132 GEOLOGY. 



evidence is less strong on this point. The new flora is best represented 

 in the Potomac formation of the Atlantic coast, notably in Virginia 

 and Maryland, where it has been carefully studied by Ward and Fon- 

 taine. 1 It is represented in the Tuscaloosa formations of Alabama 7 

 at a somewhat later stage (Upper Potomac), in Kansas in a highei 

 (Washita) horizon, 3 and in the Black Hills. 4 The angiosperms do not 

 occur in the lowest plant-bearing horizon of Texas, the Trinity, nor 

 in the lowermost horizons in Kansas. The exact horizon of the angio- 

 sperms of the Black Hills, relative to that of the earliest angiosperms 

 of the Atlantic coast, is not determined, but the angiosperms form a 

 much smaller part of the flora, and its general aspect is less advanced. 

 In west Greenland, about Lat. 70° N., the Kome series contains a few 

 angiosperms, while in the next higher series, the Atane, probably 

 Upper Cretaceous, the angiosperms outnumber the lower forms. 5 While 

 exact correlation is impossible, it seems probable that the angiosperm- 

 ous evolution was there somewhat more tardy than on the Atlantic 

 coast of the United States. In Portugal, primitive types of angio- 

 sperms appear in the Aptian stage (p. 109), but not among the 88 species 

 of the Neocomian stage. At the top of the Lower Cretaceous, or base 

 of the Upper (Albian stage), angiosperms are much more abundant, 

 and belong to familiar genera (Sassafras, Laurus, Eucalyptus, Myrica). 

 Interstratified with the several plant beds are f ossiliferous marine beds 

 which resemble those of the Comanchean series, but they do not afford 

 the means of exact correlation, though they indicate that the Fredericks- 

 burg series approximately corresponds to the middle or upper por- 

 tion of the Lower Cretaceous of Portugal, and favor the view that 

 the Atlantic coast took precedence, both in time and numbers, in the 

 evolution of the angiosperms. The limitation of the angiosperms 

 to the mere border of the eastern continent is also more consistent 



1 Ward, Am. Jour. Sci., Vol. XXXVI, 1888, pp. 119-131; 15th Ann. Rept. U. S. 

 Geol. Surv., 1896, Pt. I, pp. 463-542; Science, Vol. V, 1897, pp. 411-419. 



Fontaine, Am. Jour. Sci., Vol. XVII, 1879, pp. 151-157, 229-239; Mon. XV, 

 U. S. Geol. Surv., 1889 ; Proc. U. S. Nat. Mus., Vol. XV, 1892, pp. 487-495; Bull 

 145, U. S. Geol. Surv., 1896. 



2 Smith, Rept. Geol., Coastal Plain, Ala., 1894, pp. 307-308. 

 3 Knowlton, Am. Jour. Sci., Vol. L, 1895, pp. 212-214. 



4 Ward, Jour. Geol., Vol. II, 1894, pp. 250-266; 19th Ann. Rept. U. S. Geol. Surv., 

 1897-98, pp. 521-712. 



5 Heer, Flora Fossilis Arctica. White and Schuchert, Bull. Geol. Soc. Am., Vol 

 IX, 1898. 



