Petroleum 



321 



Figure 244. Positions of known 

 offshore oil seeps. 



rock from erosion and causing the tar- 

 splotched areas to stand out in relief as 

 much as 3 mm. Tar-splotched rock has 

 been noted at nearly all places along the 

 coast where rock is exposed. More com- 

 mon, however, is the finding of small sticky 

 masses of soft black tar on sand beaches, 

 where they enclose sand grains, dry out, 

 and become buried or are carried back out 

 to sea. Because the fresh soft tar is most 

 easily found on the feet of bathers and 

 others who walk on the beaches, it is notor- 

 ious in well-frequented beaches such as 

 Santa Barbara, Santa Monica, Huntington 

 Beach, Oceanside, La Jolla, and San Diego. 

 The latter areas are remote from known off- 

 shore seeps, and some of the tar may have 

 come from tankers. In areas closer to the 

 seeps, such as Carpinteria, Summerland, 

 Coal Oil Point, Goleta Point, and Elwood, 

 the tar is much more common per unit 

 area of beach and is frequently associated 

 with oil that gives the water an appearance 

 of a brown emulsion smelhng strongly of 

 petroleum. 



Navigational charts published by the 

 U. S. Coast and Geodetic Survey indicate 

 oil seeps at the head of Redondo Submarine 



Canyon and on the shelf west of San Miguel 

 Island. Many other seeps are readily evi- 

 dent from aboard ships by odor and by 

 smooth shcks on the sea surface. They 

 have been observed in abundance in the 

 nearshore area from Point Conception to 

 about 8 km east, near Coal Oil Point, 

 Summerland, and Elwood, and a few kilo- 

 meters east of Anacapa Island (Fig. 244). 

 In some of these seeps large bubbles of gas 

 and masses of tar can be seen rising to the 

 surface of the water — the gas to escape into 

 the air, the oil to spread atop the water, and 

 the tar to be carried away by currents. A 

 deep seep was found at 304 fathoms (556 

 meters) on the north slope of San Pedro 

 Basin, where a sample (no. 5905) contained 

 slabs of tar as much as 20 X 12 X 2 cm, 

 droplets of oil, and a petroleum odor. 



Floating pieces of tar have been noted far 

 from known seeps, some even in the deep- 

 sea area 60 km west of Northeast Bank. 

 Most are brown and the larger ones are flat 

 and round (5 mm thick and 15 cm in di- 

 ameter). Their rims are slightly scalloped 

 and folded back on themselves as though by 

 the buffeting action of wavelets. Some 

 samples of the shelf sediments near the areas 



