A, FE. Verrill—The Bermuda Islands; Geology. 8 
~T 
containing the peat was above sea-level. But a subsequent gradual 
subsidence would permit their growth on top, provided the surface 
remains always a few feet above the sea, for the fresh water of the 
upper layers will not readily mix with the brackish water below. 
Pembroke Marsh, near Hamilton, is now but little above the sea, 
yet according to Governor Lefroy, who had it tested in 1872, the 
peat is, in places, 40 to 48 feet deep. This would show that the 
bottom of this valley or sink extends to at least 30 to 35 feet below 
the sea-level, and that the islands must have subsided as much as 
that, since the peat began to form. Several other bogs and marshes 
are known to extend below sea-level, but I am not aware of any 
reliable records of their depths. The instances given show well 
how peat beds happened to be buried in Hamilton and St. George’s 
Harbors (see p. 81), by subsidence. 
C. Evidences of Subsidence from submerged Sinks, Sounds, and 
Channels. 
That sounds, sinks, and subterranean passages, due in part to the 
caving in of the roofs of caverns, exist here beneath the sea, just like 
those on the land, and formed in the same way by the solvent action 
of rain-water, when the land stood at a higher level, is certain. No 
doubt most of the smaller, deep, isolated sinks, harbors, sounds, and 
“holes” are of this origin. No other explanation of their origin is 
available. The same is true of many of the passages through and 
under the reefs. Probably, however, the larger ship-channels and 
the broader sounds were largely due to the erosion of the rocks by 
running streams during the time of Greater Bermuda, but many of 
those streams may have had underground channels, as they do in 
many limestone regions. The much greater extent of the land, at 
that time, and its height must have given rise to streams of consider- 
able size and velocity, which would have cut away and undermined 
the soft limestones with great rapidity, whether above ground or 
underground. If the falling in of large caverns took place to form 
sinks, these would have been rapidly enlarged by the erosion of the 
shores, either by fresh water or sea water, according to their eleva- 
tion. 
Therefore, at the present time it is impossible to determine which 
factor was of the most importance in the excavation of the larger 
sounds. In either case the land must have been raised above sea- 
level to a height equal at least to the present depth of the deepest 
