STATE OF RONAlD REAGAN, Governor

THE RESOURCES AGENCY NORMAN 13, UVERMORE, JR., Admlni.>trotar

DEPARTMENT OF CONSERVATION

E T 1

1

1416 Ninth Socromento

95814

DIVISION OF MINES AND GEOLOGY lan Campbell, State Geologist

12s•oo'

1. Aune, Q. A., Reconnaissance geologic map of a part of the Shoeinhorse 1\~tn. quadrangle and vicinity, scale I: 62,500, unpublished, 1963.

Danehy, E. A., Unpublished notes on the geology of the Shoeinhorse Mtn. quadrangle, 1960-61.

2. Averill, C. V., 1931, Preliminary report on economic geology of the Shasta quadrangle: California Div. Mines Mining in California v. 27, no. I, pp. 3-65, Map: Eco­nomic geology and location of mines, Shasta quadrangle by Southern Pacific Company Geological Department, scale I :250,000. (Modified in part by S. J. Rice, Califor­nia Div. Mines and Geology, unpublished, 1959.)

3. Back, \iVilliam, I957, Geology and ground-water features of the Smith River plain, Del Norte County, California: U.S. Geol. Survey Water-Supply Paper I254, 76 pp., Pl. 5, scale I :62,500. (Additional information by S. J . Rice, ref. !Sa.)

4. Cater, F. \V., Jr. and Wells, F. G., 1953, Geology and mineral resources of the Gasquet quadrangle, California­Oregon: U .S. Geol. Survey Bull. 995-C, pp. 79-133, Pl. 11, scale 1:50,000.

5. Churkin, Michael, Jr. and Langenheim, R. L., Jr., 1960, Silurian strata of the Klamath Mountains, California: Am. Jour. Sci., v. 258, pp. 25S-273, Fig. I, scale I :79,200.

6. Davis, Gregory A., Metamorphic and igneous geology of pre-Cretaceous rocks, Coffee Creek area, northeast­ern Trinity Alps, Klamath Mountains, California, scale 1: 21,120, University of California, Berkeley, unpublished Ph.D. thesis, 1961.

Davis, Gregory A., I963, Structure and mode of em­placement of Caribou Mountain Pluton, Klamath Moun­tains, California: Geol. Soc. Am. Bull. v. 74, pp. 331-348, Pl. I, scale approx. I :21,500, (this map covers only the southern ~art of thesis area).

7. Hail,W.Roger,Regional geologic map, Shasta Valley area, California Dep't. Water Res., scale I :62,500, unpublished departmental report, 1959.

S. Harbaugh, J. W., Reconnaissance geological map of Shasta Lake area, California, scale 1:62,500, Stanford University, unpublished, I956.

9. Holdaway, M. J., Petrology and structure of metamor­phic and igneous rocks of parts of northern Coffee Creek and Cecilville quadrangles, Klamath Mountains, Califor­nia, plate I, scale I :42,240, and Fig. I, scale approx. I :425,000, University of California, Berkeley, unpublished Ph.D. thesis, 1962. (Glacial deposits in southern part of this area by R . P. Sharp, 1960, Pleistocene glaciation in the Trinity Alps of northern California: Am. Jour. Sci., v. 25S, pp. 305-340, Fig. 3, scale approx. 1: I50,000.)

10. Hotz, P. E., Geology of the Condrey Mountain quad­rangle, scale I :48,000, U.S. Geol. Survey, work in prog­ress I963.

STATE OF CALIFORNIA

Edmund G. Brown, Governor THE RESOURCES AGENCY Hugo Fisher, Administrator

EX PLANA TORY DATA

WEED SHEET GEOLOGIC MAP OF CALIFORNIA

OLAF P. JENKINS EDITION

Compiled by Rudolph G. Strand, 1963

DEPARTMENT OF CONSERVATION DeWitt Nelson, Director

INDEX TO GEOLOGIC MAPPING USED IN THE COMPILATION OF

THE WEED SHEET

THIS DATA SHEET IS A REPRINT OF THE DATA SHEET ACCOMPANYING THE WEED

SHEET, GEOLOGIC M AP OF CALIFORNIA, OLAF P. JENKINS EDITION, FIRST PUB­

LISHED IN 1963. IT HAS NOT BEEN ALTERED. THE GEOLOGY SHOWN O N THE WEED

SHEET OF THE BOUGUER GRAVITY MAP OF CALIFORNIA IS ALSO REPRINTED FROM

THE GEOLOGIC MAP OF CALfFORNIA, 1963. THE GRAVITY DATA PRESENTED WAS

COMPILED IN 1972 AND PUBLISHED IN 1973. .

