238 SEE— FURTHER RESEARCHES ON [Apr.124, 



or oscillatory movements of the earth's crust. One of Lyell's 

 greatest disciples was Charles Darwin, whose views we shall now 

 very briefly recall. 



§ 39. J'iczvs of Charles Darzi'in. — The views of Darwin are 

 very briefly and lucidly set forth by Professor Suess (" Face of 

 the Earth," Vol. I, p. 104), as follows: 



"The earthquake of February 20, 1835 (at Conception, Chili), gave rise 

 to one of the most important works on the elevation of mountains, indeed I 

 may say to the the only attempt, based on direct observation of nature, to 

 establish more exactly the older theories concerning the force which is sup- 

 posed to have raised up mountain chains. The author of this work is Charles 

 Darwin. Since that time no second attempt, or at least no attempt of equal 

 importance, has been made in this direction. To day, more than half a 

 century later, it is possible to hold other opinions on these questions and yet 

 to recognize the boldness of the generalization which even then revealed 

 the master. 



" Darwin saw the awakening activity of the volcanoes during and after 

 the earthquake; he believed he saw elevation, although not uniform eleva- 

 tion of the solid ground ; in addition he saw the terraces along the coast. 

 But he also knew that similar terraces occur on the east coast of South 

 America, where there are no volcanoes and no earthquakes. The earthquakes 

 must therefore have appeared to his eyes as the local expression of a uni- 

 versal force. The secular contraction of the earth, a theory already eagerly 

 advocated by several investigators, Darwin justly held to be entirely un- 

 suited to explain those intermittent elevations which the terraces betrayed, 

 and thus he reached the conclusion : 



" ' That the form of the fluid surface of the nucleus of the earth is sub- 

 ject to some change, the cause of zvliich is entirely unknown and the effect 

 of which is slon', intermittent but irresistible.'" 



§ 40. J'iezvs of Professor James D. Dana. — The views of this 

 eminent geologist have been carefully discussed in the paper on 

 " The New Theory of Earthquakes and Movmtain Formation as 

 Illustrated by Processes Now at Work in the Depths of the Sea," 

 § 13. The reader is referred to that discussion. Here it must 

 suffice to say that, although Dana recognized that there was a funda- 

 mental relationship between the depth and extent of an ocean and 

 the height of the mountains which surround it, he was unable to 

 define this relationship except in very general terms, and could 

 not assign any definite cause for the law which he pointed out. 

 He considered the oceanic basins as subsiding, while the continents 

 were beiner elevated. 



