356 D tiler — Klamath Mountain Section, California. 



period was one of subsidence and the sea gradually transgressed 

 until the Klamath Mountain region was almost if not com- 

 pletely covered by the sea. The remnants of the once exten- 

 sive Cretaceous deposits on the flanks of the Klamath Mountains 

 contain only open sea forms, and all were once continuous. 

 Their present distribution is due to post-Cretaceous folding 

 along axes running approximately northeast and southwest, or 

 nearly perpendicular to the lines of older deformation which 

 determine the distribution of the Paleozoic rocks in the Kla- 

 math Mountains. Anderson in his Physiography of the 

 Klamath Mountains refers to two systems of folds and regards 

 the northwest-southeast folds as the younger. It is possible, 

 however, that a series of movements occurred along both sys- 

 tems at various times throughout their geologic history. 



Eocene. 



Eocene strata of marine origin touch the northern end of 

 the Klamath Mountains on Rogue River at the mouth of the 

 Illinois. They are chiefly sandstones with shales and con- 

 glomerates well characterized by various fossils and locally 

 containing small masses of coal. 



During the Eocene the Klamath Mountain region was a land 

 area and only fresh water deposits could reasonably be expected 

 within its borders and along its eastern base. In the vicinity 

 of Ashland, Ore., sandstones and conglomerates occur contain- 

 ing fossil leaves which were once considered Miocene, but now 

 that the beds of the John Day region have been thoroughly 

 studied, the beds near Ashland are regarded by Mr. Knowlton 

 as Eocene.* Some fossil leaves recently found in the Hay Fork 

 beds according to Professor Knowlton appear to be Eocene. 

 They will be noticed, however, in connection with associated 

 strata of Miocene age. 



Miocene. 



The preliminary general geological map of the Klamath 

 Mountain region f shows five areas of Miocene deposits, the 

 largest of which is about Weaverville upon the southern 

 border of the Klamath Mountains. Some notes were pub- 

 lished concerning these deposits in the Fourteenth Annual, 

 and later in Bulletin 1964 



*U. S. Geol. Survey, Bulletin 204, p. Ill, and letter dated Feb. 17, 1903. 



t Plate xlv, Fourteenth Annual Report, U. S. Geological Survey. 



X These deposits and others closely related have been discussed also by Mr. 

 F. M. Anderson (The Physiographic Features of the Klamath Mountains, 

 Jour. Geo!., x, 144), and by 0. H. Hershey (Neocene Deposits of the Klamath 

 Region, California, Jour. Geol., x, 377). 



