1917] Nomland: The Etchegoin Pliocene of Middle California 207 



grain and more argillaceous, with a more yellowish color. Above 

 this, or in the lower part of the upper Etchegoin, the blue or bluish- 

 gray so-called "vivianitic" sandstone usually first appears. These 

 beds do not, however, appear in all parts of the district at the same 

 time, but in some areas extend down into the lower Etchegoin. The 

 striking blue color is particularly well shown in the Kettleman Hills. 

 Somewhat higher up and continuing to the top the beds consist more 

 predominantly of clays with interbedded argillaceous sandstone. 



North of Coalinga the beds which have been correlated with the 

 lower Etchegoin in the Jacalitos Hills are apparently at least in part 

 of non-marine origin. The basal beds in this region are composed of 

 red, brown, or gray clays. In the upper part of the lower Etchegoin 

 the beds are more conglomeratic, consisting largely of a coarse gray 

 sandstone with interbedded pebbles. The first invertebrate fossils 

 appear in the lower part of the upper Etchegoin in this region. These 

 beds are composed almost entirely of ' ' vivianitic ' ' sandstone with beds 

 of conglomerate. Near the middle these grade into beds consisting of 

 soft yellowish clays with argillaceous sands which continue to the top. 

 This has been mapped as the San Joaquin Clays by F. M. Anderson. 27 



In Priest Valley the plane of separation of the Etchegoin from 

 the Santa Margarita ( ?) below has not been definitely determined. 

 All the lower part of the formation is nearly devoid of diagnostic 

 fossils. These beds as a whole, up to the middle of the upper Etche- 

 goin, are characterized, however, by a brown sandstone of medium 

 texture with only a small proportion of conglomeratic material. 

 Above this the deposits grade into a predominantly fine-grained shale 

 and clay, with a large amount of interbedded coal and carbonaceous 

 material. From here up to the top of the Etchegoin the yellowish- 

 brown or grayish, rather coarse-grained sandstone is the most evident. 



Fossils indicative of middle Etchegoin have been found on the 

 west side of the Diablo Range near Lonoak, Monterey County, Cali- 

 fornia. These fossils are imbedded in a thick series of beds composed 

 largely of light-colored shale and volcanic ash. The rock is fine- 

 grained, with only a very small proportion of coarse arenaceous 

 material. 



COAL AND CAEBONACEOUS DEPOSITS 



Carbonaceous shale and beds of coal occur at various horizons of 

 the Etchegoin. A seam of coal was found in what apparently are 



27 Anderson, F. M., A stratigraphic study in the Mount Diablo Eange of 

 California, Proc. Calif. Acad. Sci., 3d ser., vol. 2, no. 1, 1905. 



