bands are small ry in nearly all of th ese rocks and may make areas of younger rocks. A small area of up several percent. Plagioclase in rocks of Cretaceous sandstone crops out in Illinois this type commonly falls in the oligoclase­ Valley, and nearly flat-lying Tertiary and andesine compositional range. Hornblende is Quaternary conglomerates and sandstones are rare, and of several sections of quartzite scattered in the quadrangle. Younger dikes, examined under the microscope only one con­ possibly Cretaceous in age, are widespread. tained a few small crystals of hornblende, Close folds parallel to the north-northeast Clinozoisi te and epidote appear to be lacking. trend are the dominant structures of the region. Thr ust faults parallel to the axes In many places the gneiss has been of these folds and complicated faulting at metasomatically altered, and small veinlets of angles to them modify the fold-pattern, quartz, albite, hornblende, epidote and clino­ zoisite, chlorite, and rarely of prehnite, have Some alluvium is found in the broader cut and replaced the host rock, A few grains parts of the stream valleys. of apatite were seen in one thin section.

2 Along the contact of the diorite and gneiss in doubtless were originally more calcic. Almos t the valley of Little Chetco River thin layers invariably the pyroxenes have been altered to of chlorite and of gneiss alternate in a zone actinolitic hornblende. Chlorite is rare in which is called lit-par-lit structure. The these rocks, but in almost every specimen same structure is found along the contact of either clinozoisite or epidote, or both, are the gneiss and peridotite at the head of Todd conspicuous. Some of the rock shows traces of · Creek. In both areas the hornblende of'the flow structure, and a vesicular or amygdaloidal gneiss is recrystallized to a very coarse­ structure is common. Calcite is so abundant in grained mass, some of the crystals being as many of the layers as to suggest that the lavas much as 4 inches in length, flowed into a basin, where they mixed with limy muds accumulating there, and later we re con- · The formation strikes from a few degrees solidated as vesicular breccia bound together east of north to northeast and dips steeply to by a calcareous matrix. the east. Some westward dips are found, and detailed mapping might disclose the folds and Agglomerates and flow breccias are common make it possible to determine the thickness of in the southeastern corner of the area, and the formation. Drag folds of all dimensions just to the east of the quadrangle on French are a characteristic feature of the gneiss, Mountain. The agglomeratic structure is seen Large drag folds are most conspicuous in the best on weathered surfaces, where angular and siliceous beds, whereas smaller folds--even of subangular amygdaloidal fragments are set in microscopic size--are found in the thinly a fine-grained, partly calcareous matrix. Part �oliated layers. of the series probably consisted originally of fine-grained, thin-bedded tuffs. The greatest width of the outcrop belts of gneiss is 2 to 3 miles. If the thickness The formation as mapped includes some of the exposed gneiss is repeated once by small bodies of basic intrusive rocks, and some close folding, its true thickness probably lenses of argillite, a few feet to a few tens does not exceed 5,000 feet. of feet in thickness, which were impracticable to map separately. The larger lenses of The amphibole gneiss is belived to be argillite, some of which are several hundred the product of metamorphism of an assemblage feet thick and several miles long, have been of sedtmentary volcanic material, some of which mapped with other metas edimentary rocks. was high in calcium and some quite siliceous. Interlayered with it were flows of a different Metasedimentary rocksr--Metasedimentary composition. In its general character the rocks m�e up from one-third to one-half of gneiss resembles the •younger metamorphic that part of the Applegate group which crops rocks8 of the Medford quadrangle, which are in out in the Kerby quadrangle - a far greater part a metamorphosed facies of Applegate group proportion than is found in the same group to of Triassic(?) age. They differ distinctly the east. Though sedimentary strata may occur from the 86ld schists• of the Grants Pass and in sequences totaling s�veral thousand feet in ftedford quadrangles . thickness, they usually contain some inter­ bedded volcanic rocks. In general the sedi­ Triassic(?) system ments have undergone some metamorphism and today consist principally of chert, argillite, Applegate group quartzite, fine-grained quartzite, conglomerate and lentils of marble. A thick assemblage of metamorphosed ' volcanic rocks with lens-shaped interbeds of The cherts are commonly white to dirty argillite, chert, quartzite, conglomerate, and gray, rarely red or black, They are fine­ marble is exposed over hundreds of square miles grained, dense and usually thin-bedded (less in southwestern Oregon and northwestern than 2 inches), and contain abundant remains Califor nia. It extends from the Tertiary over­ of microscopic radiolaria. In places the lap in the Medford quadrangle west for about cherts grade into gray or whiie limestone, now thirty-four miles to the thrust fault that recrystallized to marble, The bodies of marble separates these rocks from the Galice forma­ rarely exceed 100 feet in thickness and a few tion in the northwestern part of the Grants hundred feet in length. Lime Rock, a bold out­ Pass quadrangle and in the southeastern part crop on the mountain southeast of Kerby, is a of the Kerby quadrangle. This assemblage of conspicuous example. The marbles grade by rocks is here named the Applegate group after interlayering into silty argillites, the drainage basin of Applegate River, where the gvoup is the prevailing country rock. Conglomerates form distinctive beds in the The th ickness of the giDup is unknown, but is sediments. The constituent pebbles are pre­ probably to be measured in miles, although its dominantly small though in some of the beds appa�ent thickness may be exaggerated by fault­ they exceed an inch in length, They are ing and close folding. principally subangular gray or black chert fragments, but occasionally a small rounded The Applegate group underlies about 60 pebble of fine-grained mica schist may be square miles in the southeastern part of the found. The conglomerates grade into and are Kerby quadrangle. interbedded with even-grained and coarse pebbly quartzit�. Rock fragments, largely Metavolcanic rocks.--The metavolcanic from basic flows, and quartz pebbles constitute rocks are pale green to greenish gray, and the bulk of the coarser grains in the their textures range from moderately coarse-. quartzites, and much of the material co�ld grained to fine-grained. A large part of the properly be classed as a graywacke. Inter­ series consists of porphyritic rocks, probably bedded with the conglomerates and cherts are andesitic or basaltic lavas. The micro­ argillites, They are fine-grained, have a crystalline groundmass contains phenocrysts of tabular cleavage, and where unweathered are plagioclase and what was once pyroxene. These usually black. Originally they were silty feldspars are more or less cloudy and now sandstonea and siltstones, and where deeply approach albite in composition, though they 3 weathered these rocks break down into their component grains. Small outcrops of such The formation is bounded on the west by weathered material are hard to distinguish metamorphic and igneous rocks, and its bounda­ from younger less-metamorphosed formations. ry is very irr egular in detail. From Deer Creek southward the Galice formation crops out With a few exceptions the attitude of the in two separate pr ongs divided by a mass of metavolcanic rocks is known only from their periodotite. The eastern prong continues to contact with the interlayered metasedimentary the south boundary of the quadrangle and rocks. These d1p steeply to the southeast and beyond. It is constricted to the vicinity of strike prevailingly east of north. O'Brien by the southwestern extension of Triassic rocks but increases to a width of six Strongly metamorphosed schistose (plagio­ m1les at the sou them boundary. The western clase) amphibolites, quartz-hornblende gneiss prong is cut out by the westward extension of and quartz-mica schist with thin beds of the peridotite. quartzites, marble or lime silicate rock have been �apped as-contact aureoles in.the Grants The Galice formation is made up of rocks Pass quadrangle. They are with few exceptions of many different lithologic characteristics marginal to igneous stocks, and they grade into which may be grouped into a lower predominantly normal metavolcanic and metasedimentary rocks volcanic member made up largely of agglomerates, of tbe Applegate group. They closely resemble tuffs and flows and an upper sedimentary member the amphibole gneiss found in the Kerby quad­ made up of shales or slates, a small amount of rangle, so it is suggested that the two may sandstone and a very few thin discontinuous be correlative and that all these rocks are layers of grit or conglomerate. metamorphosed facies of the Applegate group. The shaly and slaty parts of the forma­ No rocks that are known to be older than tion erode easily so that the areas underlain the Applegate group are exposed in the Kerby by them are characterized by broad valleys of quadrangle, hence the basament on which the low relief; th e volcanic rocks on the contrary Applegate group accumulated is unknown. In tend to stand as bluffs and form a very rugged the Grants Pass quadrangle the group is sepa­ terrain, a good example of which is the rated from older schists by igneous intrusions Craggies, a sharp saw-toothed ridge between or f�ulting. If the amphibole gneiss is a Babyfoot and Carter Creeks. metamorphosed facies of the Applegate group, then the Upper Jurassic Galice formation rests The structural complexities of these with angular unconformi·ty on the Applegate rocks and the various conditions under wh ich group. they were accumulated from place to place introduce irre gularities into this grouping. Age and correlation.--Diller (7) briefly In the northern part of the area slates are described the rocks of the Applegate group. interlayered with the volcanic rocks, but to He did not give them a name but on the basis the south the lower member contains little if of fossil determinations by Kindle, classified any slate, though stratified tuffs are common. these rocks as Paleozoic in age. Diller placed The upper member is almost free of volcanic part of them in the Devonian system and part rocks, but a large percentage of the con­ in the Carboniferous. Highly metamorphosed stituents of the sediments are of volcanic facies of these rocks he (Diller 8) named the origin. May Creek formation. Subsequent writers have followed Diller's dating, as did the writer Volcanic member.--Although the types of (Wells, 19,20) on the preliminary maps of the volcanic rocks are irregularly intermingled Grants Pass and Medford quadrangles, where both vertically and horizontally throughout they are called metavolcanic and metasedimenta­ the volcanic member and it has, therefore, ry rocks. After the publication of the geo­ been impossible to map any distinctive hori­ logi� map of the Grants Pass quadrangle, aons, nonetheless certain general groupings Reeside studied the collections uf fossils have been recognized. The lower part of the made by the writer and reexamined the collec­ member which crops out from the northern tions made by Diller. He pronounced them to boundary of the quadrangle to Illinois River, be of Mesozoic age, probably Upper Tr iassic. is characterized by thick andesitic flows and flow breccias, and coarse agglomerates. This Jurassic system is overlain by tuffs and thin flows, many of which are of dacitic and a few of rhyolitic Galice formation composition; many of the intercalated tuffs are well bedded and water stratified. This Distribution �d general character.--The tuffaceous sequence is overlain by dominately Galice formati:>n was named from Galice Creek, andesitic flows and agglomerates. From north which rises just to the north of the Kerby of Onion Mountain south to Days Gulch the base quadrangle and empties into Rogue River 5 of this agglomerate zone is characterized by miles farther north. As defined by Diller (5) maroon to rusty-broV'm scoriaceous lavas; inter­ the Galice formation included only the slates mingled with this type of lava are irregular and sandstones in the type area, but mapping masses of red or brown chert and varied pyro­ by the writers clearly shows that the volcanic clastic material. rocks are intercalated with the slates and sa�dstones and form part of a continuous cycle The flows of the Galice formation show a of deposition. Therefore these latter have wide variety of textural and structural been included in the formation, which has been features. They range in composition from tra�ed by the writers from the type locality andesite to dacite and rhyolite. The most south-westward into and beyond the Kerby quad­ common type is a gray to greenish-gray, fine­ rangle. These sedimentary and interbedded grained, porphyritic andesite conta ining volcanic rocks crop out over most of the euhedral phenocrysts of feldspar and horn­ northeastern quarter of the quadrangle and as blende recognisable in hand specimens. Under far south as Deer Creek. The maximum width the microscope the groundmass is seen to be a of outcrop is _3 miles in this a�ea. 4 felt-like mass of plagioclase laths; epidote grw.ina a.re usually eo11111on and ehlori te may be The tuffaceous rocks are well bedded, the present though in general the rocks are not beds ranging in thickness from a fraction of much altered. The groundmass of the aphanitic an inch to a foot or more. Light-colored beds type may be glassy; more commonly it is a are prevalent; light gray is the moat common glass with scattered needle-like mierolites of color; pale-green, buff and light-red beds are feldspar. The coarse-grained flows have a also common. Medium- and coarse-grained sandy poorly developed diabasie texture. Augite is tuffs are found, but in general the tufts usually present in this type, and alteration range from fine sand to silt. In places the to epidote and chlorite is more common. Many tuffs are cross-bedded, and occasionally they of the flows have an amygdaloidal structure; show gradational bedding. the'amygdules may be filled with calcite, �artz, chlorite and rarely epidote. The tuffs range in composition from gray dense rhyolitic tuff through daeitie to green The daeitic flows are light-colored, andesitic tuff. Under the hand lens fresh fine-grained holocryatalline rocks with a feldspar crystals, glass shards, some chlorite porphyritic texture. Buhedral fresh-looking plates, and drawn-out fragments of pumice can plagioclase, and possibly orthoclase, crystals be seen in the dacitie tuffs. Brief micro­ about 3 millimeters long and occasional small scopic examination has shown the rock to be a crystals of euhedral black hornblende are set fine-grained crystal tuff with fragments of 1n a trechytie groundmass, albite, secondary chlorite and epidote. In some of the specimens the grains show round1ng Although some of the rhyol1te .may be by water. intrusive into the other volcanic rocks, it is believed, nevertheless, to be a part of the Sed1menta� member.--The sedimentary Galice formation, The rhyolite is usually member ofthe �lice formation is made up porphyritic with euhedral phenocrysts of ortho­ largaly of slaty shale with subordinate sand­ clase and �artz in a very fine-grained, light­ stone, a little grit, and a few thin lenses colored groundmass. Bodies of this rock are of conglomerate. The distribution of these ·generally quite small. rock types through the section is not definite­ ly known. On Rough and Ready Creek and about The fragmental character of the volcanic ·two m1les to the south, on the West Fork of breccia of the Galice formation can be dis­ the Ill1nois River, at the contact with the earned only 1n large exposures either in bluffs, peridotite the formation 1s largely sandstone or in long stretches of waterworn outcrops and grades upward into shale. Diller (5) along large streams. In small outcrops it can­ found a similar sequence on Graves CTeek, 11 not be distinguished from flows; hence it is miles north of the Kerby quadrangle. Neither difficult if not impossible to map along the of these local1 ties is known to be the depo­ strike well exposed breccia layers which are sitional base of the formation. Where the known to be hundred or thousands of feet thick. fonnation lies unconformably on the amphibole The breccias are best seen along Illinois gneiss, careful traverses along the transecting River upstream from the mouth of Fall Creek. streams showed slaty siltstone and shales rest­ Here the rocks are mostly dark greenish gray ing on the gneiss and continuing for thousands to gray, and in places purplish to maroon in of feet higher in the formation. No system­ color, Where weathering is favorable frag­ atic distribution of the grits and conglomerates ments of various shapes, ranging in size from has been found. an inch or less to 5 inches, can be seen scattered through a dense to fine-grained Shale or siltstone makes up the bulk of matrix, The fragments are chaotically mixed the sedimentary member of the formation. It and some are angular, but many are elongate may be interbedded with sandstone, and in rounded bombs with smooth knobby protusions. places, for example along U. S. Highwa� 199 at Most commorily they have a vesicular structure, Hayes Hill and north of Dryden, "ribbon" shales but fragments of dense, fine-grained lava and consisting of alternating black shale and gray or porphyritic lava are also present. A few siltstone an inch or so thick can be seen. In .bombs with seoriaeeous surfaces, and a few general, however, one can traverse the beds of fragments of granitoid rock were found, streams across the strike for thousands of feet without seeing any sandstones,, or at most a few Some of the breccias are flow breccias thin beds less than 6 inches thick. The shale wbich, except where favorable weathering has is da.rk gray to black. Where the rock is revealed their fragmental character. may be smooth and polished by stream action it may mistaken for flows. Commonly they consist of appear massive although fine color and textural masses of small irregular fragments of fine­ banding is not rare. Those bands which range grained vesicular and porphyritic lava set in from a millimeter to a few centimeters in thick­ a green matrix of plagioclase, epidote, and ness show alternating gray and black layers; chlorite and occasionqlly hornblende. These the gray layers may grade from clay to silt masses lie between large fragments of flow sizes. In places the very thin layers show rock, ptygmatie folding probably formed in the uncon­ solidated mud. Generally individual m1neral Well stratified fine- to medium-grained grains cannot be recognized with the unaided tuffs are scattered through the volcanic eye and are even seen w1tb difficulty through sequence. They may occur as small lentils the hand lens. The microscope shows the shale within the coarse pyroclastic �eks and flows, to have an average grain size of less than but more commonly they are associated with 0.01 m1lllmeter. Angular crystal frag;nents of thin interlayered, light-colored, dense, platy quartz, and plagioclase of an intennediate flows. Together they form masses a hundred to composition are the principal identifiable min­ several hundred feet thick that have been erals. Kaolin and black opa�ue argillaceous traced for thousands of feet along the strike, material is very abundant and may mask the Such masses are common from north of the other grains. Slight metamorphism is commonly Illinois River to south of Little Cheteo River indicated by the presence of tiny flakes of and are excep�ionally well exposed in the biotite, sericite, and some pale chlorite, bluffs of Whetstone Butte. 5 Bpidote and clinozoisite grains are rarely grains and forming strong bonds between them. present. Opaque material seen under the Ferruginous material in the form of hematite microscope is probably magnetite, ilmenite or CODIDonly is seen in the cement and is very pyrite; though some of it may be carbonaceous abundant in the reddish-brown sandstone. The material. sandstone and siltstone could be called gray­ wacke. Carbonaceous strata with plant remains Carbonaceous layers up to 4 inches thick si.milar to those found in the shale are also have been found in a few places. These layers present in the sandstone. are black· and have a sooty appearance 1n some places; mare commonly, however, they contain Although it has been !mpossible to follow many carbonized fragments of woody plant re­ any bed o� gri.t or conglomerate for more than mains. a thousand feet along the strike, a traverse that crosses a few thousand feet of the sandy Interbedded with the shales are beds of parts of the sedimentary sec��on will disclose sandstone from one to several feet thick, In one or more lenses of grit and conglomerate. parts of the formation sandstone may be present The conglomerate i.s either pebbly wi.th a sand­ to the almost complete exc�sion or shale, as stone matri.x, or composed entirely of sub­ for example, near the moutn ot Rough and Ready angular and angular rock fragments bound Creek. together by silica cement. Coarse-grained grits consisting of rock fragments between 2 The fresh sandstone is generally gray, and 5 m1llimeters in diameter are more abundant. dark gray, or reddish brown. Generally it is In general the degree or rounding seems to be thick-bedded_ although rhythmically bedded greater the larger the fragment, so that the strata are present, Almost invariably the grit fragments are angular, whereas the con­ sandstone 1s very dense andwoll l1thified so glomerate fragments are subangular to sub­ that is is broken with difficulty. Cross rounded. The f·ragments are not well compacted bedding was seep in a few outcrops. Highly but are strongly bound together with si.lica lenticular and local pebbly layers are inter­ cement. ,Pieces of vari-colored chert, volcanlc spersed through the coarser facies, and the 1'9Ck, sandstone, and shale are the most common uniform texture of the sandstone is inter­ constituents and are similar to the fragments rupted in places by single or scattered sub­ found in the sandstones. rounded pebbles. Lens-shaped subangular frag­ ments of black shale up to a foot long are Structure.