RELATION OF MYRTLE FORMATION AND SHASTA SERIES 395 



the Knoxville where found in contact with the Dothan shows less silicifi- 

 cation. ]\Iuch of the silicification of the Dothan occurred before the 

 deposition of the Knoxville, just as that of the jMariposa in California, 

 but the silicification of the Knoxville of the Dillard area evidently 

 occurred at a later epoch, most likely at the close of the Knoxville, for 

 that M^as a time of deformation in the Dillard region. 



It is interesting to note in this connection that in the Bohemia mining 

 region, which lies in the same axis of deformation, 35 miles northeast of 

 the Dillard area, there are large auriferous quartz veins in the Tertiary 

 lavas of the Cascade range. The quartz veins of the Bohemia region are 

 doubtless later than those of tlie Dillard area and demonstrate decided 

 activit}' along the northeastern extension of this axis in Tertiary times. 

 This fact facilitates the explanation of a considerable degree of silicifica- 

 tion in the Dillard region at the close of the Knoxville. 



Relation of the "^'Myetle Formation" of Oregon to the Shasta 



Series of California 



The areas of the "Myrtle formation" in Oregon are entirely discon- 

 nected from those of the Shasta series in California, so that their relation 

 can not be determined by their contact, but must be inferred from their 

 stratigraphic relation to associated rocks and their fossil contents. 



Beneath the Shasta series, on the western side of the Sacramento val- 

 ley, there is a conspicuous unconformity. The successively newer over- 

 lying beds of that series overlap to the eastward and cover the older highly 

 tilted and somewhat altered pre-Shasta rocks. On the Cold fork of 

 Cottonwood creek (near 7, figure 1) the great unconformity is between 

 tlie Knoxville and the Paleozoic strata, farther northeast the Horsetown, 

 and finally, about the northern end of the Sacramento valley, the Chico 

 rests on the Paleozoic with conspicuoiis discordance. 



The same general relation is shown on the southwest slope of the Kla- 

 math mountains. At Big Bar and Eattlesnake creek, localities 4 and 5, 

 which are approximately on line northAvest of 7, figure 1, there are iso- 

 lated patches of strata which from their faunal relations belong to the 

 Knoxville and rest with marked unconformity upon the Paleozoic rocks 

 of that region. At Eedding creek (6, figure 1), which is east of the line 

 of Knoxville outcrop, the Horsetown beds rest on the Paleozoic strata, 

 just as it does at the village of Horsetown in tlie Sacramento valley. 

 The isolated masses of Shasta 1)eds at 4, 5, and 6, figure 1, were once con- 

 nected not only among themselves, but directly with the large mass of the 

 Shasta strata along the western side of the Sacramento valley, forming a 



