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/3302/

Suggested Citation: Dartnell, P., Phillips, E.L., Finlayson, D.P., Conrad, J.E., and Kvitek, R.G., 2014, Colored shaded-relief bathymetry, 

Offshore of Coal Oil Point map area, California, sheet 1 in Johnson, S.Y., Dartnell, P., Cochrane, G.R., Golden, N.E., Phillips, E.L., 

Ritchie, A.C., Kvitek, R.G., Dieter, B.E., Conrad, J.E., Lorenson, T.D., Krigsman, L.M., Greene, H.G., Endris, C.A., Seitz, G.G., Finlayson, 

D.P., Sliter, R.W., Wong, F.L., Erdey, M.D., Gutierrez, C.I., Leifer, I., Yoklavich, M.M., Draut, A.E., Hart, P.E., Hostettler, F.D., Peters, K.E., 

Kvenvolden, K.A., Rosenbauer, R.J., and Fong, G. (S.Y. Johnson and S.A. Cochran, eds.), California State Waters Map Series—

Offshore of Coal Oil Point, California: U.S. Geological Survey Scientific Investigations Map 3302, pamphlet 57 p., 12 sheets, scale 

1:24,000, http://dx.doi.org/10.3133/sim3302.

ISSN 2329-132X (online)

http://dx.doi.org/10.3133/sim3302

US Army Corps

of Engineers

Figure 1. Map showing areas of multibeam-echosounder and bathymetric-sidescan surveys (pink shading), 

bathymetric- and topographic-lidar surveys (orange diagonal lines), and publicly available interferometric 

synthetic aperture radar (ifSAR) topography (yellow shading). Also shown are data-collecting agencies 

(CSUMB, California State University, Monterey Bay, Seafloor Mapping Lab; FP, Fugro Pelagos; USACE, U.S. 

Army Corps of Engineers; USGS, U.S. Geological Survey) and dates of surveys if known.

USACE, 2009

USGS, 2006

CSUMB, 2007

FP, 2008

Coal Oil Point

USGS, 2007

USGS, 2008

120°0' 119°55' 119°50'

34°30'

34°25'

100

200

100

80

60

40

20

DISCUSSION 

This colored shaded-relief bathymetry map of the Offshore of Coal Oil Point map area in southern 

California was generated from bathymetry data collected by the U.S. Geological Survey (USGS), by California State University, Monterey Bay (CSUMB), and by Fugro Pelagos (fig. 1). Most of the nearshore and shelf 

areas were mapped by the USGS in 2006, 2007, and 2008, using a combination of 117-kHz (2006, 2007) and 

234.5-kHz (2008) SEA (AP) Ltd. SWATHplus-M phase-differencing sidescan sonars. A small area in the 

far-eastern nearshore and shelf was mapped by CSUMB in 2007, using a 244-kHz Reson 8101 multibeam 

echosounder. The outer shelf and slope were mapped by Fugro Pelagos in 2008, using a combination of 

400-kHz Reson 7125, 240-kHz Reson 8101, and 100-kHz Reson 8111 multibeam echosounders. In addition, 

the nearshore bathymetry and coastal topography were mapped by Fugro Pelagos in 2009 for the U.S. Army 

Corps of Engineers (USACE) Joint Lidar Bathymetry Technical Center of Expertise, using the SHOALS1000T bathymetric-lidar and the Leica ALS60 topographic-lidar systems. These mapping missions combined 

to collect bathymetry from the 0-m isobath to beyond the 3-nautical-mile limit of California’s State Waters. 

During the USGS mapping missions, differential GPS (DGPS) data (2006, 2007) and GPS data with 

real-time kinematic corrections (2008) were combined with measurements of vessel motion (heave, pitch, and 

roll) in a CodaOctopus F180 attitude-and-position system to produce a high-precision vessel-attitude packet. 

This packet was transmitted to the acquisition software in real time and combined with instantaneous soundvelocity measurements at the transducer head before each ping. The returned samples were projected to the 

seafloor using a ray-tracing algorithm that works with previously measured sound-velocity profiles. Statistical 

filters were applied to discriminate seafloor returns (soundings) from unintended targets in the water column. 

Finally, the soundings were converted into 2-m-resolution bathymetric-surface-model grids.

During both the CSUMB and the 2008 Fugro Pelagos multibeam mapping missions, an Applanix POS 

MV (Position and Orientation System for Marine Vessels) was used to accurately position the vessels during 

data collection, and it also accounted for vessel motion such as heave, pitch, and roll (position accuracy, ±2 m; 

pitch, roll, and heading accuracy, ±0.02°; heave accuracy, ±5%, or 5 cm). To account for tidal-cycle fluctuations, CSUMB used NavCom 2050 GPS receiver (CNAV) data, and Fugro Pelagos used KGPS data (GPS data 

with real-time kinematic corrections). In addition, sound-velocity profiles were collected with an Applied 

Microsystems (AM) SVPlus sound velocimeter. Soundings were corrected for vessel motion using the 

Applanix POS MV data, for variations in water-column sound velocity using the AM SVPlus data, and for 

variations in water height (tides) using vertical-position data from the CNAV receiver and also the KGPS data. 

Most soundings in the Offshore of Coal Oil Point map area were converted to 2-m-resolution 

bathymetric-surface-model grids; however, soundings along the outer shelf and slope in water depths greater 

than 80 m were converted to a 5-m-resolution bathymetric-surface-model grid because of lower sounding 

density. 

