F. H. Knowlton — Jurassic Flora of Oregon. 35 



in Douglas County ; (3) along the forks of Elk River in Curry 

 Connty. In California there are also three areas : (1) Big Bar 

 and (2) Rattlesnake Creek in the Klamath Mountains, Trinity 

 County, and (3) near Oroville, Butte County, tlie latter at the 

 western hase of the Sierra Nevada. 



The Lower Cretaceous floraf is found along Iron Mountain 

 Creek in the vicinity of Riddles, Douglas Connty, Oregon ; at 

 Redding Creek, Tehama Connty, California, and very exten- 

 sively along the western side of the Sacramento Valley in 

 Shasta and Tehama counties, California. The Jurassic and 

 Lower Cretaceous floras, although occurring in the same 

 areas, are perfectly distinct and have never been found com- 

 mingled. 



Steatigraphic Relations of the Beds Containing the 

 " Jurassic Floba op Oregon." 



1. Thompson Greek, Douglas County, Oregon. 



The beds exposed along Thompson Creek are 1000 feet or 

 more in thickness and dip westward at an angle of about 38°. 

 The lower three-fourths of the section is composed of con- 

 glomerates, with small local beds of sandstones and shale, 

 while the upper third is made up of sandstone and shale. 

 Although plant fragments are found at various points in the con- 

 glomeratic portion, the principal plant beds are in shaly sand- 

 stone about 180 feet below the top of the exposed Mesozoic 

 section. This is one of the richest of the Jurassic plant local- 

 ities, having furnished 66 species (see pp. 43-45). 



As regards the invertebrates found at this locality Mr. 

 Diller says :* "Shells are of exceptional occurrence in the leaf 

 beds. Though carefully sought for, they have rarely been 

 found. A doubtful fragment found with the plant fossils in 

 Thompson Creek was referred to Doctor Stanton, who reported 

 that "the fragment seems to be part of a shell and is probably 

 an Aucella, although there is not enough of it for positive 

 identification." 



2. Bucli Peak, Douglas County, Oregon. 



On the northeastern side of Buck Peak, 1,200 feet below 

 the summit, there is an important plant locality which is really 

 embraced in the Thompson Creek area already considered. 



*The flora, called in this paper the "Lower Cretaceous Flora," has here- 

 tofore been called the "Shasta flora," but since it does not occur throughout 

 the whole of the Shasta series it has seemed best to abandon its use. It may 

 be desirable at some time in the future to give separate names to the portions 

 of the Shasta series containing the Cretaceoiis and Jurassic floras respec- 

 tively. 



fGeol. Soc. Am., Bull., vol. xix, p. 373, 1908. 



