[135]

As a proof of more rapid growth externally than internally.─ It must be remembered that much of the sand in lagoon, mem: same argument at Tahiti, & all dryland is the growth of outside as well as foundation & all detritus on profound external slope on the strips.— If the fact that those strong species which alone could withstand pressure pr require (which is analogy to limited powers of accommodation of the lower orders) found lurking water the nearly whole difficulty of sho barrier of shoal coral is done away with ─ muddy flat [sketch]

Truly much on nature of foundation in lagoons near rocky (NB. the shallow the Lagoon the more fresh water would be injurious.— (add this

Tolats (& in proportion to size of lagoon). when there is on foundation there are reefs.— V. gambica. Mannicollo. Barrier reefs latter strongest example.— It might be made foundation of argument: where in a lagoon do we see much reefs: rocky shore.— answer.—

NB when we anchored the most impassable white mud

At Tahiti within lagoon: when shore was of Coral. Coral lined where sand nothing: Mem: introduced [sketch] to St Georges Sound that Calc beaches are found.—

[135v]

Looking at the nature scale of a Lagoon Island, some cause must retard the growth this Coral in the lagoon as compared to the outer.— I exclude here the conversion into dry land by cemented fragments─

In the first places, the most solid kind Ash Madrepora & Corallina appear only flourish outside,—

The weak branched kinds must be inefficient as compared to the more solid ones.— The absolute height outside must be more than within which however chiefly affects the formation of dry land — The sand thrown through the opening of the reefs — & not removed when once there: the calc mud must be fatal — the Fresh water. — the Fish & perhaps other animals, — When near land sediment from coast, sandy or muddy beaches, disturbance by swall.— The branching corals are known to increase very rapidly, but I have expatiated on the difficulty of absolutely filling up the last 5 ft (or rather more) water:— Where much is dead, the water may be turbid & injurious to the growth of Corals [sketch] I rely most on greater absolute heights & strong kinds & slippery bottom. of sand or mud