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 https://doi.org/10.3133/ofr20181023

Suggested Citation: Johnson, S.Y., and Hartwell, S.R., 2018, Seismic-reflection profiles, Offshore of Gaviota map area, California, 

sheet 7 in Johnson, S.Y., Dartnell, P., Cochrane, G.R., Hartwell, S.R., Golden, N.E., Kvitek, R.G., and Davenport, C.W. (S.Y. Johnson and 

S.A. Cochran, eds.), California State Waters Map Series—Offshore of Gaviota, California: U.S. Geological Survey Open-File Report 

2018–1023, pamphlet 41 p., 9 sheets, scale 1:24,000, https://doi.org/10.3133/ofr20181023.

ISSN 2331-1258 (online)

https://doi.org/10.3133/ofr20181023

DISCUSSION

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

area, providing imagery of the subsurface geology in the western Santa Barbara Channel. The width of the continental shelf in the map area ranges from about 4.5 to 6 km; the shelf slopes are highly variable in the map area because of 

the presence of the large Gaviota sediment bar (see figs. 4, 5, 7, 8, 10; see also, sheet 9), which extends obliquely 

southwestward across the shelf for about 11 km. In the east half of the map area, the shelf break is at a depth of about 

87 to 91 m and trends about 276°. Farther west, the shelf break is notably embayed, bends to a trend of about 236°, 

and is as shallow as 52 to 73 m in an area of significant slope failure. 

The high-resolution seismic-reflection profiles displayed on this sheet (figs. 1, 2, 3, 4, 5, 7, 8, 9, 10) were 

collected in 2014 on U.S. Geological Survey (USGS) cruise S–01–13–CC, using the SIG 2Mille minisparker system. 

This system used a 500-J high-voltage electrical discharge fired 1 to 2 times per second, which, at normal survey 

speeds of 4 to 4.5 nautical miles per hour, gives a data trace every 1 to 2 m of lateral distance covered. The data were 

digitally recorded in standard SEG-Y 32-bit floating-point format, using Triton Subbottom Logger (SBL) software 

that merges seismic-reflection data with differential GPS-navigation data. After the survey, a short-window (20 ms) 

automatic gain control algorithm was applied to the data, along with a 160- to 1,200-Hz bandpass filter and a heave 

correction that uses an automatic seafloor-detection window (averaged over 30 m of lateral distance covered). These 

data can resolve geologic features a few meters thick (and, hence, are considered “high-resolution”), down to subbottom depths of as much as 400 m.

Figure 6 shows a migrated, deep-penetration, multichannel seismic-reflection profile collected in 1984 by 

WesternGeco on cruise W–37–84–SC. This profile and other similar data were collected in many areas offshore of 

California in the 1970s and 1980s when these areas were considered a frontier for oil and gas exploration. Much of 

these data have been publicly released and are now archived at the U.S. Geological Survey National Archive of 

Marine Seismic Surveys (Triezenberg and others, 2016). These data were acquired using 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 as much as 4 km.

The shelf is underlain by Neogene sedimentary rocks and uppermost Pleistocene to Holocene sediments (see 

sheet 9). Neogene units include the Miocene Monterey Formation and the upper Miocene and lower Pliocene Sisquoc 

Formation. On high-resolution seismic-reflection profiles, these strata commonly yield parallel to subparallel, 

continuous, variable-amplitude, high-frequency reflections (terminology from Mitchum and others, 1977); however, 

these strata commonly are folded, in many places too steeply folded to be imaged on seismic-reflection profiles. 

Local zones that lack reflections probably also are the result of the presence of interstitial gas within the sediments. 

This effect has been referred to as “gas blanking,” “acoustic turbidity,” or “acoustic masking” (Hovland and Judd, 

1988; Fader, 1997). The gas scatters or attenuates the acoustic energy, preventing penetration. Not surprisingly, this 

effect is especially prevalent near the Molino Anticline (see figs. 7, 8, 10) and near the crests of other small anticlines.