II. Irwin, W. P., I960, Geologic reconnaissance of the Northern Coast Ranges and Klamath Mountains, with a summary of the mineral resources: California Div. Mines Bull. 179, SO pp., Pl. 1 (reconnaissance mapping by William P. Irwin and Donald B. Tatlock), scale I: 500,000. (Additional information regarding the geology at Slate Creek, Orleans quadrangle, by the California Dep't. Water Resources, W . R. Hansen, B. G. Hicks, and R. S. Ford, Scale 1:2400, unpublished, I954.)

12. Jones, David L., Geologic Map of the Upper Cretaceous strata in the vicinity of Hornbrook, California, scale 1:24,000, U .S. Geol. Survey, unpublished, I95S.

13. Mack, Seymour, I95S, Geology and ground-water fea­tures of Scott Valley, Siskiyou County, California: U.S. Geol. Survey Water-Supply Paper 1462, 98 pp., Pl. I, scale 1:62,500. (Modified in part by mapping of Southern Pacific Company geologists, see ref. 22.)

14. Mack, Seymour, I960, Geology and ground-water fea­tures of Shasta Valley, Siskiyou County, California: U.S. Geol. Survey Water-Supply Paper 14S4, 115 pp., Pl. 1, scale 1:62,500.

15. Masson, P. H., Geology of the Gunsight Peak district, Siskiyou County, California, scale I :33,000, University of California, Berkeley, unpublished M.A. thesis, I949. (Stratigraphy reinterpreted in part by Southern Pacific Company geologists, see ref. 22.)

16. Maxson, J. H., I933, Economic geology of portions of Del Norte and Siskiyou Counties, northwesternmost California: California Div. Mine;; Rep't., v. 29, nos. 1 and 2, pp. I23-160, Pl. 4, scale f: 1S7 ,500. (Modified in part by \Vm. P. Irwin, see ref. 11.)

17. Pratt, Walden P., eology of a part of the Scott Bar quadrangle, California, scale I :62,500, Stanford Univer­sity, unpublished Ph.D. thesis in preparation, I963 . (Mar­ble deposits mapped by James R. Evans, California Div. Mines and Geology, unpublished limestone investiga­tions, I962. Additions to mapping by Carl Seyfert, Jr., 1963, see ref. no. 21.)

18a. Rice, S. J ., Geology of the Crescent City, Klamath, Orick and Trinidad quadrangles, California, scale 1:62,-500, California Div. Mines and Geology, unpublished, 1951-52. (Information regarding the upper Pliocene along the coast, Trinidad quadrangle, by J. Wyatt Durham, University of California, Berkeley, oral communication, 1962. Franciscan volcanic rocks in the Trinidad quad­rangle by E. Alexander, J. DeLapp, E. Gladish and R. Skolmen of the Pacific Southwest Forest & Range Experiment Station- U.S. Forest Service, scale 1: 31,6SO, I959-60.)

ISh. Rice, S. J ., Data on the geology of the area adjacent to the Klamath River (Hornbrook quadrangle), California Div. Mines and Geology, unpublished, I962.

WEED 0

Butte ~ Reservoir lJ!

MACDOEL

26a Goose Nt1t

The Whole bock

Mount Shoslo

19. Romey, W. D., Geology of a part of the Etna quad­rangle, Siskiyou County, California, scale I: 31,680, Uni­versity of California, Berkeley, Ph.D. thesis, 1962.

20. Rynearson, G. A. and Smith, C. T., I940, Chromite de­posits in the Seiad quadrangle, Siskiyou County, Cali­fornia: U.S. Geol. Survey Bull. 922-J, Pl. 40, scale l:I25,000. Map also published in U.S. Geol. Survey Bull. 94S-B.

21. Seyfert, Carl, Jr., Geology of the north one-half of the Sawyers Bar quadran~le and vicinity, California, scale 1:62,500, Stanford Umversity, unpublished Ph.D. thesis in preparation, I963.

22. Southern Pacific Company, Land Dep't., Regional geo­logic mapping program. Geologic maps of T4SN R3-IOW, T43-47N R7-IOW, T42N R2-IOW{ T40-41N R2-9W, T39N R3,4,6-9W, T3SN, R4L-9W,T36,37N R2-IOW MDB&M by R. J. Anti!, H. F. Bonham, Jr., J . T. Col­lier, J. W. Cooksley, Jr., W. L. Coonrad, A. B. Cun­ningham, E. A. Danehy, R. R. Dorsey, A. R. Glockzin, E. Kojan, R. T. Laird, W. A. Oesterling, G. W. Olcott, D. E. Pruss, J. V. A . Sharp, W. H. Spurck, F. A. Stejer, J. S. Vanderpool, R. E. Willson, scale I:24,000, unpub­lished, 1957-I961. (Glacial deposits in the southwestern part of this area by Sharp, R. P., I960, Pleistocene glacia­tion in the Trinity Alps of northern California: Am. Jour. Sci., v. 25S, pp. 305-340, Figs. 3,5,6, and 7.)

