A, EF. Verrili— The Bermuda Islands; Geology. 125 
Mr. Agassiz believed that these reefs and atolls were formed out 
of the ordinary xolian limestones, superficially hardened over the 
surfaces and edges by the local action of the sea-water itself. If, as 
I believe, these limestones were already much hardened, nearly 
throughout, long before they became submerged beneath the sea, 
and had also in most cases a horizontal stratification, as they now 
do on the adjacent shores (fig. 11 and pls. xvi-xx), the whole prob- 
lem of the formation of the remarkable serpuline atolls along this 
shore becomes much simplified. 
However, I do not wish to deny that such reefs and atolls can also 
be formed by the cutting away of ordinary eolian ledges, when the 
strata are favorable, as Mr. Agassiz states, for I have seen the same 
process. But as we find hundreds of these remarkable atolls along 
this south shore, and very few in other places, it seems reasonable to 
connect the littoral outcrops of a suitable, hard, horizontally strati- 
fied limestone with the parallel line of atolls and flat reef at a little 
distance from the shore. Indeed, it is possible, at low tide, to wade 
out to some of the atolls figured in my plates, as was done to obtain 
the photographs. In other cases the atolls are actually connected 
with the flat benches of limestone exposed between tides, or with 
the shore cliffs. 
j. Cutting Channels ; forming Harbors and Bays. 
In many cases the gradual erosion of the sea-cliffs by the waves 
and the encroachments of the sea have connected sinks and low 
valleys with the outside waters by means of narrow or wide chan- 
* At the Island of Anticosti, Gulf of St. Lawrence, I have studied the action 
of the waves over a large expanse of nearly flat reefs that extend along the shore 
for a great many miles, between tides, or barely submerged. They are formed 
of hard layers of Silurian limestones, nearly horizontal in position, from which 
the overlying softer strata have been removed by the undercutting of the cliffs 
between tides, and above, by the violent action of the sea-waves, aided no doubt 
by the frosts of winter, and by the existence of layers of soft shales, between 
the limestones. The flat reefs are often 100 to 200 yards wide. Their surfaces 
contain irregular depressions, and shallow pools of water, large and small, are 
left in them at low tide, but very few deserved to be called ‘‘ pot-holes.” The 
shore cliffs there vary from 20 to 300 feet or more high, and the summit of the 
higher ones usually overhangs the base. The outer edge of the flat reefs, below 
low tide, is also undercut or abrupt in most places, just like many of those at 
Bermuda. In fact, the phenomena of erosion are in many respects similar to 
those of the south shore of Bermuda, though on a much grander scale. But the 
organisms for forming coral-encrusted reefs and serpuline atolls do not exist in 
northern waters. 
Trans. Conn. Acap., Vou. XII. 9 DECEMBER, 1905. 
