U.S.

Department of the Interior Scientific Investigations Map 3327

U.S. Geological Survey Sheet 1 of 6
Pamphlet accompanies map

121°20’ 121°15’ 121°10’ 121°5’

Qms
CORRELATION OF MAP UNITS

Qms Qmsf Qmss Qmsl Qmc Qls Holocene

QUATERNARY
Pleistocene

KJug
Pliocene

Qmss
Tus TERTIARY
Tm Miocene
Tus

Qms
CO
AS
Qmss
Ksl KJug
KJug Cretaceous

SA
Qms

T
MESOZOIC

RA
KJug?

N
Tus Qms/Tus
KJug Qms Jo KJf Jurassic

NG

SI
Qms/KJug?
Point

ME
Qmss Tus 35°40’

ES
Qmss Qms

Piedras Blancas
Tus
Qmss Qms DESCRIPTION OF MAP UNITS

ON
Jo
Qmss
Qms
[Note that composite units (gray-stippled areas) are designated on map by composite label indicating both overlying
Jo
35°40’ sediment cover and lower (older) unit, separated by slash (for example, Qms/Tus indicates that thin sheet of Qms

FA
Qmss KJug
Tus OCE overlies Tus)]

ANI

U
Qms/Tus Qms Marine nearshore and shelf deposits (Holocene)—Mostly sand; ripples common
Jo Qmss
C FA

LT
Qms/Tus KJug KJug KJug

ULT
KJug? Qmss
Tus Qmsf Fine-grained marine nearshore and shelf deposits (Holocene)—Predominantly mud to muddy sand
Qmss Qmss
Qms Qmss Marine shelf sorted bedforms (Holocene)—Inferred to be coarse sand and possibly gravel; found as
single depressions or in fields of depressions interspersed with elevated shelf sediments (unit Qms).
Although no direct camera observations of these bedforms were made in map area, their composition is
inferred from similar features directly observed elsewhere on California shelf
Qmss Qmsl Marine slope deposits (Holocene)—Sand and mud; found offshore of shelf break (more than about 80 m
Tus
deep) on seaward-dipping (6°–8°) surface

Tus
KJug KJug
San Simeon Qmc Marine channel deposits (Holocene)—Predominantly coarse sand; characterized by high backscatter

KJug? Qmss KJug Qmc Qls Landslide deposits (Holocene and latest Pleistocene)—May represent various forms of submarine
Tus Qms sediment instabilities, including slumps, slides, and collapse depressions. Characterized by hummocky
Qmss
Tus bathymetry and headscarps incised into shelf (unit Qmsf) or slope (unit Qmsl) deposits
KJug? KJug
Tus
Tus Sedimentary bedrock (Tertiary)—Includes sedimentary rocks from the Monterey and Pismo Formations;
Qmsf
Tus
Qmss distinguished on basis of bedding character in shallow seismic-reflection data and (or) multibeam
Qmc
imagery. Stippled areas (composite unit Qms/Tus) indicate where thin sheets of Qms overlie unit
Tus KJug
Tus
Qms/Tus
Tus Qmss KJug Qmss Tm Monterey Formation (Miocene)—Diatomaceous, porcelaneous, and opaline shale; tuffaceous siltstone;
Tus Qms KJf and claystone
Qmss
Tus Tm? Ksl Unnamed sandstone and interbedded shale (Late Cretaceous)—Sandstone and interbedded shale and
Tus
Tus KJug
KJug Qmc siltstone; mapped in Sam Simeon and Morro Bay areas, in accordance with adjacent onland mapping
Tus Tus Qms (Hall, 1973a, 1974). Correlated with the unnamed sandstone and interbedded claystone unit (Kslc),
Tm
Tus
Qmss
KJug mapped in Point San Luis area (see sheet 5)
KJf
Tus KJug Unnamed graywacke (Cretaceous and Jurassic)—Thick-bedded, medium-grained sandstone; also locally
Qms/Tus
Tus KJug Tus Qmss present is thinly bedded siltstone that has crossbedding, cross-laminations, and graded bedding.
Qmss
Tus Mapped only in San Simeon area, west of Hosgri–San Simeon Fault Zone at Point Piedras Blancas, in
20
KJug accordance with adjacent onland mapping (Hall, 1976). Stippled areas (composite unit Qms/KJug)
Qms/Tus
indicate where thin sheets of Qms overlie unit
Tus KJf Franciscan Complex (Cretaceous and Jurassic)—Includes fine- to coarse-grained sandstone, siltstone,
Tus
Qmss and some claystone, as well as mélange. Mélange is mainly composed of sheared claystone that
KJf contains exotic clasts of conglomerate, blueschist, schist, greenstone, chert, graywacke, and shale.
Tus Tus Qms Stippled areas (composite unit Qms/KJf) indicate where thin sheets of Qms overlie unit
Tus
Qmss Qmss Jo Coast Range ophiolite (Jurassic)—Includes diabase, basalt, microdiorite, dikes and sills, diorite, and
Qmss
Qmc serpentinite. Ophiolite sequences mapped onland at Point Piedras Blancas and Point San Luis (Hall,
Qms Qmss 1973a, 1976). Serpentinite, which often is faulted and sheared within the Franciscan Complex, is found
Tus in lenses along fault zones
Qmss Qms/Tus

