SALIENT FEATURES OF THE GEOLOGY OF OREGON 89 



north slope of the range, and W. D. Smith' notes fossils from near 

 the summit of the range. These faunas are considered by J. P. 

 Smith as representing a portion of the Hosselkus limestone of Karnic 

 and Noric stages of Upper Triassic. 



Jurassic. — This system is well developed in southwestern Oregon 

 and is also known from the Blue Mountains. Recognizable Juras- 

 sic fossils were obtained by Condon- from Beaver Creek, a tributary 

 of Silvies River, and from Red Butte, north of Burns. Nothing has 

 been recorded regarding the extent or geologic relationships of 

 these fossiliferous beds. Hyatt,-' who examined the Condon col- 

 lection, describes the matrix as a red sandstone. An examination 

 of the specimens in the Condon Museum shows a fine-grained cal- 

 careous matrix, which is presumably "an impure limestone. 



The fauna includes Peaten acutiplicatus Meek, and Pholadomya 

 nevadana Gabb as its most representative forms. These place 

 the age of the beds as Lower Jurassic, of the Hargrave stage. 



Diller'' has shown the Jurassic rocks comprise the major portion 

 of Oregon south and west of Rogue River. These rocks consist of 

 sedimentary, metamorphic, and igneous rocks representing a wide 

 range of rock types. The sedimentaries have been designated as 

 the Galice and Dothan formations. Both formations are litho- 

 logically similar, and although now separated by a mass of green- 

 stone and a zone of faulting the justification for separation into two 

 formations has been questioned. ^ 



The Galice formation outcrops as a band several miles in width 

 extending northeasterly from the Oregon-Cahfornia boundary. 

 Northwest and roughly paralleling this is the type section some 

 three miles wide and twenty to twenty-five miles long. The Dothan 

 outcrops in a wide band still farther west and possibly extends 

 northeasterly to the vicinity of Roseburg, Douglas County. 



Both formations are composed of dark shales and slates, sub- 

 ordinate amounts of conglomerate, and lenses of red or gray chert. 

 Both are steeply tilted, dipping generally to the southeast. The 



'Smith, VV. D. Mazama, Series 4, Dec. 1918, p. 238. 



^ C. Washburne, Jour. Geol., IV (1906), 222. 



3 A. Hyatt, Bull. Geol. Soc. Am., V, 401. 



" J. Diller, op. cit., Fig. 2. s Winchell, op. cit., I, No. 5, p. 35. 