-Distlnct parting has been common at certain horizons. Many beds were developed ip the shales and sandstone of the seen which have a large proportion of black Galice formation since deposition. The rocks shale fragments up to an inch long and a frac­ are slatY- shales rather than true slates, tion of an inch wide, because thei.r cleavage and degree of meta­ morphism are not strongly enough developed to The feldspathic nature of the sandstone allow them to be placed 1n the class of slates is clearly recognizable with the hand lens. (though other wri.ters including Diller and Brilliant crystals of plagioclase and q1artz Talia:ferro have called them slates). The are the most noticeable minerals and the cleavage ls fairly good but discontinuous, the principal constituents. Fragments of chert planes being .intersected by cross fractures and greenstone can also be recognized but which either cause the rock to break completely other fine-grained minerals and rock fragments or allow the cleavage to pass on to another are not identifiable. The mineral grains plane. In most places it can be shown that average about 0.26 millimeters, but the foreign the cleavage parallels the stratification, but rock fragments are larger than the mineral on the crest of. tight folds it very commonly grains. Both grains and fragments are angular, lies at an angle to the bedding. It likewise more so in some specimens than in others. In intersects the laminae in cross-bedded struc­ general the rock fragments show slightly more tures. rounding than the mineral grains. The sand­ stone is"commonly •dirty•, and in all speci­ Several joint systems can be observed. mens studied the sorting was poor. Although There is usually a prominent joint which trends well Hthif.ied the compaction is not good, more or less parallel to the strike of the beds, and were it not for the siliceous cement the ei.ther parallel or at an angle to the dip. rock woul4 have a high porosity. These joint planes dip to the east or west depending upon the direction of inclination of Under the microscope the quartz is clear the beddlng. Another set of joints normal to and free · of inclusions. The feldspar has the the beddlng can be observed dipping north or composition of andesine or oligoclase-andesine, south at steep to moderate angles. The usual but albit1c varities have bee� recognized, and northwest-northeast joint pattern holds in the grains of orthoclase have been found i.n a few Galice formation as well as the other rocks, specimens. The ratio of feldspar to quartz is and is thought to have been the result of about 3 to 1, there being from 60 to 75 per­ strain produced by compression from an east­ cent feldspar and 20 to 26 percent quartz. west direction. They lie more or less at 45 Other minerals wnich are present but never degrees to the bedding. Bedding joints are abundant are: sericite, magnetite, biotite, common in the massive sandstone. chlorite and epidote, sphene, clinozoisite and apatite, rutile, zircon and garnet. Lithic •pencil structure" is common in the shale fragments includ� chert, shale, altered diabase on the crest of folds and 1s useful for deter­ and basic lava, occasional quartzite and rarely mining the axis of folds. It consists of pumice. or these fragments chert, shale, and short pencll-like prisms due to closely spaced altered basic lavas are by :far the most common. converglng cleavage planes. The lithic fragments rarely amount t� more than 10 percent of the rock. Drag folds are common and occur in thinly bedded sandstone layers as well as in the shale, The strong lithification of the sandstone In fact, where a sandstone is between shale is due to silica cement rilich can be seen as beds, the shales are more commonly crumpled and vel'J finely crystalline quartz surrounding the 6 broken, whereas the sandstone is folded, Many These sedimentary rocks can beet be drag folds are found on the larger structures; studied in the canyons of the Illinois and occasionally they are broken and pass into Chetco Rivers, but they are also well exposed small faults. in the bed of the North Fork of Smith River, where they are accessible by road. Sandstone The folds seen in good exposures are makes up about 40 percent of the formation, typical of the deformation of relatively in­ ahale close to 30 percent, chert 10 percent, competent beds, They are small tight struc­ and conglomerate about 5 percent, tures, generally asymmetrical and discontinuous, and tend to have their axial planes dipping The sandstone is very hard and massive, southeast at high angles, Some are slightly Rarely can bedding be discerned in it, and it overturned to the west and plunge to the south breaks into irregular blocks, Fractures pass at moderate angles, through the sand grains, The rock is commonly cut by many narrow veinlets of white quartz These numerous small folds can be traced which about l inch wide are irregular in for only a few feet and larger folds have course, and have no systematic arrangement, been followed for a fraction of, or at most, In weathered exposures the sandstone is straw­ a mile. Both are undoubtedly small plications colored to reddish brown, but on freshly broken on major folds which may have involved . . the su�faces it is typically light gray to greenish whole formation. gray, On close examination the rock is seen to be speckled, poorly sized, and fine- to In the absence of marker beds or of per­ medium-grained, In places the sandstone is si stent zones of distinctive lithology, it is coarser grained (3-5mm, ) and is a grit. With impossible to interpret with certainty the the hand lens fresh angular plagioclase crystals structure of the Galice formati·on and hence and angular to subangular quartz grains can be to determine its thickness. Any reasonable distinguished, generally in greater amount than interpretation of the facts ascertained in the sum of the other constituents. Some specl• mapping the formation over.a distance of 50 mens contain many shale fragments; pieces of miles from Rogue River to the South Fork of chert and volcanic rock can also be recognized, Smith River indicates that the vo lcanic member Greenish chloritic material is common as inter­ is about 10,000 feet thick and that the sedi­ stitial material, and flakes of biotite can be mentary member is at least 15,000 feet thick, seen, The constituent grains are cemented by silica, s�ch a rock is commonly called a gray­ Age and correlation, --The Galice forma­ wacke. tion was assigned an Upper Jurassic age by Diller (5) who correlated it with the Mariposa Evidence of the beginning of recrystalli­ formation of California on the basis of its zation under strong dynamic action is found in fossil fauna, Taliaferro + (15) has correlated parts of the sandstone, and consists of an it with the Kimmeridgian of Eurpoe. The forma­ abundance of sericite aligned in a common tion rests with angular unconformity on the direction. The microscope may reveal sericite amphibole gneiss. The gneiss, whatever its between the grains, and some of it appears age, has been subjected to a period of dynamic under the hand lens to be growing out of the metamorphism that was not experienced either mineral fragments, Biotite flakes give further by the Galice or the Dothan formations, In evidence of recrystallization, and the align­ both the Kerby quadrangle and the Grants Pass& ment of these minerals gives the rock an quadrangle to the east, the Galicee.a.:L� formation:!� incipient schistose structure, The recrystalli­ of the J.N>l<'l.&�!&�grou_E. _ along its ­ zation has not progressed to the stage where gin s-in thrust-faUlt contact with t m t the plagioclase or quartz are affected, ca�. �Ji,nd me_� asedimenhry �I.'_'?c�§J;- The Galice orma�!on may comprise the first deposits th at It is important to note that under the accumulated on these rocks after they were microscope thin sections of sandstone of the highly folded, As the Galice formation and Dothan formation are identical in appearance the Dothan formation are nowhere in contact with sandstone from the Galice formation, in within the Kerby quadrangle, no new direct that they show the same degree of angularity evidence as to their relationship has been of grains, poor sorting and compaction, excel­ observed, lent cementation with silica (and sometime hematite), fresh plagioclase and similar com­ Dothan formation position, Furthermore, the same accessory minerals in both rocks can be found in the same Distribution, --The name Dothan formation proportions, In brief, the sandstones in the is retained in this report for the sedimentary Dothan and the Galice sediments are both typical rocks that were mapped in reconnaissance by arkosic sediments of the graywacke type, Diller (7) from their type locality near Dothan post office on Cow Creek, Douglas County, south­ Shale is less common in the Dothan forma­ westward into the northwestern corner of the tion than in the Galice. It forme interbeds Kerby quadrangle. Interlayered with the sedi­ between the massive sandstone layers and is ments are irregular tabular bodies of altered usually associated with. chert lenses and basalt flows. This assemblage of rocks extends basaltic lava. It is black to dark gray, along the western border of the quadrangle usually somewhat massive, and �cks well­ from its northern to i4s southern boundary; defined bedding. In places it is hard and according to Butler (2) it extends westward to brittle but nowhere seems to show the degree the Oregon coast. On the east these rocks are of lithification of the slaty-shales of t�e bounded by various intrusive and some gneiss; Galice formation. The shale is commonly a peridotite cuts them out in the southwestern microcrystalline argilla ceoue rock alt hough corner of the quadrangle, and in the north­ in places it may be sandy, Where it occur�··as western corner of the quadrangle they are thin interbed£ between massive sandstone �ayers, separated from the rocks of the Knoxville it is usually strongly sheared, As in the for mation to the west by serpentine and intru­ Galice some shale beds are distinctly carbo­ sive diorite except where all these rocks are naceous and carry carbonized wood fragmemts, buried beneath a southern prong of Tertiary conglomerate and sandstone, 7 Conglomerate rarely occurs in the Dothan folds with successive axial planes leas than formation within the Kerby quadrangle. There 1,000 teet apart have been mapped on the are a few pebbly lenses in the sandstone but Illinois River near the mouth or Klondike 'Creek they are rare . The conglomerate lenses are and on the Chetco River at the western edge of like those in the Galice_tormation. the quadrangle. Drag folds are not common, though they have been observed in the shale Chert lenses are· 'C'OimDOn in the Dothan interbeds . Where a relatively thin shale bed formation. They are not confined to one is confined between thick massive sandstone horizon, but where one lena is present there members, it is usually much c�pled, broken, are likely to be others . They are rarely more and sheared. than 300 teet thick or a quarter ot a mile long, and are interbedded in the sandstone but The folds are ot small amplitude , short­ usually have a little shale associated with rarely exceeding a mile in length but aligned, them, moat often at their base. and tend to plunge to the south. Only one large folded structure, an anticline in the The chert ia dense and cryptocrystalline. North Fork or Smith River near Sourdough, has It is commonly light gray or cream-colored but been followed for any distance. On the limbs occasionally has a greenish tinge. Some ot it ot this told, which ma1 be called the Sourdough is pink to reddish. Rarely 1a 1 t dark gra1 to anticline, are small anticlin�a and synclines black . The chert ia commonly fractured and which have the character of drag folds . It ia tilled with narrow ve1nlets ot ail1oa. The quite possible that there are other folds simi­ rock ia generally very massive. lar in magnitude to the Sourdough anticline , but the absence of good marker beds and the A distinct stratigraphic horizon ot difficulties of the terrain have made it basaltic lava lies at the· top ot the Dothan impo ssible to map them. formation within the Kerby quadrangle. It crops out continuously along the diorite con­ The deformation has been more severe in tact from the valley of the North Fork ot the northern parta'of the belt of the Dothan Silver Creek south to Tincup Creek and apott1.ly fonnation than in the centra1 part , between trom there to ita moat southern exposure on the Illinois River and Johnson Butte, where the east slope ot Johnson Butte. Several other the beds are inclined at moderate angles or small lentils or lava in the sandstone are are flat lying. Even here , they are considera­ scattered through the rest of the Dothan forma­ bly disturbed, however, for altitudes change tion north of Tincup Creek . rapidly acrose the strike, indicating very small, fairly flat folds . To the north and The basalt weathers to various shades or south, however, the beds are inclined at green or, as· on the ridges to the north and mioderate to steep angles and the folds are south ot Tincup Creek, a reddish-brown color, compressed much more closely. not unlike the color ot weathered peridotite. In places it 1a aphanitic and l9oks like green As previously mentioned, bedded structures chert. The weathered surfaces have a blocky are difficult to ascertain, but prominent joints appearanc·e in many places and some appear to that seem to be parallel to the. bedding are be flow breccias. Well developed pillow common. In addition there are prominent cross­ structure can be seen in the masa of lava which joints like tho se in the Galice formation. orops out on the rid8e just west of the bead ot Yukon Creek. Slaty cleavage is not a feature of the shales, though a pseudoclevage--probably due' to In the hand specimen a tresh surface ot movement in the massive confining beds--is basalt ia greenish and tine-grained, and may developed in a few places. be porphYritic. Some specimens are also amygdaloidal with spherical amygdulea l �o 3 Thickness.-Because of lack of marker beds millimeters in diameter; the amygdulea common­ and structural data it is difficult to estimate ly are tilled with white chalcedony, or green the thickness of the Dothan formation. Further­ crystalline epidote or chlorite. Plagioclase more , the western limit of the formation does crystals . about a millimeter long, light- . not lie within the quadrangle and the eastern greenish u·ralit1c hornblende, and in some limit may not be at the top of the formation. specimens , dark -green to black stubby pryoxene It can be assumed, however, that the beds crystals a·re visible with the hand lena . Small exposed in the Chetco River are nearly flat specks of magnet ite and not uncommonly grains lying, because only gentle folding would allow ot epidote and greenish microcrystalline· one horizon to remain at the surface for chloritic material can also be seen. several miles in a direction normal to the strike. Here, then, the fo rmation must be at The lava is sheared in places to .a dark­ least 3,000 feet thick, for there is that much green phylli tic rock which occasionally has a relief and the Dothan crops out from top to aerpentinous appearance. Along the contact bottom. As this part of the aectton ia near with the •diorite•, the basalt ia altered to the top and close to the ·eastern margin of the a schistose rock or transformed to a light­ formation which extends many miles to the colored, fine-grained rook similar to a fine­ northwest, it is not unreasonable to assume grained diorite. that an equivalent thickness lies beneath the horizon at the river level. The refore , we may Struoture.-The structure of the Dothan with safety estimate that the Dothan is from formation, Uke that or the Gali ce. 1a. the 5,000 to 7,000 feet thick. Diller {8) esti­ product ot great tangential compression. Being mates the thickness or the Dothan fonnation in dominantly a sandstone formation, it has react• the Riddle quadrangle to lie from 5,000 to (),000 ed to these forces more competently than the teet. slates ot the Galice formation. Faulting apparently ia more CODIIIOn in the Dothan. The In general the basalt along the eastern small aoale isoclinal folding which character­ contact is gently inclined and it appears thick· ! izes the alatn ot the Galice has not been er than it actually ls. The thickness or the obilerYed in the Dothan formation, though tight basalt here varies between 1,000 and 2,000 teet. 8 Stratigra�hio pos ition and age.--There It was impractical to map eeparatel7 the bas been ·muoh 1sousslon of the stratigraphic different va.rietiea. position and age or the Dothan formation. If the reader is interested in the controversy he More than 225 square miles, or alight may read the literature to which references more than one quarter of th& area of the K Louderback ( 10) , Ward ( 16) , Diller ( 5, 6, 7, 8), quadrangle, is underlain by ·per1dot1te. T lpowlton (9), Taliaferro (15) are given. No largest body extends from the edge of the fossils have been found in the formation Illinois Valley westward a distance of ten with1h the Kerby quadrangle. Mapping of the miles along the southern boundary of the quadrang�e has proved that the Galice formation quadrangl e; to the north it widens to 13 � rests unconformably on gneiss in.the north­ in the latitude of Hawks Rest and Joeephin eastern part and that the Dothan formation h "ounta1n, where it forks. The eastern for 1n fault contact with similar gneiss 1n the continues northward with d1m1n1ah1ng widtb aoutbrlestern part of the quadrangle. No other near Squaw "ounte1n, wbere the rock is ma� new structural or stratigraphic evidence perti­ milea locally aa serpent ine, but about 2 . nent to the problem has been found. Nowhere far�her north it is mapped as peridotite, in the quadrangle have the Galice and Dothan thence continues as two parallel strips no fp ;'lllatiotl!t . been seen in pontact. Until new northeast .to the northern bouna&ry of the ap�_ oo nvino1ng· paleontolog1 oal data are found quadrang�e. The western belt ·ia d�scontln ,.or .tin.tg :!tUffJ..c',en� SJatematio lnlipping of the but the nUIIIerouo bodies or per1dot1t.e and t,-pe. . looa11t1es .of' the two formations and the eerpentlne that occur at intervals in a no iptervlln1ng , �errain is don&, .the . writers think northeast direction to the northern bounds . lt be'st to follow the conclusions of Diller, of the quadrangle are probably part of . a c namely, that the Dothan is younger than the continuous shee.t which has been. cu� out · he G!l1ce., and is equivalent in age to the and there by later igneous intrusion and Prl.l)o_hollJl group of the Coast Ranges of subsequent erosion. This great body of California. The lithologic atmilar1ty of the peridotite will be called the Josephine DOtbllii llfid Franciscan can be attested to by per1d?t1te sheet. the' wr.iters . Weathered peridotite is character1at1 Late Ju rass1o or earlt Cretaceous 1ntrus1Ye rocks buff to rusty red; the dun1te variety is commonly buff, and the eaxon1te becomes rt Intrusive igneous rooks occupy more than w1 th increase in pyroxene content . A.s thE . half of' the Xe�y quadrangle , and a belt of soil on peridotite is uaua�ly thin and vef · these rooks 15 miles wide crosses the quad­ tat1on is sparse, areas unaerla1n by perle rangle from north to south . They are varied are distinctive . Everywhere the per1dot1t in textur& and structure and range in oompo­ cut into blocks by numerous jolnts. Sheet a1t1pn f'rom ul train&fie to dao1t1o·. Where or reticulate jo1nt1ug 1a dominant in plac �co�r� : together they form hetetogeneous .. but 'generally the joints are appare�tly mixtu�s · a�d th� : relat1pnsh1ps. of one to patternless and irregularly curved • . The another . �!:'� oj'ten; in doub�. " The problem of surface of a peridotite terrain is strewn the gehe'sizi'. of th�s complex petr!)graph1o · either with blocks and scattered piles of ass��a�e . o�ot be s�lv�d until more detailed blocks projecting through a scant, �oon· stu� has·been made . In assigning relative colored soil or, with accumulations of she ages ·�o tile: v.ar1ous rook. types· where c;:roas­ sized p'elleta of iron oxide. Tufts of SQ\ outt!n&.·�ela t1o�sh1ps are lacking. or are grass are common, and in wet spots luxuril amb1guou§ �. the writer has set up a se�ence growths of pitcher plants are almost diag· basea· on a widely held petrologic �oncept , noetic. name�y, that in any region igneous intrusion progressively changes from basic to a111c1o. In weathered outcrop the dunite may t This �xped1ent is used as the moat favorable smooth and even-grained, like a medium-grt working hypot�a1a. sands tone, with an occasional black grain chromite or magnetite.' Saxon1te surfaces Ultramafic rocks stmilar except that the aurface .may pe th! . mm. . studded w1th 2 to 5 crystals of enstat Per1do t1te.--P'er1dotites are medium­ In places ' the . enstat'ite crystals may be .i•< g�atnedroc ks , consisting of olivine with or large and thiclf that they; make f!. !:.'O�gh sw wi�hout otner marie minerals. They are some­ thus grading 1nto . a pyroxene-r1qh _ saxonitt times called ultramafic rocks, a term which even in pyroxenite. On pearaoll . Peak th�' tmpl �es essentially a high proportion of mag­ aaxonite is coarse-grained and cleavage�p: nesium and iron. Peridotites of various compo­ of pyroxene an inch lpng can be seen s)l.itl! sitions are designated by varietal names; a in the sun. Dun1 te or pyroxen1te ' may 'bo<:t t� con,ta1nlng more than 95 percent olivine anywhere · within saxonl te aa. irregular bod: and little or no pyroxene 1a called duni�e; Occasionally they are rudely layered. DU fttuirea.il a :variety with more than 95 percent leta of dun1 te and pyroxenite .out the . a &XI pyroxene ·.u called pyroxenite. The moat and each other. Concentration• of_ chrom11 co..On variety of peridotite in the Kerby are deacrib d . elaewhere 1n th1s report. , � quadriuigl'e contait).a from 5 to 95 pe;cimt of .the orthbrhomb1e pyroxene, enstatite, and 1s · ' Pr·eshly brolceri pei'1dot1te · rangell !1'01 called aaxon1te. The ultramafic rocks as a water-green or yellowish-green v1treoua · r, whole are commonly . called serpentine by the to greenish-black .fe.lt -like rock dependin1 prospector and geologist alike, because they the degree of ilerpent'inization . Light-co: �e more or leas altered to minerals of the peridotite 1s' but 11ttle' altered; w�e�eaa' aerp!'tit1ne group. ·This praoti�e. ,has be'im dark-colored rook is almost compl·eteiy al· follbfted in all the previously pub lished to .• felt-like maaa of antigorite. Th.� , geologic mapa of southwestern Oregon. · In thi* . cleavage of the pyroxenes is easily .seen :

