Perry.] 142 _ [February 28, 
to have exceeded this many fold”! So the Peat period, which 
brings into view the sphagnous moss deposits, as well as those of 
infusorial silica, could not have been of short duration. Taking not the 
thickest beds as the standard, but one of twelve and one half feet, and 
allowing that there was each century an average deposition of half an 
inch of compacted matter, we have thirty thousand years as the dura- 
tion of the time. Accordingly, if we remember that marl of the Older 
Holocene period is found some eighteen feet thick, and that there are 
Newer Holocene beds of peat from twenty-five or thirty to fifty and 
sixty feet in thickness, exclusive of the infusorial deposits, we see, 
after makine all necessary deductions, that the Holocene times, in- 
stead of being a mere cipher, represent a work, or rather a series of 
works, which could have been accomplished only by processes not a 
little protracted. As a moderate estimate, therefore, the two periods 
may be regarded as fifty thousand years in length. 
VI. THE RECENT TIMES. 
The growth of swamp-mosses so characteristic of the Newer Holo- 
cene period in New England, did not entirely cease with its close. 
Both this and the deposition of marl have been continued to the 
present, only on a far more limited scale. Species of sphagnum and 
of affiliated plants had flourished and taken their places as deposits, 
to such an extent that the majority of the marshes, bogs and swamps 
were in a large measure filled with their remains. Thus these 
growths and their consequent deposition no longer played so impor- 
tant a part in this region as they had at an earlier day. Most of the 
depressions having reached a given level, the predominant conditions 
were no longer favorable to sphagnum; other and larger vegetable 
erowths intervened; in the end gigantic trees and huge forests stood 
where once water plants alone, or for the most part, prevailed. 
And these did their work, and they have continued to do it, even 
up to the present hour. By alternate growths and decays, or rather 
by a long succession of these natural processes, many depressions 
have come to be more elevated. This operation no doubt went on, 
so that in not a few instances, even in places which once were ponds, 
and afterwards marshes, many successive generations of deciduous 
trees made their appearance and passed away before the time was 
reached of which we have any distinct tradition. The sea had long 
before retired; for the most part the marl beds had been finished in 
1 Second Annual Report on the Geology of Vé.(1846,) p. 144. 
