Volume 14 Australasia - dana ward's homepage

CORALLINE FORMATIONS. 31sequently interrupted bj' large fluvial estuaries.Nor can they secure a footing ontoo rapidly shelving rocks. Hence certain coasts which vre should expect to be formedof "living" coral are found to consist only of " dead " matter. The work is alsohindered or arrested altogether in certain storm-tossed seas, where the deeper andcolder waters are churned up and driven landwards. Thus may perhaps boexplained the absence of corals along a great part of the arid and parched seaboardof Somaliland.But apart from these few interruptions, the shores and islands of the equatorialzone are everywhere fringed or encircled by coral reefs. Besides the polypi, ortrue coral builders, of which there are numerous species, other organisms alsosecrete calcareous matter, and thus contribute towards the enlargement of the di'vland.Account must also be taken of the seaweeds, algaj, nulUpores, and the like.Fig. 11. Zone of the Coeaxline Islands,Scale 1 : 12ii,oiX»,000.r30°