GEOLOGIC MAP OF THE MONTEREY 30'x60' QUADRANGLE AND ADJACENT AREAS, EXPLANATION FOR THE GEOLOGIC MAP OF THE MONTEREY Q UADRANGLE, CALIFORNIA Regional Geologic Map Series, 1:100,000 Scale Map No. 1 Plate 2 of 3

SALINIAN BLOCK (SOUTHWEST OF THE ) NORTHEAS T O F THE S A N AN DREAS FAU L T

e Q af Qe Qd Qs Qg Qcf Qb Qfl Q n Qg Qp Qb ALLUVIUM ARTIFICIAL EOLIAN DUNE SAND STREAM GRAVEL CANYON FILL BASIN FLOOD ALLUVIUM oce

l Unconsolidated stream FILL SAND SAND Sand to boulder size particles. (offshore) DEPOSITS PLAIN Unconsolidated stream STREAM GRAVEL and basin deposits.pyp Clay and basin deposits.pyp Clay PATTERSON ALLUVIUM BASIN Silty clay. DEPOSITS Sand to boulder size particles. DEPOSITS Ho to boulder size particles. Qls to boulder size particles. Qls OF LETTIS (1982) Silty clay. Qms Qt Qsl MARINE SEDIMENTS Qocf Qrb TERRACE DEPOSITS (offshore) Gravel, sand, silt, and clay SAN LUIS ALLUVIUM Qo Qod Qf OLDER CANYON FILL RELICT BEACH Qo deposited on stream cut OF LETTIS (1982) LANDSLIDE (offshore) DEPOSITS surfaces. LANDSLIDE OLDER DUNE SAND DEPOSITS DEPOSITS e OLDER ALLUVIUM ALLUVIAL FAN DEPOSITS Qct (offshore) OLDER ALLUVIUM Dissected alluvial deposits. Sand, silt, and gravel. Arrows show direction of Dissected alluvial deposits. Arrows show direction n Qlb movement (Includes submarine SUBMARINE of movement. slumps in Monterey Bay). ALLUVIAL FANS OF CANYON TERRACE LOS BANOS ALLUVIUM

oce DUPRÉ AND TINSLEY (1980) OF LETTIS (1982) t

UATERNARY FAN DEPOSITS s Qfa of Antioch i

Q Qar Qae Qaf e FAN DEPOSITS Qt Qtw Qmt

l Qfc of Chular

P AROMAS SAND FAN DEPOSITS MARINE TERRACE DEPOSITS Eolian and fluvial deposits TERRACE DEPOSITS Qfp of Placentia Gravel, sand, silt, and clay deposited of clay, silt, sand and gravel. Gravel, sand, silt, and clay deposits on stream-cut surfaces. on wave cut surfaces. PLIO - PLEISTOCENE CONTINENTAL DEPOSITS Qar - Undivided FAN DEPOSITS QT Qfg of Gloria Qt - Undivided Conglomerate, sandstone, siltstone, and claystone. (Includes Qae - Eolian Santa Clara Formation and San Benito Gravel). Qaf - Fluvial Qtw - Watsonville terrace QTf QTl QT Puc Pus Pv PLIO-PLEISTOCENE FLUVIAL PLIO - PLEISTOCENE CONTINENTALA DEPOSITS AND LACUSTRINE DEPOSITS e Conglomerate, sandstone, siltstone, and claystone. Nonmarine gravel, sand, silt, and n Includes Paso Robles Formation. UNNAMED PLIOCENE PLIOCENE BASALTIC ROCKS thin bedded limestone. (Peckham CONTINENTAL DEPOSITS Near San Felipe Lake. Formation of Leith, 1949). Mostly mudstone. Pus - sandstone QTf - Fluvial conglomerate with red and green oce QTl - Lacustrine PURISIMA clay. FORMATION li Sandstone and silt- Ppu Ppr P stone; marine. (Also in offshore area). PANCHO RICO FORMATION Diatomaceous mudstone; marine. MPe

