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/ofr20181024

Suggested Citation: Dartnell, P., 2018, Data integration and visualization, Offshore of Point Conception map area, California, sheet 4 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 Point Conception, California: U.S. Geological Survey Open-File Report 2018–1024, pamphlet 36 p., 9 sheets, scale 

1:24,000, https://doi.org/10.3133/ofr20181024.

ISSN 2331-1258 (online)

https://doi.org/10.3133/ofr20181024

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.

40

20

80

60

120

100

140

0

DISCUSSION

Mapping California’s State Waters has produced a vast amount of acoustic and visual 

data, including bathymetry, acoustic backscatter, seismic-reflection profiles, and seafloor video 

and photography. These data are used by researchers to develop maps, reports, and other tools 

to assist in the coastal and marine spatial-planning capability of coastal-zone managers and 

other stakeholders. Seafloor-character, habitat, and geologic maps may be used for fisheries 

management, for designation of Marine Protected Areas, for monitoring of environmental 

change such as sea-level-rise impacts, for prediction of sediment and contaminant budgets and 

transport, and for assessment of earthquake and tsunami hazards. To achieve these goals, it is 

helpful to integrate the different datasets and then view the results in three-dimensional 

representations such as those displayed on this data integration and visualization sheet for the 

Offshore of Point Conception map area.

The map view in the center of the sheet is similar to the colored shaded-relief bathymetry 

map of the Offshore of Point Conception map area (see sheet 1 of this report). Numbered 

arrows show viewing directions of the perspective views on this sheet (figs. 1, 2, 4, 5, 6); the 

numbers indicate the figure number of the perspective view.

The perspective views in figures 1, 2, 4, 5, and 6 show the colored shaded-relief bathymetry of the Offshore of Point Conception map area, as viewed from different directions. These 

views highlight the seafloor morphology in the offshore of Point Conception map area, which 

includes asphalt mounds, differentially eroded bedrock, and pockmarks. 

Video-mosaic images created from digital seafloor video (fig. 3) can display the geologic 

(rock, sand, mud, asphalt) and biologic complexity of the seafloor. Whereas photographs 

capture high-quality snapshots of smaller areas of the seafloor, video mosaics can capture 

larger areas and, thus, can show transitional zones between different seafloor environments.

Draping the acoustic-backscatter imagery (see sheet 3 of this report) over the bathymetry 

data (fig. 6) highlights the relations between the backscatter intensity and the seafloor 

morphology. It also aids in seafloor habitat and geology interpretations and mapping 

sediment-transport pathways.

Block diagrams (fig. 2), which combine the bathymetry with seismic-reflection-profile 

data (see sheet 7 of this report), help reveal the stratigraphic and structural relations between 

the surface and subsurface.

EXPLANATION

Depth (in meters) and illumination (bright areas are illuminated, facing false 

sun; dark areas are in shadow, facing away from false sun)

Shallow

Deep

Direction of illumination from false sun—Position of false sun is at 300° 

azimuth, 45° above horizon [arrow included in explanation for illustration 

purposes only; not shown on map]

Data Integration and Visualization, Offshore of Point Conception Map Area, California

By

Peter Dartnell

2018 

Perspective views by Peter Dartnell, 2016. Seismic-reflection profile in figure 2 from sheet 7, this report. Video-mosaic image in 

figure 3 by Peter Dartnell, 2015, using software developed by Dr. Yuri Rzhanov, Center for Coastal and Ocean Mapping, University 

of New Hampshire, through joint U.S. Geological Survey–University of New Hampshire cooperative agreement. Acousticbackscatter imagery in figure 6 from map on sheet 3, this report 

GIS database and digital cartography by Nadine E. Golden and Stephen R. Hartwell

Manuscript approved for publication February 13, 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 1, this report

Universal Transverse Mercator projection, Zone 10N

NOT INTENDED FOR NAVIGATIONAL USE

Map view. Colored shaded-relief bathymetry map of 

Offshore of Point Conception map area, generated 

from multibeam-echosounder and bathymetric-lidar 

data. Colors show depth: reds indicate shallower 

areas; greens, deeper areas. Black areas indicate 

where bathymetric data are not available. 

Illumination azimuth is 300°, from 45° above horizon. 

Ripple patterns and parallel lines that are apparent 

within map area are data-collection and -processing 

artifacts; these artifacts are made obvious by 

hillshading process. Numbered arrows show viewing 

directions of perspective views shown on this sheet; 

numbers correspond to figure numbers of views. 