Qmss EXPLANATION OF MAP SYMBOLS

Qms/Tus
Qmss Contact—Approximately located
Qmss
Tus
Qmss 40 Fault (offshore)—Solid where location is certain, dashed where location is inferred, dotted where location
Tus Tus Qms Tus
Qmss is concealed, queried where existence is questionable
Tus
Fault (onshore)—Solid where location is certain, long-dashed where location is approximate, short-dashed
Qmsl
Qmss where location is inferred
Tus
Folds—Solid where location is certain, dotted where location is concealed
Tus Tus
Qms/Tus
Tus KJf Antiform
Tus Jo?
Qmsf
60 Qmss Synform
Tus
Qmss Qmss
Tus Tus
Tus Qms Monocline

KJf KJf Headscarp of submarine landslide—Sharp, distinct scarp at head of landslide; in places, forms contact
Tus Tus
Tus between landslide deposits (Qls) and other units. Hachures point downscarp
Shelf break—Boundary between continental shelf and upper slope, mapped on basis of distinct break in
Tus KJf
80
Tus
Tus
Qms/KJf
35°35’ slope that is visible in multibeam bathymetry or on seismic-reflection profiles. Forms contact between
Qms/Tus Qmss
shelf (Qmsf) and slope (Qmsl) deposits. Coincident with submarine landslide scarps offshore of
Tus Cambria
Qms/Tus
Qmsf Tus KJf Ksl Slope break—Break in slope along top of latest Pleistocene nearshore bar
35°35’ Qms/Tus Tus
Qmss CA
MB Boundary of multibeam-bathymetry survey
Tus Qms
Tus KJf

RI
Tus
100 Tus Qms Area of “no data”—Areas not mapped owing to insufficient high-resolution seafloor mapping data
Tus Tus Qms/KJf Qmss
A
Qms/Tus KJf Ksl FA
Qms
KJf
U LT
REFERENCES CITED
Friday, D.Z., Taylor, L.A., Eakins, B.W., Carignan, K.S., Grothe, P.R., Lim, E., and Love, M.R., 2011, Digital elevation
120 Tus Tus Tus
Qms
models of Port San Luis, California—Procedures, data sources, and analysis: National Oceanic and Atmospheric
Qms/Tus
KJf
Administration National Geophysical Data Center, Coastal DEMs, accessed December 2011, at
http://www.ngdc.noaa.gov/mgg/coastal/coastal.html.
140 Qms/Tus Tus Tus Hall, C.A., 1973a, Geologic map of the Morro Bay South and Port San Luis quadrangles, San Luis Obispo County,
Cambria
Qms/Tus
121˚15’ 121˚ 120˚45’ Qmss
California: U.S. Geological Survey Miscellaneous Field Studies Map MF–511, scale 1:24,000.
Tus Hall, C.A., 1974, Geologic map of the Cambria region, San Luis Obispo County, California: U.S. Geological Survey

HO
160 Miscellaneous Field Studies Map MF–599, scale 1:24,000.
Qms
Hall, C.A., 1976, Geologic map of the San Simeon–Piedras Blancas region, San Luis Obispo County, California: U.S.
SS

Tus
Tus
F

Geological Survey Miscellaneous Field Studies Map MF–784, scale 1:24,000.

SG
180 Hartwell, S.R., Finlayson, D.P., Dartnell, P., and Johnson, S.Y., 2013, Bathymetry and acoustic backscatter—Estero
PPB
Qmsl Bay, California: U.S. Geological Survey Open-File Report 2013–1225, available at http://pubs.usgs.gov/of/

RI
SS 2013/1225/.
200 National Oceanic and Atmospheric Administration National Geophysical Data Center, 2011, U.S. coastal relief model,

FA
vol. 6—Southern California: National Oceanic and Atmospheric Administration National Geophysical Data
Center, U.S. Coastal Relief Model, accessed December 2011, at http://www.ngdc.noaa.gov/mgg/coastal/grddas06/

U
OF 220
grddas06.htm.

LT
CF
U.S. Geological Survey and California Geological Survey, 2010, Quaternary fault and fold database of the United
RF
HF

CM 240 Qms States: U.S. Geological Survey database, accessed January 3, 2012, at http://earthquake.usgs.gov/hazards/qfaults/.