Eustasy was an important control on latest Pleistocene to Holocene shelf deposition in the Offshore of Gaviota 

map area. Surficial and shallow sediments were deposited on the shelf in the last about 21,000 years during the 

sea-level rise that followed the last major lowstand and the Last Glacial Maximum (LGM) (Stanford and others, 

2011). Global sea level was about 120 to 130 m lower during the LGM, at which time the shelf on the north flank of 

the Santa Barbara Channel was emergent. The post-LGM sea-level rise was rapid (about 9 to 11 m per thousand 

years) until about 7,000 years ago, when it slowed considerably to about 1 m per thousand years (Stanford and others, 

2011). The sediments deposited on the shelf during the post-LGM sea-level rise (above a transgressive surface of 

erosion) are shaded blue in many of the high-resolution seismic-reflection profiles (figs. 1, 2, 3, 4, 5, 7, 8, 10), and 

their thicknesses are shown on sheet 8.

On most profiles, the base of the post-LGM depositional unit is a flat to concave angular unconformity characterized by an obvious change in reflectivity. The post-LGM sediment unit has its maximum thickness (36 m) in the 

Gaviota sediment bar (figs. 4, 5, 7, 8, 10), which is as wide as 2 km and extends southwestward for about 9 km from 

the mouth of Cañada de la Gaviota to the shelf break. The bar, which faces southeast, has a relatively flat (about 1.4°) 

top that extends to water depths of 60 m. The steep (as much as 5°) bar front, formed by advancing clinoforms (figs. 

4, 5), is bounded seaward by an apron of coalescing slump deposits and mass-flow lobes (see figs. 7, 8; see also, 

sheets 1, 2, 9). Post-LGM sediment thins markedly, and is locally absent, both southeast and northwest of the Gaviota 

sediment bar. 

All but the westernmost one-sixth (about 2 km wide) of the map area includes the shelf break and upper slope. 

For the eastern two-fifths (about 7 km wide) of the map area, the shelf break is relatively sharp, and it locally contains 

a relatively thin (as much as 12 m) mound of sediment that is interpreted as a lowstand shelf-break delta (figs. 7, 8). 

Seismic-reflection profiles that cross the smooth upper slope south of the shelf break reveal continuous, subparallel, 

offshore-dipping reflections (figs. 7, 8, 10), inferred to represent LGM-lowstand and older Quaternary deposits. 

Although the upper slope in this area is locally as steep as 6°, the seismic-reflection data lack the chaotic to massive 

reflections that are interpreted as buried landslide deposits in the Goleta landslide complex to the east (Fisher and 

others, 2005; Greene and others, 2006; Lee and others, 2009) and the Conception fan to the west.

Farther west, the shelf break and the distal portion of the Gaviota sediment bar are incised by three large (150- to 

300-m-wide) channels (see sheets 1, 2, 9) that have been referred to as “the Gaviota Canyons” (Fischer and Cherven, 

1998) or as “Drake Canyon,” “Sacate Canyon,” and “Alegria Canyon” (Eichhubl and others, 2002). The upper slope 

below this part of the shelf break consists of a hummocky, incised debris apron, referred to as the Conception fan 

(Fischer and Cherven, 1998; Eichhubl and others, 2002). Seismic-reflection profiles that cross the hummocky upper 

slope reveal massive, reflection-free zones and chaotic reflections (figs. 1, 2, 4, 5) that are interpreted as submarinelandslide deposits, in marked contrast to the smooth slope and continuous reflections that characterize the upper slope 

to the east (see figs. 7, 8, 10).

High-resolution seismic-reflection profiles in the Offshore of Gaviota map area primarily show Neogene strata 

that, on a larger scale, are folded within a large homocline that extends from the south flank of the Santa Ynez 

Mountains (see fig. 1–2 in pamphlet) into the offshore. The homocline formed above the blind Pitas Point–North 

Channel Fault system (fig. 1–3 in pamphlet), as indicated on nearby regional cross sections (Tennyson and Kropp, 

1998; Redin and others, 2005) and on industry seismic-reflection profiles (see fig. 6; see also, Sorlien and Nicholson, 

2015). The tip of the fault system is inferred to be buried to a depth of about 2 km below sea level (about 1.5 sec 

two-way travel time [TWT]) about 10 km offshore, beneath the slope on the north flank of the Santa Barbara Basin. 