report , peridotite 11 used to deno�e· all rock• the fresh �· and is discernible even· · i, ot the .•group whose general ph)'sica1 appearance highly· �1tered . one8 . · a\111 reaa.blea that ot th� original rocks. Examination of:the map aho�a tbat -PYroxenite.--Dikeleta of pyroxenite an peridotite and serpentine are �idespread in �eh �tWO in width cut the.peridotite maaaed the Applegatb .group and within the volcanic in many places. Jarro� dikes .a t� feet in· member of the Galice formation , but are Pd.dth are alao found, and ·aeveral small map� .... sparingly present 1n the sedimentary member of ble maasea of pyroxenite �ith or w1thout peri.; the Gall"ce ·and apparently .absent in the Dothan doti te occur as roof ·pendantS iri the dlori te. formation. The distribution of the serPentine - �ee of these �hich are from 0�5 to l mile in the Applegate group, as for example on the long and up�arda or 0.25 of a mile M.de are west slope of Alder Kountain, suggests tbat found in the diorite in the vicinity of the

the two are interlayered. Chetco River; two other smaller· onea �ere mapped �eat of Gold Basin. Ita distribution ·in the volcanic rocks of · · the Galice formation merits discussion. Serpen­ . The pyroxenite ia a dark l!ireen,coaraely tine areas 30 or 40 acres in extent are crjatalline rock .With large (3/13 to 1-l/4 incb)· scattered through these volcanic rooks , and eryatala of green pyroxene aia1lar in t,pl)!tar- · . outcrop areas of one or two acres have been lnce to that in the suon1te. GeDera.lly 100 . tound but not . plotted. . So- of the · areas are percent or the rock ia pyroxene, but occasion­ lenticular, others have a rectilinear outline. ally a gray feldapar occurs interetitiallT and !hey may occur at intervals along the strike large -.gnetite grains are commonly aaaociated of the formation,· sugge�ting that they ·are ftith the feldspar.� These patches are irregular parts of larger once continuous sheets which in ·outline and the feldspar content is usually are so thin in places that their croppings are small but in a r� places it may be aa much aa lost or have been complicated by faulting. 2� .percent . · Kany or them have rando• di·stribution. That not all the bodies of ultraaatic rock in the SerDentine.-The rocks mapped aa aerpBn'­ Galice formation are of th is character, how­ tine arethO ae perido·tite masaea or parts of ·ever, can be seen in the -lla of t� canyon peridotite maaaea that have been so completely of upper Babyfoot Creek . Here a nearly hori­ ·altered to lllinerala of the serpentine group zontal body of serpentine croaaes the canyon and sheared (o� iJll3; to the structural �eaknesa rudely semi-circular cross section of the of these minerals) that the rooks are distinc­ and . . maaa can be aeen in both walla. It seems ti·ve in outcrop, . and readily di"stinguished f� apparent; however, that in general the the leas-altered and lesa•deformed perido tite� ultramaft·c bodies �ithiri the Galice formation The prcsspectora sometilllea call the rock are thin, roughly eon!'ormable, and tab.�ar �ith 8illiokentite ..• Suc'!l material ia found in major irregular boundaries in plan. fault zones that cut across or toll� the edges �r the larger . peridotite bodies ; in The tabular structure and conformable· places it also makes up the wbole of a thin relationships of the peridotite sheet exposed sheet �hich has been completely crushed by the along Josephine Creek can be seen in aany fault mov-ent . A good example or the tor.er places. ·The tabular form is b"eat aeen. when the condition is found in upper Josephine Creek mau of peridot! te capping County Line Ridge and of the latter west or Onion lt:Nntain. near Pearaoll Peak is vie�ed froa the southwest. Pold1ng haa been so intense throughout the .The con!'ormable contact or the peridotite and rocks that any thin sheet of peridotite -y the Galice formation is exposed near Whetstone have been crushed and altered .to serpentine. Butte and the conformable contact of the rn· some places younger igneous. rocks haTe peridotite �itp the Dothan formation is well intruded peridotite and intenaely aerpentiniaed exposed in the canyon of the lorth Pork of · it nearby. This material haa been crushed by Smith River. Along the upper reaches of '!'Odd later. movements. A good exaaple is near and Briggs Creeks th!' contact of the &lllphibole �ee Cabin. · gneiaa and the peridotite sho�s a alight angu­ lar relation, and near Chetco Peak the �ell .OUtcrops of the moat intensely defor.ed exposed contact sho�a an angular discordance. serpentine are greeni sh gray. Such material The interpretation of the structure of the 1a cut by iDDWlerable slip surf'acea -tted . Josephine sheet that beat explaina all the tosether to form plaits which are braided on .. known facts ia the assumption that the peri­ larger scale. !he pla1:ta cuM'e around scatter­ dot! te �aa intruded aa a great sheet and caae ed blocks or unaheared felt-like serpentine in along pl�ea of weakness. In places it that ia usually dark green· to black in color. .. followed the unconformity between the amphibole · -In slumped outcrops this material .fol'IU a -•• gneiaa and the Galice formation; elsewhere it of flakes and lumps altered al..-ost white; md foll�ed the contac� between lithologically scattered through it are the blocks of w. different mM!bera of the Galice formation or · sheared serpentine, now weathered on the sur-· ·other bedding planes and joint planes. Hence face to a rusty red. Leas intensely sheared the sheet doea not occur at one horizon but ia serpentine is cut by .any slickenaided p1.anea multiple, compoaed of several connected layers. of mov-ent, and is characterized by curyed or Purthe:r:more any layer may jog up or down from bellied polished surfaces. !he rock -y be one horizon to another. There ia evidence that honey-colored, green to dark green or eyen it �as folded during and after consolidation, black. !he lighter colored pieces haTe a and �aa involved in the faulting �h1ch waa the "tXT to horny luster, and are co_,nly trans- . last phase or isoclinal folding. lucent.