23. Stanford Geolo~ical Survey (W. R . Dickinson in charge), Geologic map of Seiad Valley area, Siskiyou Co., California, scale 1:62,500, Stanford University, un­published, I959.

24. Wells, F. G., I940, Preliminary geologic map of the Grants Pass quadrangle, Oregon: Oregon Dep't. Geol. and Min. Industries, Map 5, by F. G . Wells, G. 0. Gates, R. M. Grantham, P. E. Holtz, H. L. James, W. E. Kennett, J. V. Neuman, Jr., G. A. Rynearson, C. T. Smith, E. C. Tabor, and E. J. Tate, scale I :96,000.

25. Williams, Howe!, 1934, Mount Shasta, California: Zeit­schrift fur Vulkanologie, vol. 15, pp. 225-253, Pl. I6, scale I: 240,000. Additions by Southern Pacific Company geological mapping, see ref. 22.)

26a. Williams, Howel, I949, Geology of the Macdoel quad­rangle: California Div. Mines Bull. 151, pp. 7-60, Pl. 1, scale I~ l25,000. Modifications in the Butte Valley area from: Wood, P. R ., 1960, Geology and ground-water features of the Butte Valley region, Siskiyou County, California: U.S. Geol. Survey Water-Supply Paper 1491, I50 pp., Pl. I, scale I :62,500, and modifications in the northern part of quadrangle by Southern Pacific Com­pany, see ref. 22.)

26b. Wmiams. Howe!, 1949, Geology of the Macdoel quad­rangle: California Div. Mines Bull. 151, pp. 7-60, Pl. 4, Sketch map of geology along Highway 99, Weed to Hilts, Siskiyou County, California, scale I: 125,000.

For a complete list of published geologic maps of this area see Division of Mines and Geology Special Reports 52 and 52-A.

-~~~========~~========~------~~------------~~~~--------------~----------------------~----~

u 0 N 0 z w u

u 0 2j "' w ::t

AGE

i 5 ~

0

I I I

~~ S1

I I I

! •• 0:

l

STATE MAP

SYMBOL

Qs

Qol

Qrv

Orv 0

Qrvb

OrvP

Ql

Qg

Qt

Om

Qc

Qpv

Q pv'

Qpvo

Qpvb

QpvP

QP

Pu

Pv 0

PvP

Tm

Mu

Tc

Ti

Ti'

T i 0

Tib

Tv

Tv'

TvP

Ku

KJI

KJiv

STRATIGRAPHIC NOMENCLATURE- WEED SHEET

STATE MAP UNIT State Map Units li•ted here a re not -necem•rily i.n otratigrophi~

sequence; the sequence uoed has been olandordized for all •heeh of the Geologic Mop of California

RECENT DUNE SAND

RECENT ALLUVIUM

RECENT VOLCANIC ROCKS:

UNDIFFERENTIATED

ANDESITIC

BASALTIC

PYROCLASTIC

QUATERNARY LAKE DEPOSITS

QUATERNARY GLACIAL DEPOSITS

QUATERNARY NONMARINE TERRACE DEPOSITS

PLEISTOCENE MARINE DEPOSITS AND MARINE TERRACE DEPOSITS

PLEISTOCENE NONMARINE SEDIMENTARY DEPOSITS

PLEISTOCENE VOLCANIC ROCKS:

UNDIFFERENTIATED

RHYOLITIC

ANDESITIC

BASALTIC

PYROCLASTIC

PLIOCENE-PLEISTOCENE NONMARINE SEDIMENTARY DEPOSITS

QUATERNARY AND/ OR PLIOCENE CINDER CONES

UPPER PLIOCENE MARINE SEDIMENTARY ROCKS .

PLIOCENE VOLCANIC ROCKS:

ANDESITIC

BASALTIC

PYROCLASTIC

TERTIARY MARINE SEDIMENTARY ROCKS

UPPER MIOCENE MARINE SEDIMENTARY ROCKS

TERTIARY NONMARINE SEDIMENTARY ROCKS

TERTIARY INTRUSIVE (HYPABYSSAL) ROCKS:

UNDIFFERENTIATED

RHYOLITIC

ANDESITIC

BASALTIC

TERTIARY VOLCANIC ROCKS:

UNDIFFERENTIATED

RHYOLITIC

BASALTIC

PYROCLASTIC

UPPER CRETACEOUS MARINE SEDIMENTARY ROCKS

FRANCISCAN FORMATION

FRANCISCAN VOLCANIC AND METAVOLCANIC ROCKS

STRATIGRAPHIC UNITS AND CHARACTERISTIC LITHOLOGIES (The formally named formati ons grouped within an individual State Map Unit

are lieted in stratigraphie sequence from youngest to oldest.)

