A. E. Verrill—The Bermuda Islands; Geology. 119 
In nature, however, such changes in level rarely if ever occur 
suddenly, to anything like this amount. Such an emergence would 
be likely to cover centuries of time. In that case the bizarre cliffs 
and pinnacles would be greatly eroded, as fast as they emerged 
above the sea, and by the time the entire elevation had been accom- 
plished only a part would remain, and these mostly much reduced 
in height and size. Channels would be eroded, at the same time, to 
allow the tides to flow freely into the larger sounds. Meantime the 
vast areas of fine loose sands, gradually uncovered, would afford 
immense quantities of materials for the wind to drift into sand- 
dunes on the newer as well as on the older lands. 
g. Erosion of the South-shore Cliffs and Reefs. 
Along the south side of the Main Island the shore cliffs are almost 
continuous and are usually higher and more precipitous than on the 
north side. In most parts the waves at high tide, at least in storms, 
dash against the bases of the cliffs. But at low tide there may be 
a wide beach of shell-sand exposed in front of the cliffs, as near 
Tucker’s Town, Elbow Bay, and many other places. Or these may 
be nearly flat, broad benches, or smooth shelves of hard limestone, 
laid bare in front of the cliffs by the tide. At several points, as at 
Elbow Bay and Tucker’s Town, there are extensive sand beaches. 
The erosion of the cliffs on this side is similar to that on the north 
side, but on a larger scale, owing to higher cliffs and to the greater 
violence of the storms, though the outlying lines of reefs and serpu- 
line atolls serve to more or less break up the heavy seas, and thus 
give considerable protection in many places. However, owing to 
the fact that the harder limestones of the Walsingham formation 
(pp. 72-74, fig. 11) outcrop in thick, nearly horizontal beds, at and 
below tide-level in many places, the erosion has been materially 
modified in certain ways, especially in the formation of the flat tidal 
ledges, and flat-topped outer reefs and serpuline atolls, so charac- 
teristic of this shore, as mentioned on a former page. 
h. Pot-holes. 
The hard flat beds have also been favorable for the formation of 
pot-holes, both on the tidal ledges and on the reefs. Some of the 
shallow pot-holes have, apparently, been started in slight depressions 
and eroded spots in the surface, and then worn deeper by the plung- 
ing and whirling action of the waves and the stones carried by them. 