Point Conception

Figure 3. Video mosaic generated from seafloor video 

captured over large asphalt deposit west of Point 

Conception (see fig. 1 for location). Mosaic reveals lobes 

of relatively fresh asphalt that have little or no sediment 

or biological cover, as well as two possible asphalt 

vents. Camera-sled tow direction is from bottom to top; 

width of mosaic changes because field of view of 

camera changes as camera sled raises and lowers 

relative to seafloor. Green dots are lasers on camera 

sled that used to scale features on seafloor. Video 

mosaic created using software developed by Dr. Yuri 

Rzhanov, Center for Coastal and Ocean Mapping, 

University of New Hampshire, through joint U.S. 

Geological Survey–University of New Hampshire 

cooperative agreement.

~90 cm

Figure 6. Perspective views to north along inner shelf and nearshore area east of Point Conception, showing colored shaded-relief bathymetry (A) and acoustic-backscatter 

imagery (B). In acoustic-backscatter imagery, lighter tones indicate stronger backscatter intensity, suggesting rock or coarser grained sediment, whereas darker tones indicate 

weaker backscatter intensity, suggesting finer grained sediment. In nearshore areas (0 to about 10 m water depth), bathymetry is from bathymetric-lidar data (see sheets 1, 2), 

and backscatter data are not available for this shallow zone; black areas indicate where bathymetric and (or) backscatter data are not available. Views show differentially 

eroded and fractured bedrock along coast and smoother asphalt deposits farther offshore (i). Asphalt deposits have intermediate backscatter intensities (lower than rock, but 

higher than sediment), which could indicate that mounds are covered by thin sediment layer, or it could indicate that surface is smoother (and, thus, reflects acoustic energy 

differently) than bedrock. Parallel lines in backscatter imagery are data-collection and -processing artifacts. Vertical exaggeration of perspective views, 2x; distance across 

bottom of both views, 2.4 km.

B

i

i

A

Figure 5. Perspective view to northeast over inner shelf and nearshore areas between Point Conception and Point Arguello, showing folded and differentially eroded 

bedrock, mapped as mudstone and shale of the upper Miocene and Pliocene Sisquoc Formation (see sheet 9 of this report). In places (h), outcrop has as much as 4 m 

of local relief. Faint ripples and parallel lines along flat seafloor are data-collection and -processing artifacts. Vertical exaggeration, 2x; distance across bottom of 

image, about 2.5 km.

h

Figure 4. Perspective view to north toward Point Conception, showing asphalt deposits in nearshore (f), pockmarks along outer shelf (g), and relatively 

smooth sediment seafloor in midshelf area. Bathymetric profile A–A' highlights series of midshelf, low-relief, northeast-trending sand ridges, which 

probably formed by mobilization and transport of sediment by strong currents that wrap around Point Conception. Vertical exaggeration of perspective 

view, 2x; distance across bottom of image, about 1.6 km; vertical exaggeration of profile A–A', about 2x. 

Distance (m)

0 100 200 300 400 500 600

Depth (m) 77

76

78

A A’

700 800 900 1000 1100 1200

A'

A

f

f

g g

Point Conception

Figure 2. Perspective views to west-northwest over midshelf area south of Point Conception. A, Perspective view of asphalt deposits (b, c) in nearshore area and pockmark fields (d, e) 

mapped on outer shelf (see sheet 9 of this report). Black line shows location of seismic-reflection profile in B below. B, Same perspective view as A, converted to block diagram that 

combines bathymetry with northeast-trending seismic-reflection profile GS–07 (also shown in fig. 8 on sheet 7 of this report, at reduced vertical exaggeration). Block diagram reveals 

presence of large syncline in midshelf area and two prominent angular unconformities (green lines). Dashed green lines highlight continuous reflections. Dashed purple line is 

prominent angular unconformity. In smooth, gently dipping midshelf area, bedrock is covered by thin uppermost Pleistocene and Holocene sediment layer (blue shading). Dashed yellow 

line shows seafloor multiple (echo of seafloor reflector). Vertical exaggeration in both views, 2x; distance across bottoms, about 1.1 km.

B

Point Conception

b

d

A

Point Conception

e

d

c

b

Figure 1. Perspective view to northeast over midshelf area west of Point Conception, showing large asphalt deposit (see sheet 9 of this report), about 900 m wide 

(north to south) and about 1 km wide (east to west). Deposit has 10 m of vertical relief at “a” above surrounding seafloor. Thin white line shows path of camera sled, 

towed 1 to 2 m above seafloor, that captured video and photographs; white arrow shows tow direction. Black rectangle shows location of video mosaic (fig. 3) 

generated from video captured over asphalt deposit. Vertical exaggeration, 2x; distance across bottom of image, about 1.1 km.

a

5

2

6

1

4

possible asphalt vent

possible asphalt vent

asphalt lobe

asphalt lobe

Open-File Report 2018–1024

Sheet 4 of 9

Pamphlet accompanies map

U.S. Department of the Interior

U.S. Geological Survey