172 



University of California Publications. 



[Geology 



the University of California working in the valley of the John 

 Day River during the summers of 1899, 1900, and 1901, and by 

 Messrs. V. C. Osmont and L. S. Davis, who collected along the 

 John Day and in the Crooked River basin in 1900. Particular 

 attention was paid in the field to the study of the vertical range 

 of species, and it is now possible to present some account of the 

 time range of a considerable proportion of the Tertiary fauna 

 of this region, and to offer some suggestions regarding the 

 correlatives of the formations containing mammalian remains. 



The writers desire to express their indebtedness to Mr. J. W. 

 Gidley, who has studied the horse material collected from the 

 Mascall and Rattlesnake beds. The John Day rhinoceroses in 

 the University of California collection have been submitted to 

 Professor H. P. Osborn for determination, but his report has 

 been delayed, pending a further revision of the group, especially 

 of the later Oligocene and Miocene North American forms. 



STRATIGRAPHIC SUCCESSION OF THE CENOZIC FORMATIONS IN THE 

 JOHN DAY BASIN. 



The stratigraphy of the John Day basin has been discussed 

 in a previous paper. 1 The section there described may be 

 expressed in tabular form as shown on the opposite page. 



The oldest formation in the basin affording mammalian 

 remains is the John Day, which overlies the plant -bearing Clarno 

 beds. On stratigraphic and palaeontologic grounds the John 

 Day has been subdivided into three divisions : lower, middle, 

 and upper. 2 



The lower division is composed of red, white, and green 

 tuffaceous shales, which weather down into mud-covered dome- 

 like hills. No unconformity has been observed between this 

 division and the Middle John Day, although it is possible that 

 one exists. The brilliant color of the lower beds, their character- 

 istic lithology, and the almost total absence of fossils separate 

 them sharply from the Middle John Day in which vertebrate 

 remains are abundant. 



- 1 Merriam, J. C. A Contribution to the Geology of the John Day Basin. 

 Bull. Dept. Geol. Univ. Cal., Vol. 2, pp. 269-314. 

 2 Merriam, Ibid. pp. 293-295. 