Duno .and and older eoli~n sand along the co.,t.

Recent stream ch.annd, flood plain and alluvial fon deposits. Fluvioglocial depo•its (may be Plci•tocene in part), and mud flow depc»its, notably •long Mud Creek on southea>t flank of Mt. Shasta.

"Shastina" pyrollene andesite-d~rk gray or black 4ndfsitir ba<alt rirh in high/ grun granu/~, of pyrox~ne {thr.e hv., are "identical" with the early flow• of Shana and hence it i~ not certain that they originated from the -Shutlna vent, William•, 19H, p. l~)).

Hypersthene-rich n•i~:\lhr andesite and ba,.ltic andesite of Goo•ene.t volcano. Dark vesic\llar, g lan-rich pyroxene andesite of Deer Mountain. Pale gray porphyritic pyroxene mdesitt lava, the laoen flow from Shasta. Pale gray andesite lavas (containing long slender prisms of brownish hornblende) of Bhck Bune dome. Hornblende andesite talus breccia in Diller Canyon on wen side of Mt. Shasta.

Pluto's Cave Basalt-black., vesicular olivine-rich augite b"Jalt. Olivint- a\lgite basalt at Copco Lake. Blocky, scoriaceous, augite­olivine bualt :~long Alder Creek. B!.ck, ve•icular, olivine-augite hualt oi Little Deer Mtn. volcano. Dark, vesicular, olivine basolt of The Whaleback. Gray and black, glo,y, pyroxene-rich andesitic baJOit of Shutina.

Dark t\lff, hpilli, and bombs of vesicular glass, on Mt. Shasta. Rtd, brown and biHk basoltic cinders in the Macdoel 30'

quadnngle.

Recent diatomite at Copco Lake. Scmiconsolidated day, volcanic a•h, diuomitr, and und in Buue Valley. Glacial lake oediments near the town of Mt. Shasta.

Late (Moni• Meodow), middle (Rush Creek), and early (Alpine Lake) Wi•conoin (age) moraine• in the Trinity Alps area. Undifferentiated glacial deposits on Mt. Shasta and elsewhere. Glacial deposits shown on this map are gener.lized; in some phces the ueu are exaggerated in 1i1.e and may include less than 50o/o glaci•l debri,,

Unconoolidated .. nd, cloy, ond gravel ternce deposits.

Bantry Formation-buff "nd btu~ land units interbedded lb"ilh !b hite, blui>h-gray, brown , ~nrl blur clay unit!.

"Older" alluvium, fon and terrace deposits. "Older" surficial agate- bearing deposi" northwe!t of Copen Dam. "Older" dune sand in th e Trinidad quadrangle.

Andesitic basolt and dense gray pyroxene ande site ( earlv flows forming the bm: of Mt. Shona ).

Pale groy rhyolitic da cite chaucteri'"d by brge phenocrym of phgioda.e. White pumicrou1 l:. va ( probably a ghny d aci te ) forming the domes sou th of Gra y Butte on Mt. Shast a.

Porphyritic pale-gny and brown, pyroxe ne andesit es h avin g distinctive platy or sl.bby h ab it and abundant ba•ic incl usion s, present ?n Mt. Shasta , Fine-guined and r. it<' or ande>itic b u •lt of the Boor Buttt and Spr ing H ill lava con~$. P.le gear and~siu and dae>te of Gra y But<e plug dom e, Colorle" gla .. -rich an de•ite of the twin domes on th~ north ,id~ of Mt . Shasta.

Butte Valley BaSJ!t-smoolh cru<ttd , black t o gray, ~·r<ic ular oJii,ine ba•alt ( in pan Recent). Pale gray to black , dtn••, ma,.ive to ve>ic ul ar basal ts t hot emanated from the Ev~r i tt Hill volcano and flowed down the Sacnmcnto Ri ver Vall~y.

Well consolidattd lapilH tuff and tu ff-b reccia on the Macdoel JO' quadrangle, (P leistocene to Rc.cnr ) . Volcanic mud How depom! and tuff· brecc1as expo~ ed in wall s o f Mud Creek Canyon (perhaps oldest nposed rocks of Mt. Sha!ta). Black tuff, lapilh, and volnn ic bombs on Mt. Shaso ..

Probable Plio-PieistoceM depo.<iU in the Or ick quadran gle. Plci,.ocene or late T ertiary te rr ace deposiu that h ave been sligh tl y deformed ond cont•in deeply weathered boulders (Hoopa quadrangle).

Pliocene (?) t o R""nt cindet co nes

Small orcas of highly fossiliferous m>rine, ncu-shore sands and grovels deposited on very irregular surfac~ along the prt<ent day coast.

