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://pubs.usgs.gov/sim/3254/

Suggested Citation: Johnson, S.Y., Sliter, R.W., Ritchie, A.C., Draut, A.E., and Hart, P.E., 2013, Seismic-reflection profiles, Offshore of 

Ventura map area, California, sheet 8 in Johnson, S.Y., Dartnell, P., Cochrane, G.R., Golden, N.E., Phillips, E.L., Ritchie, A.C., Kvitek, 

R.G., Greene, H.G., Krigsman, L.M., Endris, C.A., Seitz, G.G., Gutierrez, C.I., Sliter, R.W., Erdey, M.D., Wong, F.L., Yoklavich, M.M., Draut, 

A.E., and Hart, P.E. (S.Y. Johnson and S.A. Cochran, eds.), California State Waters Map Series—Offshore of Ventura, California: U.S. 

Geological Survey Scientific Investigations Map 3254, pamphlet 42 p., 11 sheets, scale 1:24,000, available at 

http://pubs.usgs.gov/sim/3254/.

DISCUSSION

This map sheet shows seismic-reflection profiles from two different surveys of the Offshore of Ventura 

map area, providing imagery of the subsurface geology. The area, which lies offshore of the mouths of the Santa 

Clara and Ventura Rivers, is characterized by a broad, relatively shallow (less than 40 m), flat, wave-cut shelf. 

The seismic-reflection data reveal that the shelf is underlain by thick upper Pleistocene and Holocene marine, 

deltaic, and alluvial strata (blue shading in profiles; Dahlen, 1992; Slater and others, 2002; Sommerfield and 

others, 2009; Draut and others, 2009) deposited in the last about 21,000 years, following the last major sea-level 

lowstand (see, for example, Fleming and others, 1998). The rivers are major sediment sources (Warrick and 

Farnsworth, 2009a), and the depocenter in the map area contains the largest mass of sediment anywhere on the 

entire southern California shelf (Sommerfield and others, 2009). The map area is cut by two important active 

faults. The east-west-striking, south-dipping Oak Ridge Fault (figs. 7, 8, 10, 11, 13), which cuts across the 

southern part of the map area, appears to be the western continuation of the fault responsible for the 1994 

Northridge earthquake (Yeats and Huftile, 1995). The east-west-striking, north-dipping Pitas Point Fault (figs. 2, 

3, 4, 5, 9), which cuts across the northern part of the map area, forms part of a fault system that extends for 

about 100 km through the Ventura and Santa Barbara Basins (Fisher and others, 2009). Both the Oak Ridge and 

Pitas Point Faults appear to be blind-thrust or blind-reverse faults associated with folds that clearly deform 

Holocene strata. Both high-resolution and deeper industry seismic-reflection profiles indicate that the area 

between the two faults is relatively undeformed. 

Most profiles displayed on this map sheet (figs. 1 through 11) were collected in 2007 on U.S. Geological 

Survey (USGS) cruise Z–3–07–SC (Sliter and others, 2008). Single-channel seismic-reflection data were 

acquired using two different sources, the SIG 2Mille minisparker (figs. 1, 2, 3, 5, 6, 10, 11) and the EdgeTech 

512 chirp (figs. 4, 7, 8, 9). The SIG minisparker system used a 500-J high-voltage electrical discharge fired 1 to 

4 times per second, which, at normal survey speed of 4 to 4.5 nautical miles per hour, gives a data trace every 

0.5 to 2.0 meters. The data were digitally recorded in standard SEG-Y 32-bit floating-point format using 

PC-based Triton Subbottom Logger (SBL) software that merges seismic-reflection data with differential 

GPS-navigation data. The EdgeTech 512 chirp subbottom-profiling system consists of a source transducer and 

an array of receiving hydrophones housed in a 500-lb fish towed at a depth of several meters below the sea 

surface. The swept-frequency chirp source signal was 500 to 4,500 Hz and 50 ms in length, and it was recorded 

by hydrophones located on the bottom of the fish. After the survey, a short-window (20 ms) automatic gain 

control algorithm was applied to both the chirp and minisparker data, and a 160- to 1,200-Hz bandpass filter 

was applied to the minisparker data. The vertical scale on the high-resolution seismic-reflection profiles (figs. 1 

through 11) is shown as two-way travel time in seconds, as well as in meters on the basis of an inferred velocity 

of 1,600 m/sec for near-surface sediments.

