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 

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

Digital files available at http://dx.doi.org/10.3133/ofr20151232

Suggested Citation: Watt, J.T., Hartwell, S.R., and Davenport, C.W., 2015, Offshore and onshore geology and geomorphology, Offshore 

of Pigeon Point map area, California, sheet 10 in Cochrane, G.R., Watt, J.T., Dartnell, P., Greene, H.G., Erdey, M.D., Dieter, B.E., Golden, 

N.E., Johnson, S.Y., Endris, C.A., Hartwell, S.R., Kvitek, R.G., Davenport, C.W., Krigsman, L.M., Ritchie, A.C., Sliter, R.W., Finlayson, D.P., 

and Maier, K.L. (G.R. Cochrane and S.A. Cochran, eds.), California State Waters Map Series—Offshore of Pigeon Point, California: U.S. 

Geological Survey Open-File Report 2015–1232, pamphlet 40 p., 10 sheets, scale 1:24,000, http://dx.doi.org/10.3133/ofr20151232.

ISSN 2331-1258 (online) 

http://dx.doi.org/10.3133/ofr20151232

Figure 1. Schematic map showing major offshore structural features northwest of 

Monterey Bay (modified from Nagel and others, 1986; McCulloch, 1987; Wagner and 

others, 2002; Dickinson, 2005). Red box, Offshore of Pigeon Point map area. Yellow line, 

offshore limit of California’s State Waters. Outer Santa Cruz Basin (modified from 

McCulloch, 1987) shown by blue shading and hachured lines (hachures point into 

basin). Solid black lines show traces of faults: AF, Ascension Fault (sawteeth on upper 

plate); CF, Coastways Fault; FF, Frijoles Fault; SGFZ, San Gregorio Fault Zone (also 

shown by dark-gray shading); SAF, San Andreas Fault; ZYF, Zayante-Vergeles Fault. 

Dashed magenta lines show axes of structural highs: PPH, Pigeon Point high; SCH, 

Santa Cruz high. Other abbreviations: PAN, Point Año Nuevo; PP, Pigeon Point.

122°30' 122°20' 122°10'

37°10'

37°0'

36°50'

Outer Santa Cruz Basin

PPH

SCH

AF

shelf-slope 

break

SGFZ

Monterey 

Bay

PAN

PP

CF

FF

0 5 10 Kilometers

ZVF

SAF

Clark, J.C., Weber, G.E., Rosenberg, L.I., and Burnham, K., 1999, Neotectonics of the San Gregorio 

fault zone, central coastal California, Field Trip No. 2, in Garrison, R.E., Aiello, I.W., and Moore, 

J.C., eds., Late Cenozoic fluid seeps and tectonics along the San Gregorio Fault Zone in the 

Monterey Bay Region, Pacific Section, American Association of Petroleum Geologists Guidebook 

GB-76, p. 94–119.

Davis, A.C.D., Kvitek, R.G., Mueller, C.B.A., Young, M.A., Storlazzi, C.D., and Phillips, E.L., 2013, 

Distribution and abundance of rippled scour depressions along the California coast: Continental 

Shelf Research, v. 69, p. 88–100, doi:10.1016/j.csr.2013.09.010.

Dickinson, W.R., Ducea, M., Rosenberg, L.I., Greene, H.G., Graham, S.A., Clark, J.C., Weber, G.E., 

Kidder, S., Ernst, W.G., and Brabb, E.E., 2005, Net dextral slip, Neogene San Gregorio–Hosgri 

fault zone, coastal California—Geologic evidence and tectonic implications: Geological Society 

of America Special Paper 391, 43 p.

Edwards, B.D., 2002, Variations in sediment texture on the northern Monterey Bay National Marine 

Sanctuary continental shelf: Marine Geology, v. 181, p. 83–100.

Goff, J.A., Mayer, L.A., Traykovski, P., Buynevich, I., Wilkens, R., Raymond, R., Glang, G., Evans, 

R.L., Olson, H., and Jenkins, C., 2005, Detailed investigations of sorted bedforms, or “rippled 

scour depressions,” within the Martha’s Vineyard Coastal Observatory, Massachusetts: 

Continental Shelf Research, v. 25, p. 461–484, doi:10.1016/j.csr.2004.09.019.

