374 



J. S. DILLER THE JURASSIC FLORA OF OREGON 



which Doctor Knowlton identified as Tceniopteris oregonensis ? Font., 

 and remarks : 



"Minute fragments of one species only, which seems to be the species above 

 given. Its age would seem to be the same as the so-called Oregon Jurassic ; at 

 least there are not enough data available to decide otherwise." 



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As this species occurs at several places in the 

 plant beds on Thompson creek and at the Todd 

 locality on the slope of Buck peak, its occur- 

 rence in the Eiddles region in the same bed 

 with Aucella piocM is of much importance as 

 confirming the tendency of the evidence al- 

 ready cited to show that the plant beds belong 

 to the "Myrtle formation." 



RELATION TO THE DOTHAN FORMATION 



The basal conglomerate of the plant beds on 

 Thompson creek and Seven Spring ridge, as 

 shown in figure 3, rests on the greenstone, 

 from which many of its pebbles appear to have 

 been derived.. The conglomerate thins rapidly 

 to the southwest, but continues across the West 

 fork of Doe creek and Buck creek to the point 

 where it disappears beneath the great mass of 

 Eocene. Before disappearing it passes from 

 the greenstone to the Dothan, with which the 

 plant beds are in contrast. The Dothan is 

 much altered and veined with quartz, and its 

 dip is 60 degrees to the southeast. On the 

 other hand, the plant beds show scarcely a 

 trace of silicification, and dip in the opposite 

 direction. The contact was not seen, but the 

 contrast both in character and position of the 

 two sets of strata indicates a decided uncon- 

 formity. 



This view is corroborated by their relation 

 to the adjacent greenstone, which on the one 

 hand intrudes the Dothan and on the other 

 furnished sediment for the plant beds. 



The interval between the two epochs of sedi- 

 mentation, the Dothan and plant beds, was 



