12 



U)iivci\sifij of (Jalifornia J^ublicatioxs in Geology l.'^oi.. 12 



Oligocene ( ? ) Series 

 Sespe Formation 

 Considerable variation in thickness of the Sespe in this district is 

 shown from one locality to another. As a whole, it closely corresponds 

 to the Sespe so well developed in Ventura County, and to the Pato 

 red member of the Vaqneros described by English** in the Cuyama 

 Valley district. It rests unconformably upon the Tejon group, but 

 is conformable with the Vaqueros formation of the Monterey group, 

 so it is thought probable that in this region no deformative movements 

 took place between deposition of the Sespe formation and the INIonterey 

 group. 



The Sespe in this district is best represented in the Santa Ynez 

 Mountains, where it occurs in a syncline which extends from the 

 mouth of Paradise Canon to the Painted Cave east of San Marcos 

 Pass. Anotlier area lies just south of the Santa Ynez River near 

 Mateo Canon, and is separated from the Tejon by the Santa Ynez 

 fault. The formation consists of 1700 feet of fanglomerates. cross- 

 bedded sandstones, and minor amounts of shale and limestone. All 

 the coarse material is rather highly colored, being either red, green, 

 or yellow. In more detail the section here has at its base about 

 forty feet of fanglomerate composed of angular fragments derived 

 mainly from the Franciscan rocks. The greater part of the fragments, 

 composed chiefly of the basic igneous rocks, range in size up to four- 

 teen inches in diameter. Radiolarian chert is also a common material 

 and its fragments are more angular than the others, due probably to 

 their greater hardness. The matrix consists of rather coarse unsorted 

 grains of the greenish basic igneous material. Above this fanglom- 

 erate are cross-bedded sandstones interbedded with softer layers. The 

 sandstone is well sorted, clean, and shows well developed cross-bedding. 

 The colors are also highly variegated, being in some instances purple 

 with light yellow bands, or greenish with yellow or red streaks. Above 

 these varicolored sandstones are softer red and green sandstones 

 within which are a few thin layers of a bluish gray impure limestone. 



North of the Santa Ynez River, the Sespe is much thinner, and 



appears to grade into the overlying fossiliferous coarse lower beds 



of the Vaqueros sandstone. It consists of the usual red fanglomerate 



8 English, W. A.. Geology and oil prospects of Cuyama Valley, California, 

 IT. S. Geol. Surv. Bull. 621, pp. 191-215, 1916. 



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