Graymer, R.W., Moring, B.C., Saucedo, G.J., Wentworth, C.M., Brabb, E.E., and Knudsen, K.L., 2006, 

Geologic map of the San Francisco Bay region: U.S. Geological Survey Scientific Investigations 

Map 2918, available at http://pubs.usgs.gov/sim/2006/2918/.

Hallenbeck, T.R., Kvitek, R.G., and Lindholm, J., 2012, Rippled scour depressions add ecologically 

significant heterogeneity to soft-bottom habitats on the continental shelf: Marine Ecology 

Progress Series, v. 468, p. 119–133, doi:10.3354/meps09948.

McCulloch, D.S., 1987, Regional geology and hydrocarbon potential of offshore central California, in 

Scholl, D.W., Grantz, A., and Vedder, J.G., eds., Geology and resource potential of the continental 

margin of western North America and adjacent ocean basins—Beaufort Sea to Baja California: 

Circum-Pacific Council for Energy and Mineral Resources Earth Science Series, v. 6, p. 353–401.

Murray, A.B., and Thieler, 2004, A new hypothesis and exploratory model for the formation of largescale inner-shelf sediment sorting and “rippled scour depressions:” Continental Shelf Research, v. 

24, no. 3, p. 295–315.

Nagel, D.K, Mullins, H.T., and Greene, H.G., 1986, Ascension submarine canyon, California—

Evolution of a multi-head canyon system along a strike-slip continental margin: Marine Geology, 

v. 73, p. 295–310.

Powell, C.L., II, Barron, J.A., Sarna-Wojcicki, A.M., Clark, J.C., Perry, F.A., Brabb, E.E., and Fleck, 

R.J., 2007, Age, stratigraphy, and correlations of the late Neogene Purisima Formation, central 

California Coast Ranges: U.S. Geological Survey Professional Paper 1740, 32 p., available at 

http://pubs.usgs.gov/pp/2007/1740/.

Reid, J.A., Reid, J.M., Jenkins, C.J., Zimmerman, M., Williams, S.J., and Field, M.E., 2006, 

usSEABED—Pacific Coast (California, Oregon, Washington) offshore surficial-sediment data 

release: U.S. Geological Survey Data Series 182, available at http://pubs.usgs.gov/ds/2006/182/.

Simpson, G.D., Thompson, S.C., Noller, J.S., and Lettis, W.R., 1997, The northern San Gregorio fault 

zone—Evidence for the timing of late Holocene earthquakes near Seal Cove, California: Bulletin 

of the Seismological Society of America, v. 87, p. 1,158–1,170.

Smith, T.C., 1981, Fault evaluation report, Año Nuevo and Franklin Point quadrangles, California: 

California Division of Mines and Geology FER-116, April 1981, available at 

http://www.quake.ca.gov/gmaps/WH/regulatorymaps.htm.

Stanford, J.D., Hemingway, R., Rohling, E.J., Challenor, P.G., Medina-Elizalde, M., and Lester, A.J., 

2011, Sea-level probability for the last deglaciation—A statistical analysis of far-field records: 

Global and Planetary Change, v. 79, p. 193–203, doi:10.1016/j.gloplacha.2010.11.002.

Trembanis, A.C., and Hume, T.M., 2011, Sorted bedforms on the inner shelf off northeastern New 

Zealand—Spatiotemporal relationships and potential paleo-environmental implications: 

Geo-Marine Letters, v. 31, p. 203–214, doi:10.1007/s00367-010-0225-8.

U.S. Geological Survey and California Geological Survey, 2010, Quaternary fault and fold database of 

the United States: U.S. Geological Survey database, accessed April 5, 2014, at 

http://earthquake.usgs.gov/hazards/qfaults/.

Wagner, D.L., Greene, H.G., Saucedo, G.J., and Pridmore, C.L., 2002, Geologic map of the Monterey 

30' × 60' quadrangle and adjacent areas, California: California Geological Survey Regional 

Geologic Map Series, scale 1:100,000, available at http://www.quake.ca.gov/gmaps/RGM/

monterey/monterey.html.

Weber, G.E., and Lajoie, K.R., 1980, Map of Quaternary faulting along the San Gregorio fault zone, 

San Mateo and Santa Cruz Counties, California: U.S. Geological Survey Open-File Report 

80–907, 3 sheets, scale 1:24,000, available at http://pubs.er.usgs.gov/publication/ofr80907/.

