PLANT BEDS OF BIG BAR, CALIFORNIA 379 



of Aucella in the basal conglomerate under the plant beds on Elk river 

 suggests that such fossils may yet be found in the corresponding con- 

 glomerate on Thompson creek in Douglas county. 



RELATION TO THE DOTEAN FORMATION 



Dothan fossils {Aucella erringtoni) have been found in loose pieces 6 

 miles northeast of the Forks of Elk river, on Johnson creek near the 

 mouth of Sucker creek. The black slates at the mouth of Sucker creek 

 are like the fragments containing Aucella erringtoni and are believed to 

 belong to the Dothan formation. Similar black slates, with associated 

 sandstones and calcareous nodules, occur on the South fork of Elk river 

 about 2 miles above the forks, but only indefinite shell fossils' have been 

 found in them. These strata are separated from the basal conglomerate 

 of the "]\ryrtle" by a mass of greenstone which appears to cut the slates 

 on the one hand and furnish sediments for the conglomerate on the other. 

 The relation therefore appears to be at this point essentially as on Thomp- 

 son creek — the basal portion of the "Myrtle" including the plant beds is 

 unconformable to the Dothan and separated from it by a belt of green- 

 stones intermediate in age. 



Plant Beds op Big Bar, California 



occurrence 



On Trinity river, California, about 20 miles west of Weaverville, in the 

 vicinity of Big Bar, sometimes referred to as Coxes Bar, occurs one of the 

 most important outcrops of Jurassic flora-bearing strata yet discovered in 

 the Klamath mountains. The area is a small one, scarcely 2 miles in 

 length northeast and soiithwest and three-fourths of a mile in vtddth. It 

 is dissected by several small tributaries of Trinity river into two distinct 

 masses, which afford excellent exposures in the terraces where the gravel 

 has been removed by the hydraulic process in the Pattison and Wilshire 

 mines. The whole succession of strata in this area is scarcely 200 feet in 

 thickness and composed chiefly of gray shales and sandstones, with a 

 small proportion of fine conglomerate. These rocks are generally so soft 



' Only a trace of plant fossils has yet been found In the Dothan, the trace being a 

 small plant fragment found on Catching creek about 6 miles southwest of Riddle, In 

 dark gray slates of the Dothan formation. Doctor Knowlton says of It : "This Is prob- 

 ably the upper part of a leaf of Pterophyllum, such, for example, as P. wquale, a^ fig>- 

 ured in Ward's Jurassic flora of Oregon. The tips of the leaflets and the nervation are 

 not preserved, and this determination is very much in doubt." The locality was care- 

 fully examined again without finding any fossils. 