The southwest-striking south strand of the Santa Ynez Fault (see figs. 3, 4, 5; see also, sheet 9) obliquely cuts the 

shelf in the western part of the map area. As mapped onshore by Dibblee (1950, 1988a,b), this fault is unique among 

Santa Barbara fold-belt structures in that it obliquely crosses the Santa Ynez Mountains and the dominant east-westtrending structural grain. In the offshore, the fault was difficult to map, despite our dense coverage of seismicreflection data (see trackline map), because (1) the pre-LGM section on the shelf includes massive, reflection-free 

zones that probably are caused by interstitial gas or steeply dipping strata, and (2) the adjacent slope is mainly 

underlain by the massive to chaotic seismic facies of the Conception fan (figs. 1, 2, 4, 5).

The hanging wall of the Pitas Point–North Channel Fault system (see fig. 1–3 in pamphlet) is inferred to include 

several blind splays that are structurally above the main fault, on the basis of the irregular pattern of shallow folds in 

the map area. Closely spaced seismic-reflection profiles reveal many shallow folds that have variable geometries, 

lengths, amplitudes, degrees of continuity, and wavelengths (see sheet 9). The most continuous folds are the 17-kmlong Molino Anticline (host of the Molino gas field) and the 22-km-long Government Point Syncline, both of which 

are truncated to the west and east, respectively, by the south strand of the Santa Ynez Fault (see sheets 8, 9).

REFERENCES CITED

Dibblee, T.W., Jr., 1950, Geology of southwestern Santa Barbara County, California, Point Arguello, Lompoc, Point 

Conception, Los Olivos, and Gaviota quadrangles: California Division of Mines and Geology Bulletin 150, 95 

p., scale 1:62,500.

Dibblee, T.W., Jr., 1988a, Geologic map of the Santa Rosa Hills and Sacate quadrangles, Santa Barbara County, 

California (H.E. Ehrenspeck, ed. [1988]): Dibblee Geological Foundation Map DF-17, scale 1:24,000.

Dibblee, T.W., Jr., 1988b, Geologic map of the Solvang and Gaviota quadrangles, Santa Barbara County, California 

(H.E. Ehrenspeck, ed. [1988]): Dibblee Geological Foundation Map DF-16, scale 1:24,000.

Eichhubl, P., Greene, H.G., and Maher, N., 2002, Physiography of an active transpressive margin basin—Highresolution bathymetry of the Santa Barbara basin, southern California continental borderland: Marine Geology, 

v. 184, p. 95–120.

Fader, G.B.J., 1997, Effects of shallow gas on seismic-reflection profiles, in Davies, T.A., Bell, T., Cooper, A.K., 

Josenhaus, H., Polyak, L., Solheim, A., Stoker, M.S., and Stravers, J.A., eds., Glaciated continental margins—

An atlas of acoustic images: London, Chapman & Hall, p. 29–30.

Fischer, P.J., and Cherven, B.B., 1998, The Conception Fan, Santa Barbara Basin, California, 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, 155–181.

Fisher, M.A., Normark, W.R., Greene, H.G., Lee, H.J., and Sliter, R.W., 2005, Geology and tsunamigenic potential of 

submarine landslides in Santa Barbara Channel, southern California: Marine Geology, v. 224, p. 1–22.

Greene, H.G., Murai, L.Y., Watts, P., Maher, N.A., Fisher, M.A., and Eichhubl, P., 2006, Submarine landslides in the 

Santa Barbara channel as potential tsunami sources: Natural Hazards and Earth System Sciences, v. 6, p. 63–88.

Hovland, M., and Judd, A.G., 1988, Seabed pockmark and seepages: London, Graham and Trotman, Inc., 293 p.

