420 Diller — Mesozoic Sediments of Southwestern Oregon. 



While still holding- to the view that much of the chert is 

 earlier than the Knoxville, I see no sufficient reason for con- 

 cluding that it is all older. As pointed out elsewhere, the 

 intimate association of chert with Knoxville strata furnishes 

 strong evidence of its Knoxville age. At this time I shall 

 refer to but one of the cherts in the Dillard area and that is 

 the one at several points associated with the AYhitsett lime- 

 stone. It is distinctly radiolarial and so involved with the 

 limestone that both must belong to the same horizon. 



Nomenclature. — Primarily upon lithological evidence the 

 name " Dillard series '' was proposed for the sediments of 

 the Dillard area under the impression that they were older 

 than the Knoxville. The presence of Knoxville fossils at so 

 many points throughout the area demonstrates conclusively 

 that the great part if not the whole mass of sediments within 

 the Dillard area are really Knoxville and were properly 

 included in the Myrtle formation as originally defined and 

 since unchanged. The Myrtle formation has always been 

 regarded as practically equivalent to the Shasta group of 

 California. 



As stated in this paper, the writer is of the opinion that 

 the equivalent of what is called " Franciscan " in California 

 is most likely in the Doth an and not the prevailing rocks of 

 the Dillard area. The fossils clearly show that the bulk of 

 the rocks in the Dillard area are Knoxville. No definite trace 

 of Dothan fossils or of the plant beds with " Jurassic flora " 

 were found in the Dillard area, as might reasonably be expected 

 if they occur there, for their nearest outcrops a few miles 

 to the southwest have distinctive fossils. 



It is possible that rocks of the Dothan series may yet be 

 identified in the Dillard area, but as it now stands our 

 failure to find within the area any fossils definitely older than 

 the Knoxville leaves a decided objection to adopting Louder- 

 back's term Dillard for the strata here included under the 

 Dothan. If striated Aucellae are yet discovered in the strata 

 at Dillard station proving it a type locality for strata older 

 than the Knoxville, the name Dillard should supplant Dothan 

 as a formation name. 



Mesume. 



The Mesozoic sediments of southwestern Oregon may be, 

 for the present, most conveniently considered under four heads 

 as follows : Galice formation, Dothan formation, Myrtle for- 

 mation, and Chico formation. 



The Galice formation is composed mainly of dark slates 

 and is characterized bv a late Jurassic fauna. 



