BITUMEN OF SANTA BARBARA COUNTY. 
Ill 
seam of shells of both fresh and brackish water, among which voluta, melania, 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 that 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 tide, so that no 
deposit occurs. 
7. Bitumen of Buenaventura river .—This is found 12 miles above the mission/along the left 
hank 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 dip 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 hank 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 hut apparently from crevices 
extending some yards and wide enough to allow a 2-inch pole to he inserted, which could be 
pushed down 4 feet, hut was then arrested by the tenacious character of the bitumen. The 
strata are not the clay rocks usually accompanying the bitumen, hut 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 
