Mkrkiam.] 



/o/ui Day Basin. 



27J 



furnished the materials of a later lacustrine formation, which con- 

 tains many vegetable remains. The material is coarse, and some- 

 times gravelly, and it is found on the Columbia River, and I think 

 also in the interior basin. Professor Condon, in his unpublished 

 notes, calls this the Dalles Group. It is in turn overlaid by the 

 beds of the second great volcanic outflow. Below the Loup Fork 

 follows the Truckee Group, so rich in extinct mammalia, 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 undeterminable fishes. The Taxodium nearly 

 resembles that from the shales at Osino, Nevada, and on various 

 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 Calamite beds. Their age is undetermined." 



In spite of Cope's assumption that the plant and fish-bearing 

 beds mentioned by him were to be correlated with his Amyzon* 

 group, Lesquereau f referred the collections 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 the Triassic or Jurassic. This horizon was deter- 

 mined by Lesquereau as Eocene. 



In a recent bulletin by W. D. Matthew § on a provisional 

 classification of the fresh-water Tertiary of the West, there appears 

 .the statement that the Mascall formation (Cottonwood beds) is 

 separated from the lower beds (John Day) by a basaltic flow. The 

 loose gravels above the Mascall are also separated as a definite 

 horizon. 



In 1898 Wortman proposed the division of the John Day beds 



*E. D. Cope, Am. Nat., 1879, p. 332. Late Eocene or Early Miocene, 

 Nevada. 



tProc. U. S. Nat. Mus., 1888, p. 13. 



% Hayden Surv. Terrs., Vol. 3, p. 16. 



2 Bull. Am. Mus. Nat. Hist., V. 12, p. 19, 1899. 