Lee, H.J., Greene, H.G., Edwards, B.D., Fisher, M.A., and Normark, W.R., 2009, Submarine landslides in the 

southern California borderland, 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. 251–269.

Mitchum, R.M., Jr., Vail, P.R., and Sangree, J.B., 1977, Seismic stratigraphy and global changes of sea level, part 

6—Stratigraphic interpretation of seismic reflection patterns in depositional sequences, in Payton, C.E., ed., 

Seismic stratigraphy—Applications to hydrocarbon exploration: Tulsa, Okla., American Association of Petroleum Geologists, p. 117–133.

Redin, T., Forman, J., Kamerling, M., and Galloway, J., 2005, Santa Barbara Channel structure and correlation 

sections—CS-32 to CS-42: American Association of Petroleum Geologists, Pacific Section, Publication CS 36, 

12 sheets.

Sorlien, C.C., and Nicholson, C., 2015, Post 1-Ma deformation history of the Pitas Point-North Channel-Red Mountain fault system and associated folds in Santa Barbara channel, California: U.S. Geological Survey National 

Earthquake Hazards Reduction Program final report, Award G14AP00012, 24 p., available at 

https://earthquake.usgs.gov/cfusion/external_grants/reports/G14AP00012.pdf.

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, available at https://doi.org/10.1016/j.gloplacha.2010.11.002.

Tennyson, M.E., and Kropp, A.P., 1998, Regional cross section across Santa Barbara channel from northwestern 

Santa Rosa Island to Canada de Molina, 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, 1 plate.

Triezenberg, P.J., Hart, P.E., and Childs, J.R., 2016, National Archive of Marine Seismic Surveys (NAMSS)—A 

USGS data website of marine seismic reflection data within the U.S. Exclusive Economic Zone (EEZ): U.S. 

Geological Survey data release, accessed June 29, 2015, at https://doi.org/10.5066/F7930R7P [formerly U.S. 

Geological Survey’s National Archive of Marine Seismic Surveys database, available at 

http://walrus.wr.usgs.gov/NAMSS/].

120°30' 120° 119°30'

34°

34°30'

Limit of California’s

State Waters

Kilometers 0 5 10

Santa Barbara Channel

Area of

Map

Santa Barbara CALIF.

MAP LOCATION

Anacapa Is.

Santa Cruz Is.

Santa Rosa Is.

San Miguel Is.

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

By

Samuel Y. Johnson and Stephen R. Hartwell

2018 

NORTH

160

0 

Approximate depth, in meters

80

240

320

1 km

VERTICAL EXAGGERATION ~ 10

Two-way travel time, in seconds

0

0.1

0.2

SOUTH

0.3

0.4

Fig. 9

well-stratified

slope deposits

 Molino

Anticline

Gaviota 

sediment bar

Figure 10. USGS high-resolution minisparker seismic-reflection profile GS–53 (collected in 2014 on cruise S–01–13–CC), which crosses shelf and upper slope southeast of Gaviota State Park; see trackline map for 

location. Profile highlights bedrock shelf and well stratified slope deposits. Dashed red line shows fault. Magenta symbols show fold axes (diverging arrows, anticlines; converging arrows, syncline). Blue shading shows 

inferred uppermost Pleistocene and Holocene nearshore and shelf deposits, deposited since last sea-level lowstand about 21,000 years ago. Dashed green lines highlight some continuous reflections that reveal 

depositional patterns and structure (not distinctive stratigraphic markers). Dashed yellow lines are seafloor multiples (echoes of seafloor reflector). Purple triangle shows location of California’s State Waters limit (yellow 

line on trackline map).