Weber, G.E., Nolan, J.M., and Zinn, E.N., 1995, Determination of late Pleistocene-Holocene slip rates 

along the San Gregorio fault zone, San Mateo and Santa Cruz Counties, California—Final 

Technical Report: National Earthquake Hazard Reduction Program, Final Technical Report, 

Contract No. 1434–93–G–2336, 70 p., 4 sheets.

Weber, K.M., List, J.H., and Morgan, K.L.M., 2005, An operational mean high water datum for 

determination of shoreline position from topographic lidar data: U.S. Geological Survey 

Open-File Report 2005–1027, available at http://pubs.usgs.gov/of/2005/1027/.

DISCUSSION

Marine geology and geomorphology were mapped in the Offshore of Pigeon Point map area from 

approximate Mean High Water (MHW) to the 3-nautical-mile limit of California’s State Waters. MHW 

is defined at an elevation of 1.46 m above the North American Vertical Datum of 1988 (NAVD 88) 

(Weber and others, 2005). Offshore geologic units were delineated on the basis of integrated analyses 

of adjacent onshore geology with multibeam bathymetry and backscatter imagery (sheets 1, 2, 3), 

seafloor-sediment and rock samples (Reid and others, 2006), digital camera and video imagery (sheet 

6), and high-resolution seismic-reflection profiles (sheet 8). Aerial photographs taken in multiple years 

were used to map the nearshore area (0 to 10 m water depth) and to link the offshore and onshore 

geology.

Onshore geology was compiled from Weber and Lajoie (1980), Smith (1981), California Geological Survey (1982a,b), Brabb (1997), Brabb and others (1998), Clark and others (1999), and Graymer 

and others (2006); unit ages, which are from these sources, reflect local stratigraphic relations. In 

addition, some units were modified by C.W. Davenport on the basis of analysis of 2012 lidar imagery.

The offshore part of the map area, which includes the seafloor off the prominent headland of 

Point Año Nuevo, extends from the shoreline to water depths of about 70 m. This offshore area is 

largely characterized by a relatively flat (less than 1°) bedrock platform that is overlain by a variably 

thick (as much as 22 m) veneer of upper Quaternary sediment (see Map B on sheet 9). Sea level has 

risen 120 to 130 m during the last about 21,000 years (see, for example, Stanford and others, 2011), 

leading to a broadening of the continental shelf, progressive eastward migration of the shoreline and 

wave-cut platform, and associated transgressive erosion and deposition. Land-derived sediment was 

carried into this setting and subjected to Pacific Ocean wave energy and strong currents before 

deposition or offshore transport. Shelf morphology and geology result from local faulting, folding, 

uplift, and subsidence.

Most of the Offshore of Pigeon Point map area encompasses a part of the continental shelf that 

lies between the Ascension Fault and the San Gregorio Fault Zone, along the northeastern margin of 

the Outer Santa Cruz Basin and the southwest limb of the Pigeon Point high (fig. 1; McCulloch, 1987). 

The northwest-striking San Gregorio Fault Zone (Weber and others, 1995; Dickinson and others, 

2005), an important right-lateral strike-slip fault within the San Andreas Fault System, cuts across land 

through the northeast corner of the map area before moving offshore at Point Año Nuevo. In the map 

area, the San Gregorio Fault system forms a distributed shear zone about 1 to 4 km wide that includes 

two main diverging fault strands (fig. 1). The west strand (known as the Frijoles Fault), which comes 

onshore approximately 0.5 km east of Año Nuevo Creek, coincides with a topographic trough to the 

north (Clark and others, 1999). The east strand (known as the Coastways Fault) forms a prominent 

scarp offshore, where rocks of the Santa Cruz Mudstone east of the fault are juxtaposed with those of 

the Purisima Formation west of the fault. Paleoseismic data presented by Simpson and others (1997) 

suggest a post–late Pleistocene slip rate of 3.5 to 4.5 mm/yr for the onshore part of the east strand. This 

estimated rate represents a minimum for the San Gregorio Fault system because fault strands to the 

west, including the Frijoles Fault, are also active. Cumulative lateral slip on this fault zone is thought 

to range from 4 to 10 mm/yr in this area (Weber and others, 1995). 

The northwest-striking Ascension Fault (fig. 1) is a high-angle reverse fault (Nagel and others, 

1986; Wagner and others, 2002; Dickinson and others, 2005) that is also considered to be active (U.S. 