The thickness of the a heet ia to be Olivine gabbro measured in tbouaanda of feet but probably does .. not ex?eed 15,000 feet. It has been possible to ou tUne a body ot olivine gabbro �1thin the bornblende . diorite .. Cobbles of peridotite a.re found in the w1th a fair degree of accuracy, and .turther­ BOraetown formation, and Diller (8) aho�a peri­ more to -P coarse-grained and fine-grained odtite (serpentine ) cutting the Knoxville · facies of this body. The boundary between the formation to the north in the Riddle qua�­ two facies can be follo�ed with -elative ease, rangle . The peridotite, therefore, ia believed but the contact between the fine'-grained facies to be of late Knoxville age. 10 of the gabbro and the diorite can be determined :with certainty only where outcrops are good . o0111mon to all the metagabb ro bodi es is U!'Ually :enough to permit the recognition· of the small present as relict corea surrounded -by fibrous gl'B.ins of :olivine whi ch serve to distinguish green ural1t1o hornblende or actinolite. 'gabbro from diorite in hand 'specimen. Original olivine .has been altered to serpentine , or hornblende, and in some instances to biotite,· , Bear York Creek, on the Illinois River· The feldspars may be cloudy, or partly or trail, tyPical coarse-grained gabb ro 1s expo sed.• .completely altered to zoiaite and calcite, It It is a dark rock with '8. gabb roid texture that 1a obvious that some of the gabb ro is younger yar1ea from coarse- tci medium-grain'ed , On than the peridotite, and that some of the weathered surfaces it is gray with rus t spots gabbro is cut by diorite, The relationship of � due to weathering of the pyroxene , On .f resh the olivine gabbro to the metagabbro is not · surfaces the feldspar is ftb.1te to bluish revealed by field evidence, plagioclase and 1nterati tial 'w1th 1't are part­ ly altered anhedral pyroxene , and brown olivine DOlerite and related dikes ·as small yellowi.ah crystals , Occaa19nally the pyroxsne 18 completely altered to uralite , and Fine- to medium-grained White .or dark­ in some specimens uralite can be seen rimming co�ored dik es cut the peridotite and serpenti"ne fresh c�atala of pyroxene , but are less commonly found cutting other near­ by rooks , The dikes are rarely. more than a On good· expoa_urea thll proportion of mafic score of feet wide or mo re than a few �ndred minerals varies greatly from place to place, feet lorig . Most of them have no t been mapped; and there are parts of the rock that are almost but a few that attain widths of over 100 feet all feldspar with but little pyroxene and no and lengths of 500 feet or more have been olivine. This rock called anorthosite, 1a plotted. The dikes appear to be localized coarsely cry�talline and on broken surfaces along zones of shearing in the peridotite and the large crystals of bluish-gray feldspar serpentine , Commonly they are tabular though ehow broad .cleayage faces with prominent twin­ some have very irregular shapes , Some of the Ding banda . dikes appear to pinch out in depth arid become isolated ma&ees or •knock ers• in the sheared The contact be�ween the coarse-grained serpentine , ·Their long dimension usually trends gabbro and the fine-grained facies iii" fairly northeast·, parallel to the regional structure . liharp·, . The latter facies vari es , however, Some of them are fairly flat lying and sill­ from fine- to medium- grained, is dark-colored like in character . None of the dikes show any and the feldspar has a distinct bluish cast, contact effects other than slight baking in a The fine-grained gabb ro arid the contiguous few places and the production of a narrow diorite are similar in texture but in hand sel'Pent1ne selvage in the peridotite, •pecimen: the gabbro 1a d1st1�1ahed by an abundance of olivine aa small {1 millimeter) The dark-colored dikes have a d1or1t1c brownish-yellow crystals. The pyroxene may composition, and either a d1abas1c or 1nter­ be easily mistaken for hornblende because it sertal texture , They consi st of abou t equal �a always accompanied by a little hornblende , amounts of aubhedral interlocking ·crystals of plagioclase that surround irregular but squal'- Under the microscope the texture of the 1sh crystals of pyroxene - either dark-green gabbro is typically hypidiomorphi c-granular. augite or p1geon1te - together with 5 to 10 !he· grain size of the coarse variety Is 3 to 4 percent of t1tan1feroua magnetite, or ilmenite millimeters ; t.hat of the fine-grained type or both, Now , however , the feldspars are mere averages 1 millimeter. The plagioclase is or less altered to sausaurite, the pyroxenes bytownite {Ab2s-3o) and occurs as large sub ­ to a fibrous ural1t1c variety of hornb lende hedral crystals that make up 50 to 6o percent and the ilmenite to leucoxene , Some of the o! the rock ; -it is fre_ah, clear, and twinned diabase contains a bladed brown variety of according to both albite· and per1cl1ne laws , hornblende that seems to be primary, but no .Anb.edral grains of hyp ersthene and au g! te are evidence of olivine could be found • interstitial with the plagioclase and make up 5 to over 20 percent of the rock, Both min­ Other dark-colored basic dikes may be erals are replaced in part by green ho rnblende , included in this group . which also varies in amount , Magnetite is. common {5 - 10 percent ), and is invariably Short sinuous dilres and niggerheads com­ associated with the ho rnblende . Pleonaste pu aed of a dens e fine-grained white rock llre. also is common , and is found with and replaced .common and conspicuous features of shear zones by magnet ite . The original ol1v.1ne content in peridotite, and rectilinear dikes of the ·was commonly less than 10 pe rcent , and the same rock are leas commonly seen in the un­ olivine is invariably-if not completely­ aheared peridotite. The dikes are usually alt ered to serpentine , less than 2 feet thick and the niggerheads leas than 2 feet in diameter. Some of the Metagabb roic complex dikes are so fine-grained that the constituent minerals cannot be resolved unde r the micro• Several bodies of dark-gray ga,bbroic rock scope, whereas in others d1poa1de , �llaston1te, occur either within the peridotit� and ser­ garnet-zois1te ,- and chlorite have been recog­ pentine or as a streamer-like bodies adjacent. nized. In many places the white rock is to the peridotites . In general they are poor­ associated with diorite, but this is not ly exposed. Judging from sma�l croppings and universal . In a few places , as for example at scattered float , they diffel' cona 1.derably in the Oregon Chrome mine {42), it grades into mineralogical composition and texture, but all the diorite by gradual gain of recognizable of them are ·holocrystalline rocks which under feldspar and of dark-colored pyroxene . These the mi croscope are seen to be much altered, dikes are unuaually .r1ch in calcium, and it 1a In places they have been cut and may be partly believed that they repres ent the and product attered by later diorite but the diorite of ·the dior1 te magma and that the ab normal com­ bodies are too small and intricately intruded position is due to the loss of constituents to to be mapped sepal'f.tely, Augite, which 1a the peridotite by the hy drothermal action of 11 solu tiona accompanying the d1or1 te. ·The as• transitional zone or lit-par-lit structure . soc1at1on, appearance, and composition or thi s Strong banding is round at places within the rock are similar to the roding1 te found in diorite. Among the smaller structures a New Zealand. Not to be confused with the rad1al arrangement or crystals was noted. �e rod1ng1 te type rock are 8blow-outs•, irregular texture varies from fine·- to medium-grained areas of a few hundred square feet or deli­ (the medium-grained being the more common, ) cately banded chalcedonic silica; these sili­ and the color varies within a hand specimen ceous bodies invariably occur in highly from light gray to greenish black, depending fractured and serpentinized peridotite, on the hornblende content , The textural and mineralogical variations give to an outcrop As all the dikes cut the per1dot1t!! and either a banded or mo ttled appearance. Under have inclusions of serpentine in them, they the mi croscope the average rock exhibits a are later than th.e serpentine and peridotites , hyp 1d1omorph1 c-granu lar textur� and consists ·Although they are associated with the ultra­ of about 50 percent plagioclase, 45 percent mafic rocks , they are not believed to be hornblende , and about 1 percent quart z. The differentiates rram them. Their relationship plagioclase is zoned and the zones range in to the olivine gabbro and hornb lende diorite composit ion from labradorite (Ab38) to is not clear. andesine (Ab54 ). Magnetite and apat ite are the common accessory minerals . Alteration is aornblende diorite and reiated rocks varied, the products being chlorite, actinolite, kaolin, zo1s1te, and hematite, Few or the D1str1but1on. --Hornblende diorite and crystals are euhedral , but some of .the larger related rocks occupy a belt about 23 miles hornblende crystals po1k111t1cally enclose • long and 5 miles wide in the northwestern rounded grains or plagioclase. 'quarter of the qu adrangle, They are bounded on the west· by the Dothan formation and on . This rock grades . ·in 'to a facies even richer the east by ultramafi c rocks, the amphibole in hornblende ·wbl ch bAs been observed at plac�s gneiss, and the volcanic member of the Galice throughout the mass . The racies contains mag­

formation. The mass is structurally, textur­ netite and the plagioclase is usually a calcic· ally and mineralogically complex. Over half labradorite. of it is composed of hornblende diorite and • there is considerable hornblende-hypersthene . Gabbro;--The average specimen of' gabbro gabb ro. A roughly elliptical body of olivine is holocrystalline, medium-grained, and dark gabbro, wh ich has been described above, is gray. The light minerals are slightly in enclosed within the diorite north or the excess or the dark minerals, The feldspar Illinois River . A small irregular body of generally has a di stinct bluish cast. Anhedral granodiorite intrudes the diorite, and also to subhedral, black to very dark-green horn­ forms a reentrant into the perido tite in the blende and pyroxene are intergrown with the vicinity of Oak Flat ; a large dike or grano­ plagioclase. The lustrous black pyroxene is diorite porphyry cuts the diorite at Pine always rimmed with dark-green to black horn­ Flat on the Illinois River. Large irregular blende . Where intergrown with pyrqxene the sporadi c masses or pegmat1t1c hornblende hornblende is anhedral, but it is not unusual diorite occur in the southern half of the to find specimens in wh ich black hornblende diorite body. Apl1t1c, and less commonly acid occurs as euhedral prisms . In such specimens pegmat1t1c dikes cross-cut the diorite in a pyroxene appears to be absent . Quartz is rare, number or places. and wh ere it occurs there is al so a little biotite . A small elongate intrusion of bioti te­ hornblende diorite about 3-1/2 miles long and Fresh calcic plagioclase makes up about 1-1/2 miles wide intrudes the main peridotite 60 to 75 percent or the rock . The composition body in the southern part or the quadrangle is fairly uniform and is within the labrador1te­ west of Mud Springs . · It , in turn, is intruded bytown1te range, the albite molecule riUlging by a light-colored, fine-grained rock which is rrom 25 to 45 percent , and being mo st often probably related to the dacite porphyry, Ab 30 • About 25 percent or the rock is com­ posed of the pyroxene minerals hypersthene and Other small intrusions O'f 511or1·t e, coarse augite. Both minerals occur commonly in the hornblende diorite, and metagabbro cut the · same Sp!!cimens , with the hyp ersthene being per1�ot1te in the vicinity of Diamond Creek at slightly more abundant. Ho rnblende is ubiqui­ the south boundary of the quadrangl e. A small tous and is invariably associated with the body of diorite cuts the Applegate group south pyroxene it replaces . In some specimens .or Page Mountain in the southeastern corner of primary hornblende , whi ch is not the pale­ the quadrangle, green, fibrous , ural1 t1c variety, completely encloses the pyroxene . It usually makes up It was not practicable to map all the less than 10 percent of the total ro ck .· Mag­ vari eties or the basic and intermediate intru­ netite is no t abundant (less than 10 percent ). sive rocks . Only those types that could be A small amount of primary quartz is round in· readily distinguished in the field were differ­ the rock, an unusual mineral fo r a rock of this entiated in the mapping . They are the olivine compos! tion. gabbro, the d1or1 te r1ch in hornblende and pyroxene, the pegmat1t1c diorite, and the Pegmat1t1c hornblende d1or1te . --Large granodiorite, irregularly shaped bodi es of pegmat1t1c diorite are concentrated in the southern end and proba­ Hornb lende d1or1te.--The hornb lende bly also near the roof of the diorite mass. diorite whi ch probably makes up the bulk or The rock shows a wide variety of textures and the igneous mass is charac�erized by a wide structures, including comb structure, but its variation in textu re and structure , much or distinctive feature is the presence or large whi ch may be seen within the confines of an prisms , commonly 2 to 4 inches long , or black average-sized outcrop. Gnei ssic structure is or dark-green hornblende. The largest crystals common, and on Little Chetco River the diorite seen crop out in the NWi sec . 26 , T. 38 S,, merges into the amphibole gneiss through a 12 R. 11 W., south of Johnson But te, whe re the ·Ceyatal.s commonly measure 2 teet in · length. Granodiorite.-Pive bodiee of granodiorite .!be amount of hornblende varies, but generally �rop out in the quadrangle; one underlie& Pine wakes up leu than halt of the rock. Associ­ Plat on the Illinois River, and another ated with the hornblende are augite and partly intrudes the northern · end of the coarse-grained 111uaau'ri tized labradorite, enclosed 1n and gabbro mass. A third body was intruded along ·interstitial with the hornblende. The minor the eastern diorite-saxonite contact, and accessory minerals are magnetite and pleonaste, underlies Oak Plat, part of Briggs Creek and .which 1118ke up about 2 percent of the pegmatite R'ed Dog Creek . The fourth body erose&$ the :md are characteristic con�rtituenta. Some of lrorth Pork of Diamond Creek at the south border the pegmatite& carry a little hypersthene, of the quadrangle, and trends approximately partly serpentinized olivine,· and in places H. 20° W. along the east side of an equally a0111e sulphide minerals·. large mass of black. hornblende-rich biotite , r The fifth and largest granodiorite body lies .Onetuic migmatite.-Under this name are at the head of ·Baldtace Creek in sees, 11, grouped a la rge number of xenolithic blocks 14, 23, and 26, T. 40 �., R. ll.W. This body renging in· outcrop area from a few acres to lies well within the peridotite mass, containa aa 1a10h aa a square mile. 'lbe larger areas two partly serpentinized pendants of llaxonite, are coBDOnly called root pendants. They occur and is cut by hornblendite. at all deptha within the exposed part of the intrus ive, and are of two types - blocks of The rock 111 characteristically light gray,. aaphibole gneiaa that are scattered through and has a medium-grained texture. Plagioclaae both the diorite and the peridotite, and and quartz are readily recognizable 1n the blocks of chlorite, actinolite, and hornblende hand specimen, and occasionally some potash schists enclosing remnants of peridotite that feldspar can be distinguished. The most common are found only within the diorite. Both types accessory minerals are biotite and hornblende. are common in the area between Soldiers Creek Muscovite ia present in both the Pine Flat and and VUlcan Peak, and both types are character­ Oak Flat bodies. ized by gneissic structure . Under the microscope the rock shows a Tbe amphibole gneiss found within the .hypidiomorphic texture. Plagioclase, e1 ther peridotite in outc�p resembles the other .andesine (Ab55) or oligoclase (Ab75-a5), makes gneiss in tbe area, except that occasionally up from 45 to 60 percent of the rock. It the hornblende seems to have recrystallized forme subhedral to anhedral crystals which into larger prisms . Where it ia found in the commonly are distinctly zoned, Orthoclase diori te, the gneiss is commonly injected by makes up from 10-20 percent of the rock. The the diorite, and cut by small diorite dikes. feldspar is usually partly fresh, but some gray There haa been interaction between the con­ alteration products are always visible. Quartz at1tuent lllinerala of boat and intruding rock. 1s interstitial with the plagioclase and averages about 20 percent of the rock. 'l'lle An excellent example of a root pendant quartz is clear in most specimens, but i.n one ot peridotite in diorite, and the resulting collected from the body west of Mud Springs, 111gmat1te extends through a sharp ridge at it is filled with hair-like i�clusiona of the bead of "lrome Creek. This body is approxi­ rutile or tourmaline. Plate-like ory•tala of mately one-half lllile long, 500 teet thick at brown biotite are characteristic accessory the crest of the ridge, and wedges out 900 minerals in all specimens and make up from 3 teet down �He dip. Partly serpentinized to 10 percent of the rook. Hornblende ia peridotite contains lenticular masses of talc present in small amount (1 to 8 percent) as and denae massive chlorite schist that lie bladed crystals which are commonly fibrous. and approximately parallel to the original struc­ frayed at the ends ; the mineral is partly re­ ture in the peridotite, which strikes lr. 10° w. placed by biotite. Muscovite is present aa a and dipa ·66• liB. The pendant 1s surrounded trace in moat of the rock, but constitutes abo by a thick contact zone of chlorite-actinolite about 5 percent in that from -Oalr: Plat , . Color­ achist with a schistosity that strikes north­ less garnet , sphene, and apatite are common west and dipa northeast. The hornblende minor accessories. Moat of the granodiorite diorite at the schist contact is tine-grained show effects of slight alteration; the �eld­ and cut by numerous quartz veinlets. At spars a.re slightly sausauritized, and there 1e Chrome Butte' the peridotite has been shattered. some· epidote, clinozoieite or chlorite, Tbe fractures are filled with talc, chlorite and actinolite, and the adjoining hornblende Structure of hornblende diorite and � contains inclusions of d.unite seamed related ·rooks. ·Theh0i'llb1e nde diorite /idth chlorite and rimmed by radiating horn­ and gabbro intrus io n 1s of bathol! thio pro_. blende ceystals. There are also coarse. portions , and it is strikingly concordant with chlorite achiats that contain remnants of the regional struoture. Both the eastern and unaltered dunite. western contacts dip east, the western contact being, in general, steeper than the eastern That these bodies may be related to the contact. · For several miles along its western pegmatitic hornblende diorite ia indicated in boundary the intrusion follows a layer of the RWf, sec. 32, T. 37 S., R. 10 W., where basalt in the Dothan formation, and in several from eaat to west the following zones of lllin­ places the changes o� strike in the Dothan are eral association are seen: hornblende diorite followed by s1m1lar changes of strike of the -grades rapidly to coarse hornblende magnetite diorite contact. Where the diorite intrudes rock: next, coarse pyroxene with interstitial the amphibole gneiss and the volcanic member plagioclase; then a central core of hornblende of the Galice formation to the east, the con­ gabbro containing partly serpentinized tacts are �or the moat part parallel to the pyroxene; this central core is bounded on the planar $t ruotures of the older rooks. In west by epidote-veined hornblende gneiss, and many places the planar structures ,in both the to the west of this is coarse hornblende peridotite and the diorite are parallel, and pegmat ite. Olivine is present in a few of the it is reasonable to assume that in such places coarse hornblen�.a magnetite rocks and increases the diorite·oame in along the base of th& in amount near inclusions of peridotite. 13 Josephine peridotite sheet, In a �ew places both the eaatern and western contacts are although parallel!._ ·of the long axea ot faulted and in a few others they are more or priau.tio minerals was rioted wher.e it is con­ leas tranagreaaive, but broadly the structure spicuous. The alignment of schlieren is ot the diorite is that or a large sill-like another common and readily determined linear sheet emplaced along the plane or weakness structure and it parallels the crystal linea­ between the Dothan formation and the older tion. rocks; .the same plane had been followed earlier by the Josephine peridotite sheet . .The other small d.ioritic intrusions out the peridotite and other rocks •.As these The structures within the sill, as weli bodies are elongate in their outcrop plana, aa the areal form and the trace of the contacts and their ·longer dimensions usually agree with ot the sill with the rocks into which lt has the trends of the folds and complementary been intruded, show that the whole body dips faults ot the region, it may be assumed that to the east at a moderate angle which averages the bodies are tabular and have been intruded about 60°. As the aill baa a fairly con­ either as aheeta along faults or as sills alo� sistent outcrop width ot about 2S,OOO teet, it bedding, probably 1e about 13,000 to 20,000 teet thick. Dacite porphyry The diorite is broken by several types ot joints, only a few ot which oan be analy&ed In the sout�eatern part or the quad­ at the present writing, rangle, especially around Soul"Ciough Cup, occur irregular-shaped knob -like maeaea and plugs of' Crose joints, or Q-joints, perpendicular light colored aphanitic to tine-grained rooks• to the lineation are very common. Moat ot Though varying somewhat in texture, they proba­ these erose jotnts trend about B. so• w. It bly are of about the aame composition and are · should be noted that this direction is nearly, here grouped together under the name ot dacite though not quite, normal to the prevalent porphyry . The largest body or the dacite 41rection or strike of the foliation. These porphyry is west of Mud Springe in the valley are tension joints and are present everywhere , of Baldtace Creek. A large dike of' this rock even where the rock does not have observable also intrudes the Dothan formation along the lineation. They are usually vertical or dip crest or the Sourdough anticline, and small at very steep angles. bodies cut the peridotite and serpentine. Dikes ot dacite porphyry also intrude the Two other common directions ot jointing granodiorite. almost invariably occur together. 'l'tley trend north-nort�eat and northeast, with the acute On weathered surfaces the rock: is very angle between them pointing nort�est and light colored , chalky white or white stained · ·southeast. These two seta of joints dip at with limoni te. Fresh aurtacea show a holo- mode�te angles in opposite directions, and are crystalline, generally porphyritic texture and interpreted as be.ing due to shearing strains in some specimens a flow structure can be dis­ set up by compression from a southeast-north­ cerned. The phenocrysts are commonly individu­ west direction. '!'hey rarely, it ever, are al rhomba ot feldspar, though i.n some spec1msna l til.l.ed with dikoo 'but may cut and ott'aot apl.ito l.oaa porfoot laths o!' feldspar a:re s:rouped to­ dikes. gether. They are from 2 to 3 millimeters across. Small water-clear crystals or quart& Plat-lying joints have been seen near the may be present. The groundmaas is very fine­ contacts and �here the lineation is well . gralned to llicroorystalline, and 1a composeC1 dev eloped, They dip at low angles (5° to 25°) or feldspar, quart&, and scattered frayed blades in any direction. Where linS�-tion is vieable of hornblende or biotite and lalsoovite. the joints are parallel to the foliation, but in several �laces they have been observed The rock: that intrudes the. peridot! te on . unaccompanied by viaable lineation. �he ri_dge north ot Sourdough Qamp 1a more or· leas typical or the more coarsely crystalline . �though the diorite is more or leas variety. It ia fine- to medium-grained and isotropic in ita ' central part , it takes on a composed of euhedral �aths .ot plagioclase in distinct foliation as either the eastern or trachyti,c arrangement . In the groundmaaa are western contacts are approached. This folia­ laths (2 - 3 mm, long) of orthoclase, and a tion is usually manifested by prismatio horn­ small amount of accessory minerals which blende and pyroxene crystals in parallel planes, include biotite and hornblende both of which and commonly the elongate priama ot these min­ tend toward euhedral development . This rook: erals are arranged with their long axes is coarser-grained in the central part of the parallel, so that a lineation is imparted to body and has a tine-grained border facies. the �&sa. Detailed petrographic studies have not . in geueral the foliation strikes north- been made of these rocks, but their megascopic northeast and parallels the conta cts. Dips characteristics allow them to be placed in the on the eastern border average 45° to the south­ dacite group and to be correlated with similar east. On the west side the dip is likewise rocks in the Port Orford•(Diller 4) and Riddle toward the southeast but is usually steeper, (Diller S) �uadranglea. between 45° and so•. In some places near the eastern contact the foliation is d.rag-folded Cretaceous system to a pronounced degree, The impression in the field has been tt)at the planar etriloture 1a Boraetown formation more perfectly developed along the eastern· than along the western contact. So !'ar aa could be Sandstone and conglomerate or the Horae­ determined, the lineation lies in the plane or town formation (Shenon 14) crop out in the the ·foliation. southern part or the Illinois Valley where the7 are exposed along the east side of the West The aoale of the map did not pel'lllit Pork ot the Illlnoia River near Waldo for a systematic mapping ot the linear structures, 14 length or 5 ailes,and �idth ot about ll ailes, Along 11111ch or their eastem boundary they are diameter occupy the interstices betw�en larger in fault contact wi�h serpentine. Tb the pebble s, cobbles and boulders , the largest ot south they unconformably overlie the steeply which are over 1 toot in diameter. The dipping Galice formation, and to the west and material is in general subangular to subround­ north they are burled beneath Recent alluvium. ed; more rarely it 1s well-rounded� Di or1 te On the average the formation strikes X. 30° W. is the moat abundant rock in the conglomerat e, and dips 30"' BE. A thickness ot about 5� 000 .iNt there is some peridotite. feet is expo sed. Both black shale and gre enish sandy layers The lower beds or the Borsetown formation are scattered th.rough the formation. The black are largely or coarse conglomerate with some shale commonly is carbonaceous an� may be coaly, interbedded sandstone . The conglomerate is owing to the. abundance or carbonized plant re­ we ll exposed along the West Fbrk of the mains . In at least one place a thin stratum ,Illinois River at the base ot Indian Hi ll , ot carbonaceous shale has yielded well­ where it is a chaotic assemblage of rudely preserved fo ssil leaves . cro ss-bedded boulders , cobbles , and pebbles in a sandy matrix. The boulders , cobblBs , and .The Arago formation overlaps the sedi­ pebb les are well rounded·, and consist ot vari­ mentary rocks and basalt flows of the Dothan colored �a rtzites , black slate, porphyritic to l'!IW-tion, as well as the dioritic rocks and basic and silicia volcanic rocks , altered peridotite that intrude them . The floor on diabase, a tew variet.ies of granitic igneous Plhich the sediments were depos.ited appears to rocks and, noteworthily, a few well-rounded have been fairly smooth and rolling. The cobb les or · ooarae-grained, bastitic serpentine. formation has been only slightly disturb ed atnce deposition, so . that in general it di ps Sands tone mak es up the bulk of the forma­ onl7 about 5° toward the east. In a few places , tion. It is massive and grayish green where as near the mouth of Silver Creek , it is gent• tresh, but during · weath,ering it has a tendency ly folded. Normal faulting has depressed to deve lop large spheroidal structures, the small blocks of .the formation several hundred ·long axes or which are parallel to the poorl7 teet below the general level of the formation·. deve loped bedding . Closer inspection shows Other blocks that· have bean elevated have been some or the small spheroids-2 to 4 inches in partl7 or completely rsmoved. by eros ion. A� diameter..:..to be concretions or medium-grained the mouth ot Silver Creek the formation 1s micaceous sandstone that have. formed abou t disturbed consi derably by a high angle reverse fo ssil nucle"i . The sandstone iti remarkably fault that has brought the b�salts and sand­ even-grained over considerable areas . Angular atone ot the Dothan over the Arago . The fold­ ·quartz and some feldspar grains-tor the moat ing ot the Arago near this fault 1s probably part less than 0.10 mm. long-constitut e almotlt a reflection ot the movement along the fault. 30 percent of the prevailing sandstone, and highly altered chloritized material makes up The max1lllllll thi ckness or the Argo forma­ the remainder:. tion in the Kerby quadrangle is determinable on the ridge just south ot Indigo Creek, where Tertiary system it is about 500 feet . The formation thins rapidly toward the east, wedging out completely Arago format ion in less the.n halt a mile; and soutbJolard it thins to ab out 250 teet near the mouth or A prong of the Arago group extends south­ Silver Creek . ward into the norti:Dveatern comer or the Kerby quadrangl e, where it 1s exposed for 5 miles A fairly persistent layer of conglomerate along the east aide of the canyon of the occurs at the top of the formation; this layer Illinois River. The beds exposed here are is approximately 75 to 100 feet thick . The referred to as the Arago .fo rmation because in sediments below the conglomerate are compo sed this locality they cannot be identified with principally or sandstone, with scattered small the subdivisions ot . the grou p. They repreaent lenses of conglomerate. a shoreline facies of a marine deposit which acCUIIIIllated in a shallow arm or a sea that A collection of fossils from just north was surrounded by a mountainous sho re . The ot Indigo Creek has been studied by.Stewart formation is an assemblage of lenticular (personal communication) . Be assigns them to bodies or sandstone and conglomerate in nearly the Arago • Weaver (17) has recently reviewed equal amounts with thin interbeds or. shale. the Arago formation and assigns it to the It is characterized by poor sort·1ng, cross ·upper Eocene. bedding, and abrupt lateral and vertical vari­ ation. Old gravels