Figures 11 and 12 show deep-penetration, migrated, multichannel seismic-reflection profiles collected in 

1985 by WesternGeco on cruises W–6–85–SC and W–4–85–SC. These profiles and other similar data were 

collected in many areas offshore of California in the 1970s and 1980s when the area was considered a frontier 

for oil and gas exploration. Much of these data have been publicly released and are now archived at the USGS 

National Archive of Marine Seismic Surveys (U.S. Geological Survey, 2009). These data were acquired with a 

large-volume air-gun source that has a frequency range of 3 to 40 Hz and recorded with a multichannel hydrophone streamer about 2 km long; shot spacing was about 30 m. These data can resolve geologic features that are 

20 to 30 m thick, down to subbottom depths of about 4 km.

REFERENCES CITED

Dahlen, M.Z., 1992, Sequence stratigraphy, depositional history, and middle to late Quaternary sea levels of the 

Ventura shelf, California: Quaternary Research, v. 38, p. 234–245.

Draut, A.E., Hart, P.E., Lorenson, T.D., Ryan, H.F., Wong, F.L., Sliter, R.W., and Conrad, J.E., 2009, Late 

Pleistocene to Holocene sedimentation and hydrocarbon seeps on the continental shelf of a steep, 

tectonically active margin, southern California, USA: Marine Geophysical Research, v. 30, p. 193–206.

Fisher, M.A., Greene, H.G., Normark, W.R., and Sliter, R.W., 2005, Neotectonics of the offshore Oak Ridge 

fault near Ventura, southern California: Bulletin of the Seismological Society of America, v. 95, p. 

739–744.

Fisher, M.A., Sorlien, C.C., and Sliter, R.W., 2009, Potential earthquake faults offshore southern California 

from the eastern Santa Barbara channel to Dana Point, in Lee, H.J., and Normark, W.R., eds., Earth science 

in the urban ocean—The Southern California Continental Borderland: Geological Society of America 

Special Paper 454, p. 271–290.

Fleming, K., Johnston, P., Zwartz, D., Yokoyama, Y., Lambeck, K., and Chappell, J., 1998, Refining the eustatic 

sea-level curve since the Last Glacial Maximum using far- and intermediate-field sites: Earth and Planetary 

Science Letters, v. 163, p. 327–342.

Greene, H.G., Wolf, S.C., and Blom, K.G., 1978, The marine geology of the eastern Santa Barbara Channel 

with particular emphasis on the ground water basins offshore from the Oxnard Plain, southern California: 

U.S. Geological Survey Open-File Report 78–305, 104 p., 13 plates.

Redin, T., Forman, J., and Kamerling, M.J., 1998, Regional structure section across the eastern Santa Barbara 

Channel, from eastern Santa Cruz Island to the Carpinteria area, Santa Ynez Mountains, in Kunitomi, D.S., 

Hopps, T.E., and Galloway, J.M., eds., Structure and petroleum geology, Santa Barbara Channel, 

California: American Association of Petroleum Geologists, Pacific Section and Coast Geological Society, 

Miscellaneous Publication 46, p. 195, 1 sheet.

Slater, R.A., Gorsline, D.S., Kolpack, R.L., and Shiller, G.I., 2002, Post-glacial sediments of the California shelf 

from Cape San Martin to the US-Mexico border: Quaternary International, v. 92, p. 45–61.

Sliter, R.W., Triezenberg, P.J., Hart, P.E., Draut, A.E., Normark, W.R., and Conrad, J.E., 2008, High-resolution 

chirp and mini-sparker seismic reflection data from the southern California continental shelf—Gaviota to 

Mugu Canyon: U.S. Geological Survey Open-File Report 2008–1246, accessed April 5, 2011, at 

http://pubs.usgs.gov/of/2008/1246/.