Geological Survey and California Geological Survey, 2010) and is characterized by a series of 

northeast-dipping thrust faults sub-parallel to the San Gregorio Fault Zone. The offshore area between 

the Ascension Fault and the San Gregorio Fault Zone is characterized by a number of steeply dipping, 

predominantly northwest-striking unnamed faults and also northwest-trending folds.

The Upper Cretaceous Pigeon Point Formation (unit Kpp), which represents the oldest bedrock 

unit exposed in the offshore part of the map area, crops out on the seafloor in shallow water (less than 

30 meters deep) north of Point Año Nuevo and west of the San Gregorio Fault Zone. These basement 

rocks are unconformably overlain by Tertiary marine sedimentary rocks, which include the middle and 

upper Miocene Monterey Formation (unit Tm), the upper Miocene Santa Cruz Mudstone (unit Tsc), 

and the upper Miocene and Pliocene Purisima Formation (unit Tp; age from Powell and others, 2007). 

The undivided Oligocene to upper Pliocene sedimentary rocks unit Tu is mapped in the offshore where 

assignment to a particular formation is uncertain; this undivided unit may also include a relatively thin 

(85 m thick) section of volcanic rocks, which has been mapped onshore along the coast at Point Año 

Nuevo as the unnamed sedimentary and volcanic rocks unit (Tuv).

The Santa Cruz Mudstone (Tsc) is mapped east of the Coastways Fault (east strand of the San 

Gregorio Fault Zone) both in the nearshore and onshore in the seacliff. However, the Santa Cruz 

Mudstone is not present within the Tertiary section onshore west of the Coastways Fault, where the 

Purisima Formation unconformably overlies either the Pigeon Point Formation or the Monterey 

Formation. The Purisima Formation is exposed on the seafloor in Año Nuevo Bay between the 

Coastways and Frijoles Faults. Seafloor exposure of the Purisima Formation and the underlying 

Monterey Formation are difficult to distinguish west of the Frijoles Fault in multibeam bathymetry 

imagery (see sheets 1, 2); however, the faulted unconformity between the Purisima and Monterey 

Formations is clearly visible in seismic-reflection profiles southeast of Point Año Nuevo (see fig. 9 on 

sheet 8).

Modern nearshore sediments are mostly sand (unit Qms) and a mix of sand, gravel, and cobbles 

(units Qmsc and Qmsd). Unit Qms notably is present, in addition to on the shelf, in well-defined 

channels that cut through nearshore bedrock exposures north of Pigeon Point. These distinct channels, 

which extend to water depths of 20 to 30 m, were formed by subaerial erosion during sea-level 

lowstands (Anima and others, 2002). The coarser grained sands and gravels (units Qmsc and Qmsd) 

are recognized primarily on the basis of bathymetry and high backscatter (see sheets 1, 2, 3). Unit 

Qmsc mainly is found adjacent to bedrock, in water depths of less than 40 m.

Unit Qmsd typically is mapped as erosional lags in scour depressions (see, for example, Cacchione and others, 1984) that are bounded by relatively sharp or, less commonly, diffuse contacts with the 

horizontal sand sheets of unit Qms. These depressions typically are a few tens of centimeters deep and 

range in size from a few tens of square meters to more than 1 km2. Such scour depressions are 

common along this stretch of the California coast (see, for example, Cacchione and others, 1984; 

Hallenbeck and others, 2012; Davis and others, 2013), where offshore sandy sediment can be 

relatively thin (and, thus, is unable to fill the depressions) owing to lack of sediment supply from rivers 

and also to significant erosion and offshore transport of sediment during large northwest winter swells. 

Such features have been referred to as “rippled scour depressions” (see, for example, Cacchione and 

others, 1984) or “sorted bedforms” (see, for example, Murray and Thieler, 2004; Goff and others, 

2005; Trembanis and Hume, 2011). Although the general areas in which both unit Qmsd scour 

depressions and surrounding Qms sand sheets are found are not likely to change substantially, the 

boundaries of the unit(s) likely are ephemeral, changing seasonally and during significant storm 

events. 

A transition to finer grained marine sediments (unit Qmsf) is seen offshore Pigeon Point and 

southwest of Point Año Nuevo, at water depths of 50 to 60 m. Unit Qmsf, which commonly is 

extensively bioturbated, primarily consists of mud and muddy sand. These fine-grained shelf 

sediments are derived from local coastal watersheds, bluff erosion, and the northward advection of 

sediment from fluvial sources within, and north of, Monterey Bay (Edwards, 2002). 

