496 
Proceedings of the Royal Soeiety 
bottom of the great oceans at points far removed from land, and 
in regions where the erosive and transporting action of water has 
little or no influence. Without denying that the action of the 
tidal waves can, under certain special conditions, exert an erosive 
and transporting power at great depths in the ocean, especially on 
submerged peaks and barriers, it is none the less certain that these are 
exceptional cases, and that the action of waves is almost exclusively 
confined to the coasts of emerged land. There are in the Pacific 
immense stretches of thousands of miles where we do not encounter 
any land, and in the Atlantic we have similar conditions. What 
takes place in these vast regions where the waves exercise no 
mechanic action on any solid object ? We are about to answer this 
question by reference to the facts which an examination of deep- 
sea sediments has furnished. 
A study of the sediments recentl}^ collected in the deep sea 
shows that their nature and mode of formation, as well as their 
geographical and bathymetrical distribution, permit deductions to 
be made which have a great and increasing importance from a 
geological point of view. In making known the composition of 
these deposits and their distribution, the first outlines of a geological 
map of the bottom of the ocean will be sketched. 
This is not the place to give a detailed history of the various 
contributions to our knowledge of the terrigenous deposits in deep 
water near land, or of those true deep-sea deposits far removed from 
land, which may be said to form the special subject of this com- 
munication. From the time of the first expeditions, undertaken 
with a view of ascertaining the depth of the ocean, small quantities 
of mud have been collected by the sounding lead and briefly 
described. We may recall in this connection the experiments of 
Eoss and the observations of Hooker and Maury. These investiga- 
tions, made with more or less imperfect appliances, immediately 
fixed the attention, without, however, giving sufficient information 
on which to establish any general conclusions as to the nature of 
the deposits or their distribution in the depths of the sea. 
When systematic soundings were undertaken with a view of 
establishing telegraphic communication between Europe and America, 
the attention of many distinguished men was directed to the im- 
portance, in a biological and geological sense, of the specimens of 
