BITUMEN OF SANTA BARBARA COUNTY. Ill 



seam of shells of both fresh and brackish water, among which voluta, melaaia, natica, and 

 helix, are prominent species. Here, then, is an anterior epoch before the upheaval of the 

 asphalt, when the surface was the bottom of an estuary similar to that which rolls up the flat 

 land behind the present terrace ; so tliat three distinct periods are chronicled in this cliff, viz : 



1. The deposition of these soft clay beds. 



2. The estuary action and deposition of the brackish water shells. 



3. The elevation of this to its present height, 60 to 80 feet ; this was most probably 

 accompanied by the effusion of asphalt, the elevation being at intervals so as to allow of the 

 formation of the beach on the upper surface. 



6. The localities of the Rincon, and the mouth of San Buenaventura river, are more 

 remarkable as geological displays of the strata in which asphalt is found, than as actual 

 deposits of practical value. A magnesian and trachytic axis runs into the sea at the Rincon, 

 forming the headland. -Minor protrusive rocks occur, within a few hundred yards of each 

 other, between these points, which give the shore line a crescentic form, repeated three times, 

 the concavities being towards the sea. This excavation is formed by the sea, owing to the 

 soft nature of the strata along shore, being the same white and brownish clay rocks, overlying 

 greenish sandy beds, through which the asphalt leaks up. The strata dip inland or under 

 the shore, and are nearly vertical on the beach. In one of these indentations of the shore, the 

 strata, as they crop out on the beach and under the water, are commencing with that nearest 

 the axis. 



1. Dark greenish sandy clay rock, colored with bitumen. Two hundred feet of this could be 

 measured along its edges until the water became too deep for further examination. 



2. Coarse grit clay, with whitish quartz, seventy feet ; fossiliferous. 



3. Fine grit, with bitumen, forty feet ; making a total thickness of bituminous rocks = 310 

 feet. The bitumen is here washed ashore in small masses ; along shore the bitumen is only 

 found in threads leaking through the strata, which are cleared off by the tidC;, so that no 

 deposit occurs. 



7. Bitunieii of Buenaventura river. — This is found 12 miles above the mission, along the left 

 bank of the river, the ascent of which is unusual. Passing the range of hills which abuts upon 

 shore at this point, the river opens into a small terraced valley, and thence cuts its way through 

 an undulating country which lies between the back of the shore range and the little valley of 

 Matilihah. This is occupied by coarse brown and reddish grits, such as form the lower beds of 

 the Santa Inez range ; here they dijj northeast and southwest, within a narrow compass, owing 

 to the intrusion of trachyte, whitish felspar rock, and porphyritic felspar with orthose crystals. 

 This rock crosses the river and does not exhibit an exposed breadth of more than 60 yards ; in 

 proximity with it and on its northern edge near the left bank of the river, is a spring which 

 deposits a large quantity of sulphur ; its temperature was 64° Fahrenheit, the air being 55° 

 Fahrenheit. Along with the spring is an overflow of bitumen, which has covered up the soil 

 20 feet around and 2 feet deep ; it oozed up not from one point but apparently from crevices 

 extending some yards and wide enough to allow a 2-inch pole to be inserted, Avhich could be 

 pushed down 4 feet, but was then arrested by the tenacious character of the bitumen. The 

 strata are not the clay rocks usually accompanying the bitumen, but are the brownish sandstones 

 of Santa Inez. Here, too, as in other places where sand rock is close to trachyte, it is colored 

 red, by oxide of iron, of a vermilion tint, and in riband strata. The deposit of bitumen at this 