REFERENCES CITED

Anima, R.J., Eittreim, S.L., Edwards, B.D., and Stevenson, A.J., 2002, Nearshore morphology and late 

Anima, R.J., Eittreim, S.L., Edwards, B.D., and Stevenson, A.J., 2002, Nearshore morphology 

and late Quaternary geologic framework of the northern Monterey Bay Marine Sanctuary, 

California: Marine Geology, v. 181, p. 35–54.

Brabb, E.E., 1997, Geologic map of Santa Cruz County, California—A digital database: U.S. 

Geological Survey Open-File Report 97–489, scale 1:62,500, available at http://pubs.usgs.gov/

of/1997/of97-489/.

Brabb, E.E., Graymer, R.W., and Jones, D.L., 1998, Geology of the onshore part of San Mateo County, 

California—A digital database: U.S. Geological Survey Open-File Report 98–137, scale 1:62,500, 

available at http://pubs.usgs.gov/of/1998/of98-137/.

Cacchione, D.A., Drake, D.E., Grant, W.D., and Tate, G.B., 1984, Rippled scour depressions of the 

inner continental shelf off central California: Journal of Sedimentary Petrology, v. 54, p. 

1,280–1,291.

California Geological Survey, 1982a, Alquist-Priolo earthquake fault zone map of Año Nuevo 

Quadrangle: California Geological Survey, State of California Special Studies Zone Map, scale 

1:24,000, available at http://www.quake.ca.gov/gmaps/WH/regulatorymaps.htm.

California Geological Survey, 1982b, Alquist-Priolo earthquake fault zone map of Franklin Point 

Quadrangle: California Geological Survey, State of California Special Studies Zone Map, scale 

1:24,000, available at http://www.quake.ca.gov/gmaps/WH/regulatorymaps.htm.

LIST OF MAP UNITS

[See Description of Map Units (chapter 8, in pamphlet) for complete map-unit descriptions]

OFFSHORE GEOLOGIC AND GEOMORPHIC UNITS

[Note that composite units (gray-stippled areas) are designated on map by composite label indicating 

both overlying sediment cover and lower (older) unit, separated by slash (for example, Qms/Tp

indicates that thin sheet of Qms overlies Tp)]

Marine nearshore and shelf deposits (late Holocene)—Mostly sand; ripples common

Marine shelf scour depressions (late Holocene)—Inferred to be coarse sand and gravel, 

in low-relief scours

Fine-grained marine shelf deposits (late Holocene)—Mostly mud, very fine sand, and 

silt

Coarse-grained marine nearshore and shelf deposits (late Holocene)—Predominantly 

coarse sand and gravel

Purisima Formation (Pliocene and late Miocene)—Mostly gray and greenish-gray to 

buff, fine-grained marine sandstone, siltstone, and mudstone

Sedimentary and volcanic rocks, undivided (late Pliocene to Oligocene)—Consists of 

rocks of the Purisima Formation (Tp), the Monterey Formation (Tm), and the 

unnamed sedimentary and volcanic rocks unit (Tuv) 

Santa Cruz Mudstone (late Miocene)—Thin- to thick-bedded, siliceous mudstone that 

has carbonate concretions

Monterey Formation (late and middle Miocene)—Thin-bedded, siliceous shale, 

interbedded with arkosic sandstone 

Pigeon Point Formation (Late Cretaceous)—Sandstone and conglomerate, interbedded 

with siltstone and mudstone

ONSHORE GEOLOGIC AND GEOMORPHIC UNITS

[Units compiled from Weber and Lajoie (1980), Smith (1981), California Geological Survey 

(1982a,b), Brabb (1997), Brabb and others (1998), Clark and others (1999), and Graymer and others 

(2006); unit ages, which are from these sources, reflect local stratigraphic relations. In addition, some 

units modified by C.W. Davenport on basis of analysis of 2012 lidar imagery]

Artificial fill (late Holocene)—Rock, sand, and mud, deposited by humans

Artificial-dam fill (late Holocene)—Earth- or rock-fill dams, embankments, and levees; 

constructed to impound land-locked water bodies

Beach-sand deposits (late Holocene)—Active beaches in coastal environment; may form 

veneer over bedrock platform

Alluvial fan deposits (late Holocene)—Alluvial fan deposits; judged to be late Holocene 

