Perry.] 138 [February 28, 
Vv. THE HOLOCENE TIMES. 
This name, of course, indicates that all the fossil mollusks (not 
Vertebrata) found in the deposits which were laid down during 
their continuance belong to recent species. As the term Plistocene 
(or Newer Pliocene) has been for the most part restricted to the 
Drift, and the stratified beds of clay and sand which overlie it, (for it 
is so employed by Sir Charles Lyell,) it may be here added that Holo- 
cene as here used answers very nearly to the ‘“ Post-Pliocene” of the 
same author, and thus extends to the beginning of recent times, as 
“ Post-Pliocene” is made to do by its proposer. ‘These times an- 
swering to certain beds of marl and peat, and representing them, 
may be conveniently divided into two parts, and considered in their 
natural order of succession. 
§1. The Marl Period. 
This is equivalent to what might be called the Older Holocene 
times, and is characterized, as its name suggests, by the extensive 
deposits of marl, which were largely made during its continuance. 
While the formation is in marked contrast with both typical and 
modified Drift, the period itself is not sharply separated from the 
preceding, as we should by no means expect it would be. These 
marl beds owe their origin to large accumulations of shells made in 
the fresh-water ponds which abounded during this period. So soon 
and so fast as the land was freed from its ice -covering, such ponds 
almost everywhere came into existence. The disguised’ moraine, 
which had been concealed by the great ice-sheet, being laid bare, a 
very uneven surface must have come into view. This answered to 
the bottom of the glacial mass, which no doubt was very uneven be- 
cause of the rough, hilly nature of the region over which it moved. 
Now this bottom moraine consisting largely of clay, in which peb- 
bles and sand were indiscriminately mingled, was generally well 
suited to retain moisture. Accordingly water would accumulate in 
these depressions (in fact, in ali depressions fitted to hold it, whether 
they were more or less due to the erosion of the underlying rocks) 
from the moisture in the atmosphere and the continued melting of 
ice still lying further to the north. Such basins as were calculated 
to retain the water which flowed into them, might be filled, and 
hence there would be ponds and lakes. These overflowing, and the 
water taking its natural course, outlets must have been formed, and 
channels gradually chosen and worn. These would become the beds 
