A. E. Verrill—The Bermuda Islands; Geology. 175 
other plants there, in the pliocene, now extinct, that had fleshy or 
succulent roots of the right form, with rootlets too soft to be pre- 
served. Some species of West Indian Jpomeas have huge, fleshy 
roots, as large as a man’s body, and some of the extinct forms may 
have been even more remarkable.* It is not necessary to suppose 
that all the cavities were moulded around the stump of a palmetto or 
palm, living or extinct, if we believe them to be of vegetable origin, 
for there are many herbaceous plants with huge roots, and some of 
them are partial to sand dunes of this kind. That most of these 
cavities are in the ancient Walsingham limestone is significant, but 
similar ones occur in the later rock and at high altitudes. 
It is also important to note that in the most typical cases, where a 
large group occurs (fig. 11, and pls. xix, xx), they all start downward 
from one particular level, usually a layer of red-clay soil, or an 
ancient ‘forest bed,” though some may be deep and others shallow. 
This is contrary to what would have been the case if they had been 
due to stumps of the palmetto, buried in the drifting sands, for in 
that case the lower ends would have been nearly at one particular 
level, or in a layer of red-clay soil. In most cases we found no layer 
of red-clay at or near the lower ends. They usually terminated 
below in pure limestone, just as if dug out to variable depths by a 
mechanical tool. 
It seems to me very probable that at least part of them were 
started by the thick root or base of some plant, and that in most 
cases they were enlarged and deepened by the solvent action of the 
rain water that naturally found its way into the crevice around the 
root, or around the core of loose material and clay that later filled 
the cavity, after the roots decayed. 
DP, The initial circular cavity may have been formed in the soil 
by mechanical means. 
Rain water dripping at one particular spot from the branch of a 
tree will start, in loose soil, a circular cup-shaped cavity, which could 
easily be prolonged downward and enlarged by solvents. 
The elastic stems of grasses, shrubs, and other plants growing in 
rather loose sandy soil and exposed to the winds will often, by their 
examined by him may really have been formed around the bases of palmettos, 
for they are probably not all of the same origin. 
Thomson also refers to the pits on the inner surface of some that he examined 
(see his figs. 7, 9, and our fig. 56). 
* Some of the West Indian species have fleshy roots 4 to 6 inches or more in 
diameter and many feet long, coiled in a regular tapering spiral, like a cork- 
screw, the coil often 10 to 12 feet long. 
