548 GEORGE DAVIS LOUDERBACK 



correlation of the Dillard with the Franciscan series. The Franciscan 

 is a thick series of rock formations which is widely scattered over the 

 coastal portion of California and which bears the record of an impor 1 

 tant part of Californian geological history. Its stratigraphic bound- 

 aries so far known are the marked unconformity at its summit, sepa- 

 rating it from the base of the Knoxville (zone of the Aucella piochi), 

 and the striking unconformity at its base separating it from the older 

 holocrystalline terranes (crystalline limestones, schists, and Coast 

 Range granites, etc.). Lithologically it is characterized by its mas- 

 sive, arkose sandstones and radiolarian cherts — besides which shales, 

 conglomerates, and foraminiferal limestones occur— and by its degree 

 of lithification, which is, as far as known, unique in the coast region. 

 This latter alone separates it from all later and earlier formations 

 with which it has yet been found associated. It is also characterized 

 by being intersected by an abundance of igneous rocks — greenstones, 

 diabases, etc.: serpentines and gabbros; and more acid porphyritic 

 types — and by the presence of glaucophane and related schists. 

 Paleontologically it is characterized by a general absence of fossils, 

 those which have been found leaving the age indefinitely determined, 

 but indicating, in a general way, that they may belong anywhere 

 from the Lower Cretaceous to the Jurassic, inclusive. 



Identity with the Franciscan. — In all of its characteristics and 

 peculiarities the Dillard series is practically identical with the Fran- 

 ciscan, 1 and it fits into the same stratigraphic position, and it may be 

 concisely defined by the brief description of the preceding paragraph. 

 It was evidently formed under the same peculiar series of physical 

 conditions, has been subjected to very similar series of igneous erup- 

 tions, to practically the same degree of lithification, and to about the 

 same amount and character of disturbance and erosion. 



The Whitsett limestone fossils. — The two fossils reported by 

 Stanton as occurring in the limestone of the Roseburg quadrangle 



1 For further comparison of the characteristics and peculiarities of the Dillard 

 with those of the Franciscan, reference may be made to the description of the Francis- 

 can type locality by Professor A. C. Lawson, U. S. Geological Survey, Fifteenth Annual 

 Report (1895), pp. 415-35; and to the description of the San Luis quadrangle by Dr. 

 H. W. Fairbanks (U. S. Geological Survey, Geologic Atlas of the United States, Folio 

 No. 1 01), who has mapped a considerable area of Franciscan in the southern Coast 

 Ranges of California, about 8° of latitude south of the Dillard area, but in which the 

 peculiarities are closely the same throughout. 