PyroHne andesite and hornblende ande1ice in the M aCdoel JO' quad nngle ( possibly Pl io-Plei~t ocen t).

Olivine basal t <nd b .,~) tic ande•ite in the Macdael )01 quadrangle ( po,ibly Plio -Piei<tocene t O l.te Plci<t o<:ene ) .

Low mou nds of red cinders, remnants of cinder cones in Macdoel quadrangle .

St. Grorse Form oti<Jn dull gray-blur, momve /OJ•iJ;jrrous <ill<tonr and shale co~taining irre~:ular ltntts of sand {P liocene).

Wimer Format ion-f riable yellow Jhale and 1iltJtone thai weather brown.

Late Tertia r y auriftrou s gravel dcpmits in the Gasquet and Klam~th quadrangles.

Intrusive rocks exposed in Hornbrook and Dunsmuir are ...

Maosivc g ray m d olive-gr~<n prop ylitized p yro.ene dacite at Cedar Lake. Albite rh yoliu porph yry dikt> in the G .. qu<t quad rongle.

Andesitic volcanic n"du.

Basa ltic volcanic nec k in vicinit y of Copco Dam.

Wa•son Formation, Ro~y Formation, Celestine Formation '-hypersthene 4Uil.ite ~ndr1 ite, ba5all, &ome dacite flow!, voln nic con­glom rrale ~nd >a~ dston~ ( conoidered to b< upper Eocene tu upper Miocene by H. Williams),

llasal t ic flows in t he Gnelle area and in the .outhcast corner of the map uea ( age uncertain: may prove to-be Quatern~ry ).

Whit< to pale creoun v"<y fine-groined rhrolite plug domes in the Mocdoel JO' quadrangle.

White to cream, and pale blue -green rhyoli1e tuff, gl o5Sy pum iceous dacite tuff, and andesitic tuff-brtcci>

Horn broo k Formation- greenish-gray m4ssh·e nk.osic >andstone, conslomerat,-, and hlui<h-sray sh~le, buff and white maHin Ja,d&tone (non m orine in pan), cross -bedJed sand.tone , and coal. Coarse - to medium-grained sandston e, angular boulder con ­glomerate, and li ght -gray s)ule in the Gun~ight Peak orca.

Franciscan Formation-graywacke, interbedded shale, minor ronglomcratc, thin -bedded chert, sam~ undiffeunliated baJ41tic or spt/ittc rock1 that ha vt bern altered to green<tonc, and small ""'"e' o/ glaucophane Jchist. Kj fi' ::::Dothan Formnion- dark gray hard metagraylb'OCkc, metasandslonr, tbin-br,/ded metashal~. ,.,J ;,len·alated green metavolcanic rocks (probably L ote Jurassic , but bd1n<d by F. Wells and G. w.lkcr (USGS Mar GQ2! , 19H) to be older than the Galice formation shown as Ju on thi • mop: the Fra ncison Form>tinn and the lithologically •imilar Dothan Formoti<Jn havo been extended from their type are as from the south and from the north to the Oregon·Califocnia line wher" the rocks are known by either name) .

Metamol"phosed basi c igneous rocks within the Franci<ean Formation.

0

u

2 0 "' w ::t

I I I I I I I I I I I I I I

AGE STATE MAP

SYMBOL

gr

grt

bi

ub

Ju

Jml

Jliv

m

Is

ms

STRATIGRAPHIC NOMENCLATURE- Continued

STATE MAP UNIT Slate Map Units listed here ore not neeeuorify in stratigraphic

•equence; the 5equen<e u•ed hcu been standardized

for all $heel5 of th01 Geo logi' M<tp of C<tli farnia

MESOZOIC GRANITIC ROCKS

UNDIFFERENTIATED

GRANITE AND ADAMELLITE (QUARTZ MONZONITE)

GRANODIORITE

TONALITE (QUARTZ DIORITE) AND DIORITE

MESOZOIC BASIC INTRUSIVE ROCKS

MESOZOIC ULTRABASIC INTRUSIVE ROCKS

UPPER JURASSIC MARINE SEDIMENTARY AND METASEDIMENTARY ROCKS

MIDDLE AND / OR LOWER JURASSIC MARINE SEDIMENTARY AND METASEDIMENTARY ROCKS

JURASSIC AND /OR TRIASSIC METAVOLCANIC ROCKS

TRIASSIC MARINE SEDIMENTARY AND METASEDIMENTARY ROCKS

PRE-CRETACEOUS METAMORPHIC ROCKS, UNDIFFERENTIATED

Is = LIMESTONE AND/OR DOLOMITE

PRE.CRETACEOUS METASEDIMENTARY ROCKS

PRE.CRETACEOUS METAVOLCANIC ROCKS

STRATIGRAPHIC UNITS AND CHARACTERISTIC LITHOLOGIES (T he formally named formations grouped within an individual State M ap Unit

are listed in stratigraphie sequence from youngest to oldest.)