(less than 1,000 years) in age, on the basis of records of historical inundation or 

presence of youthful braid bars and distributary channels

Dune sand (Holocene)—Active and recently stabilized dunes, in coastal environments

Alluvial deposits, undivided (Holocene)—Alluvium; deposited in fan, terrace, or basin 

environments

Alluvial fan deposits (Holocene)—Sediment deposited by streams emanating from 

canyons onto alluvial plains; includes sand, gravel, silt, and clay; identified primarily 

by fan morphology and topographic expression 

Basin deposits (Holocene)—Fine-grained sediment that accumulates from standing or 

slow-moving water in topographic basins and, locally, between adjacent alluvial fans

Stream-terrace deposits (Holocene)—Relatively smooth, undissected, relatively 

low-lying terraces adjacent to active stream channels

Colluvium (Holocene)—Loose to firm, unsorted sand, silt, clay, gravel, rock debris, and 

organic material, in varying proportions

Landslide deposits (Holocene and Pleistocene)—Disintegrated bedrock; physically 

weathered; unit ranges from deep-seated landslides to active colluvium; queried where 

uncertain

Stream-terrace deposits (Holocene and late Pleistocene)—Sand, gravel, silt, and minor 

clay of uncertain age; underlies relatively flat platforms adjacent to stream channels

Alluvial deposits, undivided (late Pleistocene)—Mapped on gently sloping to level 

terrace surfaces, where late Pleistocene age is indicated by depth of stream incision

Alluvial fan deposits (late Pleistocene)—Mapped where older age is indicated by greater 

degree of dissection than, or where geomorphic feature is at higher elevation than, that 

of Holocene fans

Marine-terrace deposits (Pleistocene)—Sand and gravel; deposited on uplifted 

marine-abrasion platforms along coast; queried where uncertain 

Older alluvial deposits, undivided (Pleistocene)—Moderately to deeply dissected 

alluvial deposits, commonly consists of gently rolling hills that have little to no 

original planar surface preserved

Alluvial fan deposits (Pleistocene)—Moderately to deeply dissected alluvial fan deposits; 

mapped where some original fan surface morphology is preserved

Purisima Formation (Pliocene and late Miocene)—Medium-grained to very 

fine-grained, poorly indurated to friable sandstone, siltstone, and claystone; also 

includes conglomerate lenses and a few beds of white volcanic ash 

Santa Cruz Mudstone (late Miocene)—Siliceous mudstone, interbedded with 

nonsiliceous mudstone, siltstone, and minor sandstone

Santa Margarita Sandstone (late Miocene)—Friable, very fine- to very coarse-grained, 

arkosic sandstone; quartz- and feldspar-pebble conglomerate crops out locally at base 

of section

Monterey Formation (late and middle Miocene)—Porcelaneous shale and chert, 

porcelaneous mudstone, calcareous claystone; includes small amounts of siltstone and 

sandstone near base

Unnamed sedimentary and volcanic rocks (Miocene and Oligocene)—Dark gray, hard 

mudstone 

Butano Sandstone (middle and early Eocene)—Very fine- to very coarse-grained, 

arkosic sandstone, interbedded with mudstone and shale; conglomerate is present 

locally in lower part of section

Pigeon Point Formation (Late Cretaceous)—Sandstone and conglomerate, interbedded 

with siltstone and mudstone

Unnamed volcanic rocks (Cretaceous or Jurassic)—Finely-crystalline, felsic volcanic 

rock that contains quartz and albite phenocrysts

EXPLANATION OF MAP SYMBOLS

Contact—Solid where location is certain, dashed where location is approximate

Fault—Solid where location is certain, long-dashed where location is approximate, 

short-dashed where location is inferred, dotted where location is concealed, queried 

where uncertain; sawtooth located on upthrown block

Folds—Solid where location is certain, dotted where location is concealed

Anticline

Syncline

Approximate modern shoreline—Defined as Mean High Water (MHW) (+1.46 m), North 

American Vertical Datum of 1988 (NAVD 88)

