840 E. W. BERRY AGE OF THE MORRISON FORMATION 



Professor Marsh's interpretation, to jnstifv his astounding claim tliat the 

 Atlantic Coa.stal Plain Cretaceous, as liigli as beds that I correUite with 

 the Turonian and that AVeller correlated with the Senonian, are of 

 Jurassic age. 



Xine of the Kootenai plants are found in the European Wealden, all 

 l)ut one of these being also common to the Potomac. 



('(iiii|)artMl with floras which, on the basis of their iincileln'ati' faunas, 

 h;i\(' hccii I'd'ciTcd to ihc Ncocomian. we find two of tliese species in the 

 XiMicoiniau of Germany, six in tlie Xeocomian of Portugal, lour in tlie 

 Xeocoiniai) of Japan, two in the Xeocomian of Peru, and one in the 

 Xeocomiaii of Mexico. Compared with floras similarly determined as of 

 Barremian age, it may be noted that two of the Kooteiiai species occur 

 in the Barremian of Austria and fo\ir in the Barremian of Portugal. 

 Two of the species occur in the Aptian uf Portngal. In the European 

 Albian there is a common species in Switzerland and five additional in 

 Portugal. No less than nine of the Kootenai species survive as late as 

 the I'pper Cretaceous of Ja])an, (ireenland. P]urope (four species), and 

 the Atlantic Coastal Plain. They also find a representation in the 

 Ti'inity flora of Texas (two species), in the Fuson (five species) and 

 Lakota (six species) floras of the Black Hills, and in the Shasta (nine 

 species) and Horsetown (one species) beds of the Pacific coast. 



Aside from the Potomac element in the Kootenai flora, the most promi- 

 nent facts bearing on its precise age are furnished by comparisons with 

 the Kome flora of western Greenland. There are 10 species, or 32 per 

 cent, of the Kootenai forms with an outside distribution that are common 

 to Kome. Seven of these, including two of the genera, are not found in 

 the Potomac flora, and seven are likewise confined to the Kome and the 

 Kootenai. In addition to the id-entical forms, there are a lunnber of 

 closely related forms in the two areas, and this Kome fades is so promi- 

 nent in the Kootenai flora that it is emphasized by Dawson, Fontaine, 

 and Ward. The age of the Kome flora is not positively determined as 

 to its upper limits, bnt it is clearly not older than Barremian. which is 

 the age assigned to it by Heer and by the Scandinavian and Danish 

 geologists who have studied its relations, and it may even be of Aptian 

 age. 



The bearing of this conclusion on the age of the Morrison must be 

 obvious. If the Kootenai flora is of Barremian age, then at least a part 

 of the Morrison must be of Xeocomian age, since the Kootenai is either 

 partly the equivalent of the Morrison or, giving the utmost allowance for 

 the contrary opinion, the southern extension of the Kootenai is conform- 



