2 THE NATURALIST IN BERMUDA. 
It was written by Lieut. (now Col.) Nelson, of the Royal 
Engineers ; from which, as it has been acknowledged to 
be the best treatise ever produced on the subject, we 
cannot do better than glean that portion which is suited to 
our purpose, in order to shew to what particular causes the 
Bermudas owe their origin. 
This officer informs us that the hole of the islands 
are composed of a calcareous sandstone, derived from com- 
minuted shells and corals, varying in texture from loose 
sand to a hard compact limestone ; the varieties being irre- 
eularly: associated, and without any order of super-position. 
From the saddle-shaped sections observable throughout the 
islands, he concludes that the strata have evidently been 
accumulated round numerous and contiguous centres. The 
bottom of the basin consists of coral reefs (which do not 
appear above low-water mark, except at spring-tides,) and 
calcareous sand; the latter being associated with consider- 
able tracts of chalky ground, in which the best anchorages 
are found. He met with this chalk, likewise, as an occa- 
sional constituent of the rock, lying irregularly among its 
beds in a soft state, or lining caverns, but seldom exceeding 
a few square yards in surface, and a few inches in depth.* 
The only minerals noticed were small pieces of oxide of 
iron, of very questionable origin; menaccanite, found near 
the Ferry, between St. George’s Island, and Bermuda or 
Main Island; arragonite (?); and a minute quantity of 
manganese in the red earth. 

* The Royal Engineers claim to be the first to give any distinct clue to 
the origin of chalk ; though within but a few months they were followed by 
Darwin and Lonsdale, on other and perfectly independent grounds. See 
Bahama Paper, Geol. Soc. Transactions. By Colonel Nelson. 