3-nautical-mile limit of California’s State Waters 

Area of “no data”—Areas beyond 3-nautical-mile limit of California’s State Waters were 

not mapped as part of California Seafloor Mapping Program

Qbs

Qot

Qls

Qa

af

Kpp

Tm

Tsm

Tp

Qof2

Tb

adf

Qds

Qyf

Qb

Qf

Qya

Tsc

Qcl

Qt

Qmt

Qoa

Qof1

Tuv

KJv

Qms

Qmsf

Qmsd

Tp

Tu

Kpp

Tm

Tsc

Qmsc

Qb Qt Qms Qmsd Qmsf af

Pliocene

Pleistocene

Holocene

CRETACEOUS

QUATERNARY

TERTIARY

OFFSHORE GEOLOGIC 

AND GEOMORPHIC UNITS ONSHORE GEOLOGIC AND GEOMORPHIC UNITS

CORRELATION OF MAP UNITS

[See Description of Map Units (chapter 8, in pamphlet) for precise unit ages]

Miocene

Tp

Kpp

Qbs

Tsm Tm

adf Qds Qa Qyf

Tb

Qot

Tu

Tp

Kpp

Tsc Tm

KJv

Tsc

JURASSIC

Late

Early

Oligocene

Eocene

Qf Qcl

Qls Qya Qof2 Qmt Qoa Qof1

Tuv

Qmsc

37°

36°40'

122°20' 122°

Santa Cruz

Monterey

Moss 

Landing

Pigeon

Point

Limit of California’s

State Waters

Area of

Map

CALIF.

MAP LOCATION

0 5 10 Kilometers

0 5 10Nautical Miles

121°40'

Monterey

Bay

1

U.S. Geological Survey;

2

California Geological Survey

Offshore and Onshore Geology and Geomorphology, Offshore of Pigeon Point Map Area, California

 By

Janet T. Watt,1 Stephen R. Hartwell,1 and Clifton W. Davenport2

2015

ONE MILE = 0.869 NAUTICAL MILES

BATHYMETRIC CONTOUR INTERVAL 10 METERS

1 .5 0 1 KILOMETER

1000 0 1000 2000 3000 4000 5000 6000 7000 FEET

1 1/2 0 1 MILE

SCALE 1:24 000

APPROXIMATE MEAN

DECLINATION, 2015

MAGNETIC NORTH

13 / ° 1 2

TRUE NORTH

Offshore geology and geomorphology mapped by Janet T. Watt and 

Stephen R. Hartwell, 2013–2014. Onshore geology and geomorphology 

compiled by Clifton W. Davenport, 2014; from Weber and Lajoie (1980), 

Smith (1981), California Geological Survey (1982a,b), Brabb (1997), Brabb 

and others (1998), Clark and others (1999), and Graymer and others (2006); 

in addition, some units modified by C.W. Davenport on basis of analysis of 

2012 lidar imagery. Bathymetric contours by Mecedes D. Erdey, 2014

GIS database and digital cartography by Janet T. Watt, Stephen R. 

Hartwell, and Peter Dartnell 

Manuscript approved for publication December 4, 2015

Onshore elevation data from California Coastal Conservancy (available from 

National Oceanic and Atmospheric Administration [NOAA] Coastal Service 

Center’s Digital Coast at http://www.csc.noaa.gov/digitalcoast/data/

coastallidar/) and from U.S. Geological Survey’s National Elevation Dataset 

(available at http://ned.usgs.gov/). Offshore shaded-relief bathymetry from map 

on sheet 2, this report. California's State Waters limit from NOAA Office of 

Coast Survey

Universal Transverse Mercator projection, Zone 10N

NOT INTENDED FOR NAVIGATIONAL USE

30

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! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !

122°20'

122°20'

122°25'

122°25'

37°10'

37°10'

37°05'

37°05'

Qms

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Qmsf

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Qmsc

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Qmsc

Qmsc

Qmsc

Qmsc

Qmsc

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Qms

Qms

Qms

Qms

Qms Qms

Qms

Tm

Qms/Tp

Qms

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Tp

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Kpp Kpp

Kpp

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Qa Qyf

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Qmsd

Qmsc

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Tp

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Point Año 

Nuevo

Franklin

Point

Pigeon

Point

Año Nuevo 

Island

Año 

Nuevo Bay

Año Nuevo

thrust fault

Coastways Fault

Frijoles Fault

San Gregorio Fault Zone

Año Nuevo

Creek Fault

Green Oaks Fault

Open-File Report 2015–1232

Sheet 10 of 10

Pamphlet accompanies map

U.S. Department of the Interior

U.S. Geological Survey