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University of California. 



[Vol. 2. 



to their being softer and having offered less resistance to disturb- 

 ances than the more rigid strata above them. 



The Lower John Day is almost barren of fossil remains at all 

 points where it was visited, and has never, so far as can be dis- 

 covered, furnished many good specimens. Diligent search by the 

 writer at several localities has been rewarded by the discovery of 

 two or three fragments of rhinoceros teeth. An Oreodon skull 

 was found at this horizon, many years ago, by Mr. L. S. Davis, but 

 definite information regarding it is not now obtainable. 



The lower division was estimated to be 250 to 300 feet thick at 

 Clarno's Ferry. Its maximum thickness will probably exceed that 

 limit. It is not impossible that the Lower John Day will sometime 

 be found to be separated by an unconformity from the middle 

 division. Such fossil remains as have so far been found in it indi- 

 cate, however, that it belongs to the John Day series. 



The middle portion of the John Day section at Bridge Creek, 

 Clarno's Ferry, and Turtle Cove, consists of drab to bluish-green 

 beds, sometimes forming rounded hills, but more frequently exposed 

 as steep, pinnacled, and ribbed bluffs. Nodular layers and thick 

 beds with small nodules scattered through them are common in 

 this group, while they are rare, if not entirely absent, in the lower 

 division, and are not common in the uppermost beds. The strata 

 of this group are never so sharply contorted as those of the lower 

 division, though they may stand at a fairly high angle and may 

 show considerable faulting. 



This stage has probably furnished more fossil remains than the 

 upper division, partly because the remains are here frequently 

 found in hard nodules, which have protected the bones and held 

 them together. 



At Bridge Creek a rhyolite flow is interbedded with the lower 

 part of the Middle John Day, or possibly separates it from the 

 lower division. In Turtle Cove a similar flow is found at the top 

 of this division and possibly separates it from the upper group. At 

 many places, particularly in Turtle Cove, hard beds of white to 

 greenish ash and tuff are intercalated between the softer and 

 usually more fossiliferous strata. (See Fig. 2, PI. 7.) 



The middle division is at least 500 feet thick in Turtle Cove, 

 and possibly as much as 800 to 1,000 feet at Bridge Creek. 