Tv ETCHEGOIN FORMATION TERTIARY VOLCANIC ROCKS Sandstone and siltstone; marine. Msc (offshore)

C Msm SANTA CRUZ MUDSTONE Mv I Siliceous, organic mudstone; marine. SANTA MARGARITA SANDSTONE Mvqa Mvqb Mvqd Mvqr O Mvq Arkosic sandstone; marine. Interbedded Miqa Miqb Miqd Miqr

Z Msm basalt (Mv) occurs on the San Benito quadrangle. Msu QUIEN SABE VOLCANICS SANTA MARGARITA SANDSTONE Mvqa - Andesitic flows and breccia

e Arkosic sandstone; marine. NO UNNAMED MIOCENE SEDIMENTARY ROCKS Mvqb - Basaltic flows and breccia

n Granitic conglomerate and arkosic sandstone on San Benito Mmy Mvqd - Dacite flows E and Spreckels quadrangles. Marine and non-marine. Mvqr - Rhyolite flows Tv Miqa - Intrusive andesite C Mmy MONTEREY FORMATION Miqb - Intrusive basalt TERTIARY VOLCANIC ROCKS oce Siliceous shale, organic mudstone, Miqd - Intrusive dacite MONTEREY FORMATION Tva - Andesite i Mus diatomite, with minor sandstone; Miqr - Intrusive rhyolitic rocks Siliceous shale, organic mudstone, diatomite, marine. Tvb - Basalt

M with minor sandstone; marine. UNNAMED MIOCENE SANDSTONE Upper part marine arkosic sandstone and conglomerate, lower part continental Msh sandstone and conglomerate. (Includes Chamisal Formation of Bowen, 1965). Mte Mlo Mlt TEMBLOR FORMATION LOMPICO SANDSTONE Mv Sandstone, conglomerate minor LONE TREE FORMATION Calcareous, arkosic sandstone; marine. shale; marine. Sandstone, shale, limestone TERTIARY UNNAMED MIOCENE VOLCANIC ROCKS and minor conglomerate. Dacitic to andesite agglomerate and flows with interbeds of arkosic sandstone.

Φ rb Φpv RED BEDS OF KERR AND SCHENCK(1925) ORGANIC MUDSTONE PINNACLES VOLCANIC FORMATION e Red breccia and conglomerate, some sandstone. Marine. (Mapped as Monterey Formation May be part of the Zayante Formation. Rhyolite flows, tuff, and breccia; minor by Allen, 1946 - may be Eocene in part). dacite and andesite. Φvq ocen g VAQUEROS SANDSTONE Φvc

li Arkosic sandstone; marine. (Includes Pinecate Formation of Allen, 1946). O CARMELOITE OF LAWSON (1893) Basaltic andesite flows and breccia. EΦsj

SAN JUAN BAUTISTA FORMATION OF ALLEN (1946) KREYENHAGEN FORMATION e Marine sandstone with clams and barnacles. Ek LOS MUERTOS FORMATION Claystone with siliceous shale; marine.

n Elm Conglomerate, sandstone, mudstone; marine. Ess Ebu Ed DOMENGINE SANDSTONE Marine. Etp TRES PINOS SANDSTONE ARKOSIC SANDSTONE UNNAMED EOCENE SEDIMENTARY ROCKS Marine. Marine. CANTUA SANDSTONE Micaceous shale; marine. Elc Member of the Lodo Formation; marine. Eoce Ec PALEOCENE-EOCENE SEDIMENTARY ROCKS CARMELO FORMATION PEu Sandstone, mudstone, shale; marine. (Includes Sandstone and conglomerate; marine. the Bolado Park Formation). Paleocen e

TKu The Franciscan is a subduction complex consisting of a disrupted mixture of diverse rock types. Parts TERTIARY - CRETACEOUS of the Franciscan are melange (KJfm) - a chaotic mixture of rock fragments in a sheared, shaly matrix. SEDIMENTARY ROCKS Franciscan rock types have not been subdivided over much of the map area. Rock masses large Ku Sandstone, siltstone, shale,

