524 F. H. KXOWLTOX EVOLL'TIOX OF GEOLOGIC CLIMATES 



Upper Cretaceous. — By the beginning of Upper Cretaceous time, as- 

 suming that the Albian is correctly placed in the Lower Cretaceous, 

 though this view is not always accepted, the angiosperms had assumed 

 dominance, and the ferns, cycads, and conifers had fallen to the subor- 

 dinate position they have since held. In the earliest members of the 

 Upper Cretaceous the angiosperms had already been differentiated into 

 the two groups of monocotyledons and dicot\-ledons. These new types 

 spread so rapidly and so widely that it will be impossible fully to consider 

 the great number of plant-bearing beds in the many parts of the world. 



In certain particulars the most important of these Upper Cretaceous 

 floras are those of the Greenland, which occur mainly on the Xugsuak 

 Peninsula from latitude 69" 15' to T2' 15' X. This, it will be noted, is 

 well within the Arctic Circle. The oldest flora — that of the Atare 

 beds — comprises 88 genera and 181 species, TO per cent of which are 

 dicotyledons. Overlying this is a thick series of beds — the Patoot beds — 

 the upper portion of which may show transition into the Tertiary. The 

 Patoot flora includes T2 genera and about 122 species, 80 of which a-'e 

 dicot}dedons. 



Plant-bearing beds, similar if not indeed identical in age with the 

 Atane beds, are found in the Earitan formation, which extends along the 

 Atlantic Coastal Plain from Massachusetts to Maryland. The Earitan 

 flora embraces 102 genera and 220 species, 150 of which are dicot^dedons. 

 Forty-seven of the Earitan species occur in the Atane beds. 



Immediately overMng the Earitan and with much the same areal dis- 

 position is the Magothy formation, with 123 genera and 2 To species, 200 

 of which are dicotsdedons. Of approximately similar age is the Dakota 

 flora, which includes 125 genera and over 500 species. In this con- 

 nection it is of great interest to note that a small but unmistakable 

 Dakota flora has been found by Kurtz in north-central Argentina, show- 

 ing that this flora spread south a distance of 5,000 miles, crossing the 

 Equator and a land bridge that mnst have connected Xorth and Soutli 

 America at this time. 



In the Atlantic Coastal Plain and Gulf regions there are a number 

 of important floras in the approximate position of the Magothy and 

 Dakota floras, altogether aggregating several hundred species, largely 

 dicotyledons. These floras occur in the Black Creek, Eutaw, Tuscaloosa, 

 and TToodbine formations. In the Eock}' Mountain region the Upp'^i* 

 Cretaceous is more or less abundantly plant-bearing, one of the most 

 interesting being that from the Frontier formation (of the Colorado 

 group) of western Wyoming. Although consisting mainly of dicoty- 



