354 Diller — Klamath Mountain Section, California. 



strongly support either view. The characteristic fossils com- 

 mon in the Pit formation (Triassic) of the same region, as well 

 as the plant remains so well known in the Jurassic of Mariposa, 

 California, and several localities in Oregon, were carefully 

 sought for but not found in the Bragdon formation. 



Triassic. 

 The part played by Triassic sediments in the structure of 

 the Klamath Mountains is small, for they are known to occur 

 with certainty only in Shasta County along Squaw Creek, 

 between the McCloud River and the Great Bend of Pit River. 

 The rocks of this age embrace the Pit formation, composed 

 largely of shales associated with a smaller proportion of tuffs 

 and conglomerates, and the Hosselkuss limestone 200 feet in 

 thickness overlain by shales locally rich in Monotis suocir- 

 cularis. The Triassic formations appear on Cedar Creek. Com- 

 ing out from under the later lavas of the Lassen Peak region, they 

 strike nearly southwest to the vicinity of Furnaceville, where 

 they turn northerly, crossing Pit River, and then northeasterly 

 about the head of Squaw Creek, where they are limited by 

 the Carboniferous of Grizzly Peak, and disappear under the 

 great lava field of northeastern California. Undoubtedly the 

 Triassic formations once extended much further westward into 

 the Klamath Mountains than now and have been removed by 

 the great erosion of the Cretaceous and Tertiary periods. 



Jurassic. 

 Jurassic strata like those of the Trias enter into, the Klamath 

 Mountains to a small extent only, and occur along the western 

 arm of the Great Bend of Pit River, rich in fossils like those 

 of the Taylorville region.* Shales and sandstones are com- 

 mon and occasional lenses of fossiliferous limestone occur in 

 them. Conglomerates are not rare and usually contain much 

 igneous material. Near the base they include interesting 

 limestone fragments and nodules which are fossiliferous. 



Cretaceous. 

 Cretaceous strata almost encircle the Klamath Mountains 

 and a few isolated patches cling to their flanks, especially 

 about the northern and southern ends, throwing an important 

 light upon their history. Some of the outliers were noted in 

 the preliminary mapf and others have been discovered and 

 published since.J 



*Geol. Soc. of Am., iii, pp. 369-412. 



f U. S. Geol. Survey, Fourteenth Annual Eeport, pi. xlv. 



% F. M. Anderson in the Jour, of Geol., x, pp. 144-159 ; also Proceedings 

 of the California Academy of Sciences, Third Series, Geology, vol. ii, No. 

 1, 1902, and O. H. Hershey, this Journal, xlv, pp. 33-37. 



