1916] 



Dickerson : Tejon Eocene of California 



403 



member rests directly upon the basement complex. An eighth of a 

 mile west of the county line the middle member rests upon the lower 

 member which consists of rhyolitic tuff. The accompanying sec- 

 tion shows this relation graphically. 



The lower member is characteristically tuffaceous, although dis- 

 tinct beds of gravel occur within it. There are several lithologie 

 facies exhibited in this member, as follows : 



(1) A fine-grained kaolinized ash. 



(2) Red-brown tuff -breccia weathering to a red, which occa- 

 sionally contains partially altered fragments of rhyolite. 



(3) A conglomerate which consists of quartzose pebbles, schist 

 and slate fragments, along with a few rhyolitic pebbles, the whole 

 being in a rhyolitic ash matrix. This member has a low westward 

 dip throughout the field of three to four degrees, and apparently 

 underlies most of the valley border for a distance of six miles from 

 the old Fort Miller Road. This member is exposed in the lower 

 course of Burns Creek. 



DEEP-WATER EQUIVALENT OF THE IONE AT MARYS VILLE BUTTES 



Stratigraphy 



After a study of the lone along the foothills of the Sierra Nevada 

 the writer recently made another brief visit to the Marysville Buttes 

 to study the lone as mapped in the Marysville Folio. 55a 



The occurrence of Eocene strata in the vicinity of the Marys- 

 ville Buttes 50 has been described at length in a previous paper. 



The stratigraphic relations were described as follows (p. 261) : 



In general, the sedimentary beds dip away from the central core. 

 The only Eocene area which is mapped in the Marysville folio is a strip 

 about a mile and a quarter long by a quarter mile wide on the west 

 side of the buttes two miles east of South Butte. The Eocene in this 

 area is overlain by the lone formation which has a dip of 15° W, while 

 the Eocene has in most places a dip of 35° to 10° W, strike N 

 90° W, although the dip is nearly vertical near West Butte Peak. The 

 lone consists of gravels and sands, for the most part unconsolidated. Cross- 

 bedding is very common and intricate. These sediments were probably de- 

 posited on the Eocene as an alluvial fan. The lone in turn is overlain 

 by andesitic mud flows — now firmly cemented — which dip to the west 

 about 4° to 5°. 



An east-west section through West Butte largely adapted from the 

 Marysville Folio shows the following sequence on the west side: 



55a Lindgren, W., and Turner, H. W., Marysville Folio, U. S. Geological 

 Survey, Folio 17, 1895. 



so Dickerson, R. E., Fauna of the Eocene at Marysville Buttes, California, 

 Univ. Calif. Publ. Bull. Dept. Geol., vol. 7, pp. 257-298, 1913. 



