California mines and minerals . eceded the distillation of petro-leum from carbonaceous matter by the heat of metamorphism. In the figure, A represents fine shale with few fossil shells; inplaces it contains fossil fish-bones. The cracks and joints at rightangles with the planes of bedding are frequently filled with bitumen. No cracks at right angles with the plane of bedding could haveexisted in these shales until they were contorted; therefore, thesecracks were bituminized after the folding of the formation had com- 168 CALIFORNIA MINES AND MINERALS menced. Neither could bitumen have ascende
California mines and minerals . eceded the distillation of petro-leum from carbonaceous matter by the heat of metamorphism. In the figure, A represents fine shale with few fossil shells; inplaces it contains fossil fish-bones. The cracks and joints at rightangles with the planes of bedding are frequently filled with bitumen. No cracks at right angles with the plane of bedding could haveexisted in these shales until they were contorted; therefore, thesecracks were bituminized after the folding of the formation had com- 168 CALIFORNIA MINES AND MINERALS menced. Neither could bitumen have ascended through these shalesbefore they were cracked or jointed, for when these fine shales con-tain quarry water, they are impervious to oil. These different strata, BBB and CCC, are conformable, and donot pass into one another by gradation ; the lines between them areclearly marked. The muddy, fine sand does not weather as rapidlyas the coarse sands ; consequently, their faces of exposure are nearerverticality than the coarse Wi\: i lift ?ft*«ft 1.,^! f y ^>- -I -^-^ iMil 1,1 v||l)-A^V/iinv.^^- Fig. 15. — Alternating Beds of Different Sandstones. The different strata must have been derived from two formations,one being composed of altered rocks, and the other of unalteredrocks, and the changes in the derivation of the sediments composingthis formation, from the altered to the unaltered rocks, were quicklymade, either by a change in ocean currents or the sudden upliftingof the land. These strata of sand, described above, are situated on the Tina-quaic Rancho, in Santa Barbara County. The character of the bitu-minized sands near Santa Cruz is very different. They contain fewround pebbles of hard rock, and no lenticular pebbles of shale. They THE GENESIS OF PETROLEUM AND ASPHALTUM 169 are clean quartz sands, of varying fineness, and were, probably,formed by the disintegration of granite. They do not contain manyfossils, and contain gold in notable quantities. That sudden
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