52 A. EF. Verrill—The Bermuda Islands; Geology. 
2. The Greater Bermuda. 
The present dry land must be regarded as a mere remnant of a 
much larger similar limestone island, of which the former extent is 
approximately indicated by the outermost of the surrounding reefs, 
but which has been nearly destroyed, partly by erosion and partly 
by subsidence, in former periods. This larger island, known as 
“Greater Bermuda” or “ Pliocene Bermuda,” was about ten times 
the size of the present dry land. It was broadly elliptical in outline, 
with the longer axis nearly northeast and southwest, or nearly the 
same as that of the present main island (figure 12, map I). 
The area of this Greater Bermuda was probably somewhat more 
than 230 square miles. That of the present dry land is less than 20 
square miles. The best estimates are about 194 square miles or 
12,373 acres.* 
The elliptical area, now enclosed by the outer reefs, is about 22 
miles long and 11 miles wide in the widest parts. There are good 
reasons for believing that nearly all of this area was dry land, with 
numerous more or less elevated hills, especially around the borders, 
in the period of Greater Bermuda. The evidences of this will be 
given later. The amount of subsidence is believed to have been at 
least 80 to 100 feet since the period of greatest elevation. 
3. The Bermudas not a true Atoll. 
The elliptical form of the outer reefs, more or less covered with 
corals and enclosing a broad shallow lagoon, with scattered islets 
and reefs within it, is so much like that of the coral islands or atolls 
of the Pacific Ocean in appearance that the earlier writers believed 
that the Bermudas formed a true coral atoll. But this has been 
shown by various more recent writers not to be the case.t+ 
However, the careful recent investigations of the Pacific coral- 
islands, especially by Mr. Alexander Agassiz, have shown that many 
or most of the coral reefs of that region have a foundation of older 
eroded rocks, at no great depth, on which the modern coral reefs 
have been built up. Thus the conditions even there approximate 
more nearly to those at Bermuda than has been supposed by some 
recent writers. Perhaps the difference is mainly due to the less 
* See these Trans., xi, p. 465, and ‘‘The Bermuda Islands,” p. 53, for areas 
of the various larger islands of the group. 
+ Lieut. Nelson, in 1840, was perhaps the first to demonstrate the true nature 
of the Bermuda rocks. 
