120 A. E. Verrill—The Bermuda Islands; Geology. 
Some of these may eventually become of large size and several feet 
deep before they are broken through and spoiled (see fig. 25). 
But I believe that many of the deeper and more regular pot-holes 
are simply the ancient fossil structures familiarly known as fossil 
molds of “ palmetto stumps,” originally contained in the hard flat 
ledges and filled with softer sand. When the sea encroaches upon 
such a ledge as that shown in plates xix, xx, for example, if it were 
SS ol eS 
Figure 25.—Cliff and pot-hole on south shore. The upper part shows :eolian 
limestone not much altered; other parts are rudely honeycombed, encrusted, 
and infiltrated. The pot-hole, on the right, contained a loose mass of lime- 
stone, 
below tide, it would at once begin to wear and enlarge the holes 
already existing and they would soon become wider at the top and 
more cup-shaped; many would blend their margins together; some 
would have one side of the rim worn off, forming crescent-shaped 
or horseshoe-shaped pot-holes, etc., just as we now find the smaller 
and more regular pot-holes on many of the submerged ledges and 
reefs (fig. 26). 
Mr. Agassiz attributed all such pot-holes to the direct action of 
the sea. But he also believed that the so-called “ palmetto stumps ” 
were real pot-holes formed by the action of the waves. Those that 
