296 | THE ATLANTIC. (CHAP. Iv. 
all of them the water is brackish, and they are all more or less 
affected by the tide, though the rise and fall are almost imper- 
ceptible in those at a distance from the sea. 
If a well be sunk in almost any part of the island, it is filled 
with water at once, but it is only the upper layer which is fresh. 
The water at the bottom of the well is brackish, and is affected 
by the tide; and the fresh water, which is merely the rain-catch 
of the surrounding ground, lies on its surface. As there is al- 
ways a certain amount of mixture, the wells do not yield good 
drinking-water, and the people trust greatly to their rain-water 
tanks. 
The direct evidences of subsidence are everywhere very pal- 
pable. The rocks exposed between tide-marks, and now being 
subjected to denudation, are not reef-rocks formed under water, 
but are, in most cases, stratified AZolian rocks. 
The little pinnacle off the shore of Ireland Island, figured in 
the vignette at the end of this chapter, has its base composed of 
the ordinary blown sand of the sand-hills; the middle part is a 
shred of an old glacis; and the top is again horizontally stratified 
sand which has been laid down unconformably on the cut edges 
of its laminee, after it had been greatly ‘“ denuded” by rain and 
wind. The North Rock has almost exactly the same structure, 
so that we can scarcely doubt that the dry land of Bermudas 
at one time oceupied a space considerably larger than it does at 
present. Tradition and the accounts of some of the earlier voy- 
_ agers would seem to corroborate this; but soft though the rocks 
may be, and rapid the changes which take place in them in a 
geological sense, it seems difficult to believe that after they were 
consolidated any great change could have taken place in their 
distribution in the short period during which they have been 
the subject of tradition. A very careful survey was made in the 
year 1843, and up to the period of our visit there did not seem 
to have been the least alteration, even in the depth and extent 
of the passages among the living reefs—a matter of jealous in- 