Qu>r<~ diorite, diorite, gabbro, granite and granodiorite th>t have not yet been differentiated in the m1pping. Locally indud<s some ultram•fi c rocks.

Adamellite at Yellow Butte. Granite and adamellite in the Seiad Valley quodrang-le.

Hornblende-biotite grandiorite, and leucoc ratic g rmodiorite in the Etna and Coffee Creek qu adrangles. Gnnodiorite in the Seiad V alley quadrangle.

Trondhjemite in Caribou Mtn. ~rea (Cofftt Creek quadrangle) , tonalite, hornblende diorite, biotite diorite, md pyroun• diorite in the Etna and Coffee Creek quadrangles. Tonalit e in the Stiad Valley quadnngle .

H ornblende gabbro and related dark diorite, augite-hornblende gabbro, hotnblende gabbro and hornfoh comple~ in the Coffee Creek quadrangle. Hornblende g.bbro, and undifferentiated gabbro and related dark diorite in the Etna quodr",ngle. Gabbro, undifferen!iated gabbro and diorite, •nd min<Jr gronodiori te elsewhere.

Predominant! y serpentinized peridotite. Includes some unaltered peridotite,dunite, and pyroxenite, also landslide deposits of ultr~ ­mafic rocks in the Coffee Creek qu adrangle. Most <Jf the ultramafic ro~ k in the eastern part of the m~p area moy be port of a orlce-continuou• sheet that intruded a low-angle f oult along wh ich P.lrozoic strat• to the eost were thrust westward over the Abrams and Salmon Formatium (frwin and Lipman USGS Prof. Paper- 450-C Article 67,' 1.962).

G alice Formation- dark gray /o black >late, phy //;/c, and interbedded thin to ma« ive, light gray, /uffaceou < <and!IOtus; includes so me interbedded ~ndeJitic metavolcanic rocks.

Potem Formation-argillite, tuffa<'t QUS sandstone and shale, ~nd lim€slune; Arvioon Formation- (pyroda,.ic rocb deposited in a marine environment) volco>~ic breccia and agglomerate containing inlnbedded tuff, tuffaceous <a,d!la>u- and conglomerate; som.e limelione.

Met• volcanic ro~k> in the northwe5tern part of the Weed >hect (may be_ in part correluive with the R~gue Formation in Oregon •nd are in pan 1nterbeddtd wLthm the Gahcc Formallun). Bagley Andmto-flow rockl , volc~nic brecna and pyroclasttc depo11ts (Middle Jurassic) Pit Form>tion , (volcanic part of)-Keratoph,·re, light to dork colored flow rork.s, mafic flow< and wme pyrod<Jslic rocks (Triassic).

Modin Forn~ation-sh~le, <onds/one, tuff, a_gslomnale, andeJite flow rocks, limes/one, and ronglomerate; Brock Shale(1)-lhi" d~rk &hair, m Pnl calcareous; Hos.selkus L!meston.-guy, lenticular, f DJ siliferous limrston~; Pit formnion-slalf, silt<tone and s~nd • tone and some undifferentiated t•olcanic rocks .

Chiefly _undivided phyllite, chert, and metavolcanic rocks of the Wesr.ern Po leozoic and Triassic Belt of Irwin ( 196"0). (in part correht1ve With the Applegate Group of southw .. tern Oregon); tnclude• rocks of the so-called Southwestern Devonian and Southw_estern Carboniferous Belu of Dille r ' the Blue Chert and part of the Lower Slate series of Hershey,' and the Groyback FormatiOn of Maxson (193>). In Scott Bar ~nd ,Condr~y Mtn, quadrangles, includes amphibolite, quaraite, ond marble. Stuatt ~ork Form•tion- phylltlk qua~/::it~• •. graphtt~c quarfz-m•ca phyllttes, gree ~;/one and related tuff, minor marble (formerly mcluded wothm the Abrams Moe• Schm ,_ DaviS and L1pm•n, G.S.A. Bull., Dec., 1%1. Thi> formation iJ prnem in the Coffee Creek quadrangle and os probably correlauve with simil.r rock, ehewhere in the central metamorphic belt.)

White, coarsely cry•tolline limestone (marble) in the Seiad quadrangle and the Marble Mountains.

Quartzite!, metachert, and mio schist on Yellow Butte (M•~doel 30' quadnngle). Phyllite, blue -gny thin -bedded chen, somo volnnic rocks, ond minor limestone h.av~ be~n considered .. correlative with the Triassic Applegate Group). Ro~ks considered to be more highly metamorphosed equivalent5 of the Galice Form1lion, includes Wcitchpec Schin of Oscar Hershey• (1906).

