VII. 
DEEP-SEA FORMATIONS. 
Tux study of oceanic deposits has materially modified many 
of our notions regarding the mode of formation of the marine 
deposits of former geological periods. These deposits consti- 
tute a considerable portion of the crust of the earth, and we may 
to-day, as has well been said by Saporta, study their mode of 
formation, like that of the beds of the chalk, of the oólite, of 
the miocene, and of the later tertiaries, as plainly as if we had 
lived and witnessed the phenomena which have left their record 
in the geological time tables.’ 
“Tt is to-day the privilege of the special student to decipher 
the history of the past with a certain boldness, and from the 
careful study of the present to picture to himself the most 
ancient phenomena. Beds composed of globigerine, of ptero- 
pods, of fine sand, or of ooze, have long been known to, the 
geologist; but their interpretation by the knowledge of to-day 
calls up pictures of the past which his predecessors could never 
have imagined.” 
Granting the great age of our oceanic basins, it follows. that 
while there were in earlier geological periods deep-sea deposits 
similar to those laid down to-day on the floors of our oceans, 
yet they constitute but a small part of the beds which go to 
make up the thickness of the earth’s crust. Abyssal deposits 
must always have been formed near the sea-edge of the conti- 
nental nuclei, or in the track of the principal currents of those 
days; while on the continental folds were deposited in succes- 
sion the formations which have built up our continental areas. 
Then, as to-day, the coarser materials were deposited within a 
short distance of the existing shore line, while the coarser sands 
1 Saporta, Gaston de, Revue de Deux Mondes. 