Sommerfield, C.R., Lee, H.J., and Normark, W.R., 2009, Postglacial sedimentary record of the southern 

California continental shelf and slope, Point Conception to Dana Point, in Lee, H.J., and Normark, W.R., 

eds., Earth science in the urban ocean—The Southern California Continental Borderland: Geological 

Society of America Special Paper 454, p. 89–116.

Sorlien, C.C., Gratier, J.P., Luyendyk, B.P., Hornafius, J.S., and Hopps, T.E., 2000, Map restoration of folded 

and faulted late Cenozoic strata across the Oak Ridge fault, onshore and offshore Ventura basin, California: 

Geological Society of America Bulletin, v. 112, p. 1,080–1,090.

Suppe, J., Chou, G.T., and Hook, S.C., 1992, Rates of folding and faulting determined from growth strata, in

McKlay, K.R., ed., Thrust tectonics: London, Chapman and Hall, p. 105-121.

U.S. Geological Survey, 2009, National Archive of Marine Seismic Surveys: U.S. Geological Survey database, 

accessed April 5, 2011, at http://walrus.wr.usgs.gov/NAMSS/.

Warrick, J.A., and Farnsworth, K.L., 2009a, Sources of sediment to the coastal waters of the Southern 

California Bight, in Lee, H.J., and Normark, W.R., eds., Earth science in the urban ocean—The Southern 

California Continental Borderland: Geological Society of America Special Paper 454, p. 39–52.

Yeats, R.S., 1998, North-vergent thick-skinned or south-vergent thin-skinned Oak Ridge fault—A view from the 

coast, in Kunitomi, D.S., Hopps, T.E., and Galloway, J.M., eds., Structure and petroleum geology, Santa 

Barbara Channel, California: American Association of Petroleum Geologists, Pacific Section and Coast 

Geological Society, Miscellaneous Publication 46, p. 143–152.

Yeats, R.S., and Huftile, G.J., 1995, The Oak Ridge fault system and the 1994 Northridge earthquake: Nature, v. 

373, p. 418–420.

120° 119°40' 119°20' 119°

34°

34°20'

Kilometers 0 5 10

0 4 8

Nautical Miles

Santa Barbara Channel

Santa Barbara

Ventura

CALIF.

MAP LOCATION

Limit of California’s

 State Waters

Santa Cruz Island Santa Rosa Island

Area of

 Map

Anacapa

 Island

Seismic-Reflection Profiles, Offshore of Ventura Map Area, California

By

Samuel Y. Johnson, Ray W. Sliter, Andrew C. Ritchie, Amy E. Draut, and Patrick E. Hart

2013

Two-way travel time, in seconds

0

0.5

1.0

1.5

2.0

2.5

3.0

VENTURA SHELF

1 km

SOUTH NORTH Oak Ridge Fault

low-angle 

unconformity

stratigraphic

thinning

Figure 13. Industry 2-D migrated multichannel air-gun seismic-reflection profile WC–85–170 (collected in 1985 on survey W–4–85–SC), which extends south across Ventura 

shelf; see trackline map for location. Note that profile has similar horizontal scale to USGS high-resolution seismic-reflection profiles shown in figures 1 through 11, but it 

has much less vertical exaggeration (1.5:1). Note also that profile has not been depth converted and so no depth scale is shown, but it probably extends to depths of 4 to 5 

km. Profile reveals gently south-dipping (about 5°) strata on south flank of active structural arch associated with Pitas Point Fault (figs. 2, 3, 4, 5; see also, sheet 10). Dashed 

yellow lines show upward-narrowing “growth triangle” (Suppe and others, 1992) associated with Oak Ridge Fault, a blind-reverse fault that folds but appears not to offset 

strata in upper 0.5 sec of two-way travel time (about 400 m) of section, an observation confirmed by USGS high-resolution seismic-reflection profiles to east (for example, 

figs. 7, 8, 10, 11). Dashed orange line shows prominent low-angle unconformity near top of section. Dashed green lines show marker horizons within section that reveal 

south-to-north stratigraphic thinning related to uplift along Pitas Point Fault. Previous workers (Greene and others, 1978; Redin and others, 1998; Sorlien and others, 2000; 

Fisher and others, 2009) have suggested that imaged section includes (from oldest to youngest) the upper Miocene Monterey Formation, the Miocene and Pliocene Sisquoc 

Formation, the Pliocene Repetto Formation, and the Pliocene to Pleistocene Pico, Santa Barbara, and Saugus Formations.

