382 



J. S. DILLER THE JURASSIC FLORA OF OREGON 



of salt and brackish or fresh-water conditions, possiblj' due to shifting 

 sediments, or slight oscillation of the coast. 



RELATION TO ADJACENT ROCKS 



In both the Wilshire and Pattison mine the contact of the plant beds 

 with the underlying Paleozoic rocks is well exposed and their unconform- 

 ity is conspicuous, as may be inferred from the fact that the plant beds 

 in general strike northeast and southwest with gentle dip and rest upon 

 rocks whose strike is approximately at right angles and dip vertical. The 

 basal conglomerate of the plant beds, as already noted, is made up largely 

 of fragments derived from the adjacent somewhat schistose rocks and 

 vein quartz whose alteration and siliciiication antedated the deposition 

 of the plant beds. 



The age of the underlying beds is certainly in part Carboniferous, for 

 the limestone of that region is well characterized by fossils. The uncon- 

 formity at the base of the plant beds represents a long interval, whose 

 records occur in the Galice, Dothan, and perhaps other formations of 

 Oregon. 



Plant Beds of Eattlesnake Ceeek, California 



occurrence 



In Trinity county, California, 25 miles south of Big Bar, there is an- 

 other small area of plant beds. It occurs in the drainage of Rattlesnake 

 creek, 7^2 miles southwest of Peanut, by the trail to the old Scott place, 

 on the South fork of Trinity river. The strata are sandstones, shales, 

 and conglomerates, which strike north 15 degrees east and dip 30 degrees 

 northwest. 



Mr Storrs reports many shells and plants in the same strata, and their 

 association is well illustrated in the specimens collected. 



Doctor Knowlton reports as follows concerning the plants: 



FOSSILS 



"Gyclopitys oregonensls Font. 

 Twniopteris vittata Brongn. 

 Sequoia reicheniachi (Gein.) Heer. 



"The specimen of Gyclopitys mentioned above is a fairly good one and can 

 not possibly be mistaken for anything else ; but the species of Tseniopteris is 

 based on only a small scrap, though it agrees well, so far as can be made out, 

 with the species given. Sequoia reiclienhacM is a species of wide distribution, 

 and consequently of little value in fixing the age. It has not, I believe, before 

 been reported in the Jurassic beds of California and Oregon, but was identified 