The sandstone is a dirty-green hue, ·and Within the quadrangle, two areas of rotten ranges in grain size .rrom medium through gravel are found on an �ld upland surface of coarse to gritty. The average grain size is low relief . One area underlies Gold Basin, 1 to 2 m1lllllleters . . The grains are a ubangular the other lies to the northeast of Yo rk Butte. to angular, the sorting is poor, and the Both are at an alti.tude ot about 4,000 teet . entire sediment appears to be poorly washed. In his comprehensive study of the physiography Lithic grains , pieces or diorite, sandstone, of the Klamath ftountains , Diller (3 7) named , · greenstone, and a little peridotite make up this surface the �lamath peneplain and about two-thirds ot the sand grains ; the assigns the planation to the ftiocene . Further­ remainder are mostly quartz, though a tew more , he states · that • •••the condition Which feldspar crystals and an occasional pyroxene the Wymer beds record is th at of the Klamath or amphibole grain can be found. The sandstone peneplain just before it was uplifted to is loosely consolidated and cementation is initiate the plateau of the Klamath ftountains .• poor. Recent N:>rk by the wri ters in the Gasquet qu adrangle just to the south of the Kerby quad­ The conglomerate is as poorly sorted as rangle indicates that the altitude of the sur­ the sandstone . ·Pebb les an inc� or so in 1.5 face on whi ch the -w,.mer beds• rest is at or below 2, 200 feet and does not rise uniformly Galice. Several lllinlng 111en of long experleno' to the Xlamath p�eplain surface at 3,200 teet 1n the region report that the Old Channel and ab ove. Apparently ·two distinct surfaces of ·extends sou.tbward beyond Briggs Oreek to the planation that are separated b'y a marked change neighborhood or Waldo . Aa this interpretation in. al.ope were out during periods of dlf·ferent �s tenable, the writers have correlated these· baae 'level , It is questionable whether the . gl'avela w1 th the •Tel'tiary gl'aver• ( Shenon 14) dating by Diller 1a valid, but turt}ler analysia in the Takilma-Waldo area., and they are fully ot this problem 11111st await fuller diacuaeion aware or the tact that such an lnterpl'etation els.,.here. requires the Takilma area to have atood·· about 1, 500 teet higher than the saddle between Slx About 150 acre.a of the upland surface Kile Creek and Soldier Creek when the •Tertiary called Qold Baain ia underlain by a gravel gl'avel• waa deposited, · depoait, · The tllll thickness of the gravel down to the ·weathered surface of the underly.ing . 'J.'he masa of ce�ented gl'avel of the Old diorite i� well exposed in the bluffs along the Channel at Column Rook covering an al'8a roughly basin's southern edge at the head of Sluice estllllated at 10 acres, caps the terrace on the Creek • . 'fhe gn.vel is as 11111ch' aa 110 teet thick end of the divide between Swede Creek and . in ita oen�r«l part but thibs rapidly to the Onlon Cl'eek, The uppel' layer of gl'&vel, about eaat and weat. The gravel, though somewhat de­ · so teet ln thickneaa, is til'lllly cemented and colllposed,· i'a 1110re or leas firmly cemented, · and tol'llls a prolllinent bluff tro111 the top of W'lhich thls condi'tion extends throughou t the mass. rises a column of conglo111erate that ·fo rma a .It ha• been tunnelled on bedrock for 30 feet. plctul'eaque teatul'e of the l'eglon , Another .The gray el ia very poorly sorted and cpns.iata al'ea ls exposed .in the road cut ln the sou til­ generally of cobblestones. and bould..era up to western corner of aec, .36, .T. 36 s., R. 9 w·, •i feet in dia111eter lllixed with pebbles and sand, Xoat of the material ia subrounded, The pebble a of the. uppel' layer or the although so111e ia .uba:ngular and so111e ia well mass at ColUIIID Rock are generally of tufts rounded• Hornblende diorite 1a the 111oat and lavas of the Galles formation wlth minor .COIIIIIIOn rock represented 1n the trapents; quanti ties of alate of the Galice •.'l'bea ·e other common typea .are: aandatoJle and chert pebblea . are subangular and leas than an tnch· ot the Dothan fol'll!ation; 111etavoloanic rooks, in di a111eter, So111e layers s·how that the stratl­ bot� flows and agglo111erates, of �he Galice ticatlon ls horizontal and that the depoalt formation; iaetllliiOrphio rocks , includi-ng occupies a shallow valley at gentle alopea muscovite schist, quartzite &lllphib ole gneiss, cut in bedrock by an ancient stream. The peridotite, pyroxenite, and .&Jl occasional lower 150 reet ot the deposit ia coarse gravel, quartz P.ebble . The upper part of the depoal t ' so poorly ce111ented that it does not form is of tlner texture and consists or angular ledges on the slope below· the bluff • .It con­ to isubarigular trapents, 1110stly less than l tains many cobbleston.e.a 6· to 8 lnchea ln. inch in dla�eter. Scattered through it are di&llletel', whlch. al'e Yfell · rounded , · fl'esh and a few large · well rounded pebbles. The deposit smooth, without signa of weathering • . .Th ere d ll'e is capped by reddish soll� and rock decay s0111e lava bouldera, especially near the bo�tom, oxtona. from top to botto�- All types and all the lal'gest ones belng about 4. teet ln di &llleter, sizes of materlal show much weathering. Hear the top of ·the !1epos1 t,. cobbles of dense The gravel to the south on· the dlv1de aphanitic. volcanic rock, and .even cherts �re between Swede and Soldlel' Creeks ls sllllilar, . altered to clay. Alteration ia l�as int�nse but the coar.ae boulder and cobble bed was not at dep�h but. 1a always present in so111e degree, seen;