260
SAN SIMEON Tus KJf
35˚30’

KJf

Qmsf
PE Tus
Qms

CA Qms
KJf
Qms
Estero Qms
Qms
Bay
CF Qmsl Qms Qmss
MB
LOF Qms
Ksl Qms
Qmss Qms

Qmsf
LOF Ksl
ESTERO BAY Qms/Tus Ksl

Qms
SLO Tus Tus Ksl
PBU EF
35˚15’

Qms
Tus Qms
PB

DC SM
F

Qmss
Tus Qmss
F WAF Qmss
SLF
SF SB
PSL
Ksl Qmss
San Luis Qms
Ksl Ksl
HF

0 5 10 KILOMETERS
Bay O Ksl
PB OC
POINT SAN LUIS F Qms
0 5 10 MILES Qms

Tus 35°30’
Ksl

INDEX MAP SHOWING AREAS OF SHEETS 1 AND 2 (SAN SIMEON), OUTLINED IN RED, IN RELATION TO AREAS OF SHEETS 3 AND 4 Qms/Tus
(ESTERO BAY) AND 5 AND 6 (POINT SAN LUIS). FAULT ABBREVIATIONS: CF, CAMBRIA FAULT; EF, EDNA FAULT; HF, HOSGRI FAULT; Qms Qmss
LOF, LOS OSOS FAULT ZONE; OCF, OCEANO FAULT; OF, OCEANIC FAULT; PBF, POINT BUCHON FAULT; RF, RINCONADA FAULT; SF, Ksl
35°30’
SHORELINE FAULT; SLF, SAN LUIS BAY FAULT; SMF, SAN MIGUELITO FAULT; SSF, SAN SIMEON FAULT; WAF, WILMAR AVENUE FAULT. Qls
OTHER ABBREVIATIONS: CA, CAYUCOS; CM, CAMBRIA; DC, DIABLO CANYON POWER PLANT; MB, MORRO BAY; O, OCEANO; PB, Qmsl
PISMO BEACH; PBU, POINT BUCHON; PE, POINT ESTERO; PPB, POINT PIEDRAS BLANCAS; PSL, POINT SAN LUIS; SB, SHELL BEACH;
Tus Qms
SLO, SAN LUIS OBISPO; SS, SAN SIMEON. Qmss
Qms
Qmss Qms Qmss
Qms

121°20’ 121°15’ 121°10’ 121°5’

Bathymetric shaded-relief imagery (10X vertical exaggeration) from gridded multibeam bathymetry 13° SCALE 1:35 000 Offshore geology and geomorphology mapped by Janet T.
acquired, processed, archived, and distributed by California State University, Monterey Bay, Seafloor 1 1/2 0 1 MILE Watt and Samuel Y. Johnson, 2010-2013. Onshore faults
Mapping Lab (CSUMB) and by U.S. Geological Survey (Hartwell and others, 2013) from Quaternary fault and fold database (U.S. Geological
TH

1 .5 0 1 KILOMETER Survey and California Geological Survey, 2010)

TRUE NORTH

Bathymetric contours derived from gridded multibeam bathymetry (CSUMB), 1/3 arc-second NOAA
NOR

CALIF.
Tsunami Inundation DEM (Friday and others, 2011), and regional 3 arc-second NOAA DEM (National GIS database and digital cartography by Janet T. Watt,
N E T IC

Oceanic and Atmospheric Administration National Geophysical Data Center, 2011) BATHYMETRIC CONTOUR INTERVAL 10 METERS
Stephen R. Hartwell, and Theresa Fregoso
MAG

ONE MILE = 0.869 NAUTICAL MILES

Elevation data from U.S. Geological Survey National Elevation Database (1/3 arc-second); sun Edited by Taryn A. Lindquist
APPROXIMATE MEAN MAP LOCATION
illumination from northwest (315°) at 45° above horizon DECLINATION, 2015 Manuscript approved for publication April 14, 2015

Universal Transverse Mercator projection, Zone 10N

NOT INTENDED FOR NAVIGATIONAL USE

Offshore Geology and Geomorphology of San Simeon Map Area
Offshore Geology and Geomorphology from Point Piedras Blancas to Pismo Beach,
San Luis Obispo County, California Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the
U.S. Government
This map was printed on an electronic plotter directly from digital files. Dimensional calibration may vary between electronic plotters
and between X and Y directions on the same plotter, and paper may change size due to atmospheric conditions; therefore, scale and
By proportions may not be true on plots of this map.
For sale by U.S. Geological Survey, Information Services, Box 25286, Federal Center, Denver, CO 80225, 1–888–ASK–USGS

Janet T. Watt, Samuel Y. Johnson, Stephen R. Hartwell, and Michelle Roberts Digital files available at http://dx.doi.org/10.3133/sim3327 or http://pubs.usgs.gov/sim/3327/
Suggested Citation: Watt, J.T., Johnson, S.Y., Hartwell, S.R., and Roberts, M., 2015, Offshore geology and geomorphology from Point
ISSN 2329-132X(online) Piedras Blancas to Pismo Beach, San Luis Obispo County, California: U.S. Geological Survey Scientific Investigations Map 3327,
2015 http://dx.doi.org/10.3133/sim3327 pamphlet 6 p., 6 sheets, scale 1:35,000, http://dx.doi.org/10.3133/sim3327.