THE PHYSICS OF THE EARTH. 



215 



by which these mighty upHfts have been produced. The complex 

 folding of the mountains to the east of Tibet shows that the Pacific 

 aided the Indian Ocean in producing this great uplift, but we cannot 

 yet determine the relative importance of the parts played by the two 

 oceans. 



§ 28. On the Origin of the Alps and on the Extreme Crumpling 

 and Folding zvhich They Exhibit. — The remarkable crumpling and 

 folding noticed in the Alps has long been a matter of surprise and 

 wonder to the naturalist. This phenomenon has always presented 

 great difficulty to those who have attempted to explain the origin 

 of the Alps. In the paper on the " Cause of Earthquakes " (§§ 14, 

 16, 18, 23) we have outlined the theory of how the Alps were 

 formed by the sea, and criticised the old theories as totally inade- 

 quate to account for the observed crumpling. We propose here to 

 develop the new theory a little further, and to show how it accounts 

 for all the facts observed in a range such as the Swiss Alps, which 

 are generally recognized as about the most complex system of moun- 

 tains known upon the globe. If the new theory will explain the 

 Swiss Alps, it will obviously explain any other mountain system in 

 the world. The test of the theory as applied to the Alps may there- 

 fore be regarded as an expcrinientnm criicis. 



Fig. 9. Complex Folding. Section Across the Alps from the Neighborhood 

 of Zurich toward Como ; about no miles. (Heim and Prestwich.) 



Ii inilgtiKe 



rtnsferaar 



Cnmpo-Longo 



Fig. 10. Section through the Alps, Showing the Effects of Complex 

 Folding. (From Fleim's Gebirgsbildung.) The line of the St. Gotthard 

 Tunnel and the plane of equal temperature, AB, beneath it, are compiled 

 from F. Giordano, in Bollctino del R. Comitato Gcologico d'ltalia, Vol. XL, 

 1880, pp. 408-50. 