VERTICAL EXAGGERATION ~ 1.5

Two-way travel time, in seconds

0

0.5

1.0

1.5

2.0

2.5

3.0

1 km

EASTERN SANTA BARBARA BASIN VERTICAL EXAGGERATION ~ 1.5 SOUTH NORTH

low-angle 

unconformity stratigraphic

thinning

Figure 12. Industry 2-D migrated multichannel air-gun seismic-reflection profile SB85–35 (collected in 1985 on survey W–6–85–SC), which extends south across Ventura shelf; see 

trackline map for location. Note that profile has similar horizontal scale to USGS high-resolution seismic-reflection profiles shown in figures 1 through 11, but it has much less vertical 

exaggeration (1.5:1). Note also that profile has not been depth converted and so no depth scale is shown, but it probably extends to depths of 4 to 5 km. Profile reveals gently 

south-dipping (about 5°) strata on south flank of gentle, growing structural arch associated with Pitas Point Fault (figs. 2, 3, 4, 5, 9). Dashed green lines show prominent low-angle 

unconformity near top of section, as well as good example of south-to-north stratigraphic thinning within section. Previous workers (Greene and others, 1978; Redin and others, 1998; 

Sorlien and others, 2000; Fisher and others, 2009) have suggested that imaged section includes (from oldest to youngest) the upper Miocene Monterey Formation, the Miocene and 

Pliocene Sisquoc Formation, the Pliocene Repetto Formation, and the Pliocene to Pleistocene Pico, Santa Barbara, and Saugus Formations.

Fig. 2

Figure 11. North end of USGS minisparker seismic-reflection profile SB–51T (survey Z–3–07; 

Sliter and others, 2008), which extends northwest across Ventura shelf, subparallel to 

shoreline in southern part of map area, about 4 km offshore; see trackline map for location. 

Blue shading shows inferred uppermost Pleistocene and Holocene deltaic and shelf deposits. 

Dashed red lines show axial planes of asymmetric fold that developed above south-dipping 

Oak Ridge Fault (Yeats, 1988; Sorlien and others, 2000; Fisher and others, 2005, 2009), a 

blind-reverse fault that does not clearly offset upper about 200 to 300 m of stratigraphic 

section; orange lines highlight folded reflections and show upward-decreasing structural relief 

within upper stratigraphic unit. Dashed green lines show angular unconformity on north flank 

of Montalvo Anticline (Greene and others, 1978; Fisher and others, 2005). Dashed yellow line is 

seafloor multiple (echo of seafloor reflector).

NORTHWEST SOUTHEAST Two-way travel time, in seconds

0

0.1

0.2

0.3

0.4

0 

80

160

240

320

VENTURA SHELF folding above Oak Ridge Fault north flank of Montalvo Anticline

500 m

VERTICAL EXAGGERATION ~ 6.5

Fig. 8

Fig. 9

Approximate depth, in meters

500 m

SOUTHWEST VERTICAL EXAGGERATION ~ 6.5 NORTHEAST

Two-way travel time, in seconds

0

0.1

0.2

0.3

0.4

0 

80

160

240

320

VENTURA SHELF folding above Oak Ridge Fault (oblique crossing)

Figure 10. USGS minisparker seismic-reflection profile SB–60 

(survey Z–3–07–SC; Sliter and others, 2008), which extends 

southwest across Ventura shelf offshore of Ventura; see trackline 

map for location. Blue shading shows inferred uppermost 

Pleistocene and Holocene deltaic and shelf deposits. Dashed red 

lines show axial planes of asymmetric fold that developed above 

south-dipping Oak Ridge Fault (Yeats, 1988; Sorlien and others, 2000; 

Fisher and others, 2005, 2009), a blind-reverse fault that does not 

clearly offset upper about 200 to 300 m of stratigraphic section; 

dashed green lines highlight folded reflections in zone of 

deformation and also prominent angular unconformity shown in 

figure 11. Dashed blue lines show low-angle erosion surfaces. 

