48 A. E. Verrill—The Bermuda Islands; Geology. 
Nearly all the rocks of the Bermudas, above sea-level, and to a 
considerable depth below it, are made up of wind-drifted shell-sand 
(figs. 1, 4-6), with very little materials derived from corals and other 
organisms, such as foraminifera, bryozoa, corallines, ete. These 
materials, when consolidated, form a true eolian limestone, some- 
times friable, but in some places very hard and compact. 
Figure 2.—Wreck Hill, as seen from the Sea, bearing N. 34 Hast ; the hills to 
the right are those west of Gibb’s Hill Light, 100 to 175 feet high ; after 
Findlay. 
The only exceptions to this origin are small local deposits of 
limestone, near tide-level, having a laminated beach-structure, and 
containing larger fossil marine shells, barnacles, etc, of existing 
species. The latter are underlaid, as well as overlaid, by olian 
limestones.* 
Figure 3.—Hills west and east of Gibb’s Hill Light, bearing north, 150 to 240 
feet high ; after Findlay. 
The islands are diversified by rather high hills and deep valleys. 
The higher hills are mostly toward the southern side of the main 
island and are conspicuous when the islands are approached from 
the south or southwest (figs. 2, 3). Some of them, iike Wreck Hill, 
* See plates xvi to xviii; also fig. 11, p. 79. 
