1880.] on Land and Sea in relation to Geological Time. 281 



the degradatiou of wliicli tlicy were produced. " From the earliest 

 geological times the great area of (lei)osit has been, as it still is, 

 the marginal belt of sea-floor skirting the land." This double 

 process of degradation of old land, and deposit of materials for the 

 new, "belongs to the terrestrial and shallow oceanic parts of the 

 earth's surface, and not to the deep and wide oceanic basins." The 

 ' Challenger ' explorations have now furnished absolute proof, that 

 the deposits now in progress on the floors of the ocean-basins have no 

 real analogy among the past sedimentary formations which geological 

 inquiry brings into view. " We now know by actual inspection, 

 that the ordinary sediment washed off the land sinks to the sea-bottom 

 before it reaches the deeper abysses ; and that, as a rule, only the 

 finer jiarticles are carried more than a few score of miles from the 

 shore." On the abyssal depths the sedimentary deposit gathers 

 so slowly, that the particles of meteoric iron — the star-dust which falls 

 from outer sj^ace — form an appreciable part of it. 



" From all this evidence," continues Professor Geikie, " we may 

 legitimately conclude that the present land of the globe, though con- 

 sisting in great measure of marine formations, has never lain under 

 the deep sea ; but that its site must always have heen near land.'' " The 

 present Continental ridges have probably always existed in some form ; 

 and as a corollary we may infer that the present deep Ocean-basins 

 likewise date from the remotest geological antiquity." * 



It is now nearly eleven years ago, that I first ventured in this 

 place to break ground in regard to a subject, for the discussion of 

 which my previous pursuits might have been thought to give me no 

 special qualification. I then made known the conclusion which had 

 been arrived at by my colleague Professor Wyville Thomson and 

 myself, that no essential change had taken place in the great basin 

 of the North Atlantic since the elevation of the Chalk of Europe and 

 America into dry land ; and that the globigerina-ooze now accumu- 

 lating on its bottom is not a new chalk-formation, but a continuation 

 of the old, which has there gone on uninterruptedly through the 

 whole of that Tertiary period, during which a long succession of 

 varied formations has been in progress of deposit round the margins 

 of the continental lands. But I somewhat incautiously adopted the 

 expression of my friend, " that we might be said to be still living in 

 the Cretaceous epoch." This brought down a storm of geological 

 indignation on our heads. We were accused by one of our very 

 highest authorities, of attempting to disturb the well-established 

 doctrines of geological succession ; and were represented by another 

 as showing a complete ignorance of what a geological " epoch " really 

 meant. When, however, we explained that all we contended for was 

 the persistence of a deep Ocean-basin in the Atlantic area, and the 



* Lecture on ' Gcoj^raphical Evolution,' delivered before the Royal Geogra- 

 phical Society, March 24, 1879. 



