SALIENT FEATURES OF THE GEOLOGY OF OREGON 87 



tions have not been differentiated, and in both regions the 

 stratigraphy is apparently hopelessly tangled. 



In eastern Oregon Lindgren' found an argillite series with some 

 limestone, which at Winterville contains crinoid stems, of probable 

 Carboniferous age. Lindgren says of these: 



This argillite series is undoubtedly older than the Trias of the Eagle Creek 

 Mountains, and may without much uncertainty be referred to the Paleozoic, 

 possibly to the Carboniferous, which is so extensively developed in California. 

 The whole argillite series, from Weatherby to the Greenhorn Mountains, is 

 composed of fine-grained sediments, indicating deposition in deep waters. 

 Sandstones, quartzites, and conglomerates are entirely absent, according to 

 present information. 



The structural features, according to Lindgren, verified to a 

 limited extent in the field by the senior author, are quite irregular. 

 They strike in the neighborhood of the Elkhorn Range a little north 

 of west and dip 60 degrees south, but in the vicinity of Burnt River 

 and Huntington they dip to the northward and strike southwesterly. 

 No estimate of thickness of these formations, save that it may be 

 several thousand feet, has been made. 



In western Oregon there are, according to Diller^ and Winchell,^ 

 about 10,000 feet of argillites, tuffs, and sandstones and limestone 

 lenses of marine origin. This is indicated by the presence of silice- 

 ous beds containing Radiolaria. 



As WinchelP has admirably summarized the information regard- 

 ing these formations, we quote: 



The Paleozoic rocks are apparently structurally conformable both with 

 older formations and with more recent beds, but there seems to be a hiatus in 

 deposition both before and after the period. There is no unconformity known 

 between the formations included in the Paleozoic. Like the Jurassic, the 

 Paleozoic beds are nearly on edge, striking northeast and dipping steeply 

 southeast. Elsewhere in this report the writer has suggested that these beds 

 are all overturned, so that the Carboniferous beds are structurally beneath 

 to the northwest, and the Devonian (and Silurian ?) are above to the southeast. 



The classification of these Paleozoic rocks is based on fossils found in the 

 limestone lenses, each of which has a maximum thickness of about 200 feet 

 and a maximum length of about 2,000 feet. They have been assigned to four 

 chief belts. 



' W. Lindgren, op. cit., II, 578. ^ A. N. Winchell, op. cit., p. 35, p. 26. 



^ J. S. Diller, op. cit., p. 15. '' Ibid., p. 26. 



