barrier-reefs

To do this was to form my theory of the formation of barrier-reefs and atolls.

Unthreaded #8 « Climate Audit 2007

Barrier-reefs — Fringing-reefs — Conversion of fringing-reefs into barrier-reefs, and into atolls — Evidence of changes in level — Breaches in barrier-reefs —

Journal of researches into the geology and natural history of the various countries visited by H.M.S. Beagle 2003

Now bearing in mind that reef-building coral cannot live at a greater depth than from 20 to 30 fathoms, and that the scale is so small that the plummets on the right hand show a depth of 200 fathoms, on what are these barrier-reefs based?

Journal of researches into the geology and natural history of the various countries visited by H.M.S. Beagle 2003

On the other hand, although most of the islands in the Pacific which are encircled by barrier-reefs are of volcanic origin, often with the remnants of craters still distinguishable, not one of them is known to have ever been in eruption.

Journal of researches into the geology and natural history of the various countries visited by H.M.S. Beagle 2003

In my volume on Coral Formations I have published a map, in which I have coloured all the atolls dark-blue, the barrier-reefs pale-blue, and the fringing reefs red.

Journal of researches into the geology and natural history of the various countries visited by H.M.S. Beagle 2003

And as by our theory the areas including atolls and barrier-reefs are subsiding, we ought occasionally to find reefs both dead and submerged.

Journal of researches into the geology and natural history of the various countries visited by H.M.S. Beagle 2003

This human lair is encircled by barrier-reefs of coralline, broad to the south-west and large in scattered places: eastward they form

The Land of Midian 2003

Where banks of sediment have accumulated near to the surface, as in parts of the West Indies, they sometimes become fringed with corals, and hence in some degree resemble lagoon-islands or atolls, in the same manner as fringing-reefs, surrounding gently sloping islands, in some degree resemble barrier-reefs.

Journal of researches into the geology and natural history of the various countries visited by H.M.S. Beagle 2003

Encircling barrier-reefs are of all sizes, from three miles to no less than forty-four miles in diameter; and that which fronts one side, and encircles both ends, of New Caledonia, is 400 miles long.

Journal of researches into the geology and natural history of the various countries visited by H.M.S. Beagle 2003

It will be perceived more clearly by inspecting the following sections which are real ones, taken in north and south lines, through the islands with their barrier-reefs, of Vanikoro,

Journal of researches into the geology and natural history of the various countries visited by H.M.S. Beagle 2003