EAST

160

0 

Approximate depth, in meters

80

240

320

1 km

VERTICAL EXAGGERATION ~ 10

Two-way travel time, in seconds

0

0.1

0.2

WEST

0.3

0.4

Figure 9. USGS high-resolution minisparker seismic-reflection profile GS–76 (collected in 2014 on cruise S–01–13–CC), which obliquely crosses outer shelf and upper slope south and southwest of Gaviota State Park; see trackline map for location. Profile 

highlights upper slope deposits and incised heads of submarine canyons. Dashed red lines show faults. Magenta symbol shows syncline axis. Dashed green lines highlight some continuous reflections that reveal depositional patterns and structure (not distinctive stratigraphic markers). Dashed yellow lines are seafloor multiples (echoes of seafloor reflector). Fig. 2 Fig. 4 Fig. 5

Fig. 7

Fig. 8

Fig. 6

Fig. 10

“Sacate 

Canyon” “Alegria

 Canyon”

“Drake 

Canyon” shelf break

upper

slope

upper

slope

bedrock

 shelf

bedrock

 shelf

shelf break

NORTH

160

0 

Approximate depth, in meters

80

240

320

Figure 8. USGS high-resolution minisparker seismic-reflection profile GS–74 (collected in 2014 on cruise 

S–01–13–CC), which crosses shelf and upper slope southwest of Gaviota State Park; see trackline map 

for location. Profile highlights Gaviota sediment bar and flanking landslide deposits. Magenta symbol 

shows anticline axis. Blue shading shows inferred uppermost Pleistocene and Holocene strata, 

deposited since last sea-level lowstand about 21,000 years ago. Underlying reflectors locally image 

deformed Neogene strata. Dashed green lines highlight some continuous reflections that reveal 

depositional patterns and structure (not distinctive stratigraphic markers). Presence of interstitial gas 

along axis of Molino Anticline masks reflections. Dashed yellow line is seafloor multiple (echo of 

seafloor reflector). Purple triangle shows location of California’s State Waters limit (yellow line on 

trackline map). 

1 km

VERTICAL EXAGGERATION ~ 10

Two-way travel time, in seconds

0

0.1

0.2

SOUTH

0.3

0.4

Fig. 9

Gaviota 

sediment bar

well-stratified

slope deposits

shelf-break 

 delta

landslide

deposits

 Molino

Anticline

1 km

VERTICAL EXAGGERATION ~ 10

Two-way travel time, in seconds

0

0.1

0.2

SOUTH

0.3

0.4

GS-73

Figure 7. USGS high-resolution minisparker seismic-reflection profile GS–73 (collected in 2014 on cruise 

S–01–13–CC), which crosses shelf and upper slope southwest of Gaviota State Park; see trackline map 

for location. Profile highlights Gaviota sediment bar and flanking landslide deposits. Dashed red lines 

show inferred faults. Magenta symbol shows anticline axis. Blue shading shows inferred uppermost 

Pleistocene and Holocene strata, deposited since last sea-level lowstand about 21,000 years ago. 

Underlying reflectors locally image deformed Neogene strata. Dashed green lines highlight some 

continuous reflections that reveal depositional patterns and structure (not distinctive stratigraphic 

markers). Presence of interstitial gas along axis of Molino Anticline masks reflections. Dashed yellow 

line is seafloor multiple (echo of seafloor reflector). Purple triangle shows location of California’s State 

Waters limit (yellow line on trackline map).

Fig. 9

NORTH

160

0 

Approximate depth, in meters

80

240

320

 Gaviota 

sediment bar

well-stratified

slope deposits

shelf-break 

 delta

landslide

 deposits

 Molino

Anticline

Figure 6. Migrated, deep-penetration industry, 2-D, multichannel air-gun seismic-reflection profile WC–84–262 (collected in 1984 on WesternGeco survey W–37–84–SC; 

from USGS National Archive of Marine Seismic Surveys [Triezenberg and others, 2016]), which crosses shelf and slope south of Gaviota State Park and extends into Santa 

Barbara Basin; see trackline map for location. Note that vertical scale and exaggeration are significantly different than that of high-resolution seismic-reflection profiles 

shown in figures 1, 2, 3, 4, 5, 7, 8, 9, and 10. Profile highlights blind Pitas Point–North Channel Fault system (dashed red lines) and south limb of Molino Anticline (magenta 

symbol) beneath shelf. Dashed green lines highlight some continuous reflections that reveal depositional patterns and structure (not distinctive stratigraphic markers). 

