THE CRETACEOUS PERIOD 759 



sea and, land, after the deposition of the Lower Cretaceous beds 

 and before the deposition of the Upper. 



General. In general it may be said that there was little marine 

 sedimentation in the Late Cretaceous period north of the parallel 

 60 north, while the Jurassic and Lower Cretaceous systems are 

 there more wide-spread. Between the parallels of 20 and 60, on 

 the other hand, the zone where marine Lower Cretaceous is but 

 slightly developed, the Upper Cretaceous system is wide-spread. 

 Outside of China, the Upper Cretaceous system is wanting over no 

 considerable land-area within these limits. In the equatorial and 

 south temperate zones, the Upper Cretaceous seas were also ex- 

 panded much beyond the limits of the waters of the preceding 



period. 



Climate 



The climate of North America throughout most of the Creta- 

 ceous period seems to have been rather uniform and warm through- 

 out a great range of latitude. In Greenland, Alaska, and Spitz- 

 bergen, the climatic conditions seem to have been similar to those 

 in Virginia. Toward the close of the period the temperature was 

 perhaps lower, for the Laramie flora is a temperate, rather than a 

 tropical one. The fresh-water fossils of central Europe indicate a 

 climate comparable to that of Malaysia. 1 As this seems to have 

 been a period of low land, widely extended epicontinental seas, 

 extensive calcareous deposits, and slow consumption of carbon 

 dioxide in rock solution and carbonation, there was a combination 

 of conditions regarded as favorable for a mild and uniform climate. 



LIFE OF THE (UPPER) CRETACEOUS 



The Land Plants 

 Angiosperms predominated in North America at the beginning 

 of the Cretaceous, and during the period genera now living came 

 to be numerous, giving the flora a modern aspect. Among the 

 living genera of angiosperms (Fig. 513) that made their appearance 

 were those which include the birch, beech, oak, walnut, sycamore, 

 tulip-tree, laurel, cinnamon, maple, holly, sweet-gum, ivy, and 

 1 Neumayr, Erdegeschichte, Bd. II, p. 383. 