Dashed yellow line is seafloor multiple (echo of seafloor reflector). 

Fig. 11

Approximate depth, in meters

0

40

80

folding above Pitas Point Fault low-relief channels

Two-way travel time, in seconds 0.05

0.1

NORTHWEST

0

SOUTHEAST

gas-rich upper section angular unconformity above steeply dipping strata OFFSHORE OF VENTURA 

 RIVER MOUTH

Figure 9. USGS chirp seismic-reflection profile SBC–70 (survey Z–3–07–SC; Sliter and others, 2008), which extends northwest across inner Ventura shelf subparallel to shoreline; see trackline map for 

location. Blue shading shows inferred uppermost Pleistocene and Holocene deltaic and shelf deposits. Dashed red lines show axial planes of asymmetric fold associated with blind-reverse, 

north-dipping Pitas Point Fault (see, for example, Sorlien and others, 2000; Fisher and others, 2009). Dashed blue lines show low-relief channels offshore of Ventura River mouth. Area northwest of 

Pitas Point lies offshore of a few steep coastal watersheds and may include channels cut during low sea-level stands; however, shallow stratigraphy in this area is largely obscured by gas seeps. 

Dashed green lines in northwestern part of profile highlight prominent angular unconformity. Dashed yellow lines are seafloor multiples (echoes of seafloor multiple). Chirp seismic-reflection profile 

has less depth penetration than minisparker profiles in figures 1, 2, 3, 5, 6, 10, and 11, but it shows greater geologic detail in upper few tens of meters.

OFFSHORE OF PITAS POINT

VERTICAL EXAGGERATION ~13

1 km

Fig. 2

Fig. 3

Figs. 4, 5

Fig. 6

Fig. 8

Approximate depth, in meters

Two-way travel time, in seconds

0

0.05

0.1

SOUTHWEST

500 m VERTICAL EXAGGERATION ~13

0

40

80

NORTHEAST

Figure 8. USGS chirp seismic-reflection profile SBC–69 (survey Z–3–07–SC; Sliter and others, 2008), which crosses inner Ventura shelf offshore of 

alluvial plain of Santa Clara River; see trackline map for location. Blue shading shows inferred uppermost Pleistocene and Holocene deltaic and 

shelf deposits; however, unit is difficult to map in this area owing to poor depth of penetration, and its base on this profile is inferred largely on 

correlation with other nearby profiles. Dashed red lines show inferred (poorly imaged) axial planes of fold that formed above blind-reverse, 

south-dipping Oak Ridge Fault (see fig. 7). Dashed yellow lines are seafloor multiples (echoes of seafloor reflector). Cone-shaped reflections in 

water column are associated with gas seeps.

VENTURA SHELF

gas seeps folding above Oak Ridge 

Fault (oblique crossing)

Fig. 11

Fig. 9

Approximate depth, in meters

folding above 

Oak Ridge Fault

Two-way travel time, in seconds

0

0.05

0.1

NORTHWEST

0 

40

80

500 m

VERTICAL EXAGGERATION ~13

Figure 7. USGS chirp seismic-reflection profile SBC–68 (survey 

Z–3–07–SC; Sliter and others, 2008), offshore of alluvial plain of 

Santa Clara and Ventura Rivers; see trackline map for location. 

Blue shading shows inferred uppermost Pleistocene and 

Holocene deltaic and shelf deposits. Dashed red lines show axial 

planes of fold that formed above blind-reverse, south-dipping Oak 

Ridge Fault. Dashed yellow lines are seafloor multiples (echoes 

of seafloor reflector).

