16 



THE TROPICAL CONDITIONS OP THE MESOZOIC AND PALAEO- 

 ZOIC AGES. 



During the Jurasic ammonites nourished well up to 

 the polar circles, and how much further geological re- 

 search has not yet been able to determine. It would be 

 useless to recite to the youngest students in geology the 

 facts which could be massed to prove the universal dis- 

 tribution of the tropical flora and fauna of the Mesozoic 

 and Palaeozoic Ages.* The manuals and textbooks of 

 geology are overburdened with illustrations. That an 

 age of tropical climates existed prior to the temperate 

 age may be considered a geological fact, as it is univer- 

 sally taught in the textbooks of geology. 



Underneath the strata of these ages lie those of the pre- 

 vious Cambrian and Laurentian Ages, whose structure 

 and fossils likewise mark a widespread torrid climate. 

 Beneath these in turn are the enormously thick rocks of 

 pre-Cambrian and Azoic Ages, beyond which lie the 

 ages preceding those of geology and reaching into the 

 domain of cosmology. We are taught alike in the text- 

 books of the common schoolsf and in the profound 

 treatises of Geologists and PhycistsJ that during these 

 ages the Earth " was a melted fiery ball surrounded by 

 a thick atmosphere of gases and vapors." Of this stage 

 of the Earth's climatic development, Sir A. Geikie says: 

 ''At an early period of the Earth's history, the water 

 now forming the ocean, together with the rivers, lakes 

 and snowfields of the land, existed as vapor, in which 

 were mingled many other gases and vapors, the whole 



*Manual of Geology, Dana, 4th Ed., p. 711 and p. 574. 

 tTextbook of Geology, Sir A. Geikie, London, 1882. 



iWarren's New Physical Geography, p. 11, edited by Dr. Wm. H. Brewer 

 of Yale. See also Essays, p. 40, Prof. S. T. Hunt. 



