202 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA. 



In 1865 J. D. Whitney, then state geologist, in writing his report on the 

 general geology of the Los Angeles region, gave a brief discussion 3 of the 

 asphalt exposures and tar pools. He referred in his report to the "very large 

 amount of the hardened asphaltum mixed with sand and the bones of cattle and 

 birds which have become entangled in it," but did not state that the remains 

 were those of extinct forms. Whitney's discussion of these beds appears in 

 the succeeding paragraph: 



About seven miles due west of Los Angeles is the most important of the numerous tar-springs 

 seen in this vicinity. It is from here that most of the asphaltum used in the town is obtained. 

 Over a space of fifteen or twenty acres, the bituminous material (which when seen by us, in the 

 winter, had exactly the consistency and color of tar) was oozing out of the ground at numerous 

 points. It hardens on exposure to the air, and becomes mixed with sand and dust blown into it, 

 and is then known as "brea. " The holes through which the bitumen comes to the surface are 

 not large, few being more than three or four inches in diameter. On removing the tarry sub- 

 stance from the holes, by repeatedly inserting a stick, the empty cavity was very slowly filled 

 up again. At one place there was a pit several yards square, and six or eight feet deep, from 

 which the tar had been taken ; but it was filled with water, at the time of our visit, in consequence 

 of late heavy rains. ... A very large amount of the hardened asphaltum. mixed with sand 

 and the bones of cattle and birds which have become entangled in it, lies scattered over the plain. 



As nearly as can be determined, the first published statement in which 

 reference was made to the fossil remains entombed in the asphalt at Rancho 

 La Brea is the following issued by "William Denton 4 in 1875 : 



The locality is known as Major Hancock's Brea Ranch, and is about eight miles west of Los 

 Angeles, in the valley of the Santa Anna. The bed of asphaltum here covers sixty to eighty 

 acres, and at a depth of thirty feet no bottom has been reached. Thousands of tons have been 

 removed for roofing, paving and combustion, but the supply is almost inexhaustable. 



Major Hancock had about twenty-five Chinamen employed in digging out the best of the 

 asphaltum. which is soft enough to agglutinate in the heat of the sun. The material was con- 

 veyed to large, open iron boilers, in which it was boiled for twenty-four hours, and then run into 

 sand molds ; subsequently it was broken up, for it is quite brittle after being thus boiled, carted 

 for nine miles and shipped to San Francisco, where it was sold for twenty dollars a ton for making 

 asphalt pavement. The bed is about three miles south of the Santa Monica range of mountains, 

 and it appears to lie parallel with them. 



Beds of petroleum shale of tertiary age, having in many places a thickness of about two thou- 

 sand feet, are to be found along the California coast, and at some distance in the interior ; they 

 are said, by Professor Whitney, to extend from Cape Mendocino to Los Angeles, a distance of 

 about four hundred and fifty miles. They are exposed in cliffs on the coast near Santa Barbara 

 and Carpinteria. and other places. This shale, there is good reason to believe, is the deposit from 

 which all the asphaltum of California has been derived. 



Although this shale is not exposed in the vicinity of the Brea Ranch, it is exposed in various 

 localities at but a short distance, and doubtless underlies the asphaltum deposit, for hundreds of 

 "tar-springs" exist in the vicinity, from which the material is still flowing over the surrounding 



s Whitney, J. D., Geol. Surv. Calif., Geology, vol. 1. pp. 174 and 175, 1S65. 

 « Denton, Win., Proc. Boston Soc. Xat. Hist., vol. IS. p. 1S5, 1875. 



