520 r. H. KXOWLTOX EVOLL'TIOX OF GEOLOGIC CLIMATES 



In 1883 Xeumayr/^ basing his deductions on a prolonged and inten- 

 sive study of the ammonites, announced the conclusion that durin.'i 

 Jurassic and Cretaceous time there were distinct climatic zones not 

 unlike those now obtaining, that is, that there were clearly marked equa- 

 torial, temperate, and cool polar climates. Although this view obtained 

 quite wide acceptance for a time, it is now very generally discredited, 

 and it is held that his supposed temperature belts are only faunal realms. 

 For instance, Dr. T. AY. Stanton permits me to say that in his extensive 

 studies on the distribution of Jurassic faunas from Texas to Alaska 

 he has failed to find any indication of climatic zones, and Burckliardt ^^ 

 has had a similar experience in his studies of the Jurassic faunas of 

 northern South America and Mexico, where he found a striking mixture 

 of types that should appertain to two or more distinct climatic zones 

 as interpreted by !N"eumayr. 



Becently Gothan has described some supposed Jurassic woods from 

 *King Karl's Land (79° X.) which show very distinct growth rings, 

 thus offering support, it is contended, of the existence of climatic zones 

 such as advocated by Xeumayr. It now appears, as pointed out by 

 Burckhardt, that there is much doubt as to these woods having been 

 correctly referred to the Jurassic. From the account of the geology of 

 King KarFs Land as worked out by Xathorst. it is apparently established 

 that the woods come from beds that are certainly younger than Xeoco- 

 mian and may indeed be Tertiary in age. 



In discussing the faunal evidence a^ to Jurassic climate Schnchert '■' 

 still adheres to the contention that there were three '"'clearly marked 

 temperate zones," and then speaks as follows : 



"That the oceanic waters of ^Middle and (somewhat less so) Upper Jurassic 

 times were warm throughout the greater part of the world is seen not only in 

 the very great abundance of marine life — probably not less than 1.5.000 species 

 are known in the Jurassic — but also in the far northern distribution of many 

 ammonites, reef corals, and marine saurians. The Jurassic often abounds in 

 reefs made by sponges, corals, and bryozoans. Jurassic corals occur .3,000 

 miles north of their present habitat. . . . The insects of this tune were 

 again large and abundant, indicating a warm climate — evidence in harmony 

 with the plants.'" 



Cretaceous floras. — Lower Cretaceous. — So far as regards the on- 

 marching procession of plant life it is impossible to draw any very sharp 



" M. Neumayr : Ueber Klmatisclae Zonen wahrend der Jura und Kreidzeil. Denk. 

 math, naturw., Classe d K. K. Akad. Wissensch.. Wien, vol. 47, 1883. 

 '^ Carl Burckhardt : Sur le climat de Tepoque .Turassique. Mexico. 1907. 

 ^3 Charles Schuchert : Smithsonian Inst.. Ann. Kept.. 1914. p. 300. 



