merriam.i fohn Day Basin. 285 



with only an occasional harder stratum. The lithological charac- 

 ters of the lower divisions exactly duplicate those of the Knoxvillc 

 as it is usually developed in California and south central Oregon. 

 The shale seems to be capped by gravels and contains in the midst 

 of the section a great mass of an unknown eruptive. 



The total thickness of the two formations could hardly be less 

 than three or four thousand feet, of which the shales appear to 

 make up the larger part. The whole section is finely exposed in 

 the bluffs along Bridge Creek at Mitchell. It dips 20 to 30 to 

 the southeast and probably forms the west side of a syncline of 

 which the Spanish Gulch exposure is the other limb. The whole 

 area between Spanish Gulch and Mitchell is covered by Tertiary. 



At the lower end of the Knoxville section the dip of the shales 

 changes to westerly. Only a small portion of the western limb of 

 this anticline is however exposed, as the Tertiary formations mantle 

 over it. 



EOCENE, CLARNO FORMATION. 



At numerous localities along the western side of the John Day 

 basin, there are exposed, either below the lowest John Day beds or 

 above the Chico Cretaceous, several hundred feet of strata which 

 certainly do not belong to either of these horizons. To these beds 

 the name Clarno formation has been applied by the writer.* 



Typical exposures of the Clarno are to be seen at Clarno's 

 Ferry on the John Day east of Antelope, near the town of Fossil, 

 on Cherry Creek, and near Burnt Ranch. 



The Clarno formation is made up almost entirely of erupted 

 materials. Part of the section consists of rhyolite and andesite 

 flows, but the most characteristic portion comprises sedimentary 

 beds grading from ashy shale to coarse tuff. The ash and tuff 

 beds frequently contain plant remains in abundance and were 

 evidently, at least in part, deposited in water. The strata seem in 

 some places to have accumulated very rapidly. At one locality 

 where large specimens of Equisetum have been found in shaly beds, 

 the stems are standing erect and cutting across the stratification 

 planes. This could occur only where deposition or shifting of the 



z 'Jour. Geology, Jan. -Feb., 1901, Vol. IX, p. 71. 



2 



