6l2 THE JOURNAL OF GEOLOGY. 



of unmistakable Jurassic habitus, and Pentacrinus, which was 

 quite common. 



These beds lie at no great distance above the Triassic lime 

 stone of Squaw creek, and thus belong to the Jura, and probably 

 the Lias. 



THE JURA-CRETACEOUS UNCONFORMITY. 



As has been shown by J. S. Diller in his various publications 

 on northern California, the Cretaceous lies always unconformably 

 upon the eroded edges of the metamorphic rocks of the Klamath 

 mountains, sometimes upon older and sometimes upon younger 

 strata, but always with a sharp line of erosion between the two 

 series. The metamorphism of the older rocks took place in late 

 Jurassic time and has not affected the Cretaceous. 



It therefore becomes probable that the Klamath mountains, 

 the Coast Range, and the Sierra Nevada are in reality parts of one 

 great mountain system in which the main uplift and metamorph- 

 ism of the strata took place before Cretaceous time. The Klam- 

 ath mountains have been partly submerged during the Cretaceous 

 and Eocene the Coast Range partly submerged during both 

 Cretaceous and entire Tertiary times, while the Sierra Nevada has 

 kept above the sea ever since its original uplift, and has only on 

 its western flank slightly tilted deposits of Cretaceous and Eocene 

 age. James Perrin Smith. 



