6 



University of Calif onvia Publications in Geology [ VoL 11 



Associated with these sediments, are the usual peculiar types of 

 igneous rocks, including greenstones, gabbros, and serpentine, with 

 some diabase and quartz diorite, together with areas of dacite- 

 andesite. Glaucophane schists, glaucophane-garnet schists, actinolite 

 schists, and many other types consisting of varying proportions of 

 quartz, garnet, epidote, actinolite, chlorite, mica, and glaucophane are 

 found in small sporadic bodies. They occur in such a way as to indi- 

 cate that they were produced by contact metamorphic action of the 

 basic intrusive rocks. 



The extent of the belt of Franciscan areas running from southern 

 Oregon to southern California is nearly 750 miles. 



THE FRANCISCAN GROUP IN WASHINGTON 



Between southern Oregon and the Olympic Mountains, no Fran- 

 ciscan has been reported, but Franciscan rocks make up a large part 

 of the Olympic Mountains. 12 Mount Olympus consists of a complex 

 mass of metamorphic sandstone, shale, radiolarian chert, glaucophane 

 schist, and greenstone, cut by serpentine. 13 All the rocks closely 

 resemble the Franciscan in the California Coast Ranges. 



The total extent of the Franciscan, so far as it is now known, is 

 from the Olympic Mountains to southern California, a distance of a 

 little over 1000 miles. 



THE AGE OF THE FRANCISCAN GROUP 

 Difficulties Encountered 



As will appear later, it would be very helpful in discussing the 

 origin of the Franciscan sandstone, if some definite statement could 

 be made as to its age. It would then be possible to fix in a general 

 way, some of the conditions which obtained at the time of deposition 

 of the sandstone. 



The Franciscan is sometimes referred to the Jurassic, but its age 

 has never been determined with certainty, since various ways of 

 approaching the problem give contradictory" results. The radiolaria 

 in the cherts are not distinctive enough to permit a determination of 

 the age of the formation. The limestones have yielded no fossils 

 other than the foraminifera, and these are of no value for age deter- 



isDiller, J. S., Science, vol. 41, p. 55, 1915. 



is Ibid., Guide Book to Western United States, U. S. Geol. Surv., Bull. 614, 

 p. 13, 1915. 