SOUTHEAST Approximate depth, in meters

Two-way travel time, in seconds

0

0.1

0.2

0.3

0 

80

160

240

NORTHEAST

Figure 6. USGS minisparker seismic-reflection profile 

SB–64 (survey Z–3–07–SC; Sliter and others, 2008), which 

extends southwest from area directly offshore of mouth of 

Ventura River; see trackline map for location. Profile 

crosses undeformed area between Pitas Point Fault to 

north (figs. 2, 3, 4, 9) and Oak Ridge Fault to south (figs. 7, 8, 

10, 11, 13). Blue shading shows inferred uppermost 

Pleistocene and Holocene deltaic and shelf deposits. 

Dashed blue lines show low-angle erosion surfaces, 

representing oblique intersections of channels cut by 

Ventura River at lower stands of sea level. Orange dashed 

lines are offshore-dipping delta foreset beds. Dashed 

yellow lines are seafloor multiples (echoes of seafloor 

reflector).

SOUTHWEST

1 km

VERTICAL EXAGGERATION ~ 6.5

Fig. 9

Approximate depth, in meters

Two-way travel time, in seconds

0

0.1

0.2

0.3

0

80

160

240

500 m

VERTICAL EXAGGERATION ~ 6.5

Figure 5. USGS minisparker seismic-reflection profile 

SB–73A (survey Z–3–07–SC; Sliter and others, 2008); see 

trackline map for location. Blue shading shows inferred 

uppermost Pleistocene and Holocene deltaic and shelf 

deposits. Dashed red lines show axial planes of fold that 

formed above blind-reverse, north-dipping Pitas Point 

Fault (Sorlien and others, 2000; Fisher and others, 2009). 

Dashed yellow line is seafloor multiple (echo of seafloor 

reflector). Minisparker line has more depth penetration 

than chirp seismic-reflection profile collected on same 

transect (fig. 4) but, in its upper section, lacks level of 

detail provided by higher frequency chirp system.

 

Pitas Point Fault/fold

 overlaps fig. 4

SOUTHWEST NORTHEAST Fig. 9 Approximate depth, in meters

Figure 4. USGS chirp seismic-reflection profile SBC–72 (survey Z–3–07–SC; Sliter and 

others, 2008), which crosses inner Ventura shelf and partly overlaps minisparker profile 

in figure 5; see trackline map for location. Blue shading shows inferred uppermost 

Pleistocene and Holocene deltaic and shelf deposits. Dashed red lines show axial 

planes of fold that formed above blind-reverse, north-dipping Pitas Point Fault (Sorlien 

and others, 2000; Fisher and others, 2009). Dashed yellow line is seafloor multiple (echo 

of seafloor reflector). Cone-shaped reflections in water column are associated with gas 

seeps. Chirp seismic-reflection profile has less depth penetration than minisparker 

profile collected on same transect (fig. 5), but it shows greater geologic detail in upper 

few tens of meters.

Two-way travel time, in seconds

0

0.05

0.1

0 

40

80

500 m

VERTICAL EXAGGERATION ~ 13

SOUTHWEST NORTHEAST Fig. 9

overlaps fig. 5

gas seeps Pitas Point Fault

folding above

Approximate depth, in meters

0

80

160

0

0.1

0.2

Two-way travel time, in seconds

VENTURA SHELF Pitas Point Fault

Figure 3. USGS minisparker seismic-reflection profile SB–74 (survey Z–3–07–SC; Sliter and others, 2008), which extends southwest across Ventura shelf; see 

trackline map for location. Blue shading shows inferred uppermost Pleistocene and Holocene deltaic and shelf deposits. Dashed red lines show axial planes 

of fold that formed above blind-reverse, north-dipping Pitas Point Fault (Sorlien and others, 2000; Fisher and others, 2009). Dashed green lines southwest of 

Pitas Point Fault highlight prominent angular unconformity (figs. 1, 2), below which inferred upper Pliocene and Pleistocene beds dip about 5° offshore. 

Dashed yellow line is seafloor multiple (echo of seafloor reflector). Note that southwestern half of profile has low signal to noise ratio and, thus, is of poor 

quality. 