OUS enough to be shown on this map are depicted as follows: conglomerate; marine. E UPPER CRETACEOUS PANOCHE FORMATION cg Conglomerate. C (part of Great Valley Sequence) MPLEX SEDIMENTARY ROCKS Kqm Ku Kp

C Kgr Kqd Kgd Conglomerate, sandstone, Shale, sandstone, siltstone, and ss Kpss Sandstone and shale. CO I shale; marine. conglomerate; marine. UPPER CRETACEOUS KJf CRETACEOUS GRANITIC ROCKS Kpc Kps - Sandstone KJf N O SEDIMENTARY ROCKS ch Chert. RETA Mostly granodiorite and quartz diorite (Kgr); in Kpc - Conglomerate Gabilan Range divided into quartz monzonite (Kqm); (part of the Great Valley Sequence) A Z C quartz diorite (Kqd); and granodiorite (Kgd). Sandstone, siltstone, shale, and gs Greenstone - altered volcanic rock.

conglomerate; marine. SC

gb KJu I

SO um Serpentinized ultramafic rock. e

Jpb NC

E Breccia. GABBRO JURASSIC - CRETACEOUS bs Blueschist and semischist. C (offshore) SEDIMENTARY ROCKS I M (part of the Great Valley Sequence) RA Volcanic rocks - altered basalt ls Limestone. FRANCISCAN COMPLEX Jv F (greenstone). Clay shale; marine. (Includes SS Jhg Offshore (West of the San e Ophiolit Gravelly Flat Formation of Rose Gregorio Fault). g gb Gabbro. Gabbro; usually contains and Colburn, 1963).

RA JURASSIC GABBROIC ROCKS Jgb Includes hornblende quartz gabbro at Logan. sheared serpentinite. JU ? oast Ran um Serpentinized ultramafic rock. These units are not necessarily in stratigraphic sequence. PzMz PREBATHOLITHIC METASEDIMENTARY ROCKS C Includes the Sur Series of Trask (1926). msc Pzls - Carbonate rocks including the Gabilan Limestone. SCHIST OF OF ROSS (1976)

REFERENCES CITED: Allen, J.E., 1946, Geology of the San Juan Bautista Quadrangle, California: Division of Mines Bulletin 133. Bowen, O.E., 1965, Stratigraphy, structure, and oil possibilities in the Monterey and Salinas quadrangles, California: in Rennie, E.W., Jr., A symposium presented at the Fourtieth Annual Pacific Section of the American Association of Petroleum Geologists California, vol. 49, no. 7, p. 1081. Duprré, W.R., and Tinsley, J.C., III, 1980, Maps showing geology and liquefaction potential of northern Monterey and southern Santa Cruz counties, California: U.S. Geological Survey Miscellaneous Field Studies Map MF-1199, scale 1:62,500. Kerr, P.F., and Schenck, H.G., 1925, Active thrust faults in San Benito County, California: Geological Society of America Bulletin 36, p. 465-494. Lawson, A.C., 1893, The geology of Carmelo Bay, California: University of California Publications, Bulletin of the Department of Geological Science, vol. 1, p. 1-59. Leith, C.J., 1949, Geology of the Quien Sabe Quadrangle, California: California Division of Mines Bulletin 149, 60 p. Lettis, W.R., 1982, Late Cenozoic stratigraphy and structure of the western margin of the central San Joaquin Valley, California: U.S. Geological Survey Open-File Report 82-526, 203 p. Rose, R.L., and Colburn. I.P., 1963, Guidebook to the geology of the : Pacific Section of the Association of Petroleum Geologists, p. 38-45. Ross, D.C., 1976, Reconnaissance geologic map of pre-Cenozoic basement rocks, northern , Monterey County, California: U.S. Geological Survey Miscellaneous Field Studies Map MF-750. Trask, P.D., 1926, Geology of the Point Sur quadrangle, California: University of California, Department of Geological Sciences Bulletin, vol. 16, no. 6, p. 119-186.