Purple triangle shows location of California’s State Waters limit (yellow line on trackline map).

1.0

0

Two-way travel time, in seconds

2.0

3.0

1 km

SOUTH VERTICAL EXAGGERATION ~ 1.5

shelf break shelf

NORTH

Fig. 9

 Molino

Anticline

NORTH

160

0 

Approximate depth, in meters

80

240

320

Figure 5 (below). USGS high-resolution minisparker seismic-reflection profile GS–70 (collected in 2009 on cruise 

S–01–13–CC), which crosses shelf and upper slope southwest of Gaviota State Park; see trackline map for 

location. Profile highlights Gaviota sediment bar, which has internal clinoforms and debris lobes, and upper part 

of Conception fan, which consists of mixed landslide and stratified slope deposits. Dashed red line shows 

inferred fault. Blue shading shows inferred uppermost Pleistocene and Holocene strata, deposited since last 

sea-level lowstand about 21,000 years ago. Underlying reflectors locally image deformed Neogene strata. 

Dashed green lines highlight some continuous reflections that reveal depositional patterns and structure (not 

distinctive stratigraphic markers). Dashed yellow line is seafloor multiple (echo of seafloor reflector). Purple 

triangle shows location of California’s State Waters limit (yellow line on trackline map).

1 km

VERTICAL EXAGGERATION ~ 10

Two-way travel time, in seconds

0

0.1

0.2

SOUTH

0.3

0.4

Fig. 9

Fig. 3

 Gaviota 

sediment bar

Conception fan

(mixed landslide

and stratified

slope deposits)

clinoforms

debris lobes

 south strand,

 Santa Ynez Fault(?)

1 km

VERTICAL EXAGGERATION ~ 10

Two-way travel time, in seconds

0

0.1

0.2

SOUTH

0.3

NORTH

160

0 

Approximate depth, in meters

80

240

Figure 4. USGS high-resolution minisparker seismic-reflection profile GS–69R (collected in 2014 on cruise S–01–13–CC), which crosses shelf and upper slope southwest 

of Gaviota State Park; see trackline map for location. Profile highlights south strand of Santa Ynez Fault Zone, Gaviota sediment bar, “Sacate Canyon,” and upper part of 

Conception fan. Dashed red lines show faults. Blue shading shows inferred uppermost Pleistocene and Holocene strata, deposited since last sea-level lowstand about 

21,000 years ago. Underlying reflectors locally image deformed Neogene strata. Dashed green lines highlight some continuous reflections that reveal structure (not 

distinctive stratigraphic markers). Dashed yellow line is seafloor multiple (echo of seafloor reflector). Purple triangle shows location of California’s State Waters limit 

(yellow line on trackline map). 

Fig. 9

Fig. 3

shelf break

upper part of 

Conception fan

south strand, Santa

Ynez Fault Zone

 Gaviota 

sediment bar

“Sacate

Canyon”

Figure 3 (left). USGS high-resolution minisparker seismic-reflection profile GS–128 

(collected in 2014 on cruise S–01–13–CC), which crosses inner shelf west of Gaviota State 

Park; see trackline map for location. Profile highlights folded and faulted Neogene strata 

beneath shelf. Dashed red lines show faults. Magenta symbols show fold axes (diverging 

arrows, anticline; converging arrows, synclines). Blue shading shows inferred uppermost 

Pleistocene and Holocene strata, deposited since last sea-level lowstand about 21,000 

years ago. Underlying reflectors image deformed Neogene strata. Dashed green lines 

highlight some continuous reflections that reveal structure (not distinctive stratigraphic 

markers). Dashed yellow lines are seafloor multiples (echoes of seafloor reflector).