Fig. 9

1 km

VERTICAL EXAGGERATION ~ 6.5

folding above

SOUTHWEST NORTHEAST

Approximate depth, in meters

Two-way travel time, in seconds

0

0.1

0.2

0.3

0.4

1 km

SOUTHWEST NORTHEAST

Pitas Point Fault

VENTURA SHELF

0 

80

160

240

320

Figure 2. USGS minisparker seismic-reflection profile SB–78 

(survey Z–3–07–SC; Sliter and others, 2008), which extends 

southwest from Pitas Point across Ventura shelf; see 

trackline map for location. Blue shading shows inferred 

uppermost Pleistocene and Holocene shelf deposits. Dashed 

red lines show axial planes of fold that formed above 

blind-reverse, steeply north-dipping Pitas Point Fault (Sorlien 

and others, 2000; Fisher and others, 2009). Dashed green 

lines southwest of Pitas Point Fault and associated fold 

highlight significant angular unconformity, below which 

inferred upper Pliocene and Pleistocene beds dip about 5° 

offshore. Dashed yellow lines are seafloor multiples (echoes 

of seafloor reflector). 

Fig. 12

Fig. 9

folding above

VERTICAL EXAGGERATION ~ 6.5

Approximate depth, in meters

Figure 1. USGS minisparker seismic-reflection profile 

SB–79 (survey Z–3–07–SC; Sliter and others, 2008), which 

extends northwest from end of profile SB–78 (fig. 2) on 

Ventura shelf; see trackline map for location. Blue 

shading shows inferred uppermost Pleistocene and 

Holocene strata, deposited since last sea-level lowstand 

about 21,000 years ago. This upper unit overlies 

prominent angular unconformity; dashed green lines 

highlight discordance. Dashed yellow line is seafloor 

multiple (echo of seafloor reflector).

NORTHWEST SOUTHEAST

500 m

VENTURA SHELF

Two-way travel time, in seconds

0

0.1

0.2

0.3

0.4

0

80

160

240

320

VERTICAL EXAGGERATION ~ 6.5

Approximate depth, in meters

ONE MILE = 0.869 NAUTICAL MILES

1 0.5 0 1 KILOMETER

7000 3500 0 7000 FEET

2 1 0 2 MILES

SCALE 1:50 000

APPROXIMATE MEAN

DECLINATION, 2013

MAGNETIC NORTH

12 / ° 1 2

TRUE NORTH

GIS database and digital cartography by Eleyne L. 

Phillips and Florence L. Wong

Edited by Taryn A. Lindquist

Manuscript approved for publication March 11, 2013

Onshore elevation data from NOAA Coastal Services Center 

(data collected by EarthData International in 2002-2003). 

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 11N

NOT INTENDED FOR NAVIGATIONAL USE

Ventura

Pitas 

Point

Santa 

Clara

River

Punta

Gorda

Ventura River

Fig. 2

Fig. 1

Fig. 3

Fig. 4

Fig. 6

Fig. 5

Fig. 8

Fig. 7

Fig. 10

Fig. 11

Fig. 9

Fig. 12

Fig. 13

119°25' 119°20'

119°25' 119°20' 119°15'

34°20'

34°15'

34°20'

34°15'

Figure 12

Figure 9

Figure 2

Trackline Map

EXPLANATION

Tracklines of select seismic-reflection 

surveys—Thick lines show locations of 

profile lines depicted in figures; thin lines 

show full extent of surveys

Survey Z–3–07–SC (USGS minisparker)

Survey Z–3–07–SC (USGS chirp)

Surveys W–4–85–SC and W–6–85–SC 

(WesternGeco)

3-nautical-mile limit of California’s State 

Waters

Area of “no data”—Areas near shoreline not 

mapped owing to insufficient highresolution seafloor mapping data; areas 

beyond the 3-nautical-mile limit of 

California’s State Waters were not 

mapped as part of California Seafloor 

Mapping Program

Scientific Investigations Map 3254

Sheet 8 of 11

Pamphlet accompanies map

U.S. Department of the Interior

U.S. Geological Survey