1872.] : ‘141 [Perry. 
consequently, being the predominant deposit made in New England 
during this portion of the Post-Tertiary era, the time may be con- 
veniently and with fitness designated as the Peat period. 
Ordinarily overlying portions of these vegetable beds, and in most 
instances overlaid by the superior layers of the same series, there is 
another deposit which is met with in given localities. It occurs ex- 
tensively in New England, especially in some parts of Eastern Ver- 
mont, and particularly in Peacham. Although this deposit is usu- 
ally spoken of in connection with the marl-beds, and while I am not 
aware that it has been referred to an exact horizon, I am disposed, 
in view of its apparent position, to regard it as belonging to the 
period now under consideration. The beds are largely composed of 
silex in minute particles, and are from one or two to five or six feet 
in thickness. For thesmost part, the material was derived from the 
silicious shields of certain microscopic animals known as infusoria. 
This deposit being formed gradually, and almost entirely of the 
flinty bucklers of these animalcule ; as they from generation to gen- 
eration passed off the stage of existence, and a single cubic inch, 
according to Professor Bailey, containing the remains of some 15,- 
000,000,000 individuals, we see that this kind of life was necessa- 
rily very active during the period of its continuance, and that it must 
have lasted for a considerable length of time, in order to the deposi- 
tion of such masses of silicious earth. 
It is usually in the peat-beds, and often at the bottom of them, 
that the remains of the mammoth or fossil elephant have been met 
with in different parts of the country. They have been found so far 
north as Vermont, and even in several portions of Canada. On this 
account, the time might be properly designated as the mammoth 
period, several species having been peculiarly abundant during its 
continuance, if one may judge from the fossil remains that have come 
to light. 
A few words must suffice as to the duration of the Holocene times. 
The length of the marl period, or of the Older Holocene, must have 
been considerable, if merely the marl deposits be taken as the basis 
of computation. Prof. C. B. Adams, referring to the time probably 
occupied in the formation of a marl bed in Monkton, Vt., which is 
- about ten feet in depth, and saying, “a long series of years is required 
to furnish shells sufficient for a single layer,” adds: “ twenty thou- 
sand years is a very moderate estimate,” and the time “is more likely 