Stratification la hard to see but ia ·The ae.vel'al bodies of conglo111erate 1n the sufficiently well developed to show that the northwestern pal't or the Takllma-Waldo diatriq�, bea. strike 1f. 35° B. and dip 35° SB,, The chiefly on the divide between the Bast and West depo,it !a cut by widelY spaced vertica� join�a. Forks of the Illlnols River,· are evidently the Obviously the beds have been tilted toward the eroalon re�nants or a once contin�ous rol'lll&� southeast, and the whole surface of low relief tion which had· a 1118xilllllll thlcknea·a of at least on . �ich tpey rest 111ay have been tilted a few 400''. fe.et' between Allen and 3al·lor· Gulches ,· , . · degrees · in �hla direction, The for�ation was The cpnglo111.erate la 111ade up of· -11 rounded lald down . by a. strea111 which, according to cobbles. and' boulders in a-·IIIAtrlx of sandy. clay, Diller (7), flowed northward. A. feYf'of the bouldel's ar.e aa. 1111ch as S teet· in di&�eter; but most &.l'e �eas than l :foot 1n qua ternary sys te111 dia�eter. We.atb ..lng haa deco111poaed the fo�­ tlon. to · such,· an· extent that- q!Ost· of. the'- cobblea Au riferous gravels .ot the second tall to pieces l'ben l'eleased tro111 the mass . .. cycle of eroalon .The cobbles and nuclei or bouldel'a that l'emain . fll'lll cona1at:-..tnly . of greenstone, but- a· few Small patches oi atraa111 grayel ha�e beeri are of chert·: or other fine-greined• sl�iceous found on the dlvldes. between Onion and Swede sedl111entacy · rocks.. The �atl'ix la abundant and Creeks and between Swede and Soldi�r Creeks, 1n places, pa.rtlcul&l'ly ln the lower part of They are in general nearly 1,500 teet below the tor���&tion, there are lena-llke bodle.a of the Xlamath. peneplaln, and tro111 700 to 2,600 sandstone. 'l'hls fol'lll&tlon haa been aaslgned teet above the· nearest points of the Rogue and to the Tertiary by Shenon (14), · Illinoia Rivera .between "hioh they· li e.. . . Diller (7) called the111 au riteroua gravela ot . Lal'ge lUIIIpa· of oarbona·ceoua alit contain­ the · Second Cycle of Broalon, He pointed out ing 1118DY fragments or wood and lear lmpreaalona that they are probably related to the gravela were collected by the Wl'lters in 1945 from · a · ot the Old Channel at ths mouth of Galles layel' of sandy allt exposed in the bank. ot. Creek on Rogue Rlver and were probably depos it• gravel ln the Rapp diggings of the Old Channel ed by the ancestral Illinola River at a tlllle mine above Rogue River near O..lloe, 'l'hia . when that river flowad .northward tro111 . lta . gl'avel l'esemblea closely in degree of weather­ present course just above the 1110uth of Slx ing the •Tertiary gravel•,· tn . the 'l'aklJ.ma,..Waldo Klle Creek to enter Rogue River just below 16. area:. The . material -• examined by ; R. W. Brolm,_ (Personal communication) who branch of Long Creek (sec. 16, .T. 41 s., reports: •The organic material visable to the R. 8 w.), the other in upper Fresno Creek, hl.ve nak ed eye, taken from the matrix of this been recognized t·o be glacial deposits. T�e collection, consists of fossil wood of Douglas first is a well developed end moraine at an Pir (Pseudotsuga taxifolia), fragments of bark altitude ot 3,000 feet. It has the character­ of Douglas fir or pine, and shredded plant istic form of an end moraine and consists of debris of indefinite identity. From the com­ some subangular boulders of ho�nblende diorite, paratively unaltered condit·ion of the wood I and volcanic rocks of the Galice formation but suspect that the remains are of late Tertiary mostly of sandstone of the Galice. The second or, more likely,. of Pleis,tocene age •.• is a boulder moraine of peridotite piled up in the bottom of the canyon of Fresno Creek at Llano �e . Oro formation and bench grav el an altitude of 2,850 feet. Both moraines are downstream from glacial cirques. The forms of Rusty-red clay, sand, arid gravel crop out the cirques and of the moraines show no modi­ as a terrace arqund the margin of the Illinois fication by weathering or stream erosion, so· Valley and its tributaries, �d within the it is, assumed that they were formed during the valley this material occupies a��st the last glacial stage (Wisconsin) when glaciers entire area between the East Pork. �nd the West of alpine type extended down to this altitude. Pork of the Illinois River. 'It rises to an altitude or 1,500 feet around the valley edge, .Alluvium but in ·the valley bottom pas been partiallT or complet-ely removed by eroSion. Shenon ( 14) In general, all the streams west of the named these depo sits the Llano de Oro forma­ Illinois Valley except the very short ones tion after a mine of that name now included o.ccupying short , steep gulches are flowing in in the Esterley mine h9ldings. He - points out narrow steep-walled trenches that have been cut that the formation cont.rasts strongly .with down from a series of benches a� various levele the later Pleistocene - gravels and assigns it above their beds. The bed-load in these. . de­ to an early. part of the Wisconsin stage · of grading streams accumulates as transient small glaclati on. The form�tion is well exposed in bars and banks of sand, gravel, _and boulders , the zuad cuts along U.\ S. Highway 199, south in places of slack water. The gravel .depo sits of the East Fork 'of the Illinois Rivero on the lower-level terraces were part of the bed�load and like the alluvium of the present In the placer workings of the Esterley streams, with which they are included, consist mine, the depos�ts consist of alternate lenses_ of loose coarse gravel and boulders . Accord� of boulders and ��bbles and of soft ·buff silt, ing to the placer miners, the precious-metal. but in general, the formation consists pt va+ues occur throughout the· deposits and are poorly sorted clay and sand with scattered not all concentrated. on bedrock . In places pebbles and cobb les or · thin lenses of gravel the lower terrace depo sits merge into - �i'ach in sandy silt. Colors are commonly rusty red other and into the colluvium of adjoining to buff, and the material is more weathered slopes, and hence all these dep.osits are mapped than the younger alluvium. The format ion nas as alluvium. It is probable that the placer a maximum thickness of 100 feet but is common­ deposits of Althouse Creek include some materi­ ly less than 50 feet thick. �n places the al that is of the same age as the bench gravels, formation has been tilted. It 'is believed to but it is not practical to map such mat'erials be of Pleisto�ene age. separately. ·. ·· . Sou thwestern Oregon was appar�nt ly The bottoms of many of the small valleys elevated about 1,500 feet following the de­ east of the Illinois Valley are filled with position of the auriferous grav els of the colluvium or •slide ro'ck• , a jumbled mixture eecond cycle of erosion. The streams trenched of large and small angular rock fragment s, sub­ thems elves to . grade and were able to widen rounded cobbles and .pebbles, and sand. · The their canyons in areas where the rocks were placer gold which is found in many of these easily eroded. It was · then that the Illinois valleys is coarse and rough and is distributed Valley was caryed out of the sedi�entary rocks throughout the colluvium, indicating that it of the Galice formation and �he Appl egate group has· not traveled far. and the rock·· surfaces of the pr·esent high benches cut a�ong . other streams . Later,' the STRUC'l'URis country to the west of the Illinois Valley was either tilted eastward or raised relative to General statement the region to the east; while the streams to the west were busily cutting box canyons, the The dominant structural feature• of the Llano de Ore formation accumulated in the Kerby quadrangle are indicated by the distribu­ Illinois Valley: Hence the gravels on the tion of most of the rocks as parallel bands high benches are probably of the same age as trending north-northeast and dipping steeply the . lower part of the Llano de Oro. Having eastward, and by an anomalous age sequence of been deposited by degrading streams , the rocks from old on the ·east to successively bench gravels consist of coarse material, sand, yo�nger rocks toward the west. Such a distribu­

gravel, and boulder gravel commonly containing tion can be brought about by overturned iso- • boulders many . feet in dia�eter anq do not con­ clinal folding a�companied by high-angle tain the silt. and clay that make up a large reverse faulting roughly parallel to the limbs part of the Llano de :Oro formation·, These o£ the folds, followed by injection of the grav els rarely exceed 25 feet in thickness, igneous rocks along these faults or other although the bench· grav el along Jos·ephtne parallel surfaces of weakne ss such as uncon- · Creek is more than 100 feet thick in places formi ties. All the observed structural data and is fi�y cemented. It rests on decayed are in harmony with such an hypothesis •.Own­ bed . rock, as do the· gravels found along ing to the lack of widespread distinctive Althous·e Creek and elsewhere . lithologic or f·aunal horizons in any of the formationa and the necessary supporting struc­ jllacial mQraine tural data, it has been 1mpossibl� to work out even the majo� folds sufficiently to warrant two depoe1ta of coarse debris, one in a 17 describing them in this prelildD&J07 report. Some or the major reverse rault� are well northeast course outlined i·n a preceding enough known to be named and described. Others paragraph, The trace or the eastern part or undoubtedly exist but are not named because the zone across the ground eurrace indicates they are largely interpretive and their po­ that the zone dips steeply to the east; a sitions are not known. western branch has a more northerly trend and Reverse rau1te dips at low angles toward the east. The net relative displacement is east side up and must A great zone of faulting enters the quad­ amount to several thousand feet, rangle from the south, in the east slope of the valley or the West Fork or the Illinois River, The Lime Rock fault can be studied best The trace or this fault zone, which consists on the ridge east of Kerby especially at the of a plexus or braided and bifurcating rault base or Lime Rock where the fault was first planes, trends north-northeast along the west recognized and also in the northwest quarter aide of the Illinois Valley. Near Parker Creek ot sec, 9, T. 39 s., R, 7 W. This fault and a branch swings eastward. This is named the ita nume.rOus offsets can be followed along Lime Rock fault. The middle trace 1s lost this ridge and eastward into the Grants Pass under the alluvium of the Illinois River quadrangle where it is cut ott by a quartz Valley. A western branch enters the peridotite diorite stock. To the west and south the near Parker Creek and its trace follows fault is buried under the alluvium in th� Josephine Creek, Illinois River west or Bight Illinois Valley but ita junction further south Dollar Mountain, and the vall� of Squaw with the Illinois Valle y fault System hr known. Creek where part of the displacement follows Another plane of displacement appears in the the serpentine that heads toward Serpentine serpentine north or French Flat and passes Point; the other branch follows the band of west of Waldo until it enters the Galice forma­ serpentine to the east into the valley of tion where it cannot be traced. This rault Clear CreeK where it is offset by a traverse corresponds in location to the Orleans fault fault and continues north-northeast to the shown on a map by Hershey,(9) and it is proba­ Rogue River. This whole group is called the bly related to the Orleans fault but, only as Illinois Valley fault system, one or many faults that bring older rocks against the younger Galice formation. Prom the southern boundary of the quad­ rangle to two miles north of Woodcock Creek The IA.me Rock fault has been offset by the Illinois Valley fault system is marked by many tear fau lts that stri.ke from north to 45° a zone of se.verely sheared serpentine. At its west or north arid are nearly vertical, The southern end in the vicinity of Whiskey Creek Lime Rock fault dips steeply eastward from 70° and the West Pork of the Illinois River the to near�y vertical and brings the Applegate rault planes lie competely within the peri­ group against the upper part of the Galice dotite. The zone is concealed beyond O'Brien formation. The relative displacem�nt is south by the gravels at the mouth of the canyon of block up and it must amount to several thou­ Rough and Ready Creek. North or Rough and aand feet, Ready Creek the fault zone is well exposed and is topographically denoted by steep front , Other reverse faults occur to the west, aligned saddles and springs . From here to the They cannot be traced as far along the strike end of the zone the upper Galice rocks are as the faults just described, but they proba­ brought directly into contact with the peri­ bly represent major displacements. One can be dotite by the fault . recognized in the valley or Horse Creek at the Eureka mine and can be followed 3 miles south­ The average strike of the fault is N. 27° ward into Rancherie Creek. Another crosses E., the dip is at a steep angle to the west, the upper drainage basin of the Little Chetco and the relative displacement is reverse, the River in a southerly direction. Reverse faults peridotite having moved up and eastward rela­ of small dlsplacemen t are found a·long the con­ tive to the Galice block. The amount of dis­ tact of the hornblende diorite with the Dothan placement cannot be determined but must be formation. These faults probably are the several thousand feet, product of renewed movement along the major fault that, prior to the intrusion �f the The branch of the Illinois Valley fault hornblende diorite, separated the Dothan forma­ system that trends north from Parker Creek is tion from older formations to the east. A marked by a zone of crushed and comminuted reverse fault cuts ott the Argo formation in serpentine that crops out conspicuously in a the nortpwestern corner or the quadrangle at series of saddles on the spurs between the east­ the mouth of Silver Creek . Here a pillow ward flowing streams and then follows the basalt of the Dothan formation has been severe­ upper canyon of Josephine Creek, Partly ly sheared, imbricated and thrust up and over serpentinized peridotite is not a competent the Arago formation. The fault aone is over rock and completely serpentinized peridotite 100 teet wide, strikes N •. 25° B., and dips 65° ie less so, hence shearing stresses tend to be to the southeast. The displacement involved dissipated by many small displacements along in the post-Arago movement is in the order planes that horse-tail into the peridotite and of 200 to 300 feet. cannot be followed in the field, They are concentrated at intervals along the strike in The earliest date of reverse faulting ia well defined zones, in places several hundred not certainly known. Folding and reverse feet wide, or greenish-p-ay sheared serpentine faulting involve the peridotite. The intrusion that are conspicuous in the burr or rusty-red of metagabbro along the strike of the fault in peridotite. Where major shearing followed the gulch of Slate Creek and to the north thin layers of peridotit� the whole layer is a�ggests that faulting antedates the intrusion crushed to form sheared serpentine, It is of the gabbro . Both: the peridot! te and gabbro difficult if not impossible to trace or map are older than Horaetown and younger than early the actual component parts or the faulting for Knoxville. Movement has recurred along theae several reasons . There can be little doubt, f�lts even until recent times or until just however, that major high angle reverse fault- prior to the cutting of the inner box canyons, The box canyon in the valley of Josephlne Creek ing continues northward following the north- 18 and of other atreams west of the Illinois sand feet . nost of these faults are tear . Valley fault system are cut through the bench faults formed during the late stages of iso-· gravel. clinal folding and reverse faults that invalved the Galice and Dothan formations and also the Northwest-trending structures peridotite . .Similar stresses though of lesser magnitude later faulted the dioritic rocks, A normal fault separates the amphibole and adjustments have taken place along these gneiss and the Dothan formation in the south­ faults at intervals into the Pleistocene. western part of th e quadrangle. Its irregular trace trends southeaat along the southwest MINERAL DEPOSITS flank of the ridges dominated by Chetco Peak, from the south fork of Chetco River to knob 3890, This fault, here named the Chetco fault, dips at moderate angles to the southwest , The Moso rocks weather to clay, so small relative disp lacement along the Chetco fault amounts of this material are present almost is north side up and possibly is several thou­ everywhe re . No deposit of clay has been found sand feet. The strike of the Chetco fault in the Kerby quadrangle that is of good enough does not conform to the dominant structural quality, in large enough amount , and well trend of the quadrangle but is pa rallel to located for commercial exploitation. The other structures in the southwestern part of Macfarlane Brick Plant (59) has operated briefly . the quadrangle . The contact of the peridotite with the amphibole gneiss along the crest of Ghromite the ridge a few thousand feet to the northeast bas the same trend as the Chetco fa�lt , and More than 22,000 long tons of chromite , dips at a low angle toward the northeaat. But most of which came from the Kerby quadrangle , as the contact bevels the structures in the has been produced in Josephine County . The gneiss it probably rep resents an erosional Oregon Chrome mines (42), on the Illinois surface rather than a fault. A similar north­ River, are the largest producer of chromite in west trend is shown by the elongation of the the state , and are credited with a production hornplende diorite bodtthat crops out to the of more than 12,000 long tons , Othe r proper­ southeast along the strike on County Line ties with a production of 1,000 long tons or Ridge just north of Cedar Springs ; and also more are the Chollard (44) and the Sordy (24) ; by the parallel trend of the axis of Baldface the latter and the Sourdough mine have been antic line (see Dothan formation structure) described in publications of the U. S. Which lies to the southwest in the valley of Geological Survey (We llsl9 ), and other deposits the North Fork of Smi th River. have been described by Allen (1),

This major difference in structural trends Chromite, the only chromium mineral of may be restricted to the Dothan formation and economic importance , has a dense , black or the yo�nger igneous rocks intruded into it, even bluish-black color, a pitchy luster, and In that case a ma jor unconformity would exist a spe cific gravity of abou t 4,5, It occurs as between the Dothan and Galice formations, or disseminated grains as much as 2 millimeters it may involve th e Galic� formation . The in diamete r, and as aggregates of such grains. latter assumption is supported by many measure­ It is easily distinguished in the field from ments of the strike and dip of the Galice vol­ the black manganese ores by its higher speci­ canic rocks in the drainage basin of the Little fic gravity, and from the black minerals of Chetco River where they crop out to the north iron or copper by its characteristic chocolate­ of a band of peridotite several miles wide ; brown streak when scratch ed . Comme rcial these measurements indicate that the trend of quantities of chromite are found only in rocks the Galice fo rmation swings eastward, but of the peridotite group, and in southwestern other equally good measurements have the Oregon exclusively in dunite, a rock composed dominant trend to the north . Furthermo re, of 95 percent or more of olivine , Peridotite the structure of the Dothan formation in is so extensively altered to serpentine that, the northwestern part of the quadrangle con­ whether fresh or altered, it is generally forms to th e dominant structural trend, and called serpentine by miners . Prospecting for the exploratory recon.�aissance mapping of chromite, therefore, can be restricted to the Di ller (7) shows that the trend of the Dothan areas of peridotite or serpentine shown on the formation is north-northeast, parallel to the geologic map. trend of the Galice fo rmation, as must be the case if the two formations are conformable . Accumulations of chromite large enough The solution of this important structural to be mined may be more or less mixed with the problem awaits systematic mapping of the area host rock, or they may form dense aggregates west of the Kerby quadrangle , of crystals. The first type is called disseminated ore, and the latter massive ore. Cross faults No large deposits of disseminated ore have been found in the quadrangle , The dense Steep normal faults that cut across all aggregates of massive chromite vary so widely the rocks , folds and reverse faults are a in shape that the writers designate them by common structural feature of the quadrangle. the noncommittal term 11pou". The contents of The strikes of these different faults range such deposits range from a few pounds to from east to north but most commonly are hu ndreds of tons , Pods of chromite have been between northwest and west , A few faults found in many of the peridotite bodies, but have northeast strikes , The faults are verti­ the largest and the most nume rous of them have cal or dip steeply either to the northeast or discovered in the peridotite mass that extends the southwest , They range in length from a from the middle of the north boundary of the few hundred feet to seve ral miles and they quadrangle southwest by south across Pearsoll involve all the formations from the oldest to Peak to Babyfoot Creek . Apparently they are the Auriferous Gravels of the Second Cycle of most numerous along the western margin of this Erosion . The relative horizontal displace- mass . Not all the known deposits have been ment may be from a �ew hundred to many thou- 19 mined out, and it is reasonable to believe that others will be round, diorite, but no such occurrence has .been seen by the writers. Cobalt

