52 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



to the Knoxville shales was carefully examined at many 

 points along the northern slope of the Santa Lucia Moun- 

 tains and a conclusion was reached which is in accord with 

 one already published, namel}^ that the Lower and Upper 

 Cretaceous are, in this region at least, separated by an 

 unconformity. This is shown by a marked discordance in 

 the dip between the two and the extension of the upper 

 across the strike of the lower, etc," The Chico here 

 described is that of the upper horizon as previously shown. 

 And what has been so clearly demonstrated in the region 

 south of the Great Valley is exactly paralleled beyond its 

 boundaries northward in California. 



In a former paragraph mention was made of AuccIIa beds 

 occurring at the base of the Cretaceous section in the Sis- 

 kiyou Mountains, In the collections of the State Mining 

 Bureau in San Francisco is a specimen of calcareous rock 

 about two pounds in weight, consisting of a compacted mass 

 of AiLceUa fiochi shells, and bearing upon its label, " from 

 Siskiyou County, California." Miss M. Hearn of Yreka, 

 from whom this specimen was obtained, states that it came 

 from the south side of the Siskiyou Mountains, and from a 

 locality from which many Chico fossils have often been 

 collected, and one which is included in the preceding lists 

 of Chico fossils from that region. Much of the Cretaceous 

 series along Cottonwood Creek, Siskiyou County, has the 

 appearance of the soft clay shales of the Knoxville beds on 

 Cottonwood Creek, Shasta County; and to one familiar 

 with these shales, and with the unconformity between Chico 

 and Knoxville found far southward, it is not surprising that 

 Aucella beds should be found here also unconformably 

 related to the Chico. How extensive this unconformable 

 relation may be throughout the coast region is not yet 

 known; but from the observations of Dr. J. C. Merriam 

 (1901) in the basin of the John Da}'^ River, it appears to 

 have a wide range in the Oregon Cretaceous basin. He 

 says: " In the valley of Bridge Creek a great thickness of 

 conglomerates, sandstones and shales is exposed at Mitchell, 

 eighteen miles northwest of Spanish Gulch. The upper 