1 km

VERTICAL EXAGGERATION ~ 10

Two-way travel time, in seconds

0

0.1

0.2

WEST

0.3

EAST

160

0 

Approximate depth, in meters

80

240

Fig. 1

Fig. 2

Fig. 4

Fig. 5

 south strand, 

Santa Ynez Fault 

Figure 2. USGS high-resolution minisparker seismic-reflection profile GS–64R (collected in 2014 on cruise S–01–13–CC), which crosses shelf and upper slope west of Gaviota State Park; see 

trackline map for location. Profile highlights structurally complex shelf cut by south strand of Santa Ynez Fault Zone and upper part of Conception fan, which contains hummocky and chaotic 

landslide deposits. Shelf is overlain by thin uppermost Pleistocene and Holocene strata (blue shading), deposited since last sea-level lowstand about 21,000 years ago. Dashed red lines show faults. 

Dashed green lines highlight some continuous reflections that reveal structure and stratigraphy (not distinctive stratigraphic markers). Dashed yellow lines are seafloor multiples (echoes of seafloor 

reflector). Purple triangle shows location of California’s State Waters limit (yellow line on trackline map).

NORTH

160

0 

Approximate depth, in meters

80

240

320

1 km

VERTICAL EXAGGERATION ~ 10

Two-way travel time, in seconds

0

0.1

0.2

SOUTH

0.3

0.4

Fig. 9

Fig. 3

upper part of Conception fan

(hummocky and chaotic

landslide deposits)

south strand, Santa

 Ynez Fault Zone shelf break

1 km

VERTICAL EXAGGERATION ~ 10

Two-way travel time, in seconds

0

0.1

0.2

SOUTH

0.3

0.4

NORTH

160

0 

Approximate depth, in meters

80

240

320

Fig. 3

Figure 1. USGS high-resolution minisparker seismic-reflection profile GS–59 (collected in 2014 on cruise S–01–13–CC), which crosses shelf and upper slope west of Gaviota State Park; see trackline 

map for location. Profile predominantly shows reflection-free bedrock that extends to seafloor (note trackline map). Dashed red line shows inferred fault. Magenta symbol shows anticline axis 

(structural interpretation is largely based on seafloor outcrops; see sheet 1). Blue shading shows very thin layer on outer shelf (north [to right] of shelf break) of inferred uppermost Pleistocene and 

Holocene nearshore and shelf deposits. Dashed green lines highlight variably continuous reflections that reveal structure and stratigraphic architecture (not distinctive stratigraphic markers). Dashed 

yellow lines are seafloor multiples (echoes of seafloor reflector). Purple triangle shows location of California’s State Waters limit (yellow line on trackline map).

shelf break

 upper part of

Conception fan

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, 2018

MAGNETIC NORTH

12 / ° 1 2

TRUE NORTH

GIS database and digital cartography by Peter Dartnell 

and Stephen R. Hartwell

Manuscript approved for publication February 12, 2018

Onshore elevation data from National Oceanic and 

Atmospheric Administration (NOAA) Office for Coastal 

Management's Digital Coast (available 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 drom NOAA Office of Coast 

Survey

Universal Transverse Mercator projection, Zone 10N

NOT INTENDED FOR NAVIGATIONAL USE

Gaviota

State Park

 Santa Ynez Mountains

Fig. 1

Fig. 2

Fig. 3

Fig. 4

Fig. 5

Fig. 6

Fig. 7

Fig. 8

Fig. 9

Fig. 10

34°30'

34°25'

120°20' 120°15'

34°30'

34°25'

120°20' 120°15'

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 S–01–13–CC (USGS)

 Survey S–7–08–SC (USGS)

 Survey W–37–84–SC (WesternGeco)

 Survey W–40–85–SC (WesternGeco)

 3-nautical-mile limit of California’s 

State Waters

 Area of “no data”—Areas near shoreline not mapped owing to insufficient 

high-resolution seafloor mapping data

Figure 1

Figure 6

Open-File Report 2018–1023

Sheet 7 of 9

Pamphlet accompanies map

U.S. Department of the Interior

U.S. Geological Survey