SECT. 3] ESTUARIES, DELTAS, SHELF, SLOPE 



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Fig. 3. Meandering tidal creeks in mangroves, north-west Madagascar. (Photo. A. Guilcher.) 



Fig. 4. Part of the Betsiboka estuary, Madagascar. Mud flats in foreground; mangrove 

 in middle distance; bare zone in background, submerged only at high spring tides. 

 (Photo. A. Guilcher.) 



marshes (see for example Davis, 1940; Schnell, 1952, pp. 197-218; Lindeman, 

 1953). On Atlantic coasts, the mangrove trees consist mainly of Rhizophora and 

 Avicennia, and also Laguncularia and Conocarpus. As a rule, Rhizophora lives 

 on the outer flats, but this distribution may be inverted in young mangroves, 

 and Avicennia may be found seaward of Rhizophora, for example in Guinea, 