Greenstone md greenstone schi•t having metasedimentary interbeds of chert, argillite and limestone (these rocks may be corre­htive with the Applegate Group) . Meudiabase intru<ive rock south of Gunsight Peak northe .. tword to Paradise Craggy in the Hornbrook quadrangle.

--------+-+~ ----~--4rnr--l-------~-------------l

, ~he "m,·" unit north. of Sei.~d ~alle_y depicts coarse-grained, foliate and/ or lineate black amphibolite of metamorphic grade __!!molar t~ that of the ad1acent p~ untt. How~ver F. Wel !.s__jpersonal communicallon to W . DickinlOn) belieVes that the black amph>bohte re<ern bles meta morphoc ph35es of und~ubted App!eg><c G rou p , whereas the hornblende schist ('"pS" unit) is unlike anythmg known to be Applegate Group or '" equ1valents.

u ()

0

u

2 0 w ~

~

I I I

z • ~ •

I I

H ;{ ; I

I

~ I

I 11 I I I I I I I

c

CM

D

Dv?

s

0

pS

pSs

pSv

PERMIAN METAVOLCANIC ROCKS

PERMIAN MARINE SEDIMENTARY AND METASEDIMENTARY ROCKS

UNDIVIDED CARBONifEROUS MARINE SEDIMENTARY AND METASEDIMENTARY ROCKS

MISSISSIPPIAN MARINE SEDIMENTARY AND METASEDIMENTARY ROCKS

DEVONIAN MARINE SEDIMENTARY AND METASEDIMENTARY ROCKS

DEVONIAN AND PRE.DEVONIAN ? METAVOLCANIC ROCKS

SILURIAN MARINE SEDIMENTARY AND METASEDIMENTARY ROCKS

ORDOVICIAN MARINE SEDIMENTARY AND METASEPIMENTARY ROCKS

PRE·SILURIAN ? METAMORPHIC ROCKS, UNDIFFERENTIATED

PRE.SILURIAN ? METASEDIMENTARY ROCKS

PRE-SILURIAN? METAVOLCANIC ROCKS

Dekkas and Nosoni Formations undifferentia"d (BallibokkJ Group)-indurat~d tuff-breccia, rongloJtWrale, and greNJ and mar(H)n mud•lone>.

McCio\ld Limestone--light gray, rooruly crystalline limeJJone, wme d~rk. gray maHh·e or thin-brdded lime<lone.

Baird Formation-MdamorJohosed m~r(H)n a"d grun mu~<lone, multicolor<rl conglomerate, sands/one, tuff, 1nJ dark gray limcrtone (probably Mississippian).

Bragdon Formation-M~Iomorphu.ed <hole, •ill<tone, mud> lone, sond;tone and coor&e conglomer~tr.

Kennett Form1lion-Metamorpho<ed bl~ck shale and muds toM, and dark gray dense coral reef metomorphased /imntmu.

Copley Gre«nstone----Grren m.ta-andesile that wt:alhers buff, irregularly inlabedded flow>, tuff&, and tuff-breccia.

G.zelle Formuion-EHenlially unmelamorphoud volcanic graywacke, dark gray to black •il!!tone and mud,tone, <ilireous and feldspathic grit,_ chert conglomerate, limes/one .,,d limrJione conglomrrale.

Duul Formation "-Pale gray-grern uhistou gra:ywacke, phyl/itr, limestone, chert, and greenstone.

Lineated hornblende schist and medium to dark green pl:.giodase-chlorite schist in the Seiad Valley quodrangle. Chlorite -quortz­m l!scov;te schi•t in th~ Condrey Mtn. and Seiad Valley quadrangle•. Hornblende schist in the Preston Peak quadtangle.Hornblende ond chlorit., oc hi>ts in the Scou Bar quadrangle.

The5c units have been considered as equivalenu of the S1lmon Hornblende Schist ond Abums Mica Schist, how"v"r they m•y b~ nothing more than more highly metamorhposed equivolents of Triassic or Paleozoic rocks to the sourh. Dickinson (1963 written communication) bdieves that the amphibolite> Jhown as "mv" nonh of Seiad Valley are of approximately eq\livalent meumorphi~ grade to the adjacent "pS" schim.

Qu•rt7-mi ca schist< thu have been considered as Abnms Mica Schist. Grou"' Ridge formation ( Davis and Lipman, G.S.A. Bull ., D ec. 1_962) - micoceouJ and felds p~lhic q=rl; schists, olmondinr-homblrnde rockJ, hornblende <ehisls, hornblende grui« ts, snd colc-schi>ts. Rocks shown a> pSs? ( gneissic amphibolite) are con>idered by Lipman (1962) as part of the Salmon Hornblende Schilt.