During the 2009 Fugro Pelagos coastal airborne-lidar mapping mission that was completed as part of the 

National Coastal Mapping Program of USACE, the Leica ALS60 topographic-lidar and the SHOALS-1000T 

bathymetric-lidar systems were mounted on an aircraft that flew survey lines at an altitude of 300 to 400 m 

(bathymetry) and 300 to 1,200 m (topography), at speeds of between 135 and 185 knots. The ALS60 system 

collected data at a maximum pulse rate of 200 kHz, and the SHOALS system collected data at 1 kHz. Information on aircraft position, velocity, and acceleration were collected using the Novatel and POS A/V 410 systems 

(SHOALS) and the onboard GPS/IMU system (ALS60). Aircraft-position data were processed using POSPac 

software, and the results were combined with the lidar data to produce 3-D positions for each lidar shot. 

Various commercial and proprietary software packages were used to clean the data, to convert all valid data 

from ellipsoid to orthometric heights, and to export the data as a series of topography and bathymetry ASCII 

files. 

Soundings from the different mapping missions were converted into individual 

bathymetric-surface-model grids: the 2-m-resolution surface models were merged into one overall 

2-m-resolution bathymetric-surface model and clipped to the boundary of the map area; the 5-m-resolution 

bathymetric-surface model was processed as a separate grid. The overall 2-m-resolution grid and the 

5-m-resolution grid were displayed together in a GIS to create this map. An illumination having an azimuth of 

300° and from 45° above the horizon was then applied to the bathymetric surfaces to create the shaded-relief 

imagery. In addition, a modified “rainbow” color ramp was applied to the bathymetry data, using reds and 

oranges to represent shallower depths, and blues and purples to represent greater depths. This colored bathymetry surface was draped over the shaded-relief imagery at 60-percent transparency to create this colored 

shaded-relief map. Note that the ripple patterns and straight lines that are apparent within the map area are 

data-collection artifacts. In addition, lines at the borders of some surveys are the result of slight differences in 

depth, as measured by different mapping systems in different years. These various artifacts are made obvious 

by the hillshading process. 

Bathymetric contours were generated from a modified 10-m-resolution bathymetric surface where a 

smooth arithmetic mean convolution function that assigns a weight of one-ninth to each cell in a 3-pixel by 

3-pixel matrix was applied iteratively to the surface ten times. Following smoothing, contour lines were 

generated at 10-m intervals, from -10 to -100 m, and at 50-m intervals, from -100 to -250 m, then the contours 

were clipped to the boundary of the map area.

The onshore-area image was generated by applying the same illumination (azimuth of 300° and from 45° 

above the horizon) to the coastal airborne topographic-lidar data, as well as to publicly available, 3-mresolution, interferometric synthetic aperture radar (ifSAR) data, available from National Oceanic and Atmospheric Administration (NOAA) Coastal Service Center’s Digital Coast, at http://csc-s-maps-q.csc.noaa.gov/

dataviewer/viewer.html (last accessed April 5, 2011).

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]

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

seafloor mapping data; areas beyond 3-nautical-mile limit of California’s State Waters were 

not mapped as part of California Seafloor Mapping Program

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

Bathymetric contour (in meters)—Derived from modified 10-m-resolution bathymetry grid. 

Contour intervals: 1–100 m water depth, 10 m; >100 m water depth, 50 m

CALIF.

0 4 8 Nautical Miles

Kilometers 0 5 10

120° 119°40' 119°20' 119°

34°

34°20'

MAP LOCATION

Ventura

Santa Barbara

Anacapa

Island

Santa Cruz Island Santa Rosa Island

Area of

Map

Santa Barbara Channel Limit of California’s

State Waters

1 

U.S. Geological Survey;

2 

California State University, Monterey Bay, Seafloor Mapping Lab

Colored Shaded-Relief Bathymetry, Offshore of Coal Oil Point Map Area, California

By

Peter Dartnell,1 Eleyne L. Phillips,1 David P. Finlayson,1 James E. Conrad,1 and Rikk G. Kvitek2

2014

ONE MILE = 0.869 NAUTICAL MILES

BATHYMETRIC CONTOUR INTERVALS 10 AND 50 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, 2014

MAGNETIC NORTH

12 / ° 1 2

TRUE NORTH

Shaded-relief bathymetry by Peter Dartnell, 2012 (data collected by U.S. Geological 

Survey in 2006, 2007, and 2008; by California State University, Monterey Bay, 

Seafloor Mapping Lab in 2007; and by Fugro Pelagos in 2008 and 2009). Bathymetric 

contours by Andrew C. Ritchie, 2011 

GIS database and digital cartography by Nadine E. Golden and Eleyne L. Phillips

Edited by Taryn A. Lindquist

Manuscript approved for publication June 2, 2014

Onshore elevation data from NOAA Coastal Services Center (data collected by 

EarthData International in 2002-2003) and from U.S. Army Corps of Engineers 

(data collected by Fugro Pelagos in 2009). California's State Waters limit from 

NOAA Office of Coast Survey

Universal Transverse Mercator projection, Zone 11N

NOT INTENDED FOR NAVIGATIONAL USE

10

20

30

40

50

60

70

80

100

90

150

200

250

250

Goleta Point

Coal Oil Point

Isla Vista

Goleta

120° 119°55' 119°50'

34°30'

34°25'

120° 119°55' 119°50'

34°25'

Naples

Scientific Investigations Map 3302

Sheet 1 of 12

Pamphlet accompanies map

U.S. Department of the Interior

U.S. Geological Survey