METAMORPHIC SERIES OF SHASTA COUNTY. 603 



and one or two other ammonites that could not be determined 

 generically. 



About three and a half miles from the ferry, on the road 

 towards Redding, in calcareous layers in the shales were found : 



Nucitla ? 

 Rhynchonella sp. 

 Trachyceras whitneyi, Gabb. 



About two miles south of the last named locality were found in 

 very metamorphic siliceous shales, near the contact with a 

 porphyritic eruptive rock, Pseudomonotis ? and other indetermin- 

 able fossils. 



On Squaw creek, twelve miles above Copper City, at Terrup- 

 chetta (cottonwood flat), were found in a black metamorphic 

 shale, apparently in the same horizon at the beds at Silverthorn's 

 ferry, Nucula sp., Spiriferina sp., and crinoid stems. This hori- 

 zon is about 1,500 feet below the Upper Triassic limestone, 

 which lies just to the east of Squaw creek. Near Madison's 

 ranch on Squaw creek Mr. H. W. Fairbanks found in the same 

 horizon Myacites conf. humboldtensis Gabb. 



Age of the Triassic slates. The age of these slates is not 

 fully settled by the occurrence of Trachyceras whitneyi, for Dr. E. 

 von Mojsisovics 1 says that this horizon belongs to the Muschel- 

 kalk, an opinion concurred in by Professor Hyatt. 2 But in his 

 later work, "Arktische Triasfaunen," 3 Mojsisovics considers this 

 horizon to belong to the Noric, although in this he has plainly 

 confused the Trias of Taylorville, Plumas county, with that of 

 the Star peak region in Nevada. It seems probable to the 

 writer that both Muschelkalk and Noric strata are found in the 

 Star peak region, for both Trachyceras whitneyi, Gabb, and T. 

 homfrayi, Gabb, are found there, and in the Squaw creek region 

 of Shasta county, California. But in Shasta county Trachyceras 

 homfrayi is found just at the base of the Halobia slates, in rocks 

 of undoubted Upper Triassic age, while Trachyceras whitneyi is 



1 " Cephalopoden der Mediterranen Triasprovinz," p. 141. 



2 Bull. Geol. Soc. Am., Vol. III., p. 400. 



3 Mem. Acad. Imper. Sc. St. Petersburg, VII. Ser., Vol. XXXIII., No. 6, p. 129. 