The ore from the Cowboy mine is a copper ore, but contains appreciable quantities of Gold was the most important mineral cobalt . The geology ·or thi.s deposit has been resource of the Kerby quadrangle. Since the described in detail by Shenon ( 14). discovery of placer gold on the Illinois River in 1851, placer and lode mining have continued Copper with some interruptions to the present day. In the early days ·they played an important part About 6,000,000 pounds of copper as well in the development of the region. The early as some zinc, cobalt and gold have been pro.­ mining camps Waldo and Allentown nearby, duced from mines in the Kerby quadrangle, and Sevastopol and Pondtown on Canyon Creek at and under favorable price condi tions more of these above its confluence with Josephine Creek , were metals will be produced from the area� Three settlements of several bwndred persons . Now 1t different but related types of deposits have is difficult to find traces of them. The gold been found. The most productive type is output from this area can never be known, for found close to the contacts of metavolcanic records of the most productive period of placer rocks and peridotite, and most ·of them are in mining are very incomplete. Shenon estimates · those metavolcanic rocks commonly called gold production from the Takilma-Waldo area at greens tones. These deposits occu� as, irregular 14,000,000, and any reasonable estimate of bodies and lenses of massive sulfiues that production from Josephine ·Creek and Althouse have been deposited in and along fractures of Creek would ·raise this figure to over $5,000,000. the enclosing rocks . The primary (hypogene) . sulfides include chalcopyrite (copper-iron Placer sulfide ), sphalerite (zinc-iron sulfide ), pyrite, pyrrhotite, and at the Cowboy mine Placer deposits are found on most of the cobaltite (cobalt-arsenic sulfide ). A small streams . East of the Kerby fault zone these amount of gold is also present. They are depo sits fill the valley bottoms and make the everywhere associated with altered wall rocks beds of the present streams ; west of this zone and · small amounts of quartz and calcite as the streams flow on bedrock except near their gangue minerals. The per.centages of the sources, and the placers are found on the different sulfides present vary widely within terraces along them. In the eastern area the a given depos it. Only limited parts of the gravel deposits that have been mined range in massive sulfide bodies have a high enough thickness from a few feet to more than 60 feet; content of the sulfides of metals other than the average thickness of gravel in the larger iron to be classed as ore, and seve·ral of the stream is more than 20 feet. In the deeper massive sulfide deposits contain only a few deposits there are layers of clay, and the hundredths of one percent of such minerals. gravel consists largely of fairly well-rounded Oxidation and sulfide enrichment have been cobbles and pebbles. Some of the deeper placer important processes only close to the surface, gravel on the larger streams is still unworked, The largest and most productive deposits of the and may justify drag-line or dredge operations. massive sulfide type are in the Takilma-Waldo Shenon (14) has described the placers of this diqtrict, and have been described by Shenon n4). type in the Takilma-Waldo area. The shallow depo sits are a jumble of subangular to angular Where sulfide depo sits of this type are rook fragments. exposed for long periods of time to the action of downward percolating surface waters contain­ Host of the shallow placers on the small ing dissolved air, they ar� oxidi zed. All of streams were worked out in the early days . The the zinc and much of the iron are carried away early miners worked the beds of these streams in solution. Most of the copper is carried assuming that the gold would be mainly concen­ down to the water table, where it is deposited trated in the channels. It now appears that as new sulfide compounds with a higher copper they erred in so assuming , and that the small content, and if the process is continued long streams effected little concentration · of the enough under favorable condifions even native gold from the side-hill wash. Paying quantities copper is formed. Gold, being insoluble, is of gold are recovered in small scale •sniping" left behind, and is increased in relative operations which are still carried on from t·be amount by the removal of the other constituents . poorly assorted material on the banks of the Very low grade sulfide deposits on or just streams . below the old upland surface have been en- . riched to ore by this process. The Cleopatra In the western area two terrace levels are mine (sees. 3 and 4, T. 18 N., R. 2 E., H. M.) developed along the larger streams . The rock just south of the quadrangle yielded large platform of the lower one is from 10 to 30 feet lumps of native copper. This is the secoRd and the higher one from 80 to 150 feet above type of copper deposit. The Turner mine (183) the streams. The gravel deposits are from 4 to has been enriched in gold. 30 feet thick . In general they are quite coarse, and boulders up to several feet in diameter are Vein deposits of pyrite, chalcopyrite, present. On Josephine Creek these deposits are and some sphalerite associated with a great firmly cemented, and only the upper weathered deal of quartz and some calcite are found in part can be mined by placer methods. The . shear zones of the dioritic rocks of the higher terrace gravels probably are the equiva­ quadrangle. They consti tuite the the third lent of the Llano de Oro gravel in the Illinois type. Those that have been explored contain Valley. The gravel of the Second Cycle of enough gold to interest the prospectors . Erosion (Terttary gravel) has bllen mined,. and Those that have been examined are composite in the Takilma-Waldo dilitrtct llas ·yielded veins. The Old Glory mine (27) is a good considerable gold and platinum.. According to example of thfs type. Prospectors report the old miners , the gold recovered from streams deposits in which pyrite and ·chalcopyrite in that cut gravels of the Second C cle of Brosion . l small 'amounts are scattered widely through the 20 (•T�rtiarr, grav els•, called the Old Channel• by them ) has a higher fineness. Theold longed oxidation and leaching. The Turner mine, Channel gold runs 967 fine and other placer which has been described briefly by Shenon (14), gold runs BOO to 900 fine . is an example .

Lode Manganese

Tnough the larger part of the gold produced The only manganese ore that has been Dlined in the Kerby quadrangle has been recovered from -in the Kerby quadrangle came from a lens of placer mines, there has been a large production manganiferous chert in the Dothan formation from pockets �nd lodes . (Black Beauty prospect, no . 186) . The chert lenses in both the Applegate group and the Very little pocket hun ting has been Galice formatioh are also manganiferous in carried on dur ing the past few years , and the places . The manganese may be present in the writers have had very few opportunities to chert as manganese carbonate, rhodochrosite , or examine newly opened pockets . The term as the manganese silicates . The rho dochrosite •pocket" is us ed in this region to describe any deposits , where sufficiently rich, form ore 1 occurrence of free gold in a restricted space. but at present mangane se cannot be won economi­ Some of these pockets have no visible roots, cally from manganese silicates . Where the but others are obv iously associated with veins silica has been leached out by downward perco­ or veinlets . It follows from the manner of lating surface water leaving concentrations of searching for pockets that all those found lie manganese oxide , the residual material may be clo-s e to the surface . Both Hershey and ore . Th erefore chert layers near the ridge Ferguson have ment ioned that the pockets in the tops are more likely to contain exploitable Klamath Mount ains in California are formed by deposits. supergene pro cesses_ and therefore must be near the surface . Th ese writers believe that mo st, � if not all, of the gold was brought to the pocket by downward moving groundwater and that Nickel in small amounts is present in many the pockets are all on contacts of black carbo­ peridotite bodies . It occurs in the olivine, naceous slate with more competent rocks . Owing the nickel content of which may be as much as to the nature of po ckets and pockethun t ers , one-third of a percent , but is usually much record of all but the largest pockets do es not less . Under proper conditions of weathering, exist , traces of the holes are soon obli terated, the magnesium, most of the silica, and much of and memo ry of them is gone with the passage of ·the iron is removed from olivine , but the the pockethunt er. Hence the following gener­ nickel may be fixed by the iron hydroxide that alizations about pockets are based on precipitates out of the solution in the ground� fragmentary inf ormation . The mo st productive �ater ; or it may be fixed as a nickel silicate, areas have been the upper part of the basin of garnierite, wh ich is characteristically green . Althouse Creek , the basin of Canyon Creek, the In this way an ore deposit may be formed on and wes t slope of County Line Ridge from Babyfoo t below an eros ion surface . A good example Lak e to Golden Dream mine, and the ridge described by Pecora and Hobb s (12) is found at between the Illinois River and Josephine Creek , Riddle, Oregon . Garnierite has been found in northeast of Fiddler Mountain . Thes e areas are the peridotite along the edge of the Illinois underlain by pre-Dothan rocks, carbonaceous Valley, but no no teworthy deposits of n.ickel Galice slates are ab sent , thinly layered tuff­ have been found. aceous and cherty sediments and thin platy siliceous flows are commonly present , and large Platinum and allied metals masses of diorite or mo re siliceous intrus ives are not present . It follows that in the Kerby Although the presence of platinum in the quadrangle lo calization of po cke ts is not placers of Kerby quadrangle was known in the effected by carbonaceous slate or by major early days of mining , its value was not appreci­ igneous contacts . Probably contacts between ated and so it was not recovered. Since the small mas ses of more competent and 1ess compe­ turn of the century its value has been tent rocks are a factor, and the numb er of generally known, and it is sought with care by pockets that have been found on the ridge topa placer miners . The platinum of the miner is an or high up the slopes indi cates that super­ alloy of two or more of the six metals--platinum, gene processes have played a part . In con­ iridium, osmium, ruth enium, rhodium and clusion, it may be said that pockets are palladium . The value of these metals vari es: irregular and discontinuous rich pods of qua rtz for the last several years palladium has had the which may have been somewhat enriched by least value--about half that of platinum ; supergene processes . They are similar to the ruthenium and pla tinum have had about the same sma ll bodies of rich gold ore , called 8ho t value ; and iridium, osmium and rhodium each spots• by the miners , that are found in some have had about twice the value of platinum . of the more continuous quartz veins � Precise analytical data for the se metals in the "platinum" from southwestern Oregon are scanty, No well defined gold quart z veins such as but apparently it runs about 30 percent plati­ tho se develo�ed at the Ashland or Benton mines num , 32 percent iridium, 25 percent osmium , 13 have been opened up in the Kerby qu adrangle . percent ruthenium, and li ttle _or no rho dium or The smaller rudely tabular depo sits are of two palladium . The placer depo sits near Waldo , types : those composed or· quart z, free gold and along Josephine Creek, and on the Illino is a few percent of sulfide minerals , and tho se in River just below the mouth of Dear Creek, are which the sulfides constitute a large part of reported to carry platinum . Little information the depos it, and contain gold and silver values on the ratio of gold to platinum metals in the sulfide minerals . The Robert E. mine , recovered from these placers is available . described by Shenon (13) , is an example of th� According to J. T. Logan the ratio of nplati­ first ; and the Old Glory mine of the second . num" to gold in mines near Waldo is 1 to 75 .

Another type of gold deposit is the go ssan of large low-grade sulfide deposits from whi ch the sulfide minerals have been removed by pro- f.::l.!:.lli size . The deposits are formed (1) near, but not in , ma jor faults , (2) in rocks which are Pyrite , the disulfide of iron , is found porous and offer a large amo unt of rock surface in the Takilma-Waldo district as bodies that to mineralizing solutions ; such rocks are contain tens of thousands of tons . Pyrite is porous sandstones, platy schists , slates , and sometimes used in the manufacture of sulfuric shales with open partings or highly fractured acid, and if such an acid plant should be cherts , silicified serpentines, and fault constructed economically near enough to these breccias ; (3) the deposits are formed from the deposits to permi t their use , the pyrite would surface to depths of a few thousand feet . The have a market . For a description of these first two of these conditions can be found in deposits the reader is referred to Shenon (14) . the quadrangle , but whether the third condition prevailed during cinnabar mineralization Quicksilver depends on the age of the mineralization, and the relationship of the present surface to the Cinnabar , the common ore mineral of quick­ surface at that time . Both of these facts are silver, is found in the northeastern part of still uncertain . the quadrangle on Shaw Creek (Empire, no . 5), in Swede Basin (no . 56 ), and on the southern Silver boundary of the quadrangle in the valley of Diamond Creek . It is found in rocks of the No deposits rich eno ugh in silver to Galice formation or in igneous rocks that have warrant mining have been found in the quad­ intruded the Galice and Dothan format ions . rangle . The copper deposits and the gold Most of the quicksilver production in the depos�ts carry so small an amount of silver Pacific Coast States has come from calc-silica that it can only be considered a minor by­ rock , a brittle alteration product formed in product . peridotite and sedimentary rocks of Franciscan or younger age . Therefore , the chances for Zinc finding economically minable deposits of cinnabar in the Kerby quadrangle are not good . Sphalerite , the zinc-iron sulfide , is It should be borne in mind , however , that the common in the sulfide deposits of the Kerby Altoona mine , Trinity County, Calif ., had a quadrangle . Formerly , owing to the low price large quicksilver production from Franciscan of zinc, the sphalerite-rich parts of the rocks , and that the Patricks Creek quicksilve r deposits were not ore and therefore were not mine , 4 miles south of the quadrangle , has had mined except insofar as was necessary in order a small production . This mine was discovered to mine high-grade copper ore . For the same in 1943. reason , the re are no assay data fo r zinc content, and the tenor of zinc in these deposits Three conditions determine the locali- is not kno'M'l . zation of cinnabar deposits of exploitable ______

BIBLIOGHAPHY

1. Allen, J. E. Chromite deposits in Oregon : Oregon Dept . of Geology and Min . Industries Bull . 9, pp . 1-?l , 1938.

2. Butler, G. M. Preliminary survey of the geology and mining resources of Curry County , Oregon.: Oregon Bur . of Mines , Min. Res. , Oregon no . 2, pp. 1-134, 1916.

3. Diller , J. S. Topographic development of the Klamath Mountains : U. S. Geol . Survey Bull . 196, pp . 1-69, 1902.

4. Diller , J. S. Description of the Port Orford quadrangle: U. S. Geol . Survey Geol. Atlas , Port Orford folio (no . 89) pp . 1-6, 1903.

5, Diller, J. S. The Meso zoic sediments of southwestern Oregon: Am. Jour . Sci. , 4th ser. , vo l. 23, pp . 401- 421 , 1907 .

6. Diller , J. S. Strata containing the Jurassic flora of Oregon : Geol. Soc . America Bull. , vo l. 19, pp . 367 -402, 1908.

7. Diller , J. s. Mineral resources of southwestern Oregon : U. S. Geol. Survey Bull. 546, pp . l-147, 1914.

8. Diller , J. s. , and Kay , G. F. Descrip tion of the Riddle quadrangle , Oregon : U. S. Geol. Survey Geol. Atlas, Riddl e folio (no . 218) pp. 1-8, 1924 .

9, Hershey , 0. H. Del Norte County geology : Min. and Sci. Press, vol . 102, p. 40 8, _1911 .

10. Knowlton, F. H. The Jurassic age of the Jurassic flora of Oregon: Ge ol . Soc. America Bull ., vo l, 19, pp. 367 -402, 1910. 11. Louderback , G. D. The Mesozoic of southwe stern Oregon: Jour . Geology, vo l. 13, pp . 514- 555, 1905.

12 . Oregon Department of Geology and Mineral Indus tries , Oregon Metal mines handbook , Jo �ephine County: Oregon �ept . Geology and Min . Indus tries Bull. 14-C , vo l. 2, sec. 1, pp . 1-229 , 1942.

13 . Pecora , W. T. , and Hobb s, 3. W. Nickel depo sit near Riddle, Douglas County, Oreg.: U. 3. Geol. S�rvey Bul l. 931-I, pp. 205-226 , 1942 •

.14 . Shenon, P. J. Geology of the Robertson, Humdinger and Rob ert E. gold mines, southwes tern Oregon 1 U. S. Geo l. Survey Bull. 830 , pp . 33- 55, 1933 .

15. Shenon , P. J, Geology and ore depo sits of the ·rak ilma-Waldo di strict , Oregon , including the Blue Creek district : U. S. Geol. Survey Bull. 846 , pp . 141-194 , 1933 .

