KNowLTON.] GEOLOGICAL FEATUKES. 17 



At a point 6 miles south of Clarnos Ferry, near the junction of 

 Mudd}' and Currant creeks, there are several hundred feet of black 

 slates. Ko fossils have been found in these slates, which seem older 

 than the Knoxville shales. 



KNOXVILLE AND CIIICO BEDS. 



No fossiliferous Knoxville ])eds have ])een found within the basin, 

 and the presence of this formation is based on pureh^ lithological 

 grounds. At Mitchell there is exposed a section, thought ])v Merriam 

 to ])e hardly less than 3,000 or 4,000 feet in thickness, which is made up 

 of sandstone, conglomerate, and shale. The lower portion of this sec- 

 tion is composed mainly of shale which, from its resemblance to the 

 Knoxville so usually developed in (California and south-central Oregon, 

 is assumed to l)e of this age. 



The Chico is exposed at Mitchell and Spanish Gulch. Oidy a single 

 fossil has thus far been afforded by the Mitchell locality. Fossil 

 invertebrates have, however, l)een obtained at two localities near 

 Spanish Gulch. These were submitted to Dr. T, W, Stanton, who 

 reports that they indicate a '■'" horizon at or very near the base of the 

 Chico formation."' 



CLARNO FORMATION. 



The name Clarno formation has Ijeen given by Merriam to a series 

 of beds some 400 feet in thickness which rests on the Chico or Knox- 

 ville, and which consists almost entirely of eruptive materials in the 

 form of rh3'olite and andesitc flows and ash and tuff beds. It is found 

 in t3'pical exposures at Clarnos Ferry, near the town of Fossil, on 

 Cherry Creek, and near Burnt ranch. 



Where the Clarno has been found in contact with tlie John Day there is no appar- 

 ent angular unconformity of the strata. The difference in induration and weath- 

 ering is, however, very noticeable. The sedimentary parts of the Clarno show a 

 much greater degree of induration than the John Day beds inmiediately above, and 

 tend at all localities to form steep bluffs, ornamented frequently with balanced rocks 

 or grotesque figures." 



Thus far neither vertebrate nor inverteljrate remains have been 

 found in the Clarno, but at most of the localities where carefully 

 exploited fossil plants have been found, often in abundance. The 

 celebrated Bridge Creek locality falls within this formation, occurring 

 at the base of the superimposed John Day beds. I visited this 

 locality in 1901 and obtained a small collection. The plants occur 

 abundantly in a reddish shale, which weathers whitish. The other 

 plant localities in the Clarno will be listed later. 



n Merriam, op. cit., p. 286. 



Bull. 204—02 2 



