1917] Nomland: The Etchegoin Pliocene of Middle California 205 



It has been suggested that the Tulare may be at least in part of 

 Pleistocene age. The Etchegoin and the Tulare have been much folded 

 since deposition. At some localities the Tulare dips at angles of 80 

 degrees. This period of folding probably occurred during the time of 

 post-Pliocene diastrophic movements described by Professor A. C. 

 Lawson. 26 Since some or all of the folding took place in the Kettle- 

 man Hills, a region of no great relief, at least 6000 feet of strata 

 have been removed by erosive agencies. In many localities the hills 

 have been reduced to rounded outlines and extensive terrace deposits 

 formed to unknown depth. As the exposures are excellent and show 

 no evidence of faulting, it is improbable that the thickness has been 

 overestimated in the section measured. 



Structure 



The dominant structural feature of the Diablo Range in the lati- 

 tude of Coalinga is a broad fold plunging towards the southeast. 

 Superimposed upon this are numerous small anticlines and synclines 

 and in some limited areas a multitude of faults. The core of the 

 Diablo Range consists essentially of both sedimentary and igneous 

 rocks of the Mesozoic. The igneous rocks consist of granites and of 

 various later basic igneous rocks of the Franciscan and later forma- 

 tions. The sedimentaries comprise the great thickness and variety of 

 clastic deposits which make up the Franciscan, Knoxville, and Chico. 

 The Tertiary rocks are found flanking the main range or as remnants 

 folded or faulted into the older series. 



Along the eastern slope of the Diablo Range are several anticlines 

 branching away as spurs from the main fold. Of these the most 

 important, in the region studied, is the Coalinga Anticline in the 

 vicinity of Oilfields, about six miles north of the town of Coalinga, 

 and its extension in the Kettleman Hills. Along the greater part 

 of this area the Pliocene is well exposed. The structure of the 

 Pliocene beds flanking the main range in the Kreyenhagen Hills 

 and north of the Coalinga is in general the eastern limb of an anti- 

 cline. Extending along the greater part of Jacalitos Creek, the 

 upper part of the Waltham Creek basin, and then onwards through 

 Priest Valley and a part of Lewis Creek is a series of small anticlines 

 and synclines with infolded Etchegoin and Tulare. This region 



20 Lawson, A. C, The post-Pliocene rtiastrophism of the coast of Southern 

 California, Univ. Calif. Publ. Bull. Dept. Geol., vol. 1, 1893; The geoniorphogenv 

 of the coast of Northern California, ibid., vol. 1, no. 8, 1894. 



