THE DEEP SEA AND ITS CONTENTS. 333 



thus the study of the deposits on the Oceanic sea-bed has fully 

 confirmed the conclusion drawn from the present configuration 

 of the earth's surface, as to the general persistence of those 

 original inequalities which have served as the bases of the exist- 

 ing continents, and the floors of the great ocean basins. 



In the masterly lecture on " Geographical Evolution " recently 

 given by Professor Geikie before the Royal Geographical Society, 

 the importance of these results, as affording the key to the inter- 

 pretation of much of the past history of the earth, is most fully 

 brought out. " For," he unhesitatingly asserts, with all the au- 

 thority of a vast geological experience, "from the earliest geo- 

 " logical times the great area of deposit has been, as it still is, ^/le 

 " marginal belt of sea-floor skirting the land. It is there that nature 

 "has always strewn 'the dust of continents to be.' The decay- of 

 " old rocks has been unceasingly in progress on the land, and the 

 "building up of new rocks has been as unceasingly going on 

 "underneath the adjoining sea. The two phenomena are the 

 " complementary sides of one process, which belongs to the terres- 

 " trial and shalloiv oceanic parts of the earth's surface, and not to the 

 " 7vide and deep ocean basins." " No part of the results obtained 

 " by the Challenger expedition," he goes on to say, " has a pro- 

 " founder interest for geologists and geographers than the proof 

 " they furnish that the floor of the ocean-basins has no real analogy 

 " among the sedimentary formations which form most of the frame- 

 " work of the land." And after dwelling on the chief facts I have 

 already brought together, he thus sums up : — 



" From all this evidence we may legitimately conclude that 

 *' the present land of the globe, though composed in great measure 

 "of marine formations, has never lain under the deep sea, but 

 " that its site must always have been near land. Even its thick 

 " marine limestones are the deposits of comparatively shallow 

 "water. Whether or not any trace of aboriginal land may now 

 " be discoverable, the characters of the most unequivocally marine 

 " formations bear emphatic testimony to the proximity of a terres- 

 " trial surface. The present continental ridges have probably 

 "always existed in some form; and as a corollary we may infer 

 "that the present deep oceati-basins likewise date from the remotest 

 ^'■geological antiquity.^* 



