214 DISCUSSION OF THE DESICCATION QUESTION. 



Recent hjdrographic investigations carried on so actively by different 

 nations over almost evei-y portion of the globe have furnished information 

 in regard to the nature of the sea bottom which has an important bearing on 

 the question before us, and which, taken in connection with the argument 

 already advanced, justifies us in declaring that the theory of the permanence 

 of the great oceanic areas is one which, if not absolutely proved to be true, 

 is at least very strongly supported by focts. 



Guided by his investigations of the sea bottom along and near the course 

 of the Gulf Stream, Agassiz as early as 1869 was enabled io throw a new 

 light on the subject of the persistence of the continental and oceanic areas. 

 In his report on deep-sea dredging in the Gulf Stream, published in 1869,* 

 he says : " From what I have seen of the sea-bottom, I am already led to 

 infer that among the rocks forming the bulk of the stratified crust of our 

 globe, from the oldest to the 3'oungest formation, there are probably none 

 which have been formed in very deep waters. If this be so, we shall have 

 to admit that the areas now respectively occupied by our continents, as cir- 

 cumscribed by the two hundred fathom curve or thereabout, and the oceans, 

 at greater depth, have from the beginning retained their relative outline and 

 position ; the continents having at all times been areas of gradual upheaval 

 with comparatively slight oscillations of rise and subsidence, and the oceans 

 at all times areas of gradual depression with equally slight oscillations. The 

 fact that upon the American continent, east of the Rocky Mountains, the 

 geological formations crop out, in their regular succession, from the oldest 

 azoic and primordial deposits to the cretaceous formation, without the slight- 

 est indication of a great subsequent subsidence, seems to me the most com- 

 plete and direct demonstration of m}' proposition. Of the western part of 

 the continent I am not prepared to speak with the same confidence. More- 

 over, the position of the cretaceous and tertiary formations, along the low 

 grounds east of the Alleghany range, is another indication of the permanence 

 of the ocean trough, on the margin of which these more recent beds have 

 been formed. I am well aware that in a comparatively recent period portions 

 of Canada and the United States, which now stand six or seven hundred feet 

 above the level of the sea, have been under water ; but this has not changed 

 the configuration of the continent, if we admit that the latter is in reality 

 circumscribed by the two hundred fathom curve of depth." f 



* Bulletin of the Museum of Comparative Zoology. Cambridge, Vol. I. 

 t 1. e., p. 363. 



