REVIEWS 95 



nearly transverse to the axis of the valley. In them are deposits of 

 copper ore, and directly across the valley and having the same trend 

 as the metamorphics are copper-bearing veins in the granitic rocks. 



In several instances the genesis of the deposits has been ascertained. 

 This came out through a study of the -deposits and the country rock. 

 In some places sufficient mining has been done to give helpful expo- 

 sures of the deposits in depth. 



The relation of the country rock, bearing the deposits, to the other 

 rocks of the region was discussed in detail. Structural features, both 

 general and local, were given special attention. It was hoped to cor- 

 relate events with some other well-known part of the Sierras, but this 

 was not entirely possible. No fossils from the limestone were found, 

 nor have any been reported, so far as could be learned. The limestone 

 however, is much plicated and petrographicallv borders closely on to 

 marble. This would seem to suggest a relationship with that of the 

 Sierra Nevada. The Tertiary strata are made up of material of all the 

 rocks above mentioned, except the basalt, and perhaps an andesite, 

 which seems to occur later than the ryolite, and is different from the 

 andesite above mentioned. In the strata were found Pliocene verte- 

 brates and a few triassic shells — presumably from the limestone. 



The Correlation of the John Day and the Mascall. Bv Johx C. 

 Merriam and Wm. J. Sinclair. 



The age of the John Day is commonly given in geological text- 

 books as Middle ^Miocene. A study of the large collection of vertebrate 

 fossils from these beds made by the University of California, leads 

 to a different view of the age of this formation. 



The state of evolution of this fauna is practically identical with 

 that of the Upper White River. Several genera occur in the Middle 

 John Day which are found for the first time in the Protoceras beds. 

 Associated with these are such persistent types as Elotherium and 

 Mesohippiis, which range far back into the Lower White River. But 

 that the Middle John Day is not older than the Oreodon beds is shown 

 by the total absence of Creodonts and Titanotheres, while it differs from 

 the Oreodon beds in containing later introduced types, which are not 

 known to range farther back than the Protoceras beds. 



The Upper John Day contains several genera which have not been 

 found in the Middle John Day {Protomeryx, Protapiriis, Promeryco- 

 £hoerus). These seem to have entered Oregon as migrants from some 