Salmon Hornblende Sch i•t----lineald hornblende schi<l probably formed by the mclomorpbiJm of b4so/tic rocks. Included in pSv is a "tran>itional" Stuart Fork-Salrn<Jn un;t of Lipman md Davis; the mapped northward extension of this unit is however, a greenstone that h .. a similar metamorphi~: hi>tury to that of the Stu~rt Fork Form•tion, Davis and Lipman (G.S.A. Bllll., Dec., 1961) have postulated thu the Stoart Fork-Salmon contact is a major low angle thrust fault.

NOTES

1 These unit• are equivalent to a port of the \'\'estern Cascade Volcanic Series of II. \Villiams. • Diller,} . S., 1903, Klamath Mountaio section , California: Am. Jour. Sci. 4th ser. , vol. 15 , pp 342-362

Hershe}·, 0. H., 1901 , Metamorphic formations of nurthwestem Cahfomia: Am. GeolO!Zist, v<>l. 2 7, pp. 22S-245. Hershey, 0 . H., 1906, Some western Klamath stratJg:taphy: Am. Jour. txi . 4th se r. , val. 21, pp . 58-66.

'The Duzel Formation was first described by F. \Veils, G. \ Valker,_ and C . Mcrr.iam (G.S.A. Bull. , i\l ay _1959) as Upper Ordovki•n (?) based ~pon a fossil faun a at Hms<">h"" Gukh. Thi> a11e was determined by Helen Duncan (of the U.S.G.S. ) wb o recognizes the less hkely pos.,bility that thiS fau na may be Early S!lunan ( wrltten commumcanon f~om l\hss Duncan , 196 3) . C . '\\' i\lemam (written corn mu nk auon, !9h 3) l>el le••cs tl>at a different faunal assembloae which he colleded at a later date at Horsesh<>< Gulch " Sihman; howe,·er, he rec'ollnizes the pOSSlbility th at both Ordovician and Silurian strata may be present.

o' 42"0

41"00

124"00'

}.::..«-q;. ti:'

"I ~' ¢ .. ~RES CENT_

0~ CITY

~ ~e; ~

c.«-.....

"'" 1!:-'<lcS C)

._«-~ ,, C>

Ooq;.O

-KLA~A\H-~-

f' ~

,_,~

'<.!~ ();-~

v~~ (j

~ ~~ Q t ...._«;

TOPOGRAPHIC QUADRANGLES WITHIN THE WEED SHEET

AVAILABLE FROM THE U.S. GEOLOGICAL SURVEY

FEDERAL CENTER, DENVER, COLORADO 80225

1963

123"00'

~ ~· ¢ 0~ '<.!~ ~ ~ q_ v Q;-0 CJ~ ~v ¢ 0~ ~ ~~ q_..l.. ~();-" ~ OQ;-'<.!"' ~ ,~ Q~

,_,'<.! ~ q_Q;- ~ CJ

~- ~'<.! f' Q;-'<.!"' ~ ~~ ~~ v

0~ 0~ 0~ v "'"' ':) ();-'<.! ~ . 0~ CJO "'"

..1.. ~ ~~ "' «

0~ Q;-

~"' ~ ~~ ..... ~ v

,_,~ Q:-0, ~.., ~

~v"" ~v J. ..l..<v t ~..,

0 ~"' ~ ~

"'~ CJ

OQ;-«

CJO c§

c.;

~ .:::..0

'<.!Q:-'<.!"'

Q:-v

'<.!v

~~ ~' ~

~ ~<v

'<.!v 0

CJ~ ~~

CJ~ q,~

<v v

~~ ~

~<v

"'

"'"" "' ~..,

"'

12 2"00' 2"00' 4

/; ~ ~(::) ~-

~ <:> ~

~~

~- <v <v~ q_41 ~ v ~<v ~ ~ "'<v A..<v q_'<il" .::! ~~

0~ .:::.. CJ "v~ OQ;-..1..0 00

~ ,v <v<v ~ ~"' ~~ CJO ~ '<.!CJ ~"" <:>~ v «« ~

"'"" CJ

CJO q,Q ~0

"' j I 124"00 123"00 '

,\ lr. Shasta as seen from the west, extends up\\·ard to 14,162 feet and forms a classic example of a Quaternary composite \"Oicanic cone. Shasrina i,; the large parasitic composite cone that appears on rhc near flank of the mountain. The wedge-shaped gash on Shastina is Diller Canyon, a feature which H owe! \ Villiams suggests may be due to \·iolent downward explosions.

Photo by Fairchild A erial Surveys, Inc. O ct. 5,1930

4 1"00" 122 oo' .

I

The date beneath each mop sheet n{;lme lndk:ate:s yeCJr of H no dote oppearsr ih.e map sheet had not been ot the time this cover was issued.

II