474 University of California Publications in Geology [Vol. 9 



crest line mountains of 3000 to 5000 feet. These mountains and the 

 numerous moderately wide valleys of short, consequent westward- 

 flowing streams were covered by great forests of subtropical plants in 

 the lowlands and coniferous forests along the crest of the Eocene 

 Sierra Nevada. Remains of these plants have accumulated in sufficient 

 quantity to form a 12-foot seam of lone coal. During this period great 

 rhyolitic ash and mud flows changed the whole appearance of the 

 western Sierra Nevada, filling the valleys to their brims and vastly 

 altering the drainage. 



This great rhyolitic period was interrupted long enough for the 

 development of new drainage systems as represented by the inter- 

 rhyolitic channels and their correlative marine lone sandstones. After 

 this, a period of erosion ensued and then the andesitic tuffs, lavas 

 and mud flows covered all, extending even beyond the border of the 

 eastern edge of the Great Valley as is shown at Lincoln, Sacramento 

 County. Basalt of approximately the same age as the andesite capped 

 the Eocene deposits in places. This great thickness of lavas formed a 

 protective coating and preserved the latest Tejon, the lone, from 

 erosion along the eastern border of the Great Valley. In the Coast 

 Ranges farther to the west, the sediments containing the Siphonalia 

 sutterensis fauna were probably not so thick, for they were laid down 

 in deeper water and in general lacked a protective lava capping. 

 Hence their rapid disappearance over most of this area. 



CORRELATION 

 Historical 



The correlation of the Tejon with the Claiborne Eocene of the 

 Gulf States was suggested by Conrad upon his first examination of 

 the fossiliferous boulder from Canada de las Uvas which was sent by 

 Blake. Ball, Heilprin, Clark, Harris, and Arnold have all made ten- 

 tative correlations. Most of these have been based upon the identity 

 of a few species and the recognition of equivalent faunal development. 



Conrad 87 reported Natica aetites, Natica gibbosa, Venericarclia 

 plankosta, Crassatella alia, of the Claiborne Eocene as being present 

 in the Tejon of the type locality. None of these is strictly identical 

 with the corresponding Tejon form. 



Conrad, T. A., Pacific Railroad Reports, App. to Prelim. Geol. Rept. 

 of W. P. Blake, Palaeontology, pp. 5-20, 1855. 



