64 A. EF. Verrill—The Bermuda Islands; Geology. 
erosion of a thick bed of only slightly consolidated sand, in which 
many vertical fissures had allowed the percolating waters to consoli- 
date the adjacent sand into harder rocks, which now stand up like 
pillars supporting the arches of overlying limestone. No doubt 
there was a time, before the erosion had progressed so far, when 
these archways and pillars formed the supports of a cavern of con- 
siderable extent. But the pillars are not true stalactites, as they are 
in some of the other caverns, but mere vertical masses of shell-sand, 
so impregnated and encrusted by stalactitic material that they are 
very hard and resistant. Some of the larger caverns on the islands 
Figure 10.—Much eroded and undercut rocks and columns at Tobacco Bay, near 
Fort Catharine, as seen at low tide. 
have similar large columns which are so thickly covered with stalac- 
titic material that their true nature cannot be ascertained without 
fractures or sections. But all intermediate conditions occur among 
the larger stalactites and pillars of the caves. 
Probably the curiously and roughly eroded rocks and pinnacles of 
Tobacco Bay* and other similar localities had a similar origin, but 
have progressed farther toward destruction (fig. 10, and pl. xxiii, 
figs. 1, 2). 
* See also these Trans., p. 474, pl. Ixxx, fig. 1, xe, fig. 2; ‘‘The Bermuda 
Islands,” p. 62, plates the same. 
——— 
