342 DiUer — Klamath Mountain Section, California. 



Art. XXXV. — Klamath Mountain Section, California; by 



J. S. DlLLER. 



Introduction. 



The purpose of this general review of the sedimentary 

 rocks of the Klamath Mountains is to render more definite the 

 geological horizons to which a large portion of them belong, 

 and to give their general distribution and structural relations. 



A preliminary geologic map of the Klamath Mountains was 

 issued by the XL S. Geological Survey* in 1894, upon which 

 all the rocks below the Cretaceous were grouped under one 

 color. Fairbanks, Smith, Anderson and Hershey have since 

 added much to the available knowledge of the region, but 

 excepting part of Shasta County, where fossils are abundant, 

 the geological age of the horizons has not been definitely 

 determined. 



Last summer, accompanied by Dr. T. W. Stanton and James 

 Storrs, the author made a trip across the southern end of the 

 Klamath Mountains to Mad Riverf and supplemented collec- 

 tions made by him in that region at various times during the 

 last decade. 



The formations of the Klamath Mountains for the most part 

 trend northwesterly in approximately parallel belts from the 

 northern end of the Sacramento Valley to the coast between 

 the mouth of Red Wood Creek in California and Rogue River 

 in Oregon. It is evident that the lines of deformation which 

 determined the trend of outcrop follow the same course and 

 are in the main approximately parallel to those of the Sierra 

 Nevada. These belts along the western portion of the Kla- 

 math Mountains are quite regular, but nearer the mountain 

 center they become very irregular owing to the presence of 

 numerous masses of igneous rocks. Most of our attention was 

 given to the sedimentary rocks, more or less fossiliferous, which 

 may be grouped in the following categories : Pre-Devonian, 

 Devonian, Carboniferous, Triassic, Jurassic, Cretaceous, Mio- 

 cene, Pliocene and Pleistocene. 



The pre-Devonian, Devonian and Carboniferous rocks with 

 associated igneous masses form the bulk of the Klamath Moun- 

 tains, and they occur in two belts which may be designated 



* Fourteenth Annual Report, plate xlv. 



fin this work the "Rough Geological Map of Trinity County," dated 

 January 16, 1901, furnished in manuscript by Mr. Hershey, was found very 

 useful. It gives a clear general idea of the areal distribution of important 

 terranes. This map was noticed also in U. S. Geological Survey Bulletin 

 196, page 63. On page 9 of the same bulletin there is an outline map of 

 the Klamath Mountains to which reference may be made for the relative 

 position of localities mentioned in this paper. 