16 . Taliaferro , N. L. Geologic history and correlation of the Jura ssic of southwestern Oregon and California: Geol. So c. Ame rica Bull ., vol . 53 , pp . 71-112, 1942 .

17 . Ward, L. F. Status of the Mesozoic floras of the United Stat es : U. 3. Geol . Survey Mon . 48 , pp. 47-151 , 1905.

18 . Weaver , C. E. Stratigraphy and paleontology of the Tertiary forma tions at Coos Bay, Oregon: Wa shington Un iv . ( Seattle) Pub . in Geology, vo l. 6, pp . 31-46 , 1945.

19 . Wells , F. G. , and others . Preliminary geologic map of the Medford quadrangle, Oregon : Oregon Dept . Geology and Min . Indus tries, 1939 .

20 . Wells, F. G. , Page, L. R. , and James , H. L. Chromite deposits of the Sourdough area , Curry County and the Briggs Creek area, Josephine County, Oregon: U. 3. Geol. Survey Bull . 922-P, pp . 46 1-496 , 1940.

21 . Wells, F. G. , and others . Preliminary geologic map of th� Grants Pass quadrangle , Oregon: Oregon Dept . Geology and Min . Industries , 1940.

GI'O WI"SO 10-2,-11-8 2100 8-u04 23 PRELIMINARY GEOLOG IC MAP

OF THE

ISSUED BY SURVEYED BY KERBY QUADRANG LE STATE DEPARTMENT OF GEOLOGY \\ "' OF THE INTERIOR AND MINERAL INDUSTRIES 1\ � STATES GEOLOGICAL SURVEY OR EGON F. W. LlBBF.Y. DIRECTOR, PORTLAND. OREG��

,, EXPLANATION EXPLANATION MINES AND PROSPECTS CONTINUED CHROMITE DEPOSITS 10. Salt Roc� Sec. 6,T.36S,R 7W. I L Cobalt Blue Sec. 6. T. 36 S., R. 7 W. 22. Nigger.EI�horn Sec. 24, T, 36 S .. R. 9W. 24. BngB> Creek (Sordy) Sec. 14, T. 36 S., R. 9 W. Alluvium J 25. Name unkown Sec. 23, T. 36 S., R. 9 W. u (Srr�ohfi•d vrm,./, "'"'"· ""d mu . 31. Chrome King llo. I Sec. 36, T. 37 S., R. 10 W. -r prh, ;;.,, A�� tt z 44. Name unknown Sec. 22, T. 37 S., R. 9 W. (l'vo>-1� oorled ora uri, ,..,.a�• ,;,, " 0 < 45. Name unknown Sec. 15, T. 37 S., R. 9 W. all"" ;""' i" p/<1�•�: o» "':ni:hu w a• "'"''A'" et abo"• z 46. Black Rock Chmmite Sec. 9. T. 37 S., R. 9 W. !OOj.- th� " " pr�n�l otr�am•) w < 51. Gallagher Chrome Sec. 3,T.37S.. R.9W. � 52. Cavyell Horse Mt. Sec. 3,T.37S.. R.9W. UNCONFORMITY < 0 53. Jim Fisher Chrome Sec. 34, T. 36 S.. R. 9 W. 0 55. Cavyell Hotse Cr�ek Sec. 34, T. 36 S., R. 9W. 5 [1;1] 57. Black Rock Chromite Sec. 9,T.37S.. R.8W. 58. Black B�ar Sec. 9,T.37 S., R.8W. Contact. facies 60. Horseshoe Lode Sec. 33. T. 37 s.. R. a·w. f&.hd orr< <"1''J,,.Inl/i%�d J"ra»iotoiii """Ud da11 and .oato.d "'itA ,...,.q"" "' in/,....,,,� co>lla··•�; 64. Griffin Chramite Sec. 18. T. 38 S., R.SW. em(J/1 r<><:k/rt�(lm...,Uo lind lnuteo lt!totr•v.,.bdoiN par•ntloo•taioodi.­ 90. Placer Sec. 5, T. 38 S.. R.9W. ofrrra�-.IJ cal• ori11i>t4l �>tit) 91. Name unknown Sec. 6, T.38S., R.9W. 92. Name unknown Sec. 2, T. 38 S.. R. 10 W. 94. Saddle Sec. 2,T.38S.. R.IOW. � 96. Babyfoot Sec. 25, T. 38 S .. R. lOW. · Auriferous ravels of he 99. Bowse' Sec. 22, 1.38 S., R. lOW. g t Second Cycle of Erosion 101 Hanscur.o See. 14, T. 38 S.. R. \OW. 102. Marguerile and Uncle Sam Sec. 11. T. 38 S., R. 10 W. ($!""""' ffff.l."bbh• ""d p.;bl>lu in 103. Olive B. Sec. 12, T. 38 S., R. 10 W. . a •<>&<,.1. in '"''/ cot>ni of I� I •hcurinll) 115. LiUle Boy No.5 Sec. 2, T. 39 S., R. 10 W. 116. Litlle Boy No. 4 Sec. 2, T. 39 S., R. \OW. Old gravels !28. Name unknown Sec. 12, T, 39 S.. R. 9 W. pobbl••. and sand on "P­ (Cobbtu, ___,...-- ·--- - ...... 130_ Name unknown Sec. 12, T. 39 S., R. 9 W. Ia>ul "" r/i.tcu a fe et. boo• J,QOI! \33. Name unknown Sec. 6, T. 39 S .. R. 9 W. COfU'.�T materia/ J>mJ)le mM•firmlv Contact 144. Collard {Golconda) Mine Sec. I7,T.40 S., R. 7W. Co/or•e,l) 159. Pon� Shoe Sec. 15, T.4l S.. R. 7W. UNCONFORMITY 163. Owens Sec. II, T. 41 S., R. 8 W. �--' " ------· 176. EslerleyChrome Mine Sec. 22, T. 40 S.. R. 8 w. F'ault, showing dip 181. Name unknown Sec. 21, T. 39 S., R. 9 W. (IMAod w.Uro appr<>rim��to, d<>t­ 182. Dick and Dick Reynolds Set. 33, T. 40 S., R. 9 W. tod ••ltcn: itVe>"T•d: u . ..p!Ar"""' 185. Sour Oough Sec. 36, T. 40 S., R. II W. ride; 0. d"""1t1Ar<>W1t lfido) Arago group, undivided 187. lr�ne. Chromite Sec. IO, T.41 S .. R. li W. (11'-'�"�"• lrnff·vr•""- """...., 188. Winton MI. Chrome Sec. 9, T.41 S., R. IIW. ��and '11>1<'1 ''"" arkom oand.ol<»t.! � direction plunge -..tMrod l>,.ffi>t upp<'rt. w ()f 146. Soence Sec. 19, T. 40 S.. R. 7 W. " C<>a.ro• '"' tl-iltd.,rat.d c<>nulo,_ 162. Cowboy Mine Sec. 11. T. 41 S., RSW. u """/" '""'int.rboddod .,.ndoto>oo "w 165. Lilly Sec. 35, T. 40 S., R. 8 W. t...... ,.,...... ,.) Strike and dip of beds 166. Waldo Mine Sec. 36, T. 40 S., R. 8 w. UNCONFORMITY !67. Queen of Bronle Mine Sec. 36. T. 40 S., R. 8 W. / 168. C�meron Mone Sec. 34, r. 40 S.. R 8 w. Strike of vertical beds GOLD DEPOSITS

]_ BiB Four Placer Sec. 26, T. 35 S., R. 7 W. Plac�t l4JJ " " 2. Name unknown Set. 28. T. 35 S.. R. 7 W. Placer Dacite porphyry Strike and dip of foliation 3. Contact Set. 28, T. 35 S., R. 7 W. Lode (Witit o I<> pi>tk fi>to-vrainod rock 4. Flanagan Sec. 35, T. 35 S.. R. 7 W. Placer o•n...... tlll.,.,.f<>i""' fold.opar p,\ffl.,.. X 6. Havens Claim Sec. 10. T. 36 S., R. 7 W. Lode cn�•tl<>ndrock, con­ Strike of vertical joints ra;,.;,.glt<>noU.,.do, l»otito, a....: IS. Ramsey Mine Sec. 24, T. 36 S., R. 8 W. Lode �-rl•) � 19. Sa" Mone Sec. 7, T. 36 S.. R. 8 W. Place< 20. Nam� unknown Sec. 13, T. 36 S., R. 9 W. Placer Lode mine or prospect 21. Elkhorn Placer Sec. 24, T. 36 S., R. 9 W. Placet (N,.mbor rcfotr• !<>lUI "" ....,,.pi,. 26. Mel� Mine Sec. 32, T. 35 s .. R. 9 w_ Placer o/mnp) 27. Old Glory Mine Sec. 12, T. 36 S., R. 10 w. Lode Gneissic migmatite 28. Dunbar Placer Sec. 12, T.36 S., R. ll W. Placer (0.0� rock an>.. nd l>orrUro of X 29. Cobalt Group Sec. 25, T. 36 S., R, 11 W. Gold·Capo�r lode diM-it<> in !...... W.... includo-d Placer ato.d mine 30. Gold Basin Placer Sec. 32. T. 37 S.. R. 10 W. Placer r<>«/ po>t.da,.u) (Numkr rc/<:k !<> vr n 63. Anderson (Holiday) Sec. 18, T. 38 S., R. 8 W. Placer ..,;!It altl!i ..it; b(l.,.d;,.a; !iglt� /11''1.11 plth«H wW> mucA Aor>�­ 67. Golden Pnncess Sec. 30, T. 38 S .. R, 8 W. Placer bluod•. dhd; di<>riu P•v-tiU, ! Independence Placer phd) 68. Goshen Pl acer Sec. 30. T. 38 S., R. 8 W. Placer Foster Placer 69. Sutter(Norton Hulf) Placer Sec. 36, T. 38 S .. R. 9 W. Placer � 70. Name unknown Sec. �5. T. 38 S., R. 9 W. Placer 71. Bear Placer Sec. 36. T. 38 S .. R. 9 W. Placer Dolerite and related dikes 72. Gold King Sec. 36, T. 38 S.. R. 9 W. Lode (Darl<-co/Ot"od.fi...,.gra;,.� T<>Ch 73. Moody Sec. 34, T. 38 S., R. 9 W. Lode witAd�eOt"i,.ton�rlal tntu.-• 74. Billy Neil (Sego Tomek) Sec. 33, T. 38 S., R. 9 W. Lode f- '"0 dih• .. .,...... ,., ,...-ido­ . 75. Name unknown Sec. 33, T. 38 S.. R. 9 W. Place• fiU Ot" ...... t n in• ) 76. AI Blasson Sec. 35, T. 38 S.. R. 9 W. Lode 77. Blu� Sec. 35, T. 38 S., R. 9 W. Lad� 78. McGrath Sec. 26, T, 38 S .. R. 9 W. Lode 79. Peckel Knoll Sec. 26, T, 38 S., R. 9 W. Lode 80. Name unknowo Sec. 22, T, 38 S., R. 9 W. Lade Metagabbroic complex SL Name unknown Sec. 17, T. 38 S.. R. 9 W. Lode (Dark -�- ""'d'""'-��"�'"""• aJ... 82. Name unknown Sec. 17, T. 38 S., R. 9 W. Lode f•>"•drock, ,.,._, /<>non:"ll.omtal.l. 83. Name unknowo ;,. Jl""idolit<> .,...dtaiKi"ll 97. Peck Placer Sec. 23. T. 38 S.. R. 10 W, Placer biuUhfoldti><'T, 1>11""-""""· and 98. Peck Mine Sec. 23, T. 38 S.. R. 10 W. Lode olivin": .. coor ·rrrainod Jru;i.u, 100. Husles Mine Sec. 14. T. 38 S.. R. 10 w_ Lode coo:. aotdfi,.•·IITai,..e­ 121. Bowd�n Prosp�ct Sec. 39 S., R. 9 W. Lode iU bt-<>hn lnl •ltoarinu into ....aa 1!, T. Nrx;hOt'" "' all!>ngatiot> of""""'d 122. Name unknown Sec. 10, T. 39 S .. R. 9 W, Lode .,... b4Ui4d •Ai"ll tran.olwc... t pistu 123. Name un�nown Sec. 10, T. 39 S., R. 9 W. Placer 11•Uooo oAu...,.. oliv• /r&m ore.,. 124. Lucky Spot Sec. 3, 39 S .. R. 9 W. Lode to black in color-J T. 125. FrecklesPiacer Sec. 2, T. 39 S .. R. 9 W. Placer 126. Name unknown Sec. 2, T. 39 S., R. 9 W. Lode 127. Alta, Oro Fino Sec. 2, T. 39 S., R. 9 W. Lode 129. Si/v�r Nugget Sec. l2, T. 39 S., R. 9W. Placer Pyro"enite 131. Roseburg and Fi dehly Sec. 7,T.39S., R. 8W. Lade 132. Payday Sec. 7. T. 39 S .. R. 8 W. Lode vr•no """k up /.at"gt>IJI (J)g.-k M/olivin� with Ot"with ed. ,....1-e<>/Ot" In 150. Lone Star (Maiden) Mine Sec. 33, T. 40 S.. R. 7'W. Placer p/.ac .. /.aru•/11 alt..-od to •...,_. tiM!ait,.ot�d) !51. Name unknown Sec. 30, T. 40 S.. R. 7 W. Lode 153. Name unknown Sec. 6, T. 41 S., R. 7 W. Lode 154. Name unknown Sec. 5, T. 41 S .. R, 7 W. Lode 155. NJme unknown Sec. 3, T. 41 S.. R. 7 W. Lode � 156. Joh.,son Sec. 9, T. 41 S .. R. 7 w. Placer 157. Nam� unknown Sec. 9, T. 41 S., R. 7 W. Placer Dothan formation 158. Name unknown Sec. 10. T. 41 S.. R. 7 W. Lode (Ma.uiv• ;,.dwraUd .,,.d.otot>• ""d 160. Pony Shoe Sec. 14, T. 41 S., R. 7 W. Lode u.;,. 1a ll,Jdb.i>t vari""• altadoo of vr••" .,...n.oq,.-.d, in """ witA 170. Daisy Sec. 34, T. 40 S., R, 8 W. Placer am�11daloida/. .,...pilJ<>W otnu:twu 171. Name unknown Sec. 27, T. 40 S., R. 8 W. Placer .,...witA ft<>uobroccia) 172. Merrill Placet Sec. 27. T. 40 S.. R. SW. Placer 173. Platerica Mine Sec. 27, T. 40 S., R. 8 W. Placet 174. Bailey Group Sec. 33, T. 40 S.. R. 8 w. Placer I 75. tslerley Placer Sec. 22, T. 40 ..s R. 8 w_ Plac�t 177. Deep G�k fin.,..vraiteh -­ ..-al.l!l wit.A ct.>avau«, afftod. up toJ f•ot ;,. !ltO:..k,...,.and""""' 59. McFatlane Stick Planl Sec. 34, T. 37 S., R. 8 W. Clay th n-Ia II""• oo """'"""r><>rv/>!lri! O:..wit.A b.-occiaa 23. Elkhor p< 65. Nicltel Cht•d btl/otUr �mbdo:fd-­ rit;, and ""'"�daloidal pll.aH, 135. Woad Cock Sec. 36, T. 39 S.. R. 9 W. Nickel lode Jgf; ag�aU !u$o a1ld tlti" 5. Empire Sec. 3, T. 36 S.. R. 7 W. Quicksilver lode II<>��'•. JgcJ 56. Quicksilver Swede Basin Sec. l, T. 37 S., R. 9 W. Quicksilver lode 136. An occurrence of sulphides Sec. 28, T. 39 S., R. 7 W. UNCONFORMITY

Base by Department of tne Interior. Scale I'96, 000 Geology by F. G. Wells, U. S. Geological Survey, 1915 ' "--=�·�oo�l..' ..���� �--...... -"'=��' �=1'-...... � l G. L. Bell, F. W. Cater, Jr., ...... •: i e� ! P. E. Hotz, and H. L. James. l..:l' ""J":-' --..b===''- -•' ==l..' --�5 .Kilometers 0 -: == Surveyed 1940-1941 and 1945-1946 � C ontour interval 100 feet Geologic drafting by Ellen B. Bennett i Douour• io ,...... ,. ..a Wv.l ,• 1948 APPIIOXI.ATE MEAN OECliNAliON 1915