of Ediiiburgh, Session 1883-84. 525 
Wo have said that the d4bris carried away from the land 
accumulates at the bottom of the sea before reaching the abysmal 
regions of the ocean. It is only in exceptional cases that the 
finest terrigenous materials are transported several hundred miles 
from the shores. In place of layers formed of pebbles and clastic ele- 
ments with grains of considerable dimensions, which play so large a 
part in the composition of emerged lands, the great areas of the ocean 
basins are covered by the microscopic remains of pelagic organisms, 
or by the deposits coming from the alteration of volcanic products. 
The distinctive elements that appear in the river and coast sedi- 
ments are, properly speaking, wanting in the great depths far 
distant from the coasts. To such a degree is this the case that in 
a great number of soundings, from the centre of the Pacific for 
example, we have not been able to distinguish mineral particles on 
which the mechanical action of water had left its imprint, and 
quartz is so rare that it may be said to be absent. It is sufficient 
to indicate these facts in order to make apparent the profound 
differences which separate the deposits of the abysmal areas of the 
ocean basins from the series of rocks in the geological formations. 
As regards the vast deposits of red clay, with its manganese con- 
cretions, its zeolites, cosmic dust, and remains of vertebrates, and 
the organic oozes which are spread out over the bed of the central 
Pacific, Atlantic, and Indian oceans, have they their analogues in 
the geological series of rocks If it be proved that in the sedi- 
mentary strata the pelagic sediments are not represented, it follows 
that deep and extended oceans like those of the present day 
cannot formerly have occupied the areas of the present continents, 
and as a corollary the great lines of the ocean basins and con- 
tinents must have been marked out from the earliest geological 
ages. We thus get a new confirmation of the opinion of the per- 
manence of the continental areas. 
But without asserting in a positive manner that the terrestrial 
areas and the areas covered by the waters of the great ocean basins 
have had their main lines marked out since the commencement of 
geological history, it is, nevertheless, a fact, proved by the evi- 
dence derived from a study of the pelagic sediments, that these 
areas have a great antiquity. The accumulation of sharks’ teeth, of 
the ear-bones of cetaceans, of manganese concretions, of zeolites, 
