10 FOSSIL FLORA OF THE JOHN DAY BASIN, OKECJON, [i!ri,i,. 201. 



It is in turn overlaid by the beds of tlie second great volcanic outflow. Below 

 the Louj) Fork follows tlie Truckee group, so rich in extinct nuunmalia, and below 

 this a formation of shales. These are composed of fine material, and vary in color 

 from a white to a pale brown and reddish-brown. They contain vegetable remains 

 in excellent preservation, and indeterminable fishes. The Tddodlum nearly resem- 

 bles that from the shales at Osino, Nevada, and on vai'ious grounds I suspect that 

 these beds form a part of the Amyzon group (American Naturalist, June, 1880), with 

 the shales of Osino and of the South Park of Colorado. Below these is a system 

 of fine-grained, sometimes shaly, rocks of delicate gray, buff, and greenish colors 

 containing calamites,« which Professor Condon calls the (Mmnite beds. Their age 

 is undetermined." 



In spite of Cope's assumption that the plant and fish l)earing beds mentioned l)y 

 him were to be correlated with his Amyzon group, ''Lescjuereux'' referred the collec- 

 tions from Van Horn's ranch to the late Miocene. In a later statement regarding 

 the John Day stratigraphy,'^ Cope speaks of the calamite beds as doubtless belonging 

 to to the Triassic or Jurassic. This horizon was determined by Lesquereux as Eocene. 



Following is the geological section of the John Da}^ region as worked 

 out by Dr. Merriam:'' 



Eiver terraces, with undisturbed Quaternary fossils. 



Rattlesnake formation. Gravels, ash, tuff, and rhyolitic lava. 



Mascall formation. Ashes, tuffs, and possibly gravels. 



Columljia [River] lava. Basaltic flows. 



John Day series. Ashes, tuffs, and rhyolitic flows. Sands and gravels near the 



top. Lower, middle, and upper divisions. 

 Olarno formation. Ashes, tuffs, and andesitic and rhyolitic lavas. 

 Chico formation. Sandstones and conglomerates. 

 Knoxville formation. Black shales. 

 Pre-Cretaceous sedimentaries, serpentines. Granitic masses of unknown age. 



PKE-CRETACEOUS ROCKS. 



Although the oldest fossil if erous strata which have thus far been 

 found in the John Day Basin north of the southern portion of the Blue 

 Mountains belong to the Cretaceous, there are formations exposed at a 

 number of points that present the appearance, according to Merriam, 

 of being nuich older. Thus, on the Middle Fork of the John Day, 

 about 5 miles above Ritter, there are certain sedimentary rocks bor- 

 dering an area of quartz-diorite which are much more indurated and 

 deformed than any known Cretaceous within the basin. 



At Spanish Gulch, 12 miles southwest of Dayville, the Chico Cretaceous is seen 

 resting upon serpentine, which has the appearance of being intruded into it. At the 

 head of the gulch the serpentine is sej)arated from what was taken to be the Chico 

 ^ conglomerate by a zone of schist and quartzite. Not far from this locality there is 

 associated with the serpentine a considerable thickness of quartzite with quartz 

 veins, which have produced some gold. Limestones quite different from any seen 

 in the Chico are also exposed here. From the same neighborhood the writer 

 obtained a specimen of a granitic rock, said to form one wall of a tunnel. 



Although no direct proof can be presented, it seems probable that some of the 

 rocks associated with the serpentine at Spanish Gulch are older than the Cretaceous./ 



a This is apparently Equifctiim ungoiicnsc Newberry, q. v. 



^Copo, Am. Nat. 1879, p. 831!, Late Eocene or Early Miocene, Nevada. 



cProc. U. S. Nat. Mus., Vol. XI, 1888, p. 13. 



dMon. U. S. Geol. and Geogr.Surv. Terr., Vol, III, 1884, p. 16. 



e Merriam, op. cit., p. 278 



/Ibid. p. 280. 



