1898.] PECKHAM — THE GENESIS OF BITUMENS. 183 



islands and the main land. The richest deposits have been 

 found in Ventura county, on the border line that separates the Cre- 

 taceous from the Lower Miocene. None of the bitumen is found in 

 crystalline rocks ; yet the evidences of both normal and local 

 metamorphism, in strata not far distant from the bitumen-bearing 

 rocks, are abundant. The late Eli W. Blake once visited the Santa 

 Barbara islands and afterwards described to me the cascades of lava 

 that had descended from the volcanic cones in the centre of the 

 islands over precipices into the sea. Bitumen has exuded for more 

 than a century from the unaltered strata, whose upturned edges 

 form the bed of the ocean, between these islands and the main 

 land. The Tertiary formations that constitute the bluffs of the coast 

 east and west of Santa Barbara contain deposits of bitumen of 

 enormous extent and exhibit evidences of metamorphic action still 

 in progress. Almost every large bluff from Point Conception to 

 San Diego contains a solfatera, the action of which leaves the Mio- 

 cene shales, originally rich in organic matter, devoid of a trace of 

 carbon. 



The best petroleum wells of Ventura county lie in the canons of the 

 Sulphur mountain, one of the foothills of the Coast Ranges. Other 

 wells are similarly located with reference to these ranges,^ None of 

 them have penetrated crystalline rocks ; yet the core of the Coast 

 Ranges only a few miles east of the wells of the Pacific Coast Oil Co., 

 as Dr. Goodale and myself found, is granite. Fragments of crystal- 

 line rocks are washed out of many of the large canons that head in 

 the main Coast Range back of the foothills in which the oil wells 

 are drilled. Deep drilling is extremely difficult in this region on 

 account of the fragile character of the rocks. It might be impos- 

 sible to carry a well down through all the bituminous strata to the 

 crystalline rocks, but the fact that they are altered Miocene sedi- 

 ments and exist at a comparatively short distance below the surface 

 does not admit of any question. The evidences of metamorphism, 

 through the agency of hot, silicated water, are found everywhere. 

 The formations contain abundant remains of highly organized ani- 

 mals ; and the bitumens which they contain consist of benzoles 

 and naphthenes, without an " appreciable amount of paraffines, if 

 any." ^ They also contain sulphur and nitrogen. They are evidently 



^S.F. Peckham, ]\lineral Resources of the United States, "Petroleum in 

 California," 1894. 



2 Letter of C. F. Mabery to S. F. P